# Stuart triple - types of metals to get



## rhankey

Hi,

I need some help in choosing the right types of metals to obtain for a Stuart Triple Expansion engine that I am just about to start making.

First some background on me as I am new here.

I am just getting my home hobby metal shop going. I have done some metal working 30 years ago, but worked more in wood since then, so I have much to relearn. After searching for roughly 6 months, I was able to get my hands on a nice used Hardinge HLV lathe and building up the tooling for it. I am still on the lookout for a vertical mill.

My first real project will be a Stuart Triple Expansion for which I have the castings, but I am currently making a couple very simple Stuart Oscillators to make sure I am familiar with the new to me lathe, reacquaint myself with machining metal, and to make sure I can achieve the high quality and precision I wish to achieve when I dig into the triple. The HLV is a way nicer and more sophisticated lathe than the tired South Bends and larger tool room lathes Ive previously used, and I am very impressed with how easily the HLV is allowing me to achieve very nice cut quality and equally good precision. I don't care how long it takes me to make the triple, but the goal is to do a very good job of it. The triple is being built as a high quality and attractive show piece which I intend to run, but realistically it will probably not see a whole lot of use.

Enough with the quick background.

I need help/suggestions on what types of mild steel, stainless steel, and silver steel I should be getting.

The mild steel parts include the crank shaft, vertical columns, reversing gear. Most of these pars require a fair bit of machining. It kind of looks like 1018 would be a good pick for most parts, and perhaps 1144 for the crankshaft. Is this reasonable, or should I be using very different alloys?

The stainless steel is for the valve and piston rods, for which little machining appears to be required. I dont have a lubrication system and have not machined stainless before, so Im a little afraid of the unknown. What types should I be looking at?

The silver steel is for the reverse shaft and taper pins. I am not sure what the North American equivalent is for silver steel. The silver steel parts dont seem to require much machining.

I think I am ok in picking out the required brass and phosphor bronze, and have had experience cutting bronze.

I welcome any suggestions you can provide, and I promise to provide some pictures along the way, though it might be spread out over a bunch of time.

Thank you


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## GWRdriver

Hello hankey,
The Triple is an ambitious first project, good luck with it. The first thing to say is if you are in the USA, our equivalent of "silver steel" is drill rod. Simply substitute drill rod wherever silver steel is called for. The water, air, or oil hardening variety all machine about the same.

For built-up crankshafts my preference is for drill rod or ground stainless steel for the main shaft and throw journals, and whatever steel I have scraps of for the throws. As for mild steel, 12L14 is a leaded free-machining alloy and gives a batter finish than 1018 and is popular for that reason. The general preference is for either 303 or 304 stainless, I can't remember which, 304 I think and if I want steel parts to stay bright without oiling them I substitute SS for mild steel. SS, especially a leaded free-cutting SS, can be machined just like mild steel, with or without cutting lubicants, your choice. Hope this helps.


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## rhankey

Thank you Harry for you suggestions. I am in North America. And yes, I appreciate I am taking on a very ambitious first project, especially given that I want to build the engine to a high standard.

What would your recommendation be for a crankshaft made in one piece? I would prefer to avoid the built-up method. I will most likely add the counter weights as separate pieces, per the plans, but am still tossing around thoughts of machining the counter weights as part of the crankshaft, and probably won't make a final call until I see how it is working out. I appreciate a built-up crankshaft might be easier for a shaft that is roughly 9" long by 3/8" diameter and with 3 throws.

I will investigate a lead free SS and 303 & 304 SS, for if SS is as easy to machine as mild steel without lubricants, then that is an easy decision to make given I want the piece to have a bright finish and not be a rust magnet.


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## GWRdriver

hankey,
I don't know the latest and greatest of steels metalurgy but for what it is (a model, not intended for hard work) you could actually use just about anything. But one important factor will be to select something which will have minimal distortion when it's machined - and that would NOT be a cold rolled. Although I'm not an automotive guy years ago (and maybe still) competition crankshafts were turned from 4140, and no doubt there was a good reason for that, so that might be one suggestion. I'll bet someone on the board is far more up to date on this than I am and will have a suggestion.


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## kvom

For turning 303 and 304L are both fine, but 304 can be quite difficult to mill. 303 would be the best choice all around. 304 is also very hard on bandsaw blades.


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## steamer

What KVOM said! 304 is UGLY......303 is fun....
I think it's the nickel content, but I'm not sure.
Dave


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## steamer

If it were me, and I wanted a strong crank, I might go for 1144SP.  If your concerned about rust though, 303 would be just fine.

I think 1144sp machines better and has fabulous properties....like nearly 100000 psi tensile,but is free machining.

Dave

PS the crank on my 12" to the foot boat engine is 303 SS.


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## rhankey

Thanks to all. It sounds like I should use 303 SS for all the mild steel and SS needs, including the one piece crank shaft. Most of these parts will need as much milling as turning, whihc on that count would seem to rule out 304 based on what you guys describe. I will stck with the drill rod for the reversing shaft and taper pins, as I presume they specd that to avoid it twisting at all. I figure I will turn the crank down in stages over a span of a month in the event the material I use has any unequal stresses.

Once again thank you all, and I'll try to provide some progress pictures along the way but I will be taking this project slowly.


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## Bill Gruby

What everyone else has said especially on the 304 Stainless. Give it a wide berth. It is nasty stuff.

 "Bill Gruby"


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## GWRdriver

rhankey  said:
			
		

> I will stck with the drill rod for the reversing shaft and taper pins, as I presume they specd that to avoid it twisting at all.


hankey,
IMHO specifying hardened (or hardenable) pins is more a tip of the hat to tradiiton than actual need. The shear forces present in the engine certainly wouldn't be great enough to require that. I like pinned and cottered and keyed connections, these were the oldest traditional way of making connections, and something you might look into is that the clockmaking world uses pinned connections so small tapered pins and reamers will be available from clockmakers suppliers.


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## mklotz

As I remember, the mnemonic goes like this...

304, she's a whore,
303, she's for me.


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## rhankey

GWRdriver  said:
			
		

> hankey,
> IMHO specifying hardened (or hardenable) pins is more a tip of the hat to tradiiton than actual need. The shear forces present in the engine certainly wouldn't be great enough to require that. I like pinned and cottered and keyed connections, these were the oldest traditional way of making connections, and something you might look into is that the clockmaking world uses pinned connections so small tapered pins and reamers will be available from clockmakers suppliers.



Funny you mention the pinned, cottered and keyed connections.

