# Building the Trevithick engine



## Brian Rupnow (Aug 27, 2020)

The Trevithick was a train engine built in or about 1805. It did prove that it could carry ten tons of freight as well as passengers for a short period of time, but was so heavy that it kept breaking the tracks. Other associated failures, and then finally a boiler explosion which killed four men was the end of the Trevithick. Similar engines were used for pumping stations  for a few years after that, but it never really caught on as a commercial engine either. Richard Trevithick, the man who designed this engine died in poverty as an old man. The external gearing and an absolutely enormous flywheel make it an ideal hobby engine to build, because there is so much visual stuff happening when this engine runs. It has a very interesting steam admission valve, which sets directly in line with the cylinder body itself. I have attached a beautiful rendering that was sone as a 3D model by someone. Julius DeWall of New Zealand made absolutely marvelous detail drawings of this engine, however I don't plan on my engine being nearly as complex as the drawings Julius made, so I will more or less be developing this one "from scratch".---Brian


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## Brian Rupnow (Aug 27, 2020)

Here is a bit of information about the original inventor, and some insight into the story behind the engine. The most complex part of what was built was the steam valve which was built into an extended portion of the cylinder. I have no doubt about my ability to recreate the overall machine, but if I can't come up with some better info about the steam valve I may have to do something a bit different there.


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## Brian Rupnow (Aug 27, 2020)

As in all things, I have to determine what scale I want to build this engine at. That is going to be easy for me this time, because the largest gear I can cut on my milling machine is 108 teeth, which is 4.584" outer diameter. All other components will have to be scaled to accommodate this known part size.


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## Brian Rupnow (Aug 27, 2020)

So, based on ratio and proportion, and the fact that my largest gear is going to have 108 teeth, this lets me establish that the smaller gears at the drive wheels are going to be 50 teeth and the small drive gear is going to be a 36 tooth. All three of these gears are tied to the large gear by a function of adding the pitch diameters together and dividing by 2. I arbitrarily select the horizontal distance between gears, and so now they are fixed in position and can not be moved. No thought has been given to the width of the Trevithick yet, because that will be dependent on the diameter of the boiler.


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## Brian Rupnow (Aug 27, 2020)

The largest gear I've actually MADE is 108 tooth. So far we don't have much, but the basic proportions are blocked out. If I don't go and eat some lunch I'm going to fall of my chair!!


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## Brian Rupnow (Aug 27, 2020)

Just as I was reaching a point where I didn't want to go any farther without more knowledge about the cylinder and valve, Julius from New Zealand has came thru with a bunch of drawings and saved me. Thank you Julius, from the far side of the world!!!


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## deeferdog (Aug 27, 2020)

As somebody who has just finished one of Julius's engines I can only add my thanks to yours, I think the man is a marvel. Cheers, Peter.


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## Scrat (Aug 28, 2020)

Hi Brian,

there is one in 5" gauge around here:
Mein Dampf- und Schiffsmodellhobby - Invicta (Lok )

This "deranged trombonist" has been a visitor to my railway years ago.

Not a passenger hauler but nice to look at.


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## Ken I (Aug 28, 2020)

Brian, Very cool - I've been thinking of building a Trevithick for years - so I'll be watching with interest.

Regards, Ken


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## johnm (Aug 28, 2020)

Brian Rupnow said:


> The Trevithick was a train engine built in or about 1805. It did prove that it could carry ten tons of freight as well as passengers for a short period of time, but was so heavy that it kept breaking the tracks. Other associated failures, and then finally a boiler explosion which killed four men was the end of the Trevithick. Similar engines were used for pumping stations  for a few years after that, but it never really caught on as a commercial engine either. Richard Trevithick, the man who designed this engine died in poverty as an old man. The external gearing and an absolutely enormous flywheel make it an ideal hobby engine to build, because there is so much visual stuff happening when this engine runs. It has a very interesting steam admission valve, which sets directly in line with the cylinder body itself. I have attached a beautiful rendering that was sone as a 3D model by someone. Julius DeWall of New Zealand made absolutely marvelous detail drawings of this engine, however I don't plan on my engine being nearly as complex as the drawings Julius made, so I will more or less be developing this one "from scratch".---Brian


The Model Engineer magazine did a series of articles about his dredger engine which was a Modified version of the locomotive engine along with a set of free drawings Sept 87 - Oct 88


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## Charles Lamont (Aug 28, 2020)

johnm said:


> ... his dredger engine which was a Modified version of the locomotive engine ...


Other way round. As early as 23 Sept 1804 Trevithick writes a long letter from Coalbrookdale to his mentor Davies Giddy "which describes nearly fifty engines as built or building up & down the country." (Quote from the Dickinson & Titley biography) These were stationary engines for a whole variety of applications.


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## Brian Rupnow (Aug 28, 2020)

More bits and pieces designed this morning. Time to stop for a coffee now.


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## bobcjohn (Aug 28, 2020)

Brian Rupnow said:


> Here is a bit of information about the original inventor, and some insight into the story behind the engine. The most complex part of what was built was the steam valve which was built into an extended portion of the cylinder. I have no doubt about my ability to recreate the overall machine, but if I can't come up with some better info about the steam valve I may have to do something a bit different there.





Brian Rupnow said:


> The Trevithick was a train engine built in or about 1805. It did prove that it could carry ten tons of freight as well as passengers for a short period of time, but was so heavy that it kept breaking the tracks. Other associated failures, and then finally a boiler explosion which killed four men was the end of the Trevithick. Similar engines were used for pumping stations  for a few years after that, but it never really caught on as a commercial engine either. Richard Trevithick, the man who designed this engine died in poverty as an old man. The external gearing and an absolutely enormous flywheel make it an ideal hobby engine to build, because there is so much visual stuff happening when this engine runs. It has a very interesting steam admission valve, which sets directly in line with the cylinder body itself. I have attached a beautiful rendering that was sone as a 3D model by someone. Julius DeWall of New Zealand made absolutely marvelous detail drawings of this engine, however I don't plan on my engine being nearly as complex as the drawings Julius made, so I will more or less be developing this one "from scratch".---Brian


Brian:
I will watch this build with great interest. I purchased the drawing set from the museum in the UK. Right from the get-go my project was doomed. I couldn't seem to do anything right, so into the shoe box it went.

I will be very interested in the firebox you design. I tried to make an aluminum casting and was only semi successful. I was also having trouble understanding how the steam valve worked.

It looks like you're doing the project right so I'll keep watching and wish you all the best.

Bob


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## Brian Rupnow (Aug 28, 2020)

Bobcjohn--This engine I am building will run on compressed air, not steam. However, many of the parts and details will be of such a nature that they could be adapted to a steam powered engine.---Brian


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## Brian Rupnow (Aug 28, 2020)

I'm getting closer and closer to decision time on the steam cylinder and valve. Charles Lamont raises a valid point---I haven't found any Trevithick engine running the type of valve that Julius has drawings for. After much googling, I have found out that the Trevithick engine used a bell-crank lever to open and close a rotary 4-way valve. This means that the cylinder is basically just a plain cylinder, and the actual valving all happens in a separate block. It undoubtedly works, because there are a few recreated Trevithick engines running round using the rotary 4 way valve operated thru a Bell crank, as well as one completed model from Germany. I like the design by Julius, because there are no Bell cranks nor pivot points involved. Of course, the immediate question is has anybody built an engine using Julius' version of the valve, and how well did it work. Since I am not a stickler for authenticity, it seems I have three choices. I can use the same valve that Trevithick used, except I would be working from "scratch" and would have to develop the design for something a lot smaller in scale---OR--I can use what appears to be a much simpler cylinder/valve designed by Julius, ---OR---I can use a cylinder and valve body almost identical to that used on the Stephenson's Rocket, although if I do it ends up being a complete departure from what Trevithick did, but I know that it works.


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## Brian Rupnow (Aug 28, 2020)

So--Today Julius DeWall from New Zealand sent me drawings of his valve/cylinder combination. I couldn't get my cheesy little printer to print them for some reason, so they have been sent out to a commercial printer and will be ready for me to pick up tomorrow morning. I am going to model this valve/cylinder combination in 3D and see if it can be reduced in scale to work on my model engine.


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## dsage (Aug 29, 2020)

Brian:
Is it possible to make the wheel spacing the same as your last engine? I mentioned before that you should make a set of rollers the engines wheels can sit on so you can run them stationary to show them off (instead of across the floor). If you made this engine the same width you'd have another one for active display. It could sit on the shelf running.


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## Brian Rupnow (Aug 29, 2020)

I have spent today making a 3D model of Julius' valve/cylinder combination. I haven't spent any time yet determining how it's going to work, but at least I have all of the components modeled and mated. As modeled, this cylinder is only 18mm bore (about 11/16") x about 3 3/8" stroke. The piston rod is 4 mm diameter, (about 0.157") diameter. There are a bunch of ports which have to be added yet to the cylinder and a number of pipes to transfer air.


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## Brian Rupnow (Aug 29, 2020)

I have been asked how the Trevithick compares size-wise to the Stephensons Rocket. It's roughly in the same ballpark, but far from being identical.


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## Brian Rupnow (Aug 29, 2020)

I have been moving the piston and steam valve around on my CAD system to see if everything makes sense. It seems to, with the exception of one cylinder port and I have asked Julius to check the position of the one hole in question. I have also asked again if anyone has actually built this configuration that he has drawn. Once I am completely happy with what Julius has sent me, I will start modifying it to give the bore and stroke that I need for my Trevithick model. Julius makes beautiful drawings. I have been badly spoiled by the practice in Canada of putting a detail of each part on it's own individual drawing. I've had to do some serious hunting on his drawings to find the parts I need to model.


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## Brian Rupnow (Aug 29, 2020)

Julius sent me this today, an animation of how the four way rotary steam valve is operated on the original Trevithick engine.


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## Brian Rupnow (Aug 30, 2020)

I am going a bit batty this morning, checking to see that the correct ports are covered and uncovered in the cylinder as the piston and valve move back and forth in the cylinder. This is the kind of thing that you really want to get right on paper (or computer) because the next phase, building it in metal gets costly and time consuming if the ports aren't where they should be.


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## Brian Rupnow (Aug 30, 2020)

It's been a long and interesting day. I have taken the cylinder that Julius sent me, changed the diameter and the stroke length, eliminated some of the seals that crossed ports in the cylinder and changed the piston rod size. All I can do now is hope that I got it right and build it. I don't have a "safety net" of other designers and engineers to check some of this stuff for me. I won't build anything else on the project until this cylinder is finished, because this cylinder is the heart of the whole operation. There are no cams or eccentrics on this engine. The spool valve inside the end of the cylinder replaces all of that. There are seven ports on the sides of this cylinder. I am going to solder short lengths of small brass tubing to the outside of the cylinder at the ports and use flexible nylon tubing to connect them all. It will all be hidden inside the body of the Trevithick boiler.  I will keep you posted as this develops.


