Tandem Compound Poppet Valve Steam Engine Build, ala Cedge

[Cedge]

The shop is now hospitable again and I'm back in gear for this season's first build project. I'm hoping to stretch things enough to do a couple of different builds, but time will tell.

I've spent the day turning out cylinders, so I'll share a bit of what was accomplished today.

I started out by cutting and cleaning up 3 pieces of junk yard brass that turned out to be some really sweet 360 free machining metal. I turned and faced the pieces to get rid of the bumps and warts and then drilled them to within 1/16 inch of the finished bores. Since one of the engines.....(yeah, there will be two when I'm finished) is a compound arrangement, the two bores will be .6250 and .750 inches.

I then broke out the HSS boring bar and got serious. In the photo below, you'll notice a lighter area just inside the bore, indicated by the red arrow.

This is a trick that Zeusrekining (Tim) taught me on my last project. Rather than blindly boring the whole length of the cylinder from the start, I bored about 1/4 inch in and used a "go/no go" gauge to get a close running fit. This particular cylinder is a 3/4 inch bore so I used a 3/4 inch slug for testing.

This left the rest of the bore untouched and the lip of the step up was easy to see while using the boring bar. The diminishing step up served as a visual indication for when things began getting close and resulted in a dead on .750 bore when the last pass was made. Nice tip, Tim...thanks.

Once the bores were done, it was time for the fun stuff to begin. Those of you who saw the recent 3D image, already know these cylinders will be contoured in a number of places. I'm nowhere near Gbritnell's level, but Ive definitely learned that I enjoy an engine with somewhat fewer hard edges.

The process began with a bit of marking up which was done on the lathe using a digital caliper that has had one tine shortened. This made easy work of locating the various elements I'd need to turn.

For those who haven;t seen this trick, the long tine gives you a means to indicate from an edge while the shorter tine marks the metal. This mark out was done with the lathe turning slowly. The long tine was held against the end of the work piece and adjusted to the needed dimensions for each mark. This also trick works well when working on the mill. (just remember it's an inside measurement so you cut TO the line)

The first cuts were made using a parting tool. It was used to make sure the corners were clean and square. This also took the worry out of aggressively removing the remaining metal between features. The flanges were filed on the lathe to round them. as were the rounded contours that flow from one flange tot he next.

The photo below shows the "before and after" of the process. You'll note things get a little close near the chuck. You'll want to give your undivided attention to filing this close to the spinning jaws. I use small needle files for this work and stand away from the chuck as much as possible.

Here is today's harvest after a bit of polishing has been started. The heavy bases will stay attached for some of the upcoming mill work ans then the cylinders will be transfered to mandrels for some further lathe work. Two of these will be used on the compound engine while the third will become a single cylinder version. Stay tuned.... lots of things to do before these are ready to run.

Welcome aboard.....
Steve

 

[joe d]

Steve

This is looking good already... and you've only done two parts. Looking forward to following along!

Cheers, Joe

 

[Deanofid]

Nice candle sticks! ; )
Really, they look quite nice already, Steve. Nice to make something pretty on the first day of a new project.

I have a boring bar like the one you show there. Mine is quite bendy!

Dean

 

[Maryak]

Nice start Steve.

Best Regards
Bob

 

[Philjoe5]

Nice work Steve. You've introduced some new tricks to me, and the journey has just begun. :bow:

Cheers,
Phil

 

[SAM in LA]

Steve,

Shoot, you just started and I have learned several new things from your build.
Keep up the great work. My learning curve is nearly vertical and my head is starting to hurt. I'm looking forward to following your build.

SAM

 

[cfellows]

Looks Good, Steve. Thanks for the tips. I, too, like the engines with curves and valleys or maybe those are called beads and coves?

Chuck

 

[Cedge]

Chuck
Beads and Coves it is..... my head didn't supply the needed words when asked...(grin). Thanks.

Things got a little delayed this week as I needed to clean about 20 engines for the first showing of the season. Saturday was spent with a few machining friends, 50 plus engines , loads of warm springtime sunshine and a great crowd of friendly onlookers. I'll have to say I didn't really miss being in the shop....(grin).

Today I got back to things and made a bit of progress with the cylinders.

The photo below shows one of the cylinders after it's first trip to the mill. I machined flats on all 3 bases to give me a proper datum point for the first few modifications. This trick proved to be a life saver on my last project and has since been adopted as a regular thing.

This flat face, along with the substantial "base" gave me plenty of meat to grip while working with a lot of overhang in the vice. It also helped me assure that all the cuts would be square and at 180° in relationship to each other. The flat does require a bit more use of the wiggler when things are repositioned, but it is a lot easier than many methods I've seen.

I chose to use a 5/8 inch end mill cutting to 0.100 in depth so that the hole would have a slight wall along the outside edges. I accepted that the holes would be slightly oversized and made up for it by turning the valve bases to a press fit in order to match the holes.

The valve basse was then soldered into place using the 3/16 inch hole that was drilled in each piece. These holes will also be used as indexing points in later proce3dure. By soldering from the inside, there was less overflow to clean up on the outside. Since these pieces will see very little pressure, I chose to use a silver bearing solder for convenience.