Stuart's plans show using grub screws to lock the eccentrics and the flywheel to the crank.  I have already decided to deviate from the plan in this regard and use a keyway for the flywheel, as that would seem a much more appropriate interface for the little extra effort. I will likely use a keyway for two of the two eccentrics that can be slid on, and tossing around a couple thoughts for the third eccentric that fits between crank throws. I will just need to be very sure I have the valve timing nailed down before I broach the eccentrics. I hadnt considered the clock making world as a possible source of smaller sized broaches or tapered reams. Makes great sense. I'm actually somewhat surprised they would specify grub screws on a kit that is clearly aimed at a more advanced machinist.


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## GWRdriver

rhankey  said:
			
		

> I'm actually somewhat surprised they would specify grub screws on a kit that is clearly aimed at a more advanced machinist.


Not to detract from their worth as model projects, most of the Stuart engines aren't scale models of anything in particular and poetic license has been taken for utility and simplicity's sake but that doesn't prevent us embellishing and complicating as we see fit. There was a very interesting set of articles published some years ago in Model Engineer magazine on modifying the bones and details of model engines so to make them more faithful to prototypical practice. I'll see if I can find the reference. Then there is the "discussion", running some 40 years now, on which goes on first, the main nut of the jamb nut. Most people don't really care, and I probably count myself in that group.





> I hadnt considered the clock making world


I visited a clock restorer's shop many years ago and noted that most of the components including wheels, shafts, pinions, stanchions, etc, on an ancient Seth Thomas grandfather clock works were pinned or cottered rather than screwed and that stuck with me. Later in life when I began studying the details of older engines, beam engines in particular, I recognized immediately that they too were usually held together by pins and cotters and wedges rather than nuts and bolts.


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## GWRdriver

And with that The _Discussion_ rages on . . . . . ;D


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## ZAPJACK

Congratulations, great project. :bow: :bow: :bow:
to inform you, I build it a couple of year ago. 315 hours of works, but nice engine and run well!!


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## rhankey

Hi All,

I just wanted to post a follow up now that I've made some progress with the Stuart Triple Expansion. As I mentioned previously, this is my first metal working project  a rather ambitious one at that. I wish to thank all for the recommendation to use 303 SS.

I have completed the 8 vertical columns (started with easy parts to get used to the metal), then moved directly onto probably one of the most difficult parts; the crank shaft which I completed yesterday. The finished crankshaft is 11" long shaft (for grins I made mine about 2" longer than specified) x 3/8" diameter with three throws which I chose to make from a single piece of 1.5 diameter bar stock (rather than trying to make a built up shaft). The crankshaft came out perfectly, is dead straight and looks wonderful with a mirror like finish. I couldn't imagine having tried to make this crankshaft if I was also dealing with a more challenging metal. Once I've made and mounted the counter weights, which I'm going to make out of SS too (rather than using the supplied cast iron blanks), I feel like I'll have the courage/confidence to take on the sole plate and cylinder heads for which there are also an abundance of critical measurements that I need to nail in order for everything to align properly. This has been a lot of fun so far.

Again, thanks for the metal recommendations.

I know Ill have more questions in the coming many months as I carry on with the build.


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## Swede

I think you are telling tall tales... post a picture to PROVE that you have produced this wonderful crank from 1.5" solid.  ;D
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(Of course we believe you, we are just picture and video junkies!)   Seriously, if you have a cheap digital camera that you can knock about the shop, you will be glad in the future that you took some images along the way.


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## rhankey

I understand - pictures, or it didn't happen...

I've not dealt with uploading pictures before to this site, and my camera lens lacks a macro setting, so what is in focus appears to have blemishes that aren't in the real crankshaft.


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## Groomengineering

Nice looking parts, and the pic is fine. Thm:

Cheers

jeff


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## dalem9

HI great looking crank .Kozo tells how to do this too . I've been going to try it. Agian great job! Dale


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## ShedBoy

That crank looks great.

Brock


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## Swede

Agreed, and from solid makes it even better. Nicely done!


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## rhankey

Attached is a shot of the completed crankshaft with counter weights. Once again, a camera expert I am not. I chose to make the counter weights from SS flat stock rather than use the supplied castings so they would match the appearance of the crankshaft. I got my first taste of a bunch of hard spots which chewed up a couple cheap end mills. If I find any more hard spots in that bar, I may see if one of our area potters could stick the bar in the kiln when they fire some pottery - I assume a pottery kiln would get hot enough and cool down slowly enough. At some point I will need to cut a keyway slot in the flywheel end of the shaft, but I will wait until later when I know the exact location of the flywheel.

I think it is time to break out the first casting. I think I should machine the sole plate next, then main bearings.


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## steamer

I think the sole plate should be a good place to start. 

A couple of karma points from me.....multilobe cranks are NEVER easy.

Dave


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## doubleboost

:bow: :bow: :bow: :bow:
John


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## rhankey

The sole plate and main bearing keeps are now done. The sole plate was my first introduction to working with cast iron. What a filthy dusty mess cast iron makes. But it appears to be a pretty soft and easy material to cut. I also got to use my boring head for the first time, which produced a beautiful finish and perfectly sized hole. Below is a photo of everything that I've built so far loosely bolted together. Everything appears to align perfectly so far.

I think I should make the main bearings next.

However, I have a question... How much clearance should I allow between the bearings and the crankshaft so that there is enough room for oil and a minimum of friction yet not so loose that the crank will rattle within the bearings? Stuart specifies 3/8" for the crank and bearings and they assume the builder knows to adjust dimensions accordingly for appropriate fitting and movement. I machined the crank to .3745" figuring I will need at least .0005" of clearance. The bearings are gunmetal (which I understand to be quite slippery) and the crank is SS 303. is it advisable to machine the bearings to a tight fit, then assemble everything with a fine abrasive to lap/bed the bearings and crank to a perfect fit with the crank chucked to a slow speed drill or the lathe? If so, what clearance should I machine to, and what clearance should I be achieving after bedding such that there is enough clearance for oil? And if I don't need to bed/lap the bearings to the crank, what should the clearance be?


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## Swede

VERY nice crankshaft! That engine is going to be a jewel!  :bow:


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## pete

Rthankey,
VERY nice job so far on that engine. I'm only going from memory and it could be faulty. Years ago Model Engineer did a write up with the full "How to do it" for this engine. If? I remember correctly the author built a simple lathe faceplate fixture, Machined all of the bearing blanks to the exact same size, And then used the fixture to position each bearing for drilling,boreing, and reaming. You then end up with all the bearings dead in line with each other once their bolted down into the soleplate. If my magazines weren't in storage I'd check to be 100% sure of my facts.

As far as what tollerances that should be used between your bearings and crank? I wish I could help you. For the prices charged for the castings and drawings I think that adding those dimensions would be the least they could do. But if it was me I'd email Stuart Turner and I'm sure they would provide that information. The few times I've emailed them they were very good about answering my emails.