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## Brian Rupnow (Aug 31, 2020)

This morning the new cylinder is completely designed. I have moved all of the ports around into the bottom 60 degrees of the cylinder so they can be connected with flexible tubing. I have also redesigned the cylinder and end caps so that there is no welding or silver soldering, because I am concerned about warping the long cylinder from heat related issues. The cylinder body is now made from much heavier wall material so that I can tap the ports for 1/4"-20 threads, which lets me screw in the hose barbs with a bit of loctite so no heat is involved. I got some rather disturbing news this morning from Julius. He doesn't know if anyone has ever actually built this cylinder or not. To my knowledge I have never seen one like this myself. I don't care to be a guini pig for untried designs that haven't been built successfully by somebody else.


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## Brian Rupnow (Aug 31, 2020)

I have decided to go ahead and build the cylinder even though nobody knows if it has been built before to Julius' drawings. If it works, then Hooray, I'll be a hero. If it doesn't work, I will be able to salvage most of it to work with a more conventional valve system. I picked up the material for it today. The main cylinder body is going to be made from hot rolled steel. This is not something that I would normally use, but since the engine will be ran on compressed air it should be okay. I generally would use grey cast iron for a cylinder if it was for an i.c. engine or driven by steam.


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## Brian Rupnow (Aug 31, 2020)

And the ugly 1 1/2" piece of hot rolled has yielded a nice cylinder. 1.375" o.d. x 0.75" i.d. x about 5 1/2" long.    O.D. machined with brazed carbide at 680 rpm, inside drilled and reamed to 0.75". Hot rolled steel is such a nice steel to machine. I can get a much nicer surface finish on hot rolled than I can on cold rolled. Tomorrow I have about a billion holes to drill and tap.


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## Brian Rupnow (Sep 1, 2020)

I spent some time designing this morning, and decided to make the piston rod 3/16" diameter with all the attendant changes to parts which mate with the piston rod. (It was 1/8" diameter before). I am happy with things as they are now, and the success of this design depends on the drawing of the cylinder I received from Julius. You have to admit---it looks pretty wild!!


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## Ken I (Sep 1, 2020)

Looking great - but I cannot get my head around how that valve works - is it a spool valve ?

Regards,  Ken


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## Brian Rupnow (Sep 1, 2020)

Ken, I really don't know. It is shaped like a spool valve, and it travels back and forth with the cylinder rod. This concept was designed by Julius DeWaal in New Zealand and he doesn't know if anyone has ever built it.


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## Brian Rupnow (Sep 1, 2020)

Yow!!!--That's a lot of holes. Hope they're all in the right place---


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## Brian Rupnow (Sep 2, 2020)

I'm slowly going ahead with the valve as designed by Julius. We have visiting grandchildren this week, and next week after they all go back to school it will be too dangerous for good wife and I to see them until a Covid vaccine is found.  As for the valve which Julius designed, I can see the theory behind it, but I simply can't tell if it works until I have built one to see if it works or not. I think the cylinder is going to have a large "dead spot" at each end of the stroke, but with a large enough flywheel (which the Trevithick engine does) it may not matter. I have almost melted the internet searching for information about the original Trevithick 4-way valve, and the good news is that I think I have sussed it out. Now, whether the Julius design works or not, I simply have to build a rotary valve engine. If I do, I will publish the drawings on all my forums because this stuff is so neat that everyone should have free access to it.


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## Ken I (Sep 3, 2020)

Brian, I don't know if this helps - but this is the 4 way valve I designed for my elbow engine - it acts as a throttle and reversing gear - swinging it through 90° takes you from full ahead to full astern. Mid position is stop.




It relies on fit to avoid leakage - but it has worked well so far.
I had considered using a non-self holding taper which could be lapped into a near leak proof fit and could be tightened as necessary to accommodate wear (as opposed to the cylindrical spool indicated).
It simply swops the cylinder connections from one end to the other so it could also be used to cycle a cylinder.
My 2c worth.
Regards, Ken


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## Brian Rupnow (Sep 3, 2020)

Today we have both cylinder end caps finished. That little bit of shaft you see sticking out the end isn't really the piston rod.---I'ts just a "fooler".  I still have to make the packing gland, and then I will start on the hose barbs that screw into the sides of the cylinder. I miscounted earlier when I said there were seven ports.---Actually there are eight.


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## Brian Rupnow (Sep 3, 2020)

Ken1--Thank you for the drawing. When I get this current cylinder configuration finished I'm going to build a cylinder with this valve on it.---Brian


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## Brian Rupnow (Sep 4, 2020)

Eight little hose barbs, all in a row. This cylinder is going to look like a porcupine. If I can just get a 1/4"-20 thread on the end of each one without destroying it, I'll be very happy!!!


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## Ghosty (Sep 4, 2020)

Brian Rupnow said:


> Eight little hose barbs, all in a row. This cylinder is going to look like a porcupine. If I can just get a 1/4"-20 thread on the end of each one without destroying it, I'll be very happy!!!


Brian, You ever thought of using 1/4x40ME like the steam guys use.


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## ShopShoe (Sep 5, 2020)

I have used 1/4-28. That size is included in both my tap sets.

--ShopShoe


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## Ken I (Sep 5, 2020)

Perhaps not in the spirit of do it yourself - but Festo make barbed fittings for 2,3 & 4mm bore tubing in M3 & M5




I use bits like this on my models - the tiny self closing quick couplers are great.
That brass fitting in the middle I made myself.
Regards,
              Ken


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## Brian Rupnow (Sep 5, 2020)

Today yielded a piston, a spool valve, and a cylinder partition plate. Those o-rings are Viton---Didn't need to be because there is no heat involved, but that's what I had. I still have to drill and tap 3 holes in the cylinder partition plate.


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## Brian Rupnow (Sep 5, 2020)

1/4"-20 threads suit all of my needs. The only place I use 40 threads per inch stuff is when I build the main needle jet for carburetors.


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## Brian Rupnow (Sep 7, 2020)

The self reversing cylinder as designed by Julius is almost ready for final assembly.  I have all the parts finished, but I have to buy a very small center drill tomorrow to use for starting a 1 mm diameter drilled hole thru a collar which sets out of site inside the spool. I honestly don't know what to expect here. If it works, I will be greatly impressed. If it doesn't, I will go ahead with a design using a rotary valve as used on the original Trevithick engine.


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## Brian Rupnow (Sep 8, 2020)

I had to do it. I've been thinking of a 4 way valve for the last week, so this morning I had to spend a bit of quiet time and model one. I'm not even sure of what I will do with it yet, but at least my head is clearer now that I have a model that I can understand.


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## Brian Rupnow (Sep 8, 2020)

Unfortunately, I couldn't get the cylinder with the spool valve to work. I have tried all of the tricks that I know, and it just isn't happening for me. There is a small diameter cross pin (1 mm) thru the center shaft and a collar that is pinned to the shaft, and they are both hidden inside the spool when assembled. When trying this out with 20 psi of air pressure, the 1 mm diameter pin immediately sheared off. The pin was made of 1 mm diameter unheat-treated drill rod, so it was certainly the strongest steel that I had. I am going to go ahead and re-use the piston, piston rod, and front and rear cylinder caps and guide bushing. I will make up a new cylinder  which is operated by a 4-way rotary valve, same as the original Trevithick engine.


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## Ken I (Sep 8, 2020)

Commiserations - better luck with the 4-Way valve.

Regards, Ken


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## Charles Lamont (Sep 9, 2020)

Brian, the parallel 4-way valve you have drawn would need to have a very good fit to prevent leakage. Traditionally this type of cock is tapered and the parts are lapped together. Alternatively, you could use a flat face valve. You have already done this fairly recently when you made a reversing valve.


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## Brian Rupnow (Sep 10, 2020)

So, after a rather questionable beginning, we start again. This time it will be with a 4 way valve which I design, and a rather plain Jane cylinder. I changed the shape of the boiler, because the convex end adds a level of complexity that I don't need to deal with. This entire project is going to depend on my ability to design and build a 4 way valve, so that is where I will begin.


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## Ken I (Sep 10, 2020)

As Charles Lamont suggested a tapered version of your 3D will offer improved sealing (I said as much in an earlier post) Mine was 8mm drill rod running in a reamed hole and it works fine.
Does it leak - yes a little but only noticeable in the stopped position otherwise its just lost to the exhaust when running and therefore isn't really noticeable and mine doesn't even have "O" rings at the ends - like yours.
Regards - Ken.


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## Brian Rupnow (Sep 10, 2020)

Tomorrow I will start building a 4 way valve. The main body will be mild steel, while the green center spindle is machined from cast iron and will be lapped into the steel housing for a very close fit.  First, before I machine anything, I have to go across town to Hercules O-Ring and buy the o-rings I need to seal things up. (They are shown in red in the assembly model.) There is no heat involved here, so they will be Buna-N material. My design is very much dependent on the actual size and cross section of the o-rings. When the transparent red cap is attached to the green spindle with a #10 shcs., the rubber o-rings will be partially compressed.


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## Ken I (Sep 11, 2020)

Brian, I controlled the end "leakage" without "O" rings by shaving the spool until end float clearance was eliminated.




The above is the afterthought throttle and reversing gear I stuck on top of my V4 wobbler.




This was only Ø6 ground silver steel running in a reamed hole worked just fine.

Also my earlier comments on a non-self locking taper - not strictly true - I have an MT3 turning quite happily as a rotating axle where it is held in place by a thrust face, thus preventing it from moving in to "lock".

Not trying to teach you to suck eggs - you've probably forgotten more than I'll know - just thought you'd appreciate any input here.

Since your valve is going to rock back and forth at speed, I would be concerned for "O" ring wear - "O" rings just hate that kind of motion as they cannot self lubricate - doing just the opposite and wear out rapidly. So for your application I would try for metal to metal.

Regards, Ken


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## Brian Rupnow (Sep 11, 2020)

Well, that was pretty painless. The only catch was that the o-rings are 9 cents each, but the minimum sale is $15.00---As a result of this I have enough of that size of o-ring to last for the rest of my natural life!!!


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## johwen (Sep 12, 2020)

Hi Brian, If you made the valve a  running fit in the bore then a one or two thou end clearance would not let but a minimal amount of air escape without any o rings. If it is not leaking at the ports then it most likely can't leak at the ends. My opinion Brian. a smear of moly grease on the valve would take up a thou or two clearance mine thinkit.


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## Chriske (Sep 12, 2020)

Love this engine..!