The work pieces were then taken back to the mill to even up the surfaces of the valve bases. This surface now becomes the new datum point for future operations such as drilling and tapping the ends of the cylinders. After a bit clean up and removing the heavy base, the cylinders look less like candle sticks and more like parts of a steam engine.

Steve

 

[Blogwitch]

Those bits are starting to look rather delicious Steve.

Envy is setting in already.


Bogs

 

[Deanofid]

After a bit clean up and removing the heavy base, the cylinders look less like candle sticks and more like parts of a steam engine.

You knew I was kidding, right, Steve? You do beautiful turning work, not to mention the rest of your talents.
Keep up the fine work.

Dean

 

[Cedge]

Dean
No offense taken, they looked like candle sticks.....LOL. Thanks for the kind words.

John
If all goes well, I hope to have you absolutely green before they're running.... LOL. It looks like they are going to be an easier project than I first suspected. the thought of making 12 of everything is still a bit daunting, but I just keep repeating my mantra.... "just make one perfect part at a time".

Steve

 

[Blogwitch]

Steve,

You know I have always admired your work and flair since you started to make these one off's, and now that my time is unfortunately over in that department, I have to have something to hold in high esteem and to follow along with, even though it does make my mouth water at times.

Your mantra BTW is spot on.

I'm not trying to teach you how to suck eggs, but if making more than a couple of the same part, don't be afraid of wasting a little time making up a holding fixture or jig, they usually save time in the long run, mainly because you spend less time putting things right due to slippage etc, also, if you are soldering things up, you can safely use a bit of ali bar for lining up holes etc while you solder it all together, even if it gets stuck in there, it is usually easily removed afterwards without any damage.

John

 

[gbritnell]

Hi Steve, nice progress on the cylinder so far. One thing I have found when having to silver solder parts. I try to do all the machining, drilling and tapping before I do the silver soldering. Usually the silver soldering anneals the metal somewhat and it doesn't like to tap as well as when it's in the hardened state. If all your holes are bigger than 2-56 it's not a real concern but I do a lot of holes smaller than that so this is the procedure I have taken.
George

 

[kvom]

Good start on this one!

I need to make another field trip to see it in person.

 

[Cedge]

George,
Thanks for the tip. I'm a bit past the point of no return on this projecy but I'm filing that one away for future reference. This bit of soldering was not true silver soldering since i used a silver bearing solder with a low content. The heat requirement was not quite high enough to put me in the range to do much annealing. Keep your fingers crossed for me... eh?

John

Thanks for the show of faith....(grin). I've already been contemplating a bit of "jiggery" for some of the pieces. I'm also looking at a couple of profiling cutters to shorten up steps on a couple of others. With a bit of luck, I'll post a few more photos this evening, as I get a few more things done.

Kvom....
All ya gotta do is give me a call and let me know when you want to come. Just need a little time to tidy up.... LOL. I'd hoped to be down in your area by now, but life keeps getting in the way.

Steve

 

[steamer]

Looking great Steve....I think I found a German reference showing that style of valve gear......Maybe sometime this week....

Dave

 

[Cedge]

Finally got back to the shop after a small lapse in motivation. I've managed to get a little done, so the break was not a total loss.

The cylinders have now been drilled for the steam ports. Patience and an easy touch got the #43 holes deep enough to match up with the larger 3/16 holes coming in from the valve bases.

The 3/16 holes were drilled last to avoid the chance of breaking a drill while entering another hole from the side.

If you recall, I mentioned the valve bases became the new datum point in a previous comment. This is where they came in quite handy. Locating the various holes in relation to each other became as easy as you could ask. A simple flip of the work piece was all that was required to get perfect alignments. These indexing points still have a couple of functions to serve before they too will be replaced.

The cylinders will require a total of 5 gland nuts and two different sizes since one cylinder on the tandem uses two different diameters cylinders. Here is one of them show early in the turning phase. You can see the markup / caliper trick was used here as well as the cut off tool for heavy metal removal to depth. (keep practicing with the cutting off... its a very handy skill)

Here the photo shows one of the glands, threaded at 3/8 x 32 tpi. The piston rod will be 3/16 inch dia. so there will be plenty of room for the graphite string packing to fit in the wells. The gl;ands will be concealed by the spool, also shown in the photo. This will serve to connect the two cylinders.

Here you can see the gland as it fits the collar. The 1/16 lip was left to give added support to the piston rod and to aid in positioning the gland in the end of the cylinder.

I still have glands to make, but here is how the combination of parts will fit together. I'm currently awaiting an order from www.microfasterners.com before I begin drilling and tapping the nearly 50 holes required to fit ti all together. Hopefully that project will begin tomorrow.

Steve

 

[Deanofid]

You progress pretty fast, Steve. Everything looks good.
I don't envy you those 50 holes!

Dean

 

[Cedge]

Dean....
The 50 holes are 2-56 threaded, which won't be too bad as long as I remember to baby the drill and use only sharp taps.

The pain is the other 96 smaller holes to be drilled for small rivets..... on turned surfaces....LOL Those might prove to be some fun.

Steve

 

[Blogwitch]

Steve,

I would suggest you get yourself a small 120 degree spotting drill if you can, for all those small holes on curved surfaces. The dimple left will be more accurate and less prone to slippage than a centre drill dimple.

Just a suggestion.

John