Pete


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## rhankey

Thanks Pete.

A number of months ago I was able to track down copies of all but one of the articles in Model Engineer on the build of the Stuart triple. Given how new all of this is to me, it was very informative seeing how someone else tackled making the exact same parts I was going to have to be making. Ive been learning quickly that there are as many right ways to make a part as there are people doing this stuff. Despite how new all this is to me, Im surprised at how quickly Im finding my own unique ways of making the parts. Perhaps some of my methods might not be the best, as I lack the experience and wisdom and still working with a somewhat limited set of tools and scrap metal.

I did make the main bearings over the weekend. The big relief was that the crankshaft, bearings and crankshaft all fit together perfectly on first attempt. I cant tell you how much of a relief that was, as I had invested a heck of a lot of time into making the individual parts with no way of knowing if any of was going to fit together before this. The crank turns smoothly, but I think it is a little too stiff for what I think is acceptable, so I will hone the bearings a bit more to get it turning more freely.

Like the crank, I built the bearings a little differently than the author suggested. He temporarily soldered the halves together and built a jig that mimicked one of the sole plate webs to use as a boring jig. I saw insufficient benefit in gluing the halves together so didnt. And I saw no point in building a boring jig when I could use one of the webs of the actual sole plate as a boring jig. I simply mounted the sole plate vertically on a right angle plate, and used the top most web as my jig. Seemed far simpler and ended up with the same end result of all four pairs of bearings being perfectly aligned. Prior to boring, I also stamped each half so it was very clear which halves belong together and which went on top/bottom. As I mentioned previously, I need to hone the holes in the bearings a little more to sneak up on what feels like just the right amount of clearance. Im sure more seasoned builders would know exactly how much clearance is needed and got there in one step. Ill take longer to get to that end goal, but Im probably going to end up at the same result.

I may wait with final honing of the bearings until I make and install the flywheel, as I think turning the flywheel will give me a better feel on what is loose/tight enough. I ordered a keyway cutter and broach this morning, as I dont like the idea of using the specified set screw to attach the flywheel to such a smooth small diameter crank.

Unless folks here know, Im going to have to contact Stuart at some point with respect to the placement of the eccentrics. The IP cylinder eccentric is clear, as it is in two pieces in order to mount it in the middle of the shaft. But for the other two eccentrics which simply slide on the ends of the crankshaft, it is not clear which is for the HP and the LP cylinders. One of these has a 30% angle while than the other two (including the IP) specify a 15% angle.

Heres the what I have with bearings installed.

Robin


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## pete

Robin,
Obviously your method worked very well. Yeah different equipment, experience, past results make a large difference for how you do any job. 

I'm guessing you turned your crank between centers with center drilled holes drilled off set for each crank throw? I'd be interested how you set that up to get each end of the crankshaft blank drilled for those centers and exactly the same for each end of the crank. That's not exactly an easy job to get every thing perfect to get the crank throws correct and in the right position for the degrees of rotation. Over and above making a finished straight crankshaft from solid, The machining setup is just as hard if not harder to manage to do accurately also. Your engine is on a list long enough I may never get to it, But I am interested in how you did it.

Pete


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## Dan Rowe

rhankey  said:
			
		

> However, I have a question... How much clearance should I allow between the bearings and the crankshaft so that there is enough room for oil and a minimum of friction yet not so loose that the crank will rattle within the bearings? Stuart specifies 3/8" for the crank and bearings and they assume the builder knows to adjust dimensions accordingly for appropriate fitting and movement. I machined the crank to .3745" figuring I will need at least .0005" of clearance. The bearings are gunmetal (which I understand to be quite slippery) and the crank is SS 303. is it advisable to machine the bearings to a tight fit, then assemble everything with a fine abrasive to lap/bed the bearings and crank to a perfect fit with the crank chucked to a slow speed drill or the lathe? If so, what clearance should I machine to, and what clearance should I be achieving after bedding such that there is enough clearance for oil? And if I don't need to bed/lap the bearings to the crank, what should the clearance be?



I have a few Stuart casting sets and your question made me realize that I also do not know the answer on how much clearance to add to the bearings for the oil. For a full size engine I would look in one of the engineering books on my shelf. I am looking forward to see more progress on this engine.

The crank looks just like a 3 cylinder Shay locomotive crank Which had all the eccentrics keyed to the shaft. This is why I am really interested in calculating the angle of advance as it is set on the crank with no easy way to change it after the fact. Shays had a split center eccentric but it was still keyed on the shaft.

Dan


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## rhankey

pete  said:
			
		

> I'm guessing you turned your crank between centers with center drilled holes drilled off set for each crank throw? I'd be interested how you set that up to get each end of the crankshaft blank drilled for those centers and exactly the same for each end of the crank. That's not exactly an easy job to get every thing perfect to get the crank throws correct and in the right position for the degrees of rotation. Over and above making a finished straight crankshaft from solid, The machining setup is just as hard if not harder to manage to do accurately also. Your engine is on a list long enough I may never get to it, But I am interested in how you did it.
> 
> Pete




Pete,

Sorry for the long post, but this is how I turned the crank:

*Centre drilled each end* - I mounted the bar in a 3 jaw chuck and supported the other end with a steady rest, as the 1.5 bar was too big to slide into my 5C headstock.

*Centre drilled each of the throws*  I mounted the bar in the lathe between centres. My headstock lock pin just so happens to engage at 3 perfectly equidistant positions per revolution, so I simply locked the head stock, and scribed both ends of the bar with a cutting tool at the same time, then moved to the next headstock lock position. This ensured both ends were perfectly aligned to one another. I dont have a drill press, and the bar was too long to drill vertically in my mill, so I used my mill with the head rotated horizontally to drill the three centre holes on each end for the throws.

*Turn each of the throws*  I did all of this on the lathe. I mounted the bar between appropriate centres for the throw, but rather than driving the bar with a lathe dog, I used a slightly longer handmade centre in the collet closer and a 4 jaw chuck. The centre aligned the bar, to which I snugged the 4 jaw chuck. The 4 jaw chuck was meant to provide greater rigidity to the bar, and thus reduce/eliminate chatter. I started with the middle (IP) throw, then did the throw closest to the chuck, then flipped the bar and did the remaining throw now closest to the chuck, thus always working as close to the most rigidly supported end as possible. As I finished turning each throw which I cut using a parting tool (it was a pretty deep and narrow slot), I mounted the bar back in the centre holes to the bar and checked and corrected any run out that was found. I had to make minor bending corrections. Then I crazy glued in three precisely cut spacers around the edge of the gapping slot so that the bar would behave like I hadnt carved most of the material away already. Im not sure this next step was necessary, but I also chose to tape a couple well sized boring bars to the bar by the tail stock end to act as counterweights. I repeated the cycle for each throw.