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## Brian Rupnow (Sep 12, 2020)

Chriske--Thank you for the great video. I hadn't seen that before.---Brian


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## Brian Rupnow (Sep 12, 2020)

I think this is going to work. So far, I have only tested it with the "Blow your guts out" method, and when the spindle is turned so that the slots don't align with the port you are blowing in, you can't blow.--When they are aligned, you can. I know, that's a pretty cheesy way to test something, but it's cheap and quick. I still have to make the cap which attaches to the end of the spindle which doesn't have a flange, and compresses the o-rings.  I will make that last part tomorrow, and hopefully the valve will function the way I want it to. I am attaching a video link about Trevithick's engine, and about 13 minutes in you can see an animation of the same valve as built by Trevithick over 200 years ago.


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## Brian Rupnow (Sep 13, 2020)

The 4 way valve is finished. Not the handsomest piece I've ever crafted, but only the round metal top part with the 3/32" rod will show above the boiler housing. As the piston travels in and out, a mechanism on the cross head will move that rod thru a 90 degree arc, thus reversing the flow of compressed air to the cylinder. It is assembled dry right now for trial "fit-up", but will be greased with white lithium based grease to make it easier to rotate the center spindle for operating.  I have to figure out some way of testing it tomorrow. Might have to "borrow" a cylinder off something else to test the valve and see if it does what I want.


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## Brian Rupnow (Sep 16, 2020)

Today was very successful. I recreated Trevithick's rotary valve, and mounted it on a cylinder which it operates quite nicely. I didn't want to go ahead with any of the other parts of the model until I knew that I could make this work. i'm very pleased with the way this worked out.


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## Brian Rupnow (Sep 17, 2020)

OH MY GOD---There are an incredible number of rods and rod supports to control the cylinder valve on this monster!!! Trevithick was able to get his 4 way valve much closer to the centerline of his cylinder than I have. This is kind of "first draft" to give me some idea of what I'm dealing with. I have shown the arm which actuates the valve in three positions. I show it in the "neutral" center position and in the two "maximum" positions it swings to.


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## Brian Rupnow (Sep 18, 2020)

A couple of quick updates this morning. Originally, I had planned on welding a plate to close off the end of the boiler. Only problem with that is that there would be no possible way to get the cylinder with valve attached into place, as it has to go into the boiler endplate with the valve sticking up thru the top of the boiler all at once. So, a quick solution is to make the boiler endplate a separate piece which bolts into the end of the boiler. That way I can mount the cylinder in the endplate, then bolt the endplate into the boiler. Since I can now make the endplate from thicker material (7/16"), then I can mount the long yellow guide rod support to this plate, rather than the axle mount. This makes for a much smaller guide rod support.--In other news, I sent the large flywheel drawing (6 3/4" diameter) out to a waterjet cutter yesterday, and a quote come back for $80 to waterjet cut the flywheel. To me, this is ridiculous, so I sent it out again this morning to three other water-jet cutters for quotes.


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## Brian Rupnow (Sep 18, 2020)

I now have three quotes to waterjet cut the flywheel. One for $80, one for $125, and one for $42---it certainly pays to go out for quotes.


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## Ken I (Sep 18, 2020)

Yessir, is it steel ? - steel is more expensive than aluminium to waterjet cut (material inclusive) - you can't compare countries but I could probably get that cut in South Africa for U$25 in steel or U$20 aluminium - but I get lots of waterjet cutting and get good prices.
I got all the waterjet cutting on my Hypocycloid done for ±U$30 and the wire cutting of the annulus and pinion for ±U$55.
I like machining anything that presents a challenge but sometimes WTH - just get it done professionally.
Really cool build as always.....
Regards - Ken


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## Brian Rupnow (Sep 18, 2020)

Thanks Ken--the flywheel is steel. I have let a few things out for water-jet cutting, but usually if I can do it on my mill or lathe I do it myself. I never let out enough work to get discounted prices. There is absolutely nothing  I can learn from hogging out all the material on a flywheel like the one I am using on this build.


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## Brian Rupnow (Sep 19, 2020)

I had to step back and have another look at all the rods and supports which I had in place to operate the valve.--There were far too many. So--I spent a couple of hours this morning redoing them, and managed to eliminate quite a few. I have sent the flywheel drawing out to a waterjet cutter and he will call me when it is finished. I purchased a piece of welded steel tubing for the main boiler body. It is 4" outside diameter with a 3/16" wall thickness. Of course this was slightly different than my original model, but in this case it was cheaper/faster to change my model to accommodate the pipe size.


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## Brian Rupnow (Sep 20, 2020)

Yesterday I made a new rod end for the cylinder, and machined a new separate flange, which weirdly enough doesn't get bolted to anything on the cylinder. It does bolt to the outside of the boiler endplate and is there for show, but nothing functional. Today I cut the boiler tube to the correct length on my lathe. That steel tube had some kind of nasty varnish on the outside diameter, so I used my angle grinder and then my jitterbug sander to clean up the outside diameter while the tube was turning in the lathe. Tomorrow I will pick up some new material to make the boiler end-plates from, and Tuesday I pick up my water-jet cut flywheel. Most of this engine will get painted, so I'm not too concerned about using a combination of steel and aluminum parts.


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## Anatol (Sep 21, 2020)

Chriske said:


> Love this engine..!




thanks for pointing out this video series - its good, while not quite Fred Dinah. 
I was quite impressed with this one on machine tools


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## Anatol (Sep 21, 2020)

Brian Rupnow said:


> I think this is going to work. So far, I have only tested it with the "Blow your guts out" method, and when the spindle is turned so that the slots don't align with the port you are blowing in, you can't blow.--When they are aligned, you can. I know, that's a pretty cheesy way to test something, but it's cheap and quick. I still have to make the cap which attaches to the end of the spindle which doesn't have a flange, and compresses the o-rings.  I will make that last part tomorrow, and hopefully the valve will function the way I want it to. I am attaching a video link about Trevithick's engine, and about 13 minutes in you can see an animation of the same valve as built by Trevithick over 200 years ago.




Brian
thanks for updates on this project. Its a really great one and I'm paying attention. The puffing devil video is a really good video. I'm fascinated by Trevithicks  osciialting valve, (technically not a 'rotary' valve) since I'd come up with a similar design myself. The received wisdom is that rotary valves don't work- many have tried and failed.  But I guess this has a lot to do with what pressures and speeds one is working with- lubrication and seals being major issues. I've got a buddy whop repairs brass instruments and similar kinds of oscilating valves are often used in them. As I understand it they are slightly conical and lapped down to 10 micron or finer.


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## Brian Rupnow (Sep 22, 2020)

Now that, boys and girls, is a beautiful thing!! Water jet cutting leaves great edges that need very little clean-up. If it wasn't so expensive, I would have more of it done. The flywheel is laying on top of a bunch of plates which will be finished before the end of the day using conventional machining techniques.


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## Brian Rupnow (Sep 23, 2020)

I haven't ran off. There is a lot of time spent on fitting and creating new platework, and I didn't want to post every single part that I made. The cylinder is fitted into the boiler, with a little bit of design change to allow for clearances. The plate stands that support the boiler and provide bearing surfaces for the axles are almost finished, but as you can see, they haven't been drilled for axles yet. Tomorrow I will finish those plates and machine two more that run parallel to the boiler, and drill and tap the boiler shell for the bolts which holds the end stands in place. The wheels are going to be the last parts made for this engine. I can actually go ahead and make all the parts required to make the engine run without finishing the wheels and the gears.


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## Brian Rupnow (Sep 24, 2020)

Todays job was to finish all of the axle brackets and assemble them to the boiler shell. This gets a bit tricky, because with no real suspension, if things are a bit off you end up with one wheel out of the four "up in the air".--It won't matter so much on this model, because it's not going to be a high miler, but I do like to get it right.


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## lathe nut (Sep 25, 2020)

Thanks Brian, we are in for a another treat, of show tell and learn, hope you put the drawings up also, you do such good work, thanks again for sharing with us, Joe


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## Brian Rupnow (Sep 25, 2020)

And behold, the great horned beast!! Is it not a beautiful thing? I think it's a Rupnowsaurus!!!


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## Brian Rupnow (Sep 25, 2020)

Joe--thank you for stopping by and leaving a comment. I don't get many people stopping by to say Hi anymore.---Brian


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## Brian Rupnow (Sep 25, 2020)

You know that saying about "Old dogs can't learn new tricks".--Not really true---I'm an old dog and I'm still learning new tricks. The cross-head on this engine (purple colored) has a long protrusion welded on top of it that operates the rotary valve. The fact that it is quite long will make the cross-head want to bind as it moves under pressure from the cylinder. This is technically called an "overturning moment". The way to overcome that binding is to make the area on the cross-head which slides along the cross-head guides as long as possible. Since that is probably the next thing I'm going to build, an update to the 3D model was called for.


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## VINCENT INGRAM (Sep 26, 2020)

Brian Rupnow said:


> Joe--thank you for stopping by and leaving a comment. I don't get many people stopping by to say Hi anymore.---Brian



Hi Brian, I'm a long term lurker largely because my current 6 month project has overrun by about 4 and half years.  I love your posts with explanations that even I can mostly understand - accompanied by drawings and photos that I find inspiring.  Once my vehicle is up and running properly, I will be making a tentative foray into this world of engine-building. Thank you, Vincent.


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## lathe nut (Sep 26, 2020)

Brian, I am guilty of reading and following a post and sometimes not comment, that must stop, I had been out for almost three weeks, I live in SW Louisiana, the Hurricane came through here and the the tornadoes that it spun off finished us off, 130 mile per hour wind, I stayed up and watched the wind was bad enough but when the leaves, tin and singles are going horizontal that when you know there is a tornado close by, I did better than most there I still have a house, back to the build, you have something that most people would die for is the ability to be able to draw it out and see what it will look at, talking about a dog learning new things that is one I know that I can't get and am to old to start that, I love your work, Joe


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## Brian Rupnow (Sep 26, 2020)

Today I finished the cross-head, and I'm quite pleased with the results.  In the 3D model I posted yesterday, I thought that the extended bearing surfaces added to the cross-head looked kind of "clunky", so I changed the design after I  had posted the model, and made the two extension pieces from round brass, which extend completely thru the rectangular body. They are loctited in place. The vertical part of the cross-head which operates the valve control rod is silver soldered to the cross-head main body.


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## Brian Rupnow (Sep 26, 2020)

Today is a "banner day", as I have completed the cross-head and cross-head guides, and my air cylinder and rotary valve are moving the cross-head thru it's travel. Everything is a bit herky-jerky right now, because everything is new and stiff. Once it has been operated a number of times, any "tight spots" will be smoothed down and the travel will be much smoother.


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## gartof (Sep 26, 2020)

Brian i am also guilty of lurking and not saying anything. Just enjoying each ride. Please don't stop.
Gary


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## Ken I (Sep 27, 2020)

Great work Brian - I'd hardly call that "jerky" more like what you'd expect from an unconstrained air operated cylinder - once it starts driving a flywheel and has some "miles" on it - it will be just great.
Your prodigious workrate is inspirational - I'll be lurking for as long as this post continues.
Keep up the good work - especially the effort in posting your progress.
Regards - Ken


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## Brian Rupnow (Sep 27, 2020)

Here is a fun little video of "running in' the cross-head and cross-head guides to make them operate smoothly without binding.


