Tandem Compound Poppet Valve Steam Engine Build, ala Cedge

[Cedge]

The engines in this project are what are known as side rod style. This means there are cams on an independent shaft which runs down the side of the machine, rather than the more familiar steam chest / D valve system. It also means there has to be something to support the shaft and I've got to make them.

I've studied a quite number of photos of these little machines around the web and there are generally two ways to mount them. Some use the head bolts on the cylinders while others bolt up or are riveted to the exterior wall of the cylinder. After some consideration, I chose to go the latter route on at least one of these engines.

While I've been doing all that drilling, I've also been working through how to best duplicate some of the repetitive parts this project will require. It finally struck me, while running my pirated Crap O' Cad that there might be a simple way to do things. A simple sketch was undertaken and what began as a single arm drawing, soon became four.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-1.jpg

Once the brass was squared, the lay out was made using a center drill to locate the holes. I removed the moving jaw on my Phase II vice and bolted back on the end of the sliding body and clamped in a piece of scrap yard aluminum tooling plate I had laying on the shelf. This too was drilled at the center point and another hole was added to match the radius of the outer holes. The would become the pivot and locking points during the milling process.

The metal strip you see is a piece of 0.01 inch shim stock that I use for locating the end mill. Run the end mill down until it just begins to "scratch" at the shim. You are now 0.01 inches above the work piece. Set your Z dial or DRO to zero, run it down an additional 0.01 and you are exactly at the surface level of your work. Reset the dial or DRO to zero once more and you're ready to go to work. The reason for doing the Zero thing twice is so if you miss the mark on the way to the surface, you have a place to begin again without going through the whole procedure.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-2.jpg

Before we go any further, a small warning is in order. This is a hand controlled operation and requires you to work in relatively close proximity to a small very sharp cutting tool that cares not one whit if it is chewing on metal..... or on you. Awareness of where your hands and fingers are at all times is not to be taken lightly, even for a moment. If you aren't comfortable with the idea, please do not try it. You will do so at your own risk. It's a process that requires very small diameter tools (no larger than 3/16 here) and very light cuts. You'll also want to avoid making climbing cuts as if they were the plague. Climbing cuts WILL run away on you and do damage to the work piece and quite possibly..... YOU. DON'T DO IT!!.

Once the tooling/ jig and such were complete the first cuts were made. As you can see, center pivot for center cuts, outer holes were the pivot points for their own radii. Since the dowel pins allow easy repositioning of the part, it's a fairly quick procedure to rotate or flip the work piece. Both sides were given the same treatment to create a mirrored effect. One quick note..... The final finished depth of cut on this part will be .0625. At this stage of things, I'm only cutting own to about 0.040. This gives me a chance to correct mistakes as well as play a bit with a couple of visual ideas that might become part of the final version. Thus the reason for the ball end cuts.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-3.jpg

The phioto below shows the reason for the holes drilled at the 45° points. They are the pivots for the long cuts from one arm to the other, as well as for cutting the openings I'll soon add to the arms. Still not working to final dimension on any front. the Z is still at 0.040 and I'm working 0.020 from any of the final side cuts. If I screw up, I'm still going to be able to fix quite a lot of stupid...(grin)

http://cedesign.net/steam/images/misc/multi-valve/build/arm-10.jpg

Once I had a good visual grasp, I began to work toward the final design. The arms were freed along the long arcs, but the ends were left attached. The excess metal was removed along the edges as well as the surfaces. I'm still working above the final dimensions but things are moving quickly to the point where the final elevation and side cuts will be made. Both sides of the work piece are still getting identical cuts, so there is a lot of relocation happening between photos.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-4.jpg

http://cedesign.net/steam/images/misc/multi-valve/build/arm-4.jpg

Here the final elevation was finally cut, leaving a thickness of 0.125 inches. Plenty to work with when it comes time to do the hand filing. The webs will be opened, so I've center drilled the ends of the opening with a #30 drill, which is just slightly larger than the 1/8 inch end mill I'm using. This will let me center the mill as well as giving me just a tiny bit of room to exit the cuts without crashing into metal I want to keep.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-5.jpg

Here, the small openings are being cut in the web of the arms. These engines have a rather delicate appearnce when they are completed, so I'm avoiding having large flat areas for both the delicacy idea as well as being able to see through the parts.