*Turn the main shaft* - With the bar mounted between centres and using the 4 jaw chuck as a driver I started by turning down ½ to a few thou over final diameter at the tailstock end.  Then I removed the chuck, flipped the bar and mounted the freshly turned stub in a collet, and turned a similar nub on the other end too. I then turned the section of the shaft closest to the headstock to finished size, while supporting the other end in a tailstock centre. I then slid the finished bar all the way into the collet, leaving me a much shorter bar between the collet and tailstock centre, and turned the next section of the shaft thats between two of the throws and is closest to the headstock. Then I flipped the bar and repeated the same from the other end. When coming from the other end, I double checked that the already turned portion of the bar was perfectly centred, and made minor bending tweaks if needed, otherwise the completed crank will bind when mounted in the bearings.

*Cut the flat parts of the journals*  I removed the crazy glued spacers and took the bar over to the mill. The milling work was quick and easy work.

I thought I was going to use a steady rest more than I did, but it really wasnt needed. If the crank had to be much longer, I might have needed a steady rest when turning the crank around to turn the second outbound main section of the shaft, as that is the only time I felt like I needed to be a little lighter with the cuts. My completed crankshaft tested to <.001 of dead straight when I was done which I was plenty happy with.

Robin


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## pete

Robin,
Very clever and thank you for the time spent answering my question. It's very much appreciated.

Pete


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## rhankey

Dan Rowe  said:
			
		

> I have a few Stuart casting sets and your question made me realize that I also do not know the answer on how much clearance to add to the bearings for the oil. For a full size engine I would look in one of the engineering books on my shelf. I am looking forward to see more progress on this engine.
> 
> The crank looks just like a 3 cylinder Shay locomotive crank Which had all the eccentrics keyed to the shaft. This is why I am really interested in calculating the angle of advance as it is set on the crank with no easy way to change it after the fact. Shays had a split center eccentric but it was still keyed on the shaft.
> 
> Dan



Dan,

I have tossed around using keyways to mount the eccentrics too (Stuart specifies set screws), but I'm a little scared at the thought of finding that I need to rotated then a little later on. And I would have to use an end mill to cut keyway for the IP eccentric as it is wedged tightly between a throw and a bearing. If I can think of a way of temporarily locking the eccentrics in place with glue so I can test run the engine, then I might feel perfectly at ease with keying the eccentrics into final position. With Stuart's eccentrics for forward and reverse being milled from one piece of metal, it would seem to my inexperienced mind that I really can't make any adjustments anyway, as adjusting for one direction would be at the expense of the other direction of rotation. I will have to think on it a bit more. I dont know if the eccentrics for your locomotive are made any differently than Stuarts.

I will keep posting periodic updates in this thread to the on-going build. It might take a while for me to complete the engine, and I've probably hijacked my original thread title.

Robin


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## steamer

The old rule of thumb is. 001" / 1 inch of diameter should work just fine.
Dave


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## Dan Rowe

Robin,
You are correct if both eccentrics are made from the same piece of stock there is no adjustment that can be made they have to be fixed to the crank in the proper location. You could consider a taper pin for the IP cylinder and keys for the HP and LP.

I suspect that is is the LP that has the 300 for the angle of advance. If you know the lap of the valve which can be calculated from the drawings the sine of the angle of advance is (lap+lead)/(1/2 valve travel). Hey I just worked that out in my valve diagram thread. 
http://www.homemodelenginemachinist.com/index.php?topic=15939.msg163740#top

Dan


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## Dan Rowe

Robin,
The other thing about the eccentrics if made from the same piece of stock is the Hp and Ip cylinders face the same way so both eccnetrics are the same hand. The Lp cylinder faces the other way so if the Hp/Ip eccentric is right handed then the Lp eccentric is left handed. I know this because I made two of them the same way for a 2 cylinder Shay and there was no way I could flip one around to work the other cylinder correctly.

The main reason I am atracted to Shay locomotives is it is really a marine engine that got lost in the woods. All Shay cylinders were Hp cylinders other than that it was a typical marine engine on a locomotive boiler.

Dan


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## rhankey

Dan Rowe  said:
			
		

> Robin,
> The other thing about the eccentrics if made from the same piece of stock is the Hp and Ip cylinders face the same way so both eccnetrics are the same hand. The Lp cylinder faces the other way so if the Hp/Ip eccentric is right handed then the Lp eccentric is left handed. I know this because I made two of them the same way for a 2 cylinder Shay and there was no way I could flip one around to work the other cylinder correctly.
> 
> The main reason I am atracted to Shay locomotives is it is really a marine engine that got lost in the woods. All Shay cylinders were Hp cylinders other than that it was a typical marine engine on a locomotive boiler.
> 
> Dan



Dan,

I just scanned your thread on computing valve timing. I'll definitely need to give that a much closer read when it comes time to make the eccentrics and valves. If I do deviate from set screws for attaching he eccentrics, I think I'd prefer to use keys even for the IP where space on the crankshaft is very tight over taper pin.

I just checked the Stuart drawings with respect to your heads-up on the left and right handed eccentrics. Unless I am missing something (having not carefully read your valve timing thread yet), I think all the Stuart triple eccentrics are same handed. I say that as all appear to mount to the crankshaft the same way around, and the drawings for each are identical other than one having 30deg vs 15deg, and one being split. And in checking a hi-res photo of a completed engine from Stuart's website, it appears the eccentric rods all attach in the same way too. I'm not seeing where the LP is reversed in orientation or in operation to that of the other cylinders. Am I missing something?

Robin


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## Dan Rowe

Robin,
The eccentrics might be a little different than on a Shay. First I am thinking all D slide valves with outside admission. The thing to check for the eccentrics is ALL the ahead rods connect to the same side of the link and ALL the astern rods connect to the other. 

If they are all D slide valves the angle relationship will be the same to the crank pin of the respective cylinder. Which rod is closeer to the connecting rod might be different than a Shay. My tale was only ment as one way to goof up.

When you say 30 degrees and 15 degrees is that the angle to the axis for each eccentric or it is it the angle between the eccentrics? A sketch would be helpful. The thread on valve diagrams will tell you how to calculate the lap with the drawings.