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## Brian Rupnow (Sep 27, 2020)

I have now reached the point where I can't do much more until I mount the shaft which the flywheel mounts to.--And--the exact position of that shaft depends totally on the meshing of all the gears. I only have to actually cut 3 gears--the ones attached to the wheels will be made as one extra thick gear, then split with my parting tool to yield two identical gears. I have a tiny bit of cosmetic work to do on the "boiler", but that can wait, for now. I can make all of the smaller gears tomorrow if I have the material to make them.


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## lathe nut (Sep 27, 2020)

Brian, you skinned that cat well, neat idea, interesting, you good and thanks for sharing, Joe


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## johwen (Sep 28, 2020)

Brian Rupnow said:


> Here is a fun little video of "running in' the cross-head and cross-head guides to make them operate smoothly without binding.



Hello Brian, looking great and will be another Great Rupnow model to display. Once you have  run in the mechanisms, I would suggests if you restricted the air flow into the cylinder with an adjustable valve, the movement would be slower and smoother toward the end of the stroke but would not reduce the torque. Cheers. john


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## ozzie46 (Sep 28, 2020)

gartof said:


> Brian i am also guilty of lurking and not saying anything. Just enjoying each ride. Please don't stop.
> Gary


Me too ,sorry to say. You do great work.
Ron


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## Brian Rupnow (Sep 28, 2020)

This morning I went searching about for material to make all of my gears. Okay--Good news is that I already have a 36 tooth gear left over from some project, that can be repurposed. It is the gear which sets up on the same shaft as the flywheel, and by all rights should be made of steel. Since this is only a demonstration engine that will see very few miles, I will use this gear anyways. I hunted up two bronze flywheels from the old Rupnow Hit and Miss engine, which has been scrapped and caniballized, but they aren't really of  size that I can use. I found a really big round piece of mild steel that was a cut-off from something else I built, which will do to get the 108 tooth gear from.--And---I have a big long piece of 2 1/2" diameter hot-rolled which will work fine for the 50 tooth gears that attach to the wheels.  In other news--Yesterday, on my "fat mans walk" I lost a pair of bifocal glasses. As soon as wife and I got home, I realized that I didn't have them, so we went back and walked the trail again looking for them, but no luck. I have put up a sign at each end of the trail explaining what I had lost and my phone number, in case someone else found them.--If not, I'm out $300. That would have bought me a lot of material for my hobby.


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## Brian Rupnow (Sep 28, 2020)

Okay---Here we go---hang on. The 2 1/2" round hotrolled has been cut off, to a sufficient length to give me two or three gears and a handle to hold in my rotary table chuck.  The large outer diameter has been turned to what the actual outside diameter of the gear will be. The smaller diameter is turned to a diameter that is smaller than the root diameter of the gear teeth to be cut, and long enough so that I don't run the gear cutter into the hardened chuck jaws. That will immediately ruin a cutter. Don't ask how I know this. The center has been drilled and reamed to 1/4", which is the diameter of the axles on my Trevithick.


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## LorenOtto (Sep 28, 2020)

Brian Rupnow said:


> Joe--thank you for stopping by and leaving a comment. I don't get many people stopping by to say Hi anymore.---Brian


I'm here, I'm lurking as usual.  I don't have anything to contribute, but I do enjoy the way attach an issue.  Keep up the good work. Loren


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## Brian Rupnow (Sep 28, 2020)

Thanks Loren---I see all of the 'likes" you have been awarding my thread.
I've just finished cutting the 50 tooth gears. A couple of things here worth mentioning. Any time I cut  gears, I try and make the gear blank a bit longer than necessary. That way I get the two gears I wanted, plus a "free-bee" that I can use on some future machine. I use the tailstock support, because the material is sticking out quite a long ways from the chuck. At the very front of the table, you will see two "table stops" that I set before I started cutting, so I can't run the cutter into the hardened chuck jaws nor into the tailstock support. Lastly, you can see that I used my cut-off tool in the lathe before I started cutting the gears. I cut just deep enough to be lower than the root diameter of the gear teeth. This avoids pulling burrs on all of the gear teeth, which happens if you wait until after the teeth are cut to part off the individual gears.




.


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## Brian Rupnow (Sep 28, 2020)

This is what I end up with. Two 50 tooth gears to go on the Trevithick, and one spare to be used on some future project. The centers will eventually be removed from these two gears and they will be attached to the wheels as shown on the 3D model, but for now they can stay mounted on the axles until I finish all the gears and see that they mesh properly.


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## Larry G. (Sep 29, 2020)

I too, am here, lurking as usual.  Some of the simplest ideas can be the most useful and productive. 
 - Extra length of the blank and table stops to avoid a potential crash
 - Parting tool cuts before cutting the teeth the minimize deburring work
 - A freebie when you are all done...
Thanks for expending the effort to document your work and methods.
Larry In New Jersey


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## Brian Rupnow (Sep 29, 2020)

Hi Larry. Nice to hear from you. Every once in a while I let some jewel of machine shop wisdom loose on here, and almost every day I learns something new from the forums myself.---Brian


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## Brian Rupnow (Sep 29, 2020)

I've spent the morning preparing the 108 tooth gear blank. The gear as shown consists of outer rim, inner hub, and six spokes. If you can see it in the picture, the ends of the spokes are just below the root depth of the gear teeth. I'm going to use my new super duper TIG welder to weld the outer ends of the spokes to the outer rim, and fill the rest of the hole with filler rod up to the outer surface of the rim, which right now is 0.040" larger than the finished blank. Theory is that if the welding goes well, I will then machine off that extra 0.040" from the o.d. and machine the gear teeth. Then I will hold the gear by the i.d. of the rim, which is concentric with the outside of the outer rim, to finish drilling and reaming the center of the hub. In the background you can see that I have taken a piece of aluminum scrap and drilled it in three places for 1/4" diameter stub shafts to mount the finished 50 tooth and 36 tooth gears on to verify that they mesh correctly. (they do).


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## Brian Rupnow (Sep 29, 2020)

Everything went according to plan--Except, maybe the plan wasn't so good. The six 3/16" spokes have a lot of "give" to them. It becomes somewhat like trying to machine a sponge. Any pressure from the cutting tool and everything squirms all over the place. First I tried it without welding the spokes to the hub.--No good, in fact, terrible. Went back out to the main garage and welded the spokes to the hub on the side that doesn't show.--Marginally better, but kind of like trying to polish a turd. I will have a better idea tomorrow if I can save this or not, when I go to cut the gear teeth.


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## Brian Rupnow (Sep 29, 2020)

After thinking about the time and work involved in cutting 108 gear teeth, I've decided not to run with this idea. The gear is stuck right out on the front of the engine, and I hate wobbling and orbiting gears and flywheels worse than snakes. Not certain right now what I will use as an alternate method to spokes, but  I will think on it and let you know.


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## Ken I (Sep 30, 2020)

Brian, When I make a flywheel like that, I screw the stems to the hub - the end of the stem having a screwdriver slot and the holes reamed to be a close fit on the spokes.

See below - soldered brass - but you get the idea.





This flywheel from my hypocycloid - I left the hub on its barstock - spotfaced and tapped it - then returned it to the 4-jaw - clocked it dead true.
Fitted the rim and spokes (locktite on threads) - persuaded the rim to run dead true with a mallet and then soldered it by flame heating the ring with a butane torch while still in the lathe (the amount of heat getting through to the chuck / lathe is nothing to worry about) - followed by a clean up turn of the outside diameter and sides.Only then parting off the hub from the barstock.
The result a flywheel that runs dead true.
Regards,
              Ken


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## Brian Rupnow (Sep 30, 2020)

So, today we try for another kick at the can. My beautiful 108 tooth gear with spokes was not a good idea. Today we aim for something a little simpler, a gear machined from 1/4" mild steel plate with a bolt on hub and bronze bushing. At this point I have to say that I'm an incurable optimist.--I'm always sure that my parts are going to turn out beautiful, even when previous experience has shown me different. I have learned (over and over again) not to weld on things and expect them to stay true and square and symmetrical.


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## Brian Rupnow (Sep 30, 2020)

Holey crow!!! Start over again with 1/4" hotrolled plate.


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## Brian Rupnow (Sep 30, 2020)

And more of the same, using the "EBVQ" method. (Eats blades very quickly).


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## Brian Rupnow (Sep 30, 2020)

In this shot, the gear profile has been very roughly cut out on the bandsaw, and a hub is attached to it. This lets me grip the hub in my rotary table chuck, and machine the radiused area of the windows. The sides of the windows have not been machined yet, but that will be my next step.


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## Brian Rupnow (Sep 30, 2020)

Machining the sides of the windows was easier than I thought it would be. Once you move things around with the X and Y table controls and the rotary table until you have one of the window sides parallel, (I took 0.080" depth of cut until I was thru the 1/4" plate), then if you have 4 windows you can just advance the rotary table 90 degrees and you are ready for the next side.


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## Brian Rupnow (Sep 30, 2020)

And finally, at the end of the day, the gear is ready to have it's teeth cut. This is about where I left off yesterday. It becomes pretty clear why people make large gears and flywheels with either solid webs or circular holes in the webs. It makes far greater economic sense to buy a flywheel casting or have a gear or flywheel water-jet cut. I still have "filing and fettling" to do on this gear but it is turning out like I had hoped.


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## Bighoss (Sep 30, 2020)

Nice work it may take a while to finish but the end result is worth it


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## Brian Rupnow (Sep 30, 2020)

Thanks Bighoss.--There is certainly a lot of steps involved. If I was rich instead of good looking, I'd have had the gear water-jet cut.---Brian


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## Brian Rupnow (Oct 1, 2020)

And that, my friends, is a beautiful thing. I have a new description of anxiety---It's that feeling you get when you've finished the 108th tooth and you move the rotary table one more step, and take a final pass to see if you are cutting metal or air. All went well.


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## Brian Rupnow (Oct 1, 2020)

It's never quite as easy as I think it's going to be, but I like this. I tapped the side of the boiler and installed the big gear with a 3/8" shoulder bolt. Sid had commented that I should have used gears with a larger, coarser tooth, but I think this doesn't really seem that far out of proportion.


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## davidl (Oct 1, 2020)

Hi Brian, 
I've been looking a t your work off and on ever since I started machine on my retirement.  I stand in awe of your artistry.  Keep sharing. 
Cheers


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## Brian Rupnow (Oct 2, 2020)

Davidl--Thanks for saying Hi. I enjoy designing and machining so much, and I do like to share the steps involved with others. I love it when folks step by and have a look and leave a comment.---Brian


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## Brian Rupnow (Oct 2, 2020)

I was hoping to post a short video of all the gears and flywheel turning, but I didn't quite make it. My butt is absolutely kicked for today. Tomorrow I'll put a set-screw in the flywheel hub and make a short video.  It has been a day long thrash here, but I'm happy with what I've accomplished.


