Building Kozo's New Shay locomotive

[petertha]

The two halves were then soft soldered back together again, and the outside flats given a light pass in the mill to even them out - could not get them perfectly aligned when soldering.

I've seen soldering often referenced for 'split line' jobs like this. Have you ever tried any of the 'glues' like CA, locktite, epoxy? etc. & then subsequent heat removal to separate them after machining? I've never done either, but just interested in your take on the matter.

 

[crueby]

I've seen soldering often referenced for 'split line' jobs like this. Have you ever tried any of the 'glues' like CA, locktite, epoxy? etc. & then subsequent heat removal to separate them after machining? I've never done either, but just interested in your take on the matter.

Never tried them either. Seems like high strength loctite could work. Epoxy I would doubt for metal work, except maybe jb weld. Someone else out there must have tried other methods - anyone?

 

[crueby]

Got a start on the crank webs today. Started by milling some 303 stainless steel rod to the needed rectangular size, then cut off 3 pairs of that a little long to allow for clamping them. Each pair was marked to let me keep them together and oriented the same every time.

Second photo shows the first pair clamped together, with the table positioned and locked down for center drilling the first of the main shaft and crank pin holes. The shafts are 5/16", and centered 9mm apart.The clamps will stay in place till both holes are drilled/reamed, so that they will stay aligned with each other.

Then drilled out the first hole, starting with a smaller drill and working my way up to full size, which keeps the chatter/wander away.

Fourth photo shows reaming the hole to final size, which leaves it a press fit for the rod.

Fifth photo shows drilling the second hole - unlocked the table cross movement and moved it over to the new position and locked it again. The piece stayed clamped in the vise so that the second hole would be parallel to the first one.

Sixth shot shows the pieces out of the vise,

next photo shows the first pair drilled, ready for radiusing the ends (will do that after all 3 pairs are drilled).

Last shot shows the first pair test fit on a piece of the rod for the main shaft - nice and square to the shaft, good to go. Two more pair to drill....

 

[crueby]

Last step to do on the crank web pieces was to radius the ends. To do this, I made an arbor by turning a shoulder on the end of a bit of brass bar the same diameter as the crankshafts, and threaded the end for a bolt. Then, with a pair of the webs bolted on the shart, turned the radius on one end, swapped to the other hole, and did the other end. This also took the webs to final length.

Second photo shows the first pair turned (on the right), second pair (on the left) still in rough length and ready for thier turn.

After that, on to the eccentric cams. Started with a piece of stainless rod, and turned the shoulder for the eccentric follower on the end, and parted it off.

Next photo shows the cam blanks with the web pieces.

Last operation on the eccentrics was to offset drill the eccentrics. I wound up having to make an extra set, since I tried using the 4-jaw chuck to offset drill, but with such a small part it was too hard to measure the offset accurately and I wound up going through the side of the first ones. So, went another direction and clamped the 3-jaw to the mill table (have a chuck-thread-to-t-slot adapter), centered up the piece with the center drill, and cranked over to one side the offset distance, and locked it all down. Then I could drill all 6 of the eccentrics with that setting, wound up being a quicker way to do it than in the lathe.

Next two photos show drilling/reaming the hole in the eccentric.



Last photo shows the first pair test fit on the crank shaft - all looked fine, so went ahead and drilled the rest of them...

 

[crueby]

On to an exciting step - assembling the crankshaft. I started out by making sub-assemblies out of the cranks and eccentrics. The cranks were easy - ran a piece of rod the right length for the crank pins through the webs, a longer piece through the other hole, and drilled through the webs and rod for some drive fit pins. Since I have been keeping the web pairs together and oriented the same through the whole process, they lined up nice and straight.

Second photo shows the web pieces all pinned.

Next up was to make subassemblies out of the eccentric discs. Each pair sits back to back on the main rod, with a 19.5 degree offset from centerline for each one. I laid that out on card stock, and used that as a pattern to clamp up the pairs. Then drilled for a cross pin to hold the two discs together.

Once I had all the webs and discs ready, it was time to put it all together. Lots of measuring, checking, more measuring, rechecking the book, .... Once I had the main rod turned to length with shoulders at the ends for the u-joints, and marked out for position of the pieces, I pushed on the first crank web to its position, and drilled/pinned it in place. Then set up the rotary table vertically, with a tailstock to support the other end of the shaft, and zeroed the table with the first pinned web square to the table. You can see on the shaft that all the webs are in position and roughly to right angle (120 degrees to each other). There is also one eccentric pair in place - the others go on later at the ends, no need to put them on now. The middle eccentric will be drilled/pinned later.