Dan


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## rhankey

Dan Rowe  said:
			
		

> Robin,
> The eccentrics might be a little different than on a Shay. First I am thinking all D slide valves with outside admission. The thing to check for the eccentrics is ALL the ahead rods connect to the same side of the link and ALL the astern rods connect to the other.
> 
> If they are all D slide valves the angle relationship will be the same to the crank pin of the respective cylinder. Which rod is closeer to the connecting rod might be different than a Shay. My tale was only ment as one way to goof up.
> 
> When you say 30 degrees and 15 degrees is that the angle to the axis for each eccentric or it is it the angle between the eccentrics? A sketch would be helpful. The thread on valve diagrams will tell you how to calculate the lap with the drawings.
> 
> Dan



Dan,

I have attached a side view of one of the eccentrics for clarity. As i mentioned previously, the other two are the same, except they are 15deg and the IP one is split to mount it in the middle of the shaft. I have also included a photo from Stuart's website of the completed engine. so you can see the location and arrangement of the valve ports and the valve linkage. As you guessed, the HP and LP valves are on the outsides, but despite that all three eccentrics face the same way. I very much appreciate the heads up, as it could have been very easy for me to have not noticed if one of the eccentrics was reversed from that of the others.

With all this talk of the eccentrics, I think I might work on them and the flywheel next, and thus complete everything that attaches to the crankshaft. With more thought overnight, I'm now leaning heavily towards keyways for all three eccentrics. The same jig I intend to make to machine the eccentrics should also make it easy to nail their alignment to the crankshaft too. I'm also thinking it would look better if I made the eccentrics from SS rather than the supplied cast iron blanks.

Robin


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## Dan Rowe

Robin,
I do not have the Stuart triple but I do have a set of 6A castings and drawings. I will try my advise about the angle of advance on the 6A and report back. It looks like I was wrong as the Hp has a greater angle than the LP on the 6A so I should see more lap on the HP than the LP.

I also see that it looks like a D slide valve for all the cylinders. That is very important as the eccentrics would flip 180 degrees for piston valves.

As for the eccentrics being reversed the photo tells the story. Lets just say that the photo shows the engine set for ahead operation. Now looking at the LP cylinder the ahead rod is closer to the bed plate and bearing. Now if we look at the HP cylinder we can see that it is the astern rod that is close to the bed plate. With a Shay the last part would be reversed. So yes the eccentrics are handed but they are handed the same way so my concern was not justified.

Dan


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## Dan Rowe

Robin,
I am posting the Bilgram diagram for the 6A which shows the valve and where to measure the lap which is the radius of the circle on a Bilgram diagram.

Now knowing only the information you provided, I drew a Bilgram diagram for the Stuart triple expansion. 

This is why I feel that a Bilgram is so useful. I have answered your question that can be verified by the drawings using very little information from the drawing set.

I will post the information on how to construct a Bilgram diagram next on the valve diagram thread.










The other important bit is where on the crank do you cut the key slot? I will draw a sketch that shows the correct orientation for Stephenson valve gear with D slide valves and open rods.

Dan


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## rhankey

Don,

Wow, this is wonderful what you are computing for me.

The valves for the triple must be a little different than for your Stuart twin. I have attached a diagram of the HP valve and valve ports. In studying the drawings, the HP, IP & LP all share the exact same vertical dimensions for the ports and valves. the only differences I see is that the IP and LP are each progressively wider.

Does this change your belief that the LP is the one that gets the 30deg eccentric?

I figure I should locate the keyways at 180deg from that of the crank throw to which the eccentric belongs. In other words, if the piston is at TDC, the keyway will be at BDC. This give me the most meat to work with in the eccentric. The LP eccentric and flywheel will share the same keyway. And I'll extend the HP keyway to end of the shaft too. This might sound a little anal, but the only minor downside of this approach is that the three keyways will be 120deg out of phase with one another, which for the two outbound keyways might look a little odd. But I think function supersedes looks. Does this sound right to you?

Robin


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## Dan Rowe

Robin,
The Bilgram diagram is a graphical calculator and like the more modern ones 'garbage in'... 'garbage out'. 

Well I clearly blew it with the valve travel. I looked at the eccentric and my brain said 3/8" valve travel. That is just not true.
I checked the reverse gear for the Stuart 7A and there is a note for the throw of the eccentrics. The throw is half the valve travel and that is what is needed for the Bilgram diagram.

Can you tell me what is the throw of all the eccentrics?

Looking at the HP ports and valve the distance to the outter edges of the steam ports is 1/2" and the valve is 5/8" tall so the lap is half that distance or 1/16". From what you said the IP and the LP should have the same lap. That is why I am thinking different valve travel as the only thing left is the lead and that is usually very small or zero on a model.

The valve also has a bit of inside lap but that will not change anything. The 6A also has inside lap but I did not show it on the valve or the Bilgram diagram.

Dan


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## rhankey

Dan Rowe  said:
			
		

> Can you tell me what is the throw of all the eccentrics?



Sorry Dan, I should have provided you the throw/valve travel. All three cylinders specify a 5/32" throw for the valvss, or a 5/16" travel (in the event you are having another blond moment that we all have from time to time). Other than the width of the ports getting wider from HP to LP, and two eccentrics being 15deg and the third being 30deg, I'm not seeing any other differences.

Robin


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## Dan Rowe

Robin,
No worries, I should have looked at the drawing more carefully instead of charging ahead with a bogus answer.







The % numbers are 100% piston stroke and the cut off as a percent of piston stroke. The 6A has 60% cut off for the HP and 85% for the LP. 

That is why I now think that for the triple the HP has a 300 angle of advance and 80% cut off, and the IP/LP has a 150 angle of advance and 89% cut off.

The Bilgram diagrams show 1/64" lead for the HP and 1/64" negative lead for the IP/LP.

Dave AKA steamer or anyone else with triple expansion experience.....does that float or not?

Dan


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## steamer

Hi all

Sounds like the right neighborhood....ill need to review it to be sure

Generally, marine compounds and triples ran as long a cut-off as possible for maximum power and then relied on "linking up" to obtain economy.

Ill type more later

Dave


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## Dan Rowe

Dave and all,
I had my dimensions set to fractions for the lead not the best practice but I know that Stuart uses fractions in the drawings.

Anyway there are only two places to put the 300 eccentric on the HP or the LP. The IP is fixed at 150 because it is split.

Here are the Zeuner diagrams for the valve with both 30 and 15 degrees. Believe me it took longer to get the numbers with the Zeuner program. Well maybe not cause I did the Bilgram diagrams twice, but still I think cad and Bilgram is the way to go. I have nearly finished the post on how to construct one.

Dan


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## steamer

The diagrams will tell you the cut off between the cylinders, but you will need to construct a theoretical indicator card (PV diagram) to determine the power developed in each cylinder as a function of cut off, compression, release ect.   Generally, in small engines....you don't need exhaust lap as the parts are not going fast enough to need cushioning, and there is tons of condensate anyway.