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## Ghosty (Oct 2, 2020)

Looks good Brian, At the moment I would only got half of that done before I was kicked for the day
Cheers
Andrew


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## thegallery (Oct 3, 2020)

I built this model during the past year. You can see more at: www.thekilmerplace.com


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## Brian Rupnow (Oct 3, 2020)

And, as promised, here is a neat video of all the gear-train and flywheel in action.


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## Brian Rupnow (Oct 3, 2020)

To the "Gallery"--Your model is wonderful. It is obvious that you put a great deal more effort into your model than I have. Congratulations on a beautiful and well crafted machine.---Brian


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## Brian Rupnow (Oct 3, 2020)

After yesterdays hard slog, I wanted something a bit less critical to make today. A smoke-stack!!! Has to be visually appealing but no real finicky sizes and meshes involved. Good stuff!!! All I need on this end now is a faux burner door and a spigot to get my compressed air inside the machine.


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## werowance (Oct 3, 2020)

Brian, ive been watching and wondering about the gear ratio on the drive.  thats a whole lot of BIG to little from what learned playing with my legos back in the 70's early 80's. where i first learned about gear ratios.  but from that lesson BIG to little means fast and power robbing.  - i guess i just want to know more about this situation or even if you feel this is a situation(such as but not limited to - to fast or not enough hp to move it). (discusssion mode here not saying bad or anything)  ive been holding back on asking but curiosity has got this cat....


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## Brian Rupnow (Oct 3, 2020)

Best answer--The brass gear which is attached to the "crankshaft" is little. It drives a "big" gear. That means that the big gear will rotate more slowly, but will develop considerably more torque. Speed and torque are diametrically opposed--one goes up, the other comes down and vice-versa. The big gear turns two smaller gears, so they rotate faster, but lose the torque benefit. If I was designing something from "scratch" I wouldn't do it this way.--But remember, this design was first established 215 years ago. People were designing all kinds of new machinery and there wasn't a clearly defined method behind what they were doing. People designed a lot of new mechanical things that ultimately failed. If something failed, they didn't do it that way the next time. If something was a success, then the design was copied and refined.


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## Ken I (Oct 4, 2020)

The ratio is drivers / driven - the big wheel has nothing to do with the ratio - its as if the brass gear was directly driving the wheel gear - the big wheel is just an idler and means of transmission.

Regards, Ken


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## PSP (Oct 4, 2020)

Brian,
Just terrific, marvellous work.  On behalf of other lurkers like myself, please keep posting.
Regards, 
Andy

For anyone interested in the Beam Engines at Pool shown in the Mark Williams videos:





						East Pool Mine | Cornwall
					

Find out more about the National Trust's East Pool Mine at the heart of the Cornish Mining World Heritage Site.




					www.nationaltrust.org.uk


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## Brian Rupnow (Oct 4, 2020)

Today I had to make 4 temporary wheels for this thing. They are the same diameter and thickness as the finished wheels will be. I can keep track of where things should be and how to make dimensional allowances for it up to a certain point, and then I start to lose bits and pieces. This way keeps me on track, one less thing I have to be thinking of and remembering. These wheels were made from scrap pieces of 3/8" plate. Also, I machined an air inlet tube and screwed it into the back-plate just to the left of the smoke stack.  It is a cold, wet, and dismal day here and I'm about to head upstairs and lose myself in a good book.


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## LorenOtto (Oct 4, 2020)

Brian Rupnow said:


> Best answer--The brass gear which is attached to the "crankshaft" is little. It drives a "big" gear. That means that the big gear will rotate more slowly, but will develop considerably more torque. Speed and torque are diametrically opposed--one goes up, the other comes down and vice-versa. The big gear turns two smaller gears, so they rotate faster, but lose the torque benefit. If I was designing something from "scratch" I wouldn't do it this way.--But remember, this design was first established 215 years ago. People were designing all kinds of new machinery and there wasn't a clearly defined method behind what they were doing. People designed a lot of new mechanical things that ultimately failed. If something failed, they didn't do it that way the next time. If something was a success, then the design was copied and refined.


Mechanical evolution!


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## Brian Rupnow (Oct 5, 2020)

Before I can make any more progress, I have to back up a little and repair a problem. The elbows which feed air to my 4 way rotary valve are interfering with the inside of the "boiler" pipe. I have designed a new "close fit" elbow, and will be machining and installing a  couple of them today, so I can start working on the business end of my Trevithick.


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## Brian Rupnow (Oct 5, 2020)

This is the new "clearance style" 90 degree elbows finished. You will notice a small hole in the top of the right hand elbow. I didn't plan that. A dab of J.B. Weld will fix it. Tomorrow, assuming everything fits properly, it's almost time to turn my hand to the mechanism that operates the 4 way valve.


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## Brian Rupnow (Oct 6, 2020)

Today was a day for fettling and fitting. The new elbows on the 4 way valve gave me the clearance I needed, so I was able to bolt the end with cylinder attached to the boiler.  I routed the air supply hose from the 4 way valve to the hose barb in the back plate, and routed the exhaust thru the backplate and into the smoke stack. The only new part  machined today is the arm attached to the bronze gear which sets on the flywheel shaft. I'm hoping that my local nut and bolt store has 3/16" shoulder bolts, which will attach the "connecting rods" to the new arm and to the flywheel. I'm thinking that the boiler would look a lot better with a flange at each end. I may buy some material to add a flange to each end of the the boiler.


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## Brian Rupnow (Oct 7, 2020)

Well Rats!!! Nobody in Barrie carries 3/16" shoulder bolts. I went a head and made my own, now I can connect my connecting rods to the flywheel and crank arm.


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## Brian Rupnow (Oct 7, 2020)

If I had some 1/8" rod bent and threaded, I'd have connecting rods finished. The four brass ends are shown in place in this picture. I've got so much junk on top of my "assembly table" hat it's hard to see. Tomorrow I'll make and install connecting rods.


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## Brian Rupnow (Oct 8, 2020)

It's time for a change in my game plan. I had originally planned on using 1/8" diameter cold rolled steel round-bar with soldered brass ends for connecting rods. Tried that yesterday, but found that 1/8" is far too skinny and bendable. not going to work. Went out today and spent some of the Rupnow fortune on spherical rod ends. The con-rod diameter will now match the o.d. of the female rod ends.


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## Brian Rupnow (Oct 8, 2020)

Here we have the "heavy con-rod" on the non gear side, with a spherical rod end on each end. As things work out, the con rod on this side doesn't really need an offset, which is fine with me. Tomorrow I will work on the gear side con rod, which definitely will have an offset in it to clear the hub on the 108 tooth gear.


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## Brian Rupnow (Oct 8, 2020)

Couple of things I should mention.-- That new con-rod is way too large in diameter, but it won't deflect under load, and once the engine is running it will be replaced with a smaller diameter piece.--And--I picked up a piece of material today large enough to create "flanges" for the ends of the boiler. I think that if these boiler "flanges" are added they will do much to make this model look more like the original Trevithick engine. It's a bit difficult to imagine with the 3D model being more colors than the rainbow, but I think it will look better.


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## ShopShoe (Oct 9, 2020)

Brian,

Just gotta check in to say I'm liking this project and your usual approach to finding a way to get it all done.
I also like that you're trying your hand at making a vehicle this time (although I remember the little cart that was tethered by its air line and ran in circles.)

BTW, Just can't resist mentioning that your crowded table includes the proverbial Bigger Hammer.

--ShopShoe


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## Brian Rupnow (Oct 9, 2020)

I couldn't stand how big and clunky a 1/2" diameter con rod looked. Today I made new con rods from  5/16" diameter cold rolled steel to replace the first one which was 1/2" diameter aluminum. Everything looks a lot more proportional now. Video to follow when my camera battery is charged.


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## Brian Rupnow (Oct 9, 2020)

Shopshoe--Maybe you missed this thread?




__





						Stephenson's Rocket--Working Model
					

I am not really a model train buff. I know that any number of people are, and get great joy from model trains, but they have never really interested me that much.  However---I have always been intrigued by Stephenson's Rocket, which was the first or second commercial train engine driven by...




					www.homemodelenginemachinist.com


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## Brian Rupnow (Oct 10, 2020)

This is a video of the Trevithick engine being put through all of it's mechanical paces. It is an extremely interesting engine to see working.---Brian


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## Brian Rupnow (Oct 11, 2020)

Sometimes the game plan changes in the middle of the game. I originally did not intend to have flanges at either end of the boiler. Last week I decided I actually did want them, as separate rings that I could slide over the ends of the boiler and attach with small bolts. The only fly in the ointment was that I had already dedicated the space at one end of the boiler to support a guide rod mechanism for the slider that moves the valve. Today, I turned up some plate on my faceplate to get a curvature identical to the o.d. of the rings (one of the rings is leaning against the headstock in the picture), and then welded the resulting pieces to the rings. My tig welding is improving, but it is not very artistic. So, at this point the pieces are welded to the rings, and the resulting welds are slathered with J.B. weld which won't be dry until tomorrow. When they have dried, I will work some artistic magic on them and then attach the rings to my boiler.


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## Brian Rupnow (Oct 12, 2020)

No real machining work this morning, but a couple of hours spent updating the 3d model to reflect what was actually built. Here you can see the heavier connecting rods and the updated boiler rings which have the guide rod supports built into them.


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## Brian Rupnow (Oct 12, 2020)

Spent a very large part of the day working out tight spots and freeing everything up. This is a finicky kind of job, and it can't be done until everything is almost finished and assembled. Also got a start on the valve valve actuator rod. The two rings which go on the ends of the boiler are leaning up against the engine.


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## phred (Oct 13, 2020)

Hi Brian,
Another lurker enjoying your progress. excellent stuff.
Given that the original locomotive managed a velocity of around 5 MPH, do you know the RPM the engine was doing?
( It should be possible to calculate if you know the wheel diameters and gear ratios )
Cheers,
Fred B


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## Brian Rupnow (Oct 13, 2020)

phred--no, I really don't know. In any videos of the Trevithick that I have seen, it runs very slowly. As a general rule, models run a bit faster than the original engine, but I don't know how fast it will run.


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## Brian Rupnow (Oct 13, 2020)

Elvis has not left the building. Elvis is up to his neck in adding the flanges to the boiler and adding the valve linkage. I really, really hate making changes part way thru a job. I can make it end up pretty, as if I'd planned it this way all along, but it adds a whole page to my frustrations list. Oh well, one end is finished. Tomorrow, who knows?--The canary may sing for me!!