Something not quite obvious.... The initial idea was to leave the inner "rim" intact and square the ends. I began cutting and realized the cuts would be easier to make as a single arc, if I let the cutter run through the edge of the rim. Instead of a squared edge, the bases of the arms would flow right into the cylinder walls for a nice clean effect. I watch for small changes like this to add a bit of flourish. It also made the final separation much easier, since a single cut around the inner rim would free all four arms.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-6.jpg

All cuts have now been made to final dimension. No fresh metal to work with if I screw up now, it'll take luck and hard work to correct things if anything goes pear shaped. The piece has been cleaned up a bit with fresh ball cuts to blend the corners and shape the ends of the arms. The final arm is waiting to be released from the spare metal and all is well. Here is a good time to make even lighter cuts than normal, just so the end mill doesn't get that last nasty bite at your work.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-7.jpg

The part is now free of the original metal. I've heard it said that there is a part hiding within each piece of metal. All we have to do is remove everything that is not part and we get to liberate the part. You've just made that journey with me. My wife wandered through as I was making this photo and I almost lost the part to her. She now wants me to duplicate this stage of things in stainless steel so she can have one to wear on a chain. The hazards of metal machining are not all blood and stitches.....LOL

http://cedesign.net/steam/images/misc/multi-valve/build/arm-8.jpg

Here are the final parts, awaiting my hand and a small file. They are not nearly as rough as the camera makes them look. Between the sharp focus of the camera and the harsh light of my shop, the small machine nmarks look like the are of Grand Canyon scale. A little work with the needle files and these puppies will be ready to bolt to the tandem engine. Now if I can only come up with something a little different for the single cylinder.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-9.jpg

Steve

 

[SAM in LA]

Cedge,

You are a creative one, aren't you?

Very clever. Your work is fantastic.

Thanks for sharing.

SAM

 

[Cedge]

Sam...
I call it lazy.... One part vs 4 separate pieces... I shoot for one....LOL

Steve

 

[zeeprogrammer]

I've been following along but tonight I was cruising a little slower and got struck by the craftmanship.
Fabulous stuff.

 

[Blogwitch]

Hi Steve,

What you are really missing are the timings. Now gently tell all these kind folks how long all this actually took to make.

My guesstimate is about four to five hours, but it could be a lot more.

Most people don't seem to realise how long all this great work takes, all because it only takes a couple of minutes to read about it.

When making works of art, as you surely are, everything takes time, and lots of it.

Absolutely wonderful work.


John

 

[kcmillin]

Incredible work. A 1 job. :bow: :bow: :bow: :bow: :bow: :bow: :bow:

what els can I say.

Kel

 

[Deanofid]

Well done on these supports, Steve. You're working to a high level of detail here, and it's impressive.
I like the way you chose to do them, too.

Dean

 

[Cedge]

Thanks all....

John...
you nailed one of the drawbacks to the build log format. It's hard to convey the time it takes to do things, espcially when you try to balance the number of photos to the minimum possible. I weeded through about 50 shots to get it down to even this many.

You're not far off the mark. I actually started the first cut about noon and with quite a few interruptions, finished up about 2:00 am. With frequent breaks and a trip or two to check the forum, it probably ran to about 6 hours of actual work. It was one of those "lost time" things where the clock makes huge jumps between glances, yet it felt like an hour or less had passed each time.

I suppose not everyone would put the effort into such small things, but it makes the experience a lot more fun when the project is finally complete and even I can look at it and wonder how I did it.....LOL.

Steve

 

[Philjoe5]

Steve,
I'm enjoying your build immensely. My wife, who is in charge of cultural affairs at our house, recently signed us up for a home course in the Dutch Masters painters. As I'm watching your build and the Dutch Masters work from this course I'm struck by a parallel.

Example, here is a portrait done by Franz Hals, a well known Dutch painter:

Some of us, if we were painting this subject would have adorned her with a plain red scarf, and a solid blue dress. The Master, though, suffers the details. Portraits, model engines, same thing!

Thanks for posting, it's a treat to follow.

Cheers,
Phil

 

[Cedge]

Phil...
Interesting analogy and one with some truth to it. I'm just glad my wife thinks Dutch Masters are a brand of cigar and therefore banned from the household....LOL She did manage get me go with her for a Photography class a while back, for which I'm quite grateful, but so far I've dodged her latest idea of taking a course in conversational spanish.

I spent today sitting on the back deck in the sun with a small file and four small pieces of brass in hand. I decided to take it easy, after having broken a rib (the short floating one at the bottom of the left rib cage) over the weekend. Standing in front of the mill just didn't have a lot of appeal for, some reason. I did manage to get most of the tool marks removed as I hand shaped the pieces. Unfortunately, this turn of events is likely to slow my progress for a few days. I'll get to a few minor items, but I'm going to give the next push some delay to let some of the soreness diminish. Anyway.... here is what the pieces look like with a bit of hand work and a spot of polish. they'll still need a minor modification to the bases, but they do fit nicely.

http://cedesign.net/steam/images/misc/multi-valve/build/arm-11.jpg

Steve

 

[Deanofid]

Excellent, Steve. The delicate look of the pieces is a very attractive element.
Nice work. Do they get soldered on?