With everything aligned and zeroed, I then turned the rotary table 120 degrees for the next web, and clamped the web in the mill vise. This squared the web to the table, holding it in place for drilling. One of the webs was drilled/reamed, and a pin tapped in far enough to hold it, and the second web was then drilled/reamed/pinned. The pins were not driven home yet, I waited till it was off the mill to do that so I would not risk bending the shaft.

Then, turned the rotary table another 120 degrees and did likewise for the third web pair. With all the webs drilled and pins started, I took it off the mill and with each web sitting on the anvil tapped the pins home and filed them off flush. The middle eccentric is not drilled yet, wanted to check everything with the crankcase first.

Next photo shows the crank so far sitting on the bearings in the crankcase. It is a nice smooth fit, so all has gone good so far.

Last photo shows the bearing caps screwed on to make sure it still fits right - it does. I also slipped on the outside eccentrics to check that the shoulders at the ends were the right distance out.

Enough for today, time to walk away before getting tired and pulling a brain-fart on it. :toilet:

Next step will be to mark the positions of the eccentrics and drill/pin them. Each one needs to be at the proper angle to the corresponding web, so I will figure out a jig to hold the discs, with the web they go with clamped in the mill vise. After that is done, I will lap in the shaft on the bearings - it is a good fit, just a tiny bit tight, so the lapping should work out well. I have some of the time-saver compound that someone else recommended, will try that out on it.

 

[SilverSanJuan]

This really looks fantastic! The crank is probably the most critical piece. And, it looks like you've nailed it.

Todd

 

[crueby]

Quick update - got the eccentrics drilled/pinned on. Turned out no jig was needed since I already had each pair pinned at the correct angle within the pair, just clamped the corresponding webs in the vise, and the eccentrics self-aligned on the tops of the jaws (checked several times that I had them the right way round, they are not perpendicular to the webs but 19.5 degrees off that). Started with the center set, and clamped the eccentric in place with a spacer from the next web to get it located properly.

Second photo shows doing one of the end sets.

Last photo shows the crankshaft so far. With all the parts pinned in place, I went in with some low temp silver solder and flowed that into all the joints to lock everything in place, and keep any pins from working loose. The pins are doing the work of holding things in place against rotational forces, not the solder.

All that is left on the crank is to get it lapped into the bearings and cut away the parts of the main shaft within each web set. Next up is the universal joint sets that run out to the drive shafts on the trucks. Interesting part on Shays, the u-joints include a square shaft section the telescopes as the trucks pivot.

 

[crueby]

Time to cut out the openings in the cranks, removing the un-needed sections of the main shaft from between the webs. That always SHOULD be a good moment - never had a problem making the cranks that way before. As long as I cut in the right place....! I did get those pieces cut out this morning, and the hacksawn sides cleaned up with the mill. No movement at all in the shape of the crank, still sits nice and flat in the bearings.



Just needs a little polishing up to make it look shiny again. The lapping compound should be here Monday according to the tracking info, will lap the bearings then. In the meantime I am going on with the universal joint shafts.

 

[crueby]

I got a start on the horn couplings, which make up the inner workings of the universal joints on the drive shafts. They will be held in an outer ring with pins that let them rotate. To start, trimmed 4 pieces of stainless down to length. Each piece will make two of the horns - 8 of them are needed.

Then, drilled/bored the ends for the drive shafts. On one pair, the holes are smaller - this set will get pinned/silver soldered to the square telecoping drive shaft boxes.

With the holes done, turned down the ends to size. This will leave clearance for the outer rings to pivot in.

Next step was to mill flats on two sides of the bars. In order to ensure the flats were parallel, I clamped the parts in the mill vise (used the v-slot in the center to hold them), and milled the flats from either side without taking the part out of the vise.

Then, turned the piece sideways in the vise, resting the flat on a square bar, and drilled the pivot holes. When all the milling is done on each bar, it will be cut between these holes to make the two horn couplings.

Sixth photo shows the parts so far, with the end holes, flats, and pivot holes. Note that the one on the left has a different size end hole and shank - this will make the couplings for the square bars.

Next up was to start shaping the center area. With the bar held horizontally in the mill vise, the center area was milled down to size. Same depth was done on either side. Lots of cutting oil, a number of passes to get it down to size...