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## Brian Rupnow (Oct 14, 2020)

Mechanically, I'm at about 99%. I can tell, after playing with it half the day, that it wants to run. It is proving very difficult to set the 4 way valve so that it reverses the action of the cylinder at the end of the stroke. I've about had it for today, but wish me luck for tomorrow.


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## Brian Rupnow (Oct 14, 2020)

Game plan for tomorrow is to broach keyways in the flywheel, bronze gear, and crankshaft. Right now they are only connected with set screws, and the two offset pinions keep getting out of synch and locking things up.


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## Brian Rupnow (Oct 15, 2020)

Keyways have been added to the flywheel, bronze gear, and to the crankshaft. It helps, but still doesn't let the engine get "over the hump" at each end of the stroke and continue running. Once an engine like this runs, it quickly wears down any "tight spots" and the longer you run it, the smoother it gets. Of course, the magic is in getting it to a point where it will run under it's own power. There really aren't any more changes I can do mechanically to get it running. This leaves me with two options. Make a bigger, heavier temporary flywheel to get it running, or hook it up to an electric motor and let it run for a couple of hours to get rid of any remaining tight spots. The electric motor method is the cheapest, since I don't have to buy any material, but this is not an easy beast to hook an electric motor to. I am going to call my metal supplier and ask about the price of a 8 1/2" square plate x 1/2" thick to make a much heavier flywheel.


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## Brian Rupnow (Oct 15, 2020)

Now you know how I spent my afternoon. This started life as a piece of 1/2" x 8 1/4" x 10" hot-rolled flatbar. There is no center hole in it yet, just a good center-punch mark. It has double sided tape on the side facing the lathe jaws and is held in place by a live-center in my tailstock. I cut the 4 corners off with my bandsaw and then spent the afternoon nibbling away at it until it is perfectly round. This method always works well for me, but you can only take about 0.010" depth of cut or the tape slips.  I'm not going to put a lot more time in this flywheel. Tomorrow it will get a centerhole and keyway and set screw, and have  a #10-24 thread put in 1 1/2" off center for the  shoulder bolt which connects the con rod. If the heavier flywheel does the job and makes the engine run, I'll worry about doing some cosmetic work on it later.


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## phred (Oct 16, 2020)

Hi Brian,
having made a few assumptions regarding wheel diameter etc, I calculate that  at the nominal 5 MPH quoted as a typical speed at Penydarren ,
the engine was turning at approximately 64 RPM.
How do you think this would relate to your model?
Hope the greater mass of the new flywheel gets you over the hump with a continuously running engine.
Cheers,
Fred


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## Brian Rupnow (Oct 16, 2020)

-Big changes with the heavier flywheel. The flywheel is rocking back and forth like crazy between top dead center and bottom dead center under air pressure.  This is very promising. Based on what it's doing now, it should just require some adjusting of the valve actuators on the slide bar. I have just blown an internal hose and have to tear things down to reconnect it. Is there any kind of liquid glue that I can permanently glue the neoprene hoses to the brass or steel tubes on the 4 way valve ? I do have some small spring wire clips from the hobby shop, but at higher air pressure the hoses keep blowing off. Crazy glue sets up so quickly that I wouldn't have a chance to put some glue on the steel tubes and then slip the neoprene hoses over them. Is there something like a "delayed action" super-glue?


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## Brian Rupnow (Oct 16, 2020)

I learned three new things today. #1--There is a type of crazy glue that doesn't dry instantly--it gives you about 15 seconds between when it is applied and when it dries. This is enough time to coat a hose barb (actually a piece of 0.185" diameter brass tube) and slip a neoprene hose over it before it becomes absolutely immoveable.---If you're quick!!
---#2--If you have a bunch of air connections inside something else that requires an hours work to take it apart, then never, ever, ever use neoprene tubing  pushed onto metal tubes for connections.--Make them from metal tubing and solder them in place.
---#3---Engines which have wheels on them are as suicide prone as lemmings, which jump off cliffs into the sea. I've probably grabbed this damn thing out of the air half a dozen times today when it jumped off my desk. I haven't moved so fast since my wedding night.


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## lathe nut (Oct 16, 2020)

Brian Rupnow said:


> I learned three new things today. #1--There is a type of crazy glue that doesn't dry instantly--it gives you about 15 seconds between when it is applied and when it dries. This is enough time to coat a hose barb (actually a piece of 0.185" diameter brass tube) and slip a neoprene hose over it before it becomes absolutely immoveable.---If you're quick!!
> ---#2--If you have a bunch of air connections inside something else that requires an hours work to take it apart, then never, ever, ever use neoprene tubing  pushed onto metal tubes for connections.--Make them from metal tubing and solder them in place.
> ---#3---Engines which have wheels on them are as suicide prone as lemmings, which jump off cliffs into the sea. I've probably grabbed this damn thing out of the air half a dozen times today when it jumped off my desk. I haven't moved so fast since my wedding night.


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## lathe nut (Oct 16, 2020)

got to say your are not only good at what you do but you have a lot of patience, never give up and never give in, thanks for all that valuable information, Joe


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## minh-thanh (Oct 17, 2020)

Brian Rupnow said:


> . I haven't moved so fast since my wedding night.


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## lathe nut (Oct 17, 2020)

Brian, have never hear that statement, I think I remember but probably like you that has been 50 years, don't know if she was moving fast or I was, Joe.


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## Brian Rupnow (Oct 17, 2020)

After a full day of fixing disconnected tubing and taking things apart and then putting the parts all back together again, it was time for some analysis as to what was happening. Right now, as things set, the valve is set so that it is fully opened at the end of the piston stroke in either direction. Now, in a perfect world, where the flywheel really was doing it's job, the inertia of the flywheel should carry the crankshaft "over the top" before the piston begins to travel in the opposite direction. Since the flywheel is bouncing back and forth between the top and bottom dead center, the conclusion is that the valve is being actuated just a tiny bit too soon. If the opening was delayed for another millisecond, the crankshaft would have that space of time to get "over the hump" and  make complete revolutions rather than bouncing back and forth thru partial rotations.  So yes Charles, I do agree with what you are saying and what you show in your diagram.  With everything "as designed", I can adjust the sliders so that the valves begin to open a bit later in the cycle, which in theory mean they would close a bit later in the cycle. That would be a "best case" scenario. If that doesn't work, then as Charles suggested, shortening the radius arm on the valve would allow the valves to operate closer to the end of the piston stroke and hopefully allow the flywheel to get "over the hump" before travelling back in the opposite direction. I have the capacity with my current design to shorten up the radius arm with no other changes.


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## Brian Rupnow (Oct 17, 2020)

Bah!! Humbug!!--The easy fix (repositioning the valve actuators)  didn't work. I have never had an engine so close to running that didn't actually take off and run. I can see a number of things which I could do to fix this, but they are all progressively more and more difficult. The next easiest fix is to shorten the radius arm on the valve. Of course this will make for an extended  cantilever on the sliding brass actuator. I have a small (3mm) ball bearing that I think I can work into the equation to take a bit more friction out of the valve action. Oh well, thanks to Covid there is damn all else to do anyways.


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## Brian Rupnow (Oct 18, 2020)

This is my Trevithick engine doing something I haven't seen before. It has a unique 4 way valve mounted on top of the boiler, and the valve swings back and forth under the influence of the sliders which contact the valve arm. I don't have things set up quite right yet, so the engine is "stuttering"---The valve is being reversed before the piston gets far enough in it's linear travel to get the crankshaft over dead center and complete a full revolution. This is not what I am ultimately aiming for, but I hope that with some adjustment to the sliders I can coax it into full revolutions.---Brian


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## Ken I (Oct 18, 2020)

Brian, The problem as I see it is the valve is fully in the reverse position before the cylinder reaches the end of its stroke. 

It needs some form of over centre / sprung / cam action - such that at the end of stroke the valve is amidships and then at the last possible moment goes over centre and is flipped into full astern by the cam / spring etc. action.

Something like this...





Just a suggestion to help you get your creative juices flowing.

The crank throw pushes it to dead centre / closed - the next say 5° - the valve is still closed but the cam action goes into freefall and the valve snaps the other way just at the end of the cylinders'  stroke.

Just the first thing that went through my mind, I'm sure you can come up with something more elegant / simple.

Regards,  Ken


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## Charles Lamont (Oct 18, 2020)

Discussion ongoing at MEM forum.


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## Brian Rupnow (Oct 18, 2020)

I've tried all of the tricks in the "Rupnow Magic Hat" and I am not able to get this thing to run using the 4 way valve. It is one of those engines that wants to run so badly that you can almost taste it, but it isn't happening. I have tried all of the different settings that I can think of, and have pinched my fingers so badly that I cried like a baby, but this just isn't going to run for me. This is not to say that the project is abandoned--Just that it isn't going to run with this 4 way valve. I can salvage most of the parts and make a Trevithick engine that runs with a more conventional slide valve. I hate to admit that I haven't been able to get this to work, but I have tried everything I can think of. Weirdly enough, I can make the model look more like the original Trevithick by using a conventional slide-valve than I could of if the 4 way valve had done the job.


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## Brian Rupnow (Oct 19, 2020)

Boys, we're going to start down a new path today. I'm very disappointed that I didn't get this engine to run with the 4 way valve and I really, truly thought that I would. Ah well, so much for unbridled optimism.  The change of course is going to involve a more conventional steam slide valve on the cylinder. Due to restrictions based on everything having to fit inside the boiler, I am going to have to gear the crankshaft to a "camshaft" and mount the eccentric strap and eccentric on the camshaft. (it will revolve at the same speed as the crankshaft.) This means that the steam-chest will hang from the underside of the existing 3/4" diameter x 3" stroke cylinder, similar to the way it did on the Stephenson's Rocket. I will be getting rid of all of the exterior valve control rods and guides, and the rings with built in rod guides will revert back to being just simple rings around the ends of the boiler. The only visible difference is going to be at the smoke-stack end of the engine, where it will be possible to see the extra set of gears to operate the cam shaft, and different method of mounting the crankshaft and cam shaft. If this sounds like a lot of extra work, well, yes, it will be.-However, it's Covid time. Can't visit friends, can't go out for entertainment, can't even see my grandchildren nor take out good-wife for a restaurant meal. I'm just happy to have something fun to do!!!