Hope you're a fast healer, and that rib isn't putting you in too much discomfort for your
every day living. You know, breathing, and that kind of thing!

Best wishes for a fast recovery!

Dean

 

[Cedge]

Dean...
These will be bolted on with a pair of 1-72 studs and nuts between the supports. I though about soldering them but didn't what to gamble on the clean up if the solder got away from me.

Luckily, the rib that is affected is low enough not to cause the well known catch in breathing, but a good cough, laugh, or sudden strained gas attack do not go un-noticed. The worst so far is the damned thing can't find exactly where it wants me to sleep and my wife has a wonderful habit of draping an arm across me, in her sleep.... right where the thing hurts... everytime.....LOL. Thank the gods, I love her.

Steve

 

[steamer]

Hi Steve!

Great build man! lots a brass!...I love brass

There is no comfortable side with a broken rib....ask me how I know this...

Sorry my friend....you just suffer through.....get well soon!

Dave

 

[gbritnell]

Very, very nice Steve. There's plenty of machinists out there but the thing that separates a lot of them is the ingenuity of making parts most efficiently. Yours is a fine example.
George

 

[Cedge]

Thanks George..... if lazy counts as an efficiency, I'm all in....LOL. I simply didn't want to have to make each part individually.

The past week has been a bit of a grind. The rib has gotten less sore, but only because I haven't given in to it. Teeth are now fully ground and my reflexes are quite highly honed to any movement near the damned thing. I still managed to get a few things done, but this morning was the first time back turning the dials on the mill. Most of my time has been spent cleaning up solder spots, fine tuning some of the hand filed stuff and cussing the cat. He likes it when I'm doing bench work and tends to land in my lap at the most inopportune moments.

Today I tackled a small conundrum. The arms need two small but accurately placed holes in each of the small webs at the big ends. The snarl comes when you realize there are no straight edges to clamp in the vice. Add to that the fact the the hand shaping was done to visual standards rather than to specific measurements and you've got to think out of the box, down the block and around the corner to find your solution. Ok.... so maybe not quite that far, but I've still got to drill the holes and they have to be uniformly located to match up to studs and against a solid edge.. So what's an overbeard, nearly no haired, former leaping gnome to do?

Two points in the making of the arms were rock solid.... the two pivots. Everything I did to the arms was based on them, so we know they are indexable. That is where it begins. I drilled holes to fit 3/16 dowel pins in a small chunk of aluminum, on the same centers as the original tooling plate.

I touched off the bottom edge of the stanchion to establish my cut line and then removed it so nothing untoward happened to it. I then made a light cut and replaced the arm to check the fit. With one minor move of the X axis, the fit was nice and snug without needing any significant force to seat the dowel pin in the head hole. If you've noticed the small notch on the bottom side, you'll have to forgive me for taking you along on the second run through of this process....(grin).

Here you'll see the slot I added to give the drill bit access to the brass part when the drilling begins. The part was simply too narrow to allow drilling guide holes, so the open galley was Hobson's Choice.

The addition of a hold down was not a choice but a requirement. There isn't a lot of meat holding the base of the stanchions so some support in the way of a 6-32 screw will help ward off the gremlins from attacking during a delicate bit of drilling.

The extra metal on the "big end" will have to go if I'm to be able to access the part with a center drill. I do not drill holes without having center drilled them even in nice open easy work spots. I'm certainly not going to miss doing it in a tight spot like this. I've got one shot at getting it right, so I'm giving things a lot of ounces of prevention here. My handy dandy carbide tipped arbor saw made quick and clean work of the task.

Here is the jig after both sides were cut and the excess metal removed. The reason for needing both sides may not be obvious. The two cylinders are of different diameters. This is because they combine to form a compound system where the larger cylinder accepts expanded steam from the smaller high pressure cylinder. Expanded steam requires more room so the low pressure cylinder has a larger bore and therefore a larger outer diameter.

The arms were cut to fit the larger diameter for convenience, knowing that a modification would be needed. A .060 rim was then cut and soldered to the bases of two of the arms. This gives the holes in the heads the same elevation so they accept the 3/16 shaft without binding. Two different diameters means I had to cut two different sized arcs in the jig.