Last photo shows that done on the first bar - still need to do the same for the other three bars. After that, a 45 degree angle cut will be made at the ends of the center area to blend them into the ends - that will be next time.

 

[crueby]

Lots more done on the horn couplings for the universal joint shafts. Set up the vise at an angle to mill the slanted portion of the center section. First photo shows the setup, little hard to see what it is doing, but second photo shows the result with the four angled portions of the horn pair (making two of the horns from one piece, much easier to hold in vise for milling this way).



Then back in the vise down flat again, and drilled out the majority of the center area.

Fourth photo shows the remaining part of the center being milled out. Fifth photo shows all 4 bars with the center milled, ready to cut apart.


Next photo shows the first two pairs cut apart into the individual horns. The bottom pair has been filed to final shape - tapered the inside corners off, and rounded the ends of the horns.

Seventh shot shows the first pair test fitted on the end of the axle shaft, held in position. Still need to make the outer shell and pins.

Last photo shows all 4 pair cut apart, still need to do the filing on the rest of them....

 

[crueby]

This morning I got the rest of the horn couplings filed down like the first set, and got going on the telescoping drive shafts. First step was to make the hollow square tubes, which are made in two pieces silver soldered together. The first piece was made from a length of steel bar, with the center milled out to form the tube. The top of the channel was then milled back a little farther to hold the 'roof' of the tube. You can just see one side of that notch in the back wall of the channel in the first photo.

In the second/third photos, the flat bar for the roof is test fitted. The notced side walls hold the top piece so that a square tube is formed.



After making up a second set, got the tops/channels silver soldered together (glad it was a quick thing to solder up, it is about -5 F out there today, and that is the high temp for the next couple days, heading down to some overnights around -10 to -15!) Then, milled off the top smooth with the side walls.

Fifth photo shows how the horn coupling for the ends of the tubes go in - made up a snug fitting bit of square bar with a pin to hold the coupling, and silver soldered the coupling to the pin/bar. That assembly was then loctited and pinned into the square tube.

Sixth photo shows the next subassembly - lengths of round bar and square bar that is pinned/silver soldered together to form the inner part of the telescoping shaft. There is one long and one short bar, for the back and front drive shafts.

Last photo shows the round/square sections after silver soldering and trimming to length. Also has the horn coupling loctited/pinned in place on the end. The upper set in the photo has the square shaft in the tube, like it would be in use. The bottom one has it outside the tube, to show the parts.

Next up will be the housings/pins for the couplings. Though they do the same job as the u-joints in a car, they differ in that the pins are held in a large outer ring rather than using the cross-shaped connector that a car does. It takes up more room than a car-style joint, but there is plenty of space for it in the loco.

 

[crueby]

All right, back in the shop again today. Started on what Kozo calls the 'square pieces' for the universal joints. These are steel square rings that hold the pins for the u-joints. They start out as a piece of round bar, drilled/bored on the lathe...

Then over to the mill to square up the outside with the fly cutter.

The original curve is left at the corners - this will fit the cover ring in a few steps.

Back on the lathe, parted the square sections off to length.

Each section was then clamped in the mill vise ant the middle hole taken out to square, so that the dimensions match the outside width of the coupler horns.

With the squares made, it was time to make the retainer rings that go around the squares, and hold the pivot pins in place. The rings started as a length of brass bar, drilled/bored out to match the original diameter of the square sections. I took the hole out to size just deep enough for one ring at a time, so that it would stay strong enough to do the work on the outside - otherwise it would be like machining a long thin wall tube.

After boring the inside, the outside was turned to a curved profile, finished smooth with a file. Maybe I can go into business making cheap brass wedding bands... Anyway, after shaping the outside, the rings were parted off from the bar.

The last photo shows the rings and square pieces test fitted - the rings are a snug fit over the curved corners of the squares.

Next up will be to make the pivot pins, which go through the center of the flat sides of the squares and into the holes in the horn couplings. The heads of the pins are held in place by the brass rings. The rings will get retaining screws into the corners of the squares. Should be interesting to see it all together...

 

[fuzzymuff]

Hi Crueby. I got my copy of Building the new Shay today. Great book.

 

[crueby]

Hi Crueby. I got my copy of Building the new Shay today. Great book.

Great - hope you can build one soon and post the progress!

 

[crueby]

Here is the sequence for the rest of the u-joint assemblies. Last post I had gotten the square and round shell pieces done, so I got going on making the pivot pins. They started out as a length of stainless rod, and turned the ends down and threaded them at the tips on the lathe. The threaded portion is only there to hold it to the fixture to shape the heads, it will be cut off after that.