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## Brian Rupnow (Oct 19, 2020)

Ken 1--thank you for your input. I know what your drawing is showing, I have messed around with "toggles" before. Unfortunately there is no good way to add toggles to the existing Trevithick engine valve actuators, and as you see in the above post I have a different idea which I will now pursue.---Brian


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## Brian Rupnow (Oct 19, 2020)

Just finished the big three hour "clean-up, slick-up, put all my tools away in the correct place" dance. I try and put my tools away as I use them, but when I get into the final lap of building something I get so excited that nothing gets put away properly. When I walk into my little machine shop and the floor "crunches", I know that it's about time for a sweeping and vacuuming.  My apologies to everyone who hoped to see this run with the 4 way valve.---I did too. My apologies to anyone who I may have snapped or snarled at on the forums. I'm not normally like that. This project hasn't stopped. Very little of my work will be lost, even the cylinder will remain the same. The 4 way valve gets tossed, and I gain a cam shaft and conventional slide valve to control the cylinder. Don't go away please. There is more to come, and I promise, it will be interesting.---Brian


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## Brian Rupnow (Oct 19, 2020)

Two 25 tooth gear blanks turned and that's all she wrote for today. O.D. and hubs are turned to size from 1144 stress proof steel. Center hole has been drilled and reamed to 5/16" diameter. Next time you see them they will have teeth cut and be mounted in place.


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## Ken I (Oct 20, 2020)

Brian, I like your solution - but since you went to all the trouble of making the rotary valve and linkages etc. why not just leave them in place as cosmetic.

Regards - Ken


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## Brian Rupnow (Oct 20, 2020)

Ken--I could--But I like the look of it better with all of the linkages and non essential things gone.


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## Brian Rupnow (Oct 20, 2020)

Doing something a bit new and different. Normally, when steam-chests are used with a cylinder they are either both machined as one part from the same piece of material or soldered together, and all of the steam passages are internal inside the walls of the cylinder. In my case, I am retrofitting a steam-chest onto a cylinder which was previously operated by my 4 way valve. The steam lines are going to be external to the cylinder. I will solder brass "hose barbs" into the steam-chest and run flexible neoprene lines from the steam-chest to the cylinder ports. ( I know I cautioned against doing that but needs must.) I have never seen that done, but I can't think of any reason that it won't work.


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## Brian Rupnow (Oct 20, 2020)

It feels like I must have been taking "slow pills" today. I managed to work all day and make only one part. This is the sub base for the new slider valve. The four shcs in the corners attach it to the cylinder. The four tapped holes are where the steam-chest bolt to it. The tapped holes in the ends are drilled galleries that needed to be plugged after the fact, so they were tapped and #10 set screws threaded in to act as plugs.   There will be three tubes soldered into the block, two on one side and one on the other side. I still have some internal de-burring to do.


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## Brian Rupnow (Oct 21, 2020)

So far today, I've got a stem-chest and a steam-chest cover. I might have the internal slider by the end of the day. I'm anxious to see this controlling the cylinder.


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## Brian Rupnow (Oct 21, 2020)

I did finish all of my slide valve business today. This is the slider, the nut, and the actuating rod. The brass steam-chest is not shown in this picture, because I managed to drill four holes in the wrong place. The holes are not in a critical area, and brass is about the same price as gold around here, so they have been filled with J.B. Weld and the steam-chest has been set aside to cure for 24 hours.  Tomorrow I will make the eccentric and it's mount.


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## Brian Rupnow (Oct 22, 2020)

Last night I lay in bed reviewing what I had done yesterday, and came to the realization that I needed to get steam (air) into the new steam-chest. It already has 3 outlet tubes--One to go to the front of the cylinder, one to go to the rear of the cylinder, and one to go to exhaust. This morning I added an inlet tube to the steam-chest cover.


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## Brian Rupnow (Oct 22, 2020)

Okay, we are back up and headed for assembly. One trick I'd like to show. In the center of the brass steam chest you will see two .093" reamed holes. Dowels will fit thru them into 0.093" holes in the adapter plate below, (or it could be into a cylinder). They will not extend up beyond the top of the steam-chest. Why are they there?---Because, when you are setting these engines up to run, it is very important to know just where that slider is in regard to everything else. If you take off the steam-chest cover so you can see the slider, then it all falls apart in your hands and you lose all track of where the slider was in reference to the steam chest. With these dowels in place (loctited into the adapter plate or cylinder) you can remove the steam-chest cover plate and the steam-chest remains in place, so that you can see where the slider is in regard to the steam-chest.


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## Brian Rupnow (Oct 23, 2020)

Today we have something to show. I have removed the 4 way valve which I copied from Trevithick's original engine ( I couldn't get the engine to work with that valve on it), and replaced it with a more conventional slide valve which will be driven by an eccentric cam on a countershaft, which is driven at 1:1 ratio by the crankshaft. The attached video shows the operation of the cylinder when I manually move the slide valve control rod with a pair of pliers. This is very encouraging, and I will now move on to the countershaft and eccentric which attach to the engine end-plate right below the crankshaft. The air hissing noise you hear is due to the fact that I haven't lapped the face of the slider to the steel adapter plate it slides on yet. Sometimes you get lucky and don't have to do that, other times you do.


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## Brian Rupnow (Oct 23, 2020)

The way that the 1/8" control rod attaches to the brass slider is somewhat complex. The rod is threaded into a rectangular "nut" that "floats" inside the towers on the back side of the slider. It has to be a tight enough fit that the nut doesn't rattle around, but loose enough that it doesn't bind on the slider. If it does bind at all, it may be enough to keep the face of the brass slider from making a perfect seal against the steel face with the ports milled into it. This can be one cause of air escaping past the slider. That is easily  corrected by a little creative file work on the nut or the slider.---or---It could be passing air because the face of the slider wasn't lapped against the steel. I find that I don't generally have to lap the faces, and if it is only a very small air leak, then running for half an hour will generally correct any differences in the faces. That video was made about five minutes after I had first assembled things and they were operating okay.  I will do a bit of detective work tomorrow and see what is causing the air leak.---Brian


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## lathe nut (Oct 23, 2020)

Brian, I like you attitude if that don't work go at if different, you kinda like a Duck, if he can't walk, he will swim and if that don't work he will fly but going to get there, gosh if that stumped you us who know less are never going to be there, thanks for you videos also, Joe


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## Rdean33422 (Oct 25, 2020)

Great work Brian
following

Ray


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## Brian Rupnow (Oct 25, 2020)

Thanks for stopping by and saying Hi guys. All of the new stuff I needed has been machined. I just pulled the end plate off the engine and plugged 3 holes that were not going to be used with my new crankshaft mounts. Tomorrow will be an "assembly day" while it all goes back together.---Brian


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## Brian Rupnow (Oct 27, 2020)

Today I completely disassembled the slide valve on the cylinder, and lapped both mating surfaces on a sheet of glass, beginning with 400 grit and finishing with 600 grit. It worked !!  I have never had to do that before on any of my engines. It's one of the ten thousand things I know about but haven't actually done before. The air leak is gone---or at least so gone that it is no longer audible.---Brian


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## Brian Rupnow (Oct 27, 2020)

You don't have to be crazy to work here---but it helps!! Actually, what you see here is setting up the motor to run without the boiler. Since I can't get at any of the valve linkage when it is all inside the boiler, I will set everything up here and make all the adjustments required, then tear it down and reassemble it inside the boiler. --Sorta kinda like building a ship in a bottle.


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## Brian Rupnow (Oct 28, 2020)

All things cometh to he who waiteth---If he worketh like Hell while he waiteth!!! This is the Rupnow-Trevithick engine on it's very first run with the new slide valve. The 1 1/4" square aluminum bar and the two vices are there just to hold the end-plates securely so that I can run the engine without the boiler in place in order to make adjustments. I think my waterjet cut flywheel is too light, but I can alter that. It is very gratifying to me to see this engine run for the first time.----Brian


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## Ken I (Oct 28, 2020)

I've been waiting for that - cool. Thanks for posting.
_All things cometh to he who waiteth---If he worketh like Hell while he waiteth!!_
Droll but true.
Regards, Ken


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## phred (Oct 28, 2020)

Congratulations! Running like a train.
cheers, Fred


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## ozzie46 (Oct 28, 2020)

Looks good Brian. congrats.

Ron


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## corky (Oct 29, 2020)

love it


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## werowance (Oct 29, 2020)

nice and i like the sound as well.  cant describe what it reminds me of but its a sound i have heard before and like it.


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## Brian Rupnow (Oct 29, 2020)

Todays game plan got changed a bit. My waterjet guy was able to make my two steel rings yesterday afternoon, so today I drove over and got them, brought them home, drilled and tapped them and mounted them to the existing flywheel. It's been a cold dreary, rainy day here, but I was glad to get out of the house for a while. The flywheel was originally a piece of 3/16" mild steel plate. I have added a 1/8" steel plate to each side of the rim to make it a little heavier, in hopes that this will let me run the engine slower.


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## Brian Rupnow (Oct 29, 2020)

This video shows the engine running with the extra plates added to the flywheel. I'm very happy with this result. The engine will run much slower now.---Brian


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## Rdean33422 (Oct 29, 2020)

The extra weight has made quite a difference.
Runs smoother and slower.

Ray


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## mnay (Oct 30, 2020)

Brian,
I follow your posts and very much enjoy them.  I am still working full so my time to check up is during lunch break at my desk.
Another wonderful project.  
Mike in Utah


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## Brian Rupnow (Oct 30, 2020)

Thanks Mike---
Making progress here, one gear at a time. This morning I  reassembled the engine inside the boiler, and added the large gear on the side. Nothing is ever quite the same when you move an engine like this, so all of the battles I fought to get the engine running on my desk were repeated to get it running inside the boiler. I have the heavy flywheel on there for set-up but will eventually put the smaller water-jet cut flywheel back on. I just hung the big gear on there to see if the engine noticed any difference in the load, but the engine didn't seem to care whether the gear was there or not.----Brian


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## ShopShoe (Oct 31, 2020)

Brian,

That looks really great running. I am enjoying this build.

Thank's again for posting.

--ShopShoe


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## Brian Rupnow (Oct 31, 2020)

So, here we are!!! Everything goes round and round and up and down like I had planned. I still have to make proper wheels for this thing, and connect the gears to the wheels so the axles will be driven in the finished version. I have a nice color scheme in mind for it. I am really pleased with the results at this stage of the game.---Brian


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## Brian Rupnow (Oct 31, 2020)

Had a visit from three ghostly characters this afternoon. My grandchildren are all getting older. I'm glad they still come across town to Grandpa's house for a visit.


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## Brian Rupnow (Nov 1, 2020)

Not really a lot left on the "build" of this engine, but I still had to contend with the hole in the top of the boiler that the actuator arm for the 4 way valve (that I couldn't make work) stuck up through.  I decided that the perfect answer to that hole would be a "steam dome". Steam domes are marvelous things. They can be anything that your fertile imagination wants them to be---a safety valve, a pressure indicator, a speedometer. Most living people under 60 years of age have never actually seen a steam engine. I've been fighting a mild flue all week so I think I'll spend the rest of the day on my couch with a good science fiction book.---Brian


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## Brian Rupnow (Nov 2, 2020)

Today I'm making wheels with cut-outs in the face. My approach is a bit different, but worth posting a shot of. I have to make four wheels that are identical in the cut out areas, bores, and outer diameters.  I used a caliper and compass to lay out the diameter of the wheels on a sheet of 1/2" thick aluminum, cut out four rectangles, drilled and reamed on center and pushed a size on size rod thru  the holes to keep everything centered, then ran bolts thru two opposing corners (which will become scrap), then stacked all four plates together in my machine vice to drill all of the holes in at once. That way I only have to do the set-up once. Next trick will be to separate all of the plates and cut the corners off, then turn to size in my lathe.


