Building Kozo's New Shay locomotive

[crueby]

All right - got the steam bracket finished (added the steam inlet, got the plugs silver soldered in). It will form the platform that the engine will build upon. (photo 1)

The cylinder stock starts out as some 1-5/8" brass rod (stress relieved along with the steam bracket base the other day), that is milled down to square (Kozo does this a lot for square or rectangular stock). I have a big chunk of that size that I picked up as a drop from Yarde Metals. So, first step was to set it up with the fly cutter and take down the sides till square (since I stress relieved it, no need to flip back and forth, could take down each side in full). Several passes per side later, and lots of chips to vacuum up, bar was down to size... (photos 2,3,4)

Then, rough cut the bar to length to give the three cylinder blocks - left them a little long to trim up in the lathe. (photo 5)

I mounted each one in the 4-jaw, centered up with a dial indicator, and squared up one end, then reversed it to square up the other. (photo 6)

With the blocks squared up, but still a little long, I measured the length of each one and marked the length on the side. Quick calculation to determine how much to remove off the end to get them all down to final dimension. (photo 7)

Then, put them back in the 4-jaw, and took them down that amount. Last photo shows the three blocks next to where they will mount on the steam bracket manifold. Note that they are not evenly spaced - the leftmost one will have the steam chest on the left, the other two will have the steam chests on the right. This means the first cylinder will have several of its ports/etc on the opposite side from the other two. In order to keep track of which is which I number stamped each one in the upper corner.

Next time - boring the cylinder...

[Roger B]

That's a lot of brass to chew off    Finally on the engine, not long now 

[Dave Otto]

Nice work Crueby

Looking forward to watching the engine take shape.

Dave

[b.lindsey]

Great start on the engine crueby. I am looking forward to this

Bill

[crueby]

On to the main attraction: Act 1: The Cylinders

Last time I got the blocks for the cylinders shaped down to outside dimensions. Time for the 'boring' part. First up was to chuck the block up in the 4-jaw again, but this time offset towards one corner. (photo 1) The bore is offset to leave room for the steam passages and bolt holes. Since the number one cylinder block is facing the other way from the number 2/3 blocks, all of these operations took some careful checking to make sure I was orienting the blocks correctly (good time to be paranoid - Murphy is always out to get you!). Anyway, using the dial indicator each time, I offset the blocks the same amount in both directions (0.052", as I recall), and then drilled a starter hole for the boring bar.

Using the boring bar, I took the cylinders out to size, measuring both with calipers and checking final size with a test bar of the proper diameter. The last few passes were done with very light cuts, and very slow feed rate. (photo 2)

As you can see in the third photo, the resulting bore was mirror smooth (okay, photo is grainy, does not show it well - tough to get camera to focus in right spot!). The test bar fit nicely in each, if I plugged the bottom of the hole with my finger and dropped in the test bar, it floated down, and I could feel the suction when drawing it back out. Best I've ever had a set turn out - hope I dont mess up later on these!

Fourth photo shows the three blocks so far, in front of the manifold in the positions they will be. The steam chest for the left one will face left, and face right for the other two. You can see how the bores are offset to leave more material on the back wall and the steam chest wall.

Next steps were to make the steam passages. Kozo used a 1.5mm mill bit to cut the outer ones - I dont have one that small, so I drilled a series of 3 holes and used a micro bit in my high speed air tool (like a little dentist drill - I use it for detail wood carving) I connected up the holes to make a slot. For all these drilling operations, I set up the first block in the milll vise, using a straightedge to line it up at the edge of the vise. Then, once I had the position of the holes dialed in on the first block, I could swap out to the other ones and get the same result - saved a LOT of setup time (center/measure once, drill 3 times). (photos 5,6,7)

Next photo ( shows milling out the passage in the center - that one I had a mill the right size for.

Going to break post here and start another - it only lets me upload 8 photos at a time....