Check out Cecil H. Peabody

The Thermodynamics of the Steam Engine

http://www.archive.org/details/thermodynamicsof004310mbp

He has a full set of equations to compute the theoretical idicator card for a triple and compound.

Dave


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## Hilmar

As per Stuart Turner print: The HP is 30° the others are 15°, Throw is 5/32"
All are same handed.
Hilmar


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## rhankey

Hilmar  said:
			
		

> As per Stuart Turner print: The HP is 30° the others are 15°, Throw is 5/32"
> All are same handed.
> Hilmar



Thank you Himer and Dan for letting know which cylindre has the 30deg eccentrics.

Hopefully I can find some time to start making the eccentrics in the coming days.

Robin


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## Dan Rowe

rhankey  said:
			
		

> I figure I should locate the keyways at 180deg from that of the crank throw to which the eccentric belongs. In other words, if the piston is at TDC, the keyway will be at BDC. This give me the most meat to work with in the eccentric. The LP eccentric and flywheel will share the same keyway. And I'll extend the HP keyway to end of the shaft too. This might sound a little anal, but the only minor downside of this approach is that the three keyways will be 120deg out of phase with one another, which for the two outbound keyways might look a little odd. But I think function supersedes looks. Does this sound right to you?



Robin,
It was Hilmar that had the definite answer. My method would have worked if the lap for the valves were different.

As to the question as where to put the key way on the shaft well that really depends on where the key slot is cut in the eccentrics. It is normally in the thickest section. I made a sketch of the arrangement for open rods that are used for marine engines with link motion.







I checked the reverse gear assembly drawing for the Stuart 7A and the crank pin is not shown and the eccentric does not have a key so the position of the crank pin is NOT fully specified in the Stuart prints. Checking the prints for the Stuart Cygnet which is really a 5A with an auxiliary package, I see the key on the crank is on the same side as the counter weight. This matches the sketch in this reply.

I hope that the print for the triple has a clear sketch of this issue because as I see it the photo you posted in reply #39 shows the engine has crossed rods.

I usually check Don Ashton's book on Stephenson link motion for the correct location of the crank pin for the various things that can change it like rocker or piston valves. In this case I also checked Peabody's book on valve gear and my sketch agrees with both books.

Looking at the photo it shows the HP cylinder at BDC just like the sketch, however the rods are crossed which is in my opinion is wrong. With the crank pin in that position the rods should be open NOT crossed as the photo shows.

My sketch is the way it is shown on the Stuart Cygnet and it is how a Shay would be assembled.

Dave thanks for the tip on Peabody's other books. I have a similar book by William Ripper but I know that Peabody was the head of the Marine Engineering Dept. at MIT and recommendations do not get much better than that. I will run the 6A design through the Peabody formulas. I found several of Peabody's books in new reprint form.

Dan


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## rhankey

Dan,

Your diagram matches where I had intuitively planned on locating the keyways for each eccentric, which is opposite of the associated piston's TDC. I'm going to proceed with that.

Robin


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## Hilmar

Before I would key the parts, I would assembly everything and set the timing and then I would Key things. How do you set the timing if parts are keyed?
Hilmar


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## Dan Rowe

Hilmar,
Moving the eccentric changes the angle of advance. That is not the same thing as timing the engine.

As Robin already spotted there is only one correct way to set the eccentric if both eccentrics are made from the same lump of metal.

The best way to adjust the timing with a keyed eccentric that is common to Shays and marine engines is to adjust the length of the valve rod. Some engines had adjustable eccentric rods and the timing can be changed that way also but that leads to other issues.

I am thinking that this engine has a threaded upper end for the valve rod and that engages a nut on the rod that fits in the gap on the back of the valve.

To time a cylinder the gear is put in full gear and the lead is checked at TDC and BDC the lead is equalized for both BDC and TDC then the same thing is checked for full gear in the other direction.

Dan


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## rhankey

Hiimar, As Dan points out, with forward and reverse eccentrics machined as a pair into a single piece of metal, no real adjustment of the eccentrics is possible. Rotating the eccentric to adjust timing for one direction, will hurt the other direction. As such, there is really only one position for the pair of eccentrics. If the eccentric were separated for each direction, I would definitely want to provide for adjustment.

And yes Dan, the length of the eccentric rod is adjustable with a nut at the valve. This won't correct advance issues, but will ensure the valve is centred over the valve ports correctly.

Robin


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## Dan Rowe

Robin,
The other thing I checked for the crank pin position was the eccentrics I mentioned. I had to separate one of them to make the other hand eccentric. I now use then for a drafting tool so I make double sure I never make the same goof again.

Here is the pair with both ends set at BDC. The screws for the blades and the saddles are 00-90.




Dan


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## rhankey

The three eccentric sheaves and the flywheel are done and all are keyed to the crankshaft, as can be seen in the attached photo. The eccentrics were almost as difficult and time consuming to make as the crankshaft, with each having three centres to be turned. One of the three eccentrics is split in half so it can be installed between two of the crankshaft throws. I had to draw a double size scale drawing to figure out exactly where to locate the two cheese head screws that hold the split eccentric halves together, as I opted to install the screws before I started machining the blob of metal that Id cut in half. Fortunately, the holes and screws ended up dead on where they needed to be in the finished eccentric.

I'm almost afraid to mention how I broached the eccentrics and the flywheel, as some might disapprove, but it might come in handy for others. Being new to metalworking, I lack a press (among many other tools), and can think of numerous more basic "pressing" tools that I could make much greater use of. So, I misapplied my milling machine vice. By temporarily removing one of the large hex cap screws that hold the removable jaws in place, I was able to use the vice to drive the broach cutter through the bolt hole in the vice. The bolt hole wasn't quite as deep as the broach, nor was the travel of the vice jaws, so once I drove the broach halfway through, I'd back off, and slip the broach through a couple large sockets, then drive the broach the rest of the way through. The flywheel was too large a diameter to broach between the jaws of my vice, so I broached between the back side of the vice and a right angle plate, both of which I clamped to the milling machine table. This alternate method would allow me to easily broach a flywheel up to about 8" in diameter. The stainless steel eccentrics took a fair bit more force to broach than the cast iron flywheel, but I was amazed at how quick and easy it was to do the broaching. It took way more time to slot the crankshaft and to make and fit the keys. Hopefully this helps others who might have been afraid to try broaching.


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## rhankey

It has been a while since I have posted any on-going progress photos, due in part to a little less time in the basement of late and slogging away on a lot of little parts that don't show for much. I have now completed most of the reversing gear parts as shown in the first photo. The second photo includes little oil cups that I added to the eccentric straps, which Stuart does not specify but seemed like a wise idea. Those 6 oil cups are so small, they all fit on a head of a dime. The eccentric straps and rods where much more time consuming than I would have anticipated due to the numerous very delicate machining steps required.