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## Brian Rupnow (Nov 2, 2020)

This shows the material that will be cut out of the four wheels. The material is 1/2" thick aluminum. Two of the wheels are only going to be 5/16" thick. The two wheels which have gears mounted on them will be 0.408" thick. My next step will be to cut off all of the outer corners and then turn the wheels to be round. Then I will grip them by the round outer rim with my 3 jaw lathe chuck and thin them down to finished thickness and open the center hole out to a finished diameter of 1/4". The windows will be cut out after the wheels are thinned down.


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## Brian Rupnow (Nov 3, 2020)

And we spent a goodly portion of the day on my lathe, making shiny wheels. The two wheels on the right which have raised bosses on the face are the ones which the gears attach to. The wheels are finished now except for cutting the windows in tomorrow on my mill and rotary table.


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## Larry G. (Nov 4, 2020)

Brian Rupnow said:


> Not really a lot left on the "build" of this engine, but I still had to contend with the hole in the top of the boiler that the actuator arm for the 4 way valve (that I couldn't make work) stuck up through.  I decided that the perfect answer to that hole would be a "steam dome". Steam domes are marvelous things. They can be anything that your fertile imagination wants them to be---a safety valve, a pressure indicator, a speedometer. Most living people under 60 years of age have never actually seen a steam engine. I've been fighting a mild flue all week so I think I'll spend the rest of the day on my couch with a good science fiction book.---Brian


I greatly appreciate the effort you put into documenting the successes and failures of the build.  The four way valve is an unfortunate mystery.  I am curious about the ball end connecting rods.  Did you just happen to have them on hand, or are there forces acting on them that cause them to roll (as opposed to pitch or yaw)?  Could the cross head have just have been made a bit wider?
Thanks for sharing the adventure.  
Larry


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## Brian Rupnow (Nov 4, 2020)

That went well!!!  I still need to do a bit of hand filing, but very little. These four wheels are straight off the rotary table with no other work done on them. Putting in the windows was not difficult, but was time consuming.


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## Brian Rupnow (Nov 4, 2020)

Larry G. said:


> I greatly appreciate the effort you put into documenting the successes and failures of the build.  The four way valve is an unfortunate mystery.  I am curious about the ball end connecting rods.  Did you just happen to have them on hand, or are there forces acting on them that cause them to roll (as opposed to pitch or yaw)?  Could the cross head have just have been made a bit wider?
> Thanks for sharing the adventure.
> Larry


I have solved the 4 way valve mystery. There wasn't anything wrong with the valve. The crank arm on top of the valve which operated it was too long. This meant that the four way valve shifted too soon. If I had reworked my sliders and the rings at the ends of the boiler I could have arranged things so that the valve shifted position much closer to the end of the piston stroke, and that would let the piston reach top dead center and bottom dead center just as the valve changed position. I used ball end connecting rods because when an engine is made up of multiple bolt together pieces, there is always some "twist" to the con-rods as they move from one extreme position to the other. The ball end allows this to happen without throwing stresses into the engine and causing it to bind.---I may change the ends that connect to the cross-head to be just plain brass ends and let the ball/socket joint at the crankshaft end allow for any "twist" in the system.  I could have made the cross head wider, but it wasn't necessary. It just needed to be wide enough for the con-rods to clear the flywheel and the 108 tooth gear.


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## thegallery (Nov 5, 2020)

Brian Rupnow said:


> I have solved the 4 way valve mystery. There wasn't anything wrong with the valve. The crank arm on top of the valve which operated it was too long. This meant that the four way valve shifted too soon. If I had reworked my sliders and the rings at the ends of the boiler I could have arranged things so that the valve shifted position much closer to the end of the piston stroke, and that would let the piston reach top dead center and bottom dead center just as the valve changed position. I used ball end connecting rods because when an engine is made up of multiple bolt together pieces, there is always some "twist" to the con-rods as they move from one extreme position to the other. The ball end allows this to happen without throwing stresses into the engine and causing it to bind.---I may change the ends that connect to the cross-head to be just plain brass ends and let the ball/socket joint at the crankshaft end allow for any "twist" in the system.  I could have made the cross head wider, but it wasn't necessary. It just needed to be wide enough for the con-rods to clear the flywheel and the 108 tooth gear.


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## thegallery (Nov 5, 2020)

I had the same problem with the lengths of the cylinder rotary valve arm and the speed control arm. Once I shorten them and got the stops on the slide rods set properly it runs very well. You can see a video clip at www.thekilmerplace.com/train%20display.mp4


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## Brian Rupnow (Nov 5, 2020)

I have reached the end. The engine runs very well, and is completely finished mechanically. I started this "design and build" on the last week of August, so it has been about a ten week job. My next step will be to paint the engine and then it goes up on the shelf with all of my other engines. Thank you very much to all of the people that had a look, and thank you for the comments that were made as I progressed with the build. I hope you enjoyed it.---Brian


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## Ken I (Nov 6, 2020)

Thanks for taking us all along for the ride - much appreciated.
Regards, Ken


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## Brian Rupnow (Nov 12, 2020)

A stinky business!!!--Wish I could have done this painting a month ago when it was warmer outside. As things set, I open my big garage door, set out all the stuff to be spray painted, paint it, then move everything into my machine shop so it will dry enough for a second coat. This comes out to four trips into and out of the garage (2 coats on each side). My house smells like a body and paint shop. I am fortunate to have a very understanding wife!!!


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## ShopShoe (Nov 13, 2020)

Brian,

I really enjoyed this one. I like the engine and your posts about it were enlightening. The process of solving all the engineering problems is always a great story.

Thank You for posting.

--ShopShoe


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## Brian Rupnow (Nov 14, 2020)

Thank you Shopshoe.--I am glad that people look at my threads, maybe learn a little something, and are entertained by what is going on.---Brian


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## Brian Rupnow (Nov 14, 2020)

So, the Trevithick is completely finished. The painting was finished 3 days ago, and it was all reassembled this morning and posed for some "beauty shots". I had a few issues with this build which involved the cylinder and the 4 way valve, but in the end I used a more conventional slide valve and finished with a well running engine. Thanks for riding along with me, and saying 'Hi" once in a while. It is a very pretty engine, and now it will go up on my shelf to the place of honour along-side the Stephenson's Rocket.---Brian


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## LorenOtto (Nov 15, 2020)

Brian Rupnow said:


> So, the Trevithick is completely finished. The painting was finished 3 days ago, and it was all reassembled this morning and posed for some "beauty shots". I had a few issues with this build which involved the cylinder and the 4 way valve, but in the end I used a more conventional slide valve and finished with a well running engine. Thanks for riding along with me, and saying 'Hi" once in a while. It is a very pretty engine, and now it will go up on my shelf to the place of honour along-side the Stephenson's Rocket.---Brian


Thank you Brian for another delightful project and for sharing your techniques with us.  Loren


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## Brian Rupnow (Nov 15, 2020)

Thanks guys.--A word of warning---I would not use that brand of paint again. As soon as it dried it started flaking off. I have never had that problem using Tremclad or Rustoleum paints, but the colors are somewhat limited. This paint is "Dupli-Color Perfect Match" sold in aerosol spray cans by Canadian Tire.


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## Ghosty (Nov 15, 2020)

Brian, If the Dupli-Color that you used is the same as we have down here, it needs a primer on steel or etch primer on alloy to work. Loved the build, can't wait to see what you come up with next
.



Cheers
Andrew


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## Rdean33422 (Nov 15, 2020)

So what is next Brian?

Ray


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## Brian Rupnow (Nov 15, 2020)

Ray--I don't know. I pour my heart and soul into building these machines, and by the end of the build I am burned out. Right now my lathe is broken, and back at the suppliers in Toronto for repairs. My next build will be when the lathe comes home, and it will be something to aid a 74 year old man moving a great big heavy lathe by himself, back into a very small and hard to get to machine shop.


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## LorenOtto (Nov 16, 2020)

Brian Rupnow said:


> Ray--I don't know. I pour my heart and soul into building these machines, and by the end of the build I am burned out. Right now my lathe is broken, and back at the suppliers in Toronto for repairs. My next build will be when the lathe comes home, and it will be something to aid a 74 year old man moving a great big heavy lathe by himself, back into a very small and hard to get to machine shop.


Brian, I am sorry you are having trouble with your lathe again so soon.  I'm sure you will come up with an easier way to move it in and out.  Loren


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## Brian Rupnow (Nov 16, 2020)

Loren--I got a call this morning. Trouble was caused by a loose connection at the reverse switch. Lathe will be home on Wednesday. I have designed something to help me put the lathe back in it's place, but will start a new thread for that.---Brian


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## ddmckee54 (Nov 16, 2020)

Brian Rupnow said:


> it will be something to aid a 74 year old man moving a great big heavy lathe by himself, back into a very small and hard to get to machine shop



So I'm guessing that the project is NOT going to be some form of multi-ton bridge crane?
Don


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## Brian Rupnow (Nov 16, 2020)

I will start a new thread on moving my lathe. There is nothing real earth shattering about what I have designed and built, but it is new and a bit different. I am very conscious about the possibility of hurting myself when moving machinery, so people may find it interesting.---Brian


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## johwen (Nov 17, 2020)

No matter what you do or make in the end it is part of you and another great achievement and I'm sure it makes you very proud when you look at at them and reminisce over the hours spent in their making. Well Done! John


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## davidyat (Nov 17, 2020)

*Beautiful work on the Trevithick. I'm still stumbling my way through your "Larger Simple Beam Engine". Still having "learning" experiences. Do something wrong and "learn" not to do that again!!!
Grasshopper*


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## werowance (Nov 17, 2020)

well shoot Brian,  i was looking forward to some complicated mechanical device that you worked through and explained how you did it.  i have enjoyed the trevithich engine build (hope i spelled it right).   i want to say that i appreciate you and all the other members showing the setups and procedures for making all these intricut cuts and describing the procedures to do it.  it really helps and ill have to say i am getting to the point that i can now start adapting the information you all give into other things that i do now.

long story short - thank you for sharing your build and thanks to all the others who do / did the same.


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## Brian Rupnow (Feb 6, 2021)

A big "Thank You" goes out to Rick in Sarasota Florida. Today, in my mail, I received a 3D "stamp" of the Trevithick engine. It's about 0.8" x 1.2" in Bas-relief. Rick said that he enjoyed following my Trevithick build on the forum, so he made the stamp for me.


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