[crueby]

Continuing cylinder milling (photo 1 shows progress so far)

With the passages milled from the side, it was time to make the connecting passages. All the passages are at 20 degrees, so I set up the mill vise on the tilting table for them. Again, used a straightedge on the side of the vise to position the blocks the same every time so I could set up once and do all three blocks. Again, triple checking that I had the blocks oriented correctly! Started out with a mill to make a flat at the top of the cylinder. (photo 2)

Then, drilled the passage down till it met the slot cut in the face in the previous step. This was repeated for all three blocks, and at both ends of each block. Due to the offset of the bore, I could do the top hole for number 1 and bottom hole for 2 and 3 in one setup, then readjusted for the rest of the holes. (photo 3)

Next up was to make the passage for the exhaust, which comes in from the back wall of the block and meets the center slot. Again, started with a mill, (photo 4) and finished with a drill through to the slot (photo 5).

Last step was to make the steam inlet passage. Unlike many engines where the steam inlet comes into the steam chest cover, for space reasons the Shay has it coming in from the back wall of the block, exitting into the space inside the steam chest next to the valve slider. This was done with another angled hole in the back wall, (photo 6) and a vertical hole in the steam chest face (photo 7).

Last photo shows all the cylinders so far. Note how the number one block (on left) is a mirror image of the other two.

Enough for today (okay, some of this was done yesterday) - time to sit back and admire the work so far!    Next up will be to start drilling/tapping all the mounting holes (lots and lots of them).

[ths]

Great work Chris, getting the bores exactly the same is quite a feat. I'll be interested to see how the connection for the steam inlet is done, but it may be remarkably straightforward. Hugh.

[crueby]

Great work Chris, getting the bores exactly the same is quite a feat. I'll be interested to see how the connection for the steam inlet is done, but it may be remarkably straightforward. Hugh.

Very simple - the back face of the cylinder bolts to the steam bracket manifold, with the inlet and exhaust holes matching up. There is a gasket to seal it but no mechanical fittings. There will be a supply pipe from a boiler fitting to the manifold, the passages in the manifold split to the three cylinder blocks. Much simpler than the usual piping everywhere. The manifold also acts as the structural support for all three blocks. Neat how they designed it.

[ths]

Ahhh...

[crueby]

Bunch more done on the cylinder blocks today - started out with drilling the holes for the cylinder end caps. There are four 3-48 holes at each end. To get them all lined up properly, and also to make sure the holes in the caps get drilled to match properly later, a jig was made (one thing Kozo shows in his book is great use of jigs - a real time saver, plus it ensures repeatability of placement on multiple parts). I took a piece of brass plate and bored a hole in it to match the bore of the cylinder. With the piece still in the 4-jaw so the hole was centered still, holes were drilled on the rotary table at the distance needed for the mount holes (all sized for tapping at 3-48). Then made a pair of stepped blocks for either end, with the narrow part of the step also matching the cylinder. Note that I made the top end cap deeper than needed - will show why later in this post. With a bolt running down the center, the pieces all sit on the cylinder block the same way each time (markings on the plate show which way to turn it to line up with the front edge).  The first photo shows the jig in use, with the block held in the vise, but the vise just handheld on the table, so the drill would self-center in the hole.

Second photo shows the jig sitting next to the block to show the parts. Just a few minutes to make, but with it I was able to drill all the holes in both ends of the blocks, accurately, in just a few minutes - no more measuring/marking/etc needed. The same jig will be used later to position the holes in the end caps - they will be drilled at the tap size, then redrilled to open them up for clearance on the threads.

Next up was to make a drilling jig for the mount holes for the steam chest. There are 8 holes (all 2-56) in this jig. The same jig will be used to drill holes in the cylinder blocks, the steam chest frames, and also the steam chest lids. With the jig, all will line up correctly (as long as I position the jig right way up each time, I guess!).

Next photo shows the jig in use, clamped to the cylinder block over the face with all the steam ports on it. The clamps I am using have copper jaws, so they wont mar the surface of the bore (not clamped too hard, just enough to hold).

Fifth photo here shows the progress so far - all the holes drilled/tapped (took some breaks during the tapping process - tired fingers leads to broken taps at these small sizes). The two jigs are shown in front.