This little jig will serve double duty as I continue to hand fit the stanchions. It will give me a good reference for keeping things square as I continue to remove tool marks and head for the final polishing phase. I like it when one tool can do more than one thing. As George said.... a bit of efficiency laziness never hurt anyone....LOL.

This project didn't make any major advances in the engines, but it does give me a chance to share jig making with the new guys. There are many ways to skin a cat and setting up a jig is one of them. Don't let yourself get stymied by a vise and clamps when a part is not an easy set up. Look at it and see if you can secure it with something that is easier to tie down.... and then make your own jig.

Steve

 

[kcmillin]

Well Done Steve. :bow: Your ability to think outside the box is astounding. Thanks for the lesson. Everything is looking great.

Kel

 

[arnoldb]

Steve, I've been following along quietly.

I finally summoned enough willpower to force my jaws and mouth closed to function a bit - WOW :bow: :bow:

Thank you :bow: Your build is very, very informative, and inspiring!

Kind Regards, Arnold

 

[SAM in LA]

Steve,

Thanks for sharing. I learn so much from posts like yours. Part of the learning process is trying different ways of skinning cats. The way it goes for me is after making a part, I look at it and wonder why I didn't do it a different way. I'm rambling.

I'm looking forward to future posts from you.

Thanks again.

SAM

 

[Cedge]

Thanks guys...
I remember lots of late nights when a quick tip would have been welcome. I'm trying to share tricks as I use them. The hard part is realizing when I'm doing something that might help. I've spent enough time in corners to never forget those who helped me get out of them. If this thread helps only one poor guy to escape the alligators then all the time and typing is worth it.

I apparently lost my "box" at a very young age. It's cost me many a trip to the office, whether in school, the military or work place. Luckily I never worked for anyone but my self, after the first few years of my working life. Not having a "box" didn't mean my solution was always right, just that it was "different". That kind of "uniqueness" wasn't always understood or appreciated by those who still had boxes....LOL.

Steve

 

[Cedge]

The rib is still pretty sore so I've been doing hand work and some of the details that would normally wait until later in the project. I'm really not enjoying the lathe or the mill at the moment, so no huge dramatic tricks in this post.

The original engines of this sort had added support for the long cross head guides. I had planned to leave this detail off the engines, but since I'm stuck with doing detail work so early in the project, I decided to give it a go. This meant reheated an already complicated solder job for more soldering. The "fin" was cut on the mill for a snug fit on the ends. making it a little easier to position the piece and get it centered. I turned a plug of aluminum to fit the bore so the window pieces were supported from within. Once the fin was in place, the whole cross head guide was wrapped at 3 points on the outer surface with thin mechanics wire to lock the window against the plug. This assured nothing was going to move, even if there might be some new solder seepage. After sweating the piece in, a bit of hand work was called for to clean the joints and polish out some file marks, here is what I had when it was all over.

http://cedesign.net/steam/images/misc/multi-valve/build/detail-1.jpg

All the stanchions are now fitted and their tiny studs trimmed to size. The studs were a bit of a challenge mostly because of the 1-72 threads wanting to strip the first time I tapped them. A bit of minor adjustment to me, the operator, soon sorted things out as I once again learned the need to be patient when working with tiny things. The stanchions fit just as hoped for and the shaft alignment is dead on centerline and free enough to turn with two fingers. The fit is such that the arms are not yet bolted down in this photos. Did I mention that I really do love the DRO on the mill?

http://cedesign.net/steam/images/misc/multi-valve/build/detail-2.jpg

Almost all the 2-56 studs have been trimmed and will get their nuts when I begin the final assembly phase. The valve ports are now opened up in the low pressure cylinder and have received some hand work to give their edges a nice rounded shape. This was done using small needle files and 400 grit sand paper to keep things smooth and properly shaped. It only takes a tiny bit of misplaced sanding to show like a sore thumb, so great care is being taken to get it right. After all... I've got the time, while I'm not getting to make bigger parts....(grin)

The cylinder head was given a 3/8 ball to finish it out. This was made using my handy dandy ball turning attachment. I think it added just the right touch to the overall look.

http://cedesign.net/steam/images/misc/multi-valve/build/detail-3.jpg

Here is the obligatory test fit photo. Nothing but the cross head guide is bolted on. The joints are all nice and tight, the graphite packing is installed in the stuffing boxes of the glands and the pistons and cam shaft are aligned well enough to move by hand. Once it is all secured, a bit of run in time should loosen things up nicely.

http://cedesign.net/steam/images/misc/multi-valve/build/detail-4.jpg

Steve