I feel like I still have much to learn, but with what I have built to date on this engine, I am feeling much more confident as i tackle parts now, and have a much better feel for what I am doing.

I think I will tackle the guide bar next, which mounts across the lower portion of the rear vertical columns. Then I will make the reverse shaft bar and the reversing crank shaft and crank handle. The reverse shaft specifies a rather small 2 start thread that I am now looking forward to tackling.

Robin


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## smfr

Very nice looking work! Can't wait to see this one progress more!


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## rhankey

Thanks Simon. You will need a heeping dose of patience, as other than a couple other loose parts, that is all I have accomplished in the little spare time I have had in the last six months or so. At this rate, it will be another year before it is likely to be complete.


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## steamer

That is coming along nicely Robin!

Keep it coming!

Dave


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## rhankey

I've made a bunch of parts since the last update.

Today, I decided it was time to tackle the 2-start 3/16"X20 TPI threads for the reversing handle shaft and corresponding nut. I feared this more than making the crankshaft, and it sounds like others who have made the triple have also feared making these threads. This was the first threads I've cut on my lathe, and it was roughly 35 years ago since I cut one or two single start threads on a lathe in a high school metal working class. It went without a hitch.

I gotta say, thread cutting is almost too easy to do on my 50 year old Hardinge HLV, and you gotta wonder why more lathe manufactures haven't copied some of Hardinges very thoughtful but simple lathe cutting features.

In short, once I had everything setup it took less than 5 minutes to completely cut the external threads. The process was as follows:
Set right and left automatic carriage feed stops so it automatically stops the carriage at the shoulder on the left, and just before the 3 jaw jacobs chuck on the right that I was using as a steady rest.
Set gear box to 10TPI (20TPI / 2, since it's a two start)
Set compound to 59deg, and zeroed both the compound and cross slide to zero with the bit just touching the piece.
Cut first start thread. The HLV automatically stops the feed when it hits the carriage stop, so all I have to pay attention to is flipping a lever to retract the compound at end of cut (which does not upset the dial settings). I then fed the carriage to the right until it automatically stops at the right carriage stop. Then I reset the lever that retracted the compound, dial in the new depth of cut on the compound, and repeated the process again. The carriage stops work so well, that you can actually cut at up to 1000RPM, though being my first threading experience, I took it slower.
Once the first thread start was complete, I disengaged the threading gear box from the main headstock spindle, rotated the spindle exactly 180 deg, and re-engaged the threading gearbox. I learned this trick by accident from a Hardinge forum a few days ago, and takes all the hartache out of cutting multi-start threads. The headstock is attached to the gearbox with a 48T gear, so 1, 2, 3, 4, 6, 12 or 24 start threads can be done with ease.
Cut the second start thread just the same as the first start.

The internal thread was the exact same process, but I had to use a miniature carbide boring bar that was about as stout as a paperclip. and only about 1/16" longer than hole I had to cut. I had to be very careful retracting the compound so the bar did not scrape or cut as I withdrew it from the hole. As a result, it took me about 20 minutes to cut this thread. I broke the cutting bar on the very last cut - I was just chasing the cut I made, so it wasnt really necessary. Fortunately, the two parts fit perfectly so I don't need to get another cutter and remake the nut.

Here is a picture of the finsihed threads (still oily from coming straight off the lathe). I still have to machine the reest of the shaft.

Robin


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## Swede

Excellent write-up. I have to agree, threading with the HLV feels like cheating. It's almost too easy. The Hardinge methods works especially well for internal threads. You can cut a thread relief groove only 0.062" wide in the ID, and set up the lathe to kick out when the tool enters that 0.062" relief groove. I've noticed that the kick-out mechanism is good to within maybe 0.020, meaning the lead screw disengages plus or minus 0.010" every time.

Good tip with the multi-start thread, BTW.


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## rhankey

Swede, I agree, compared to my distant memory of cutting a couple threads on a SB 9" and a large tool room lathe 35 or so years ago, threading on an HLV is like cheating.

I found that I had to set the spindle speed before setting the carriage stops. The stops kick out very predictably for any given spindle speed. But if I changed the speed, then the carriage stops needed readjusting. A slower spindle speed seems to allow the carriage to travel futher beyond the stops than a higher spindle speed.

Robin


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## rhankey

I have finally finished the reversing gear and piston guide bar assembly. the only deviation from plans is with the reversing handle, as I did not really care for the look of the reverse handle shown in the plans. I am starting to feel rather comfortable with using the rotary table for profiling now, as can be seen with the guide bar bracket. That part required 30 seconds of minor file clean-up work after it came off the rotary table. I was a little disappointed that the castings for guide bar bracket and one of the four reversing rod brackets was a little light on metal, no matter how I positioned the part for machining, which made life a little more difficult.

At this point, I believe I have about 50% of all the parts completed. I think the next parts on the agenda will be the connecting rods and their associated bearings. Then I think I will have to start on the cylinders.

Robin


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## Swede

Looking great!! You are obviously experienced at hand finishing metal. I'm seeing crisp edges, no tool marks, and a nice finish overall.

I love the crank handle in the first picture. What is the size of that base casting?


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## rhankey

Thanks Swede,

The sole plate is 3.5" x 6", not including the bump outs for where the two pumps mount on the rear. The columns are about 4" tall, and I made the crank about 11" long. Some of the parts, like the undulating gunmetal guideplate bracket required essentially no cleanup (about 1 minute of filing and sanding). Some of the parts have required hardly any sanding or cleanup.

Robin


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## Blogwitch

> I hadnt considered the clock making world as a possible source of smaller sized broaches or tapered reams.



Last year, I started again to use castings, and so wanted to gear myself up to use tapered pins for a lot of the joints (I like to be able to get things apart easily, but retain perfect alignment).

I purchased a set of these tapered reamers, and although there is no picture of them, I can attest that they are very good quality indeed, and at a fraction of the cost of buying single units. They only come in a very small package, so postage to the US should be relatively little.

http://www.tracytools.com/index.php?route=product/product&path=20&product_id=567


John


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## Swede

A late reply, but I can vouch for those taper pins being superb at what they are designed for. I used them to assemble the crankshaft components for my large radial engine, and once driven in, using a hydraulic shop press, they are NOT coming out.

It can be a bit tricky to ream to a correct dimension/depth. Like any slow taper, if you ream too much, the pin drops in with no force; too little, and even under severe press load, they'll only go 2/3 of the way. Experimentation with scrap of similar metal is a good way to figure out how much to ream. Then, a little tape on the reamer marks the spot.

A good goal is perhaps just a few percent of the fat end of the pin standing proud of the hole... the excess can then be ground off.