Second photo shows the pile-o-pins, 16 are needed, made a couple spares in case I Murphied one or two...

The heads of the pins need to be radiused to fit under the outer retaining ring. To do that, a little fixture is made from some scrap bar stock, with shank turned to same diameter as the inside of the retaining ring, and a flat milled in the side the same distance from center as the flats on the square inner ring. The pin is put through a hole in that, and a nut on the inner side to hold it in place. Then its a simple session of turning it down to the proper radius. Once I got the setting from the first one, I zeroed the handwheel there to make the rest go quick - bolt in the pin, take several passes down to zero, remove the pin and cut off the threaded part...

Last thing to do before assembly was to drill the holes in the squared ring for the pivot pins. Set up first one in the vise with one edge aligned with the edge of the vise, centered for the hole, then could crank through the rest at the same setting.

Fifth photo shows all the pieces for both drive shafts. The upper one is assembled, the lower one still in pieces. On the left is one of the squared rings with one of the horn couplers in place. The pins on that one are cut to length, the pins laying on the right are still uncut.

Next shot shows a closeup of the assembled joint - you can see the pin heads under the outer ring. Assembling that is a little fussy, since the pin heads need to be all aligned with the high spot running lengthwise so the ring will slip over them. Without letting any fall out. Again. Oops, again...

Seventh shot shows both shaft assemblies all together - all that needs to be done is to drill/countersink for some small screws through the outer ring into the corner of the squared ring, so that the outer ring can't slip off.

Last photo shows the shafts slipped onto the ends of the crankshaft.

Just need to cross-drill the ends for pins to hold them in place. For now I'll run some small (2-56 or 1-72) bolts through the pin holes so I can assemble/disassemble it quickly while making the rest of the engine. The u-joints work very well, nice and smooth, with more than enough angle possible for the trucks to pivot. I've never made u-joints this style before, always had done the car-style. For small models I like this type, the parts are not quite so tiny on the pivots. Not sure why the Shays had this style over the inner-pivot style, maybe was easier to maintain in the field, and could be made beefy to take lots of torque.

 

[SilverSanJuan]

Lot's of work in a few days! Really looks great.

Todd

 

[crueby]

This morning was catch-up-on-little-stuff time: pinned the last connections on the shafts, ran in retaining screws on the u-joint rings, lapped the main bearings, and test fit the whole thing on the loco. The TimeSaver lapping compound (yellow) that someone here recommended worked fantastic - I got the trial set of different grits, it looks like it should last for a LOT of models since it does not take much to mix up enough with oil for small bearings. It works very quickly, and left a smooth running set of bearings. I think I will go back and relap some of the connections on my twin-beam engine, see if it will clear up the sticky spot that one has.

First photo shows drilling/tapping for the retaining screws on the outer u-joint rings.

Rest of the photos show it all assembled on the loco. Good point to sit there with it and make train noises!









Next steps in the book are to make the pistons and conn-rods.

 

[crueby]

Now to the heart of the engine - the pistons. They are bronze, pinned to a steel shaft. First photo shows a piston that has been drilled for the shaft, had the o-ring slot cut in the center with the parting tool, had the corners rounded, and is in the process of being parted off.

Second photo shows the first two pistons, one with the piston rod installed (cross-pinned and loctited). The thread at the base will be to screw into the crosshead.

After making all three pistons, spent some time fitting them to the cylinders. Two fit nicely, one needed a little shaving off from the bottom of the o-ring slot to get a good sliding fit.

Last part to make was a set of lock nuts for the crossheads. I did not have any nuts the right thread (M4) so made up a set from some steel rod. Drilled/tapped the center on the lathe, then over on to the rotary table on the mill to mill in the flats.

Back to the lathe to part off a half dozen of them.

Last photo shows the pistons assembled and ready to go.

Next step will be to make the crossheads - good project to start fresh with tomorrow...

 

[brian13b]

I dont know if I missed it, but where are you buying/getting all your stock from? Thanks B

 

[crueby]

I dont know if I missed it, but where are you buying/getting all your stock from? Thanks B

I got a lot from onlinemetals.com, stocking up during thier sales (am on thier email list for specials). Also got most of the big diameter brass from yarde metals, from their 'drop zone' where they sell offcuts cheap. Selection there is spotty since it is leftovers from their commercial sales, but prices are good.