Last step was to round over the front corner of the blocks on the side away from the steam chest. There are no passages in this area, so no need to keep all that material - in the real thing this would have been cast that way. The end-cap drill jig played another use here, as an arbor to hold the block in the 3-jaw chuck on the rotary table. This is where that deeper end of the jig came in handy - made enough room to grab it in the chuck while holding the block out a little from the jaws so I would not hit it with the end mill. I took off the corner in a series of light cuts, down to the point where the curve blended into the remaining side. (photo 6)

In the right block in the seventh photo you can see the surface left - not bad, but not too smooth. I got out my diamond-surfaced lapping plates (use them for sharpening my wood carving chisels), and used that to smooth down the faces of the block. With some oil on the plate to float off the removed brass, I held the blocks down and ran them back/forth while slowly rotating them through the curved face. Couple minutes and it left a nice polished surface. Then I did the same on the other flat faces of the block, which smoothed out any protrusions left from drilling/tapping. I spent some careful time on the face where the steam chest goes, to get a nice flat polished face for the D-valve to slide on.

Last photo shows the complete cylinder blocks and steam manifold, ready to make the steam chests....

[ths]

All is plain, looks great. Hugh.

[b.lindsey]

Jumping right in on the engine sure hasn't slowed you down one bit crueby !!  Its looking great so far.

Bill

[crueby]

Got a start on the steam chests today. Started out by cutting down/milling square to length some flat bar stock - had to take a couple mm's off the side but thickness was good. (photo 1) This bar was enough to get all three valve chests out of - it was cut into thirds, each squared up to length with the mill.

Then chucked it up in the 4-jaw on the lathe - first centered it then offset to the side so that the valve shaft will be far enough from the side for the D-valve to fit. (photo 2)

After that, turned down the end to form the boss for the o-ring holder (the valve shaft is sealed with an o-ring, with a holder ring going into the hole in the end). The hole in the end was drilled for the o-ring size, then a smaller hole farther in for the valve shaft. (photo 3)

Turned the block around, and drilled/tapped a hole in the other end for the oil pipe inlet fitting - the axle pump on the front truck pumps oil up to the steam chests (the way it is ratcheted, the pump only delivers a drop of oil every so many turns of the wheels). (photo 4)

Next step was to drill/tap the hole for the set screw that keeps the o-ring holder in place. since it was so close to the main part of the valve chest, I had to dig out my smallest center drill to start the hole (photo 5) then drill for the 2-56 thread (photo 6).

Last photo shows the valve chest so far, with the center marked out for the opening which will be milled out after I get the other two chests up to this point.

[crueby]

Continuing on the steam chests, set up in the mill and drilled corner holes for the opening in the center of the chests. Easier to accurately locate these holes and mill to them than to mill blind and try and match the edge locations. (photo 1)

After the holes were all drilled, switched to an end mill and cut out the center section, taking three passes to go the full depth. In the second picture you can see the block cut out from the center.

Third photo shows all three steam chests so far - ready to drill mounting holes.

With the steam chest clamped together with the same drill template used for the cylinders, making sure the orientation is correct (stamped numbers on the chests to match them with the cylinders), drilled through with a 2-56 tap size drill. (photo 4)

Then, removed the template and clamped the cover plate on the steam chest, went back and drilled out the holes to a 2-56 clearance size, going through both the chest and the cover - in this case, the steam chest acted as a drill guide for the cover. I had tried clamping up the chest, cover, and guide all at once, but it was too hard to line up properly - this worked out just as easy. (photo 5)

Last photo shows all the engine parts so far, with the chest/cover/cylinder all bolted together on number 3 (right end). Naturally, no matter how many screw sizes you have, you always need an in between length - had to cut down some 3/4" long ones to fit. Which Murphys' law is that one?

Anyway, great progress this week - next up are the cylinder heads and steam chest stuffing boxes.

[crueby]

With the valve chest bodies done, on to the head caps: turned them down from brass bar, with a step on the end that matches the cylinder bore. Then parted them off - used the steady rest for the first ones since the bar was sticking so far out from the chuck. (photo 1)

The rest of the bar was used to make the stuffing boxes - again, turned the end down to match the cylinder bore (they have protrusions above and below the flange - in the next photo it is the bottom side with the larger protrusion showing). Then, drilled for the piston rod and also a larger diameter hole for the o-ring. (photo 2)

Third photo shows making the upper step, and parting off from the bar.

With the caps/boxes turned to shape, last step was to use the same drill template from the cylinder blocks to drill the mounting holes in them. The stuffing boxes also get a cross-hole for a set screw in the bottom protrusion. (photo 4)

Next couple photos shows the engine assembly so far. Really taking shape quick with just the first few parts. And then a couple photos of it test mounted on the side of the boiler...