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## rhankey

It has seems like a long time since providing some update pictures. There have been a lot of little parts to make and not quite as much time to spend in the basement lately. Other than the air and water pumps, I think I have now completed the bottom end. Like the eccentric straps, I decided to add some oil cups for the connecting rod bearings. Since there was no space to add the cups directly to the bearings, I opted to attach the cups to connecting rods. So far everything seems to align perfectly with mating parts. The real acid test will be when it comes time to attach the cylinder head to the bottom end.

So far I have only found a couple minor mistakes on the plans. The supplied bolts for the drag links were too short, as it would appear Stuart changed a couple dimensions for the drag lings at some point but forgot to update the affected bolts, so I had to make my own drag link bolts. I also found that they forgot to specify or include the nuts for where the valve rods attach to the expansion links, so I will need to get into the nut making business too.

I have not decided whether to make the pumps next or get started on the cylinder head and the rest of the top end. The cylinder head scares me a bit, as there are roughly 150 - 200 holes, many of which need to be tapped.

Your comments John & Swede on taper pins will prove useful, as I need to make and install taper pins to fix all the parts to the reversing shaft. I am waiting to do this until I have completed the top end, so I can be sure to align the eccentric rods perfectly with the valve rods. I will definitely practice with some scrap metal first.

Also, since I posted my last update, I got a complete and un-started Stuart twin launch casting set with reversing gear from the late 1950's or very early 1960's, which will be my next project after completing the triple. It is much simpler to that of the triple, but should look good when done. The twin launch castings are of such amazing quality. Many of the castings almost look like completed parts ready for buffing (other than not having holes drilled). What a difference compared to the triple, in which the castings are very crude looking, requiring a fair bit of filing clean-up before I dare take a cutter to them, and many of the gunmetal castings have been very tight on metal, and even short on metal (it is almost like they did not allow sufficiently for shrink), resulting in some very careful work to make the part to specs.

Robin


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## Blogwitch

Robin,

I have been saying this for a few years now, ever since ST were taken over, it looks like they are using castings as the patterns for some of their production rather than specially made patterns. If you can get hold of earlier casting sets, then do so, they should be much better.

There has been a lot of complaints about the quality and tight on machining dimensions, in some cases they are unable to be machined to plans because the castings are so under size.

I suppose they will get even worse now that they have been taken over yet again, unless the new owners invest some money in getting new patterns made.


John


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## Charles Lamont

Bogstandard  said:
			
		

> I have been saying this for a few years now, ever since ST were taken over, it looks like they are using castings as the patterns for some of their production rather than specially made patterns.
> 
> I suppose they will get even worse now that they have been taken over yet again, unless the new owners invest some money in getting new patterns made.



The castings used to be made by shell moulding, not quite the same as conventional sand casting.The mould half is a flat plate with a half pattern on it with core prints, locating pegs & sockets, runners and risers, all in one, in steel. This is covered in a sand/resin mix which forms an accurate 'shell' over the mould. This is all done in a machine. When removed from the mould, two half shells are clamped face to face to form a flask into which the metal is poured. ST catalogues used to illustrate the process. I have not seen any recent castings so I don't know what they are doing now.


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## rhankey

Speaking of castings. How should I go about cleaning out the steam passageways that go between the valve chests to the cylinders? The passage ways have quite abrupt curves. Only one of the 6 passageways seems to be clear enough to blow air through. The other 5 are completely plugged somewhere in the middle. I'm not sure if I can disolve whatever Stuart would have used as a core with some sort of solution, or if I can poke a small diameter wire through. I figure I should probably deal with this before I start machining.

Any ideas?

Robin


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## rhankey

Here's a long overdue update.  I have had little time in the basement over the last 3 or 4 months.  The cylinders, valve chests and cylinder covers also required much more work than I anticipated.  This being my first engine, I am still falling victim to thinking parts will be easier to make than they actually are.  I have now almost completed the top end.  I still need to make and fit the pistons, lagging and pipework, then pin the reverse shaft, and then make the two pumps.  Oh, and I guess I need to make a base to set the engine on.

Attached below are two photos showing the first time I attempted to mate the top and bottom halves.  It was the first time I assembled the top end too.  I wanted to see if everything aligned and to ensure there was no binding.  The two halves slid together perfectly, and all seems to move just fine.  What a relief.

The top and bottom LP and IP cylinder covers set a new level of crappy castings for me.  They had large areas of thick cold spots.  And the LP covers have some rather visible voids that I could not avoid.  The HP covers were wonderful to work with, and appeared to be cast using a different process - perhaps they come from an older batch.  There were no cold spots or voids in the cylinder castings, but it was quite a challange positioning the finished part in the rough casting to get the best comprimises for all the valve ports and the like.  Hopefully the piston castings will be fine, as they are thicker chunks of CI.

I deviated slightly from the plans, and opted to use screw in valve tail rod guides (the semi-circular domes on the top of the cylinders) for all three valve rods, rather than just the IP valve.  I figured this would look better, and allow me greater mchining accuracy.

I think the end is in sight.


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## Rivergypsy

I'm not quite sure how I missed this thread for so long, but what beautiful work - very, very nice!!

I'll tag along for sure, and I may just have to get cracking on my compound again after seeing this


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## rhankey

[email protected] said:


> I'm not quite sure how I missed this thread for so long, but what beautiful work - very, very nice!!
> 
> I'll tag along for sure, and I may just have to get cracking on my compound again after seeing this


 
Thanks for the praise.

You will need to excuse the slow progress and less frequent updates, as I have been distracted with a lot of travel lately so am not getting much time in the shop.  The pistons and lagging are now done and I am making a couple tube bending jigs to form the steam pipes to the very tight angles Stuart specifies.  This project has been quite a fun learning curve.

Robin


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## RCW

.. and keep filing reports, with pictures!  Beautiful workmanship.

--Bob


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## rhankey

Other than mounting a brass name plate to the front of the base, I have completed my first engine.  What a fun and expensive learning curve that engine was.  At the start of this project I didn't own a lathe, mill or any other tooling and had only done a little metal working in high school more than 35 years ago.

I apologize for the shallow depth of focus, as our camera doesn't do well with taking photos of small objects.

I am now starting on a Stuart twin launch, which I'll document in a new thread.  The castings for the twin launch were produced in the early 1960's and appear to be night and day better than the castings I received for the triple (which I purchased from Stuart about 2.5 years ago prior to the change of ownership).  I'm keen to get the twin launch completed, as I am keen to get started on a Stuart (H.A. Taylor) Undertype engine with integral boiler, which is also from some old castings.

With that, I think this thread has drawn to a close.  Thank to those in this forum who provided wisdom and along the way when I had questions.  Much appreciated.


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