Building Kozo's New Shay locomotive

[crueby]

Got a start on the crossheads today. They started out as bronze rod, turned to diameter with a smaller nub at the end which was drilled/tapped to match the piston rods. The ends of the crossheads are tapered just a little so they dont scrape off the oil on the guides - that just shows in the first photo.

Second photo shows the crosshead blanks all turned/threaded, one test fit in the guides.

Next step was to mill the sides off flat. Did first one side,

then the other.

Then drilled

and reamed the hole in the side for the pin that will hold the conn-rod end.

Last photo shows the three crossheads so far.

Next step will be to mill out the recess in the end for the conn-rod...

 

[bouch]

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.

8>< snip ><8

View attachment 75390
Next steps in the book are to make the pistons and conn-rods.

Would love to see a video of all the motion spinning as you push the loco the short distance on your display track! ;D

 

[crueby]

Would love to see a video of all the motion spinning as you push the loco the short distance on your display track! ;D

Next time I have the engine bolted up I'll do that - currently have a lot of it apart to fit the cross heads and such.

 

[crueby]

Here is the rest of the work on the crossheads. With them in the mill vise, drilled 3 holes across the end to remove the bulk of the material from the inner slot.

Then went in with a small mill and connected the holes and took it out to the design width/length/depth. With the drill having done most of the work this part went quickly, just had to check thickness of the outer walls with the calipers a couple times to see how much more to take off.

Third photo shows the change from no slot on left to slotted on the right.

Next steps were to take the bottom edge to shape. Started by milling out the center section.

Then, with the pieces angled in the vise, took off the slanted part on the sides.

Last step was to mill in a shallow groove on either side to form a groove to hold more oil.

Last photo shows the parts on the piston rods, one of them in place in the cylinder assembly.

Next up are the connecting rods and thier bearings onto the crankshaft. Once those are done, will be time to bolt it up and check the action - that will be a major milestone!

 

[crueby]

Got a start on the piston connecting rods. They are in two pieces that overlap above the crank bearing and are through bolted together. To start, got some stainless bars milled down with the fly cutter to the needed sizes, one set each for the top/bottom halves.

The stock for the bottom halves was left in one piece since they are so short. With the bar held in the vise, I milled out the top sections of each. This are is where the two halves will overlap. The bolts will go through the arms. By doing all three together it was easy to get the inner widths all the same, plus it was easier to align/hold in the vise with one long part. This was one of the few places Kozo did not show the setups for the milling steps, usually does for complex parts.

After milling the openings the three parts were sawn apart. Since the upper half needs to nest all the way into the bottom half, I swung the parts vertical and trimmed out the inner corners square.

Last step in shaping the part was to trim the bottom off to the final length.

Last photo shows the bottom pieces with the blanks for the top pieces. The lower one has the bottom sitting on it to show how they will overlap, and the rest of the conrod is sketched in. The extra width at the lower side in the photo will be used to hold the part when thinning down the upper arm (next time).

 

[crueby]

Lot farther on the piston connecting rods today. Last time I got the bottom halves milled out, today started milling the upper halves to shape. First up was to narrow the bottom ends to be a snug fit in the gap in the bottom halves. Took down the ends with the side of an end mill...

With the bottom pieces pushed onto the ends of the top pieces, cross drilled for the mounting bolts.

Bolted the halves together, and it was time to drill out the hole for the crank bearing. To keep the vise jaws square, put one of the other pieces on the right side as a spacer.

Then it was time for another little drilling jig - bolted a bit of brass rod turned to press fit in the bearing hole, and a guide hole the right distance up for the crosshead pin. Used that guide to drill the upper hole in all three conn-rods.

With the holes done, ready to start shaping the upper end down. First, set the piece up on its side in the vise. Here is where the extra width left on the one side of the blank came into play - that is how it was held. With an end mill, milled out the recess in either side of the upper arm.

Then, with the piece bolted down to a aluminum block in the 4-jaw on the rotary table, started to mill out the profile of the upper arm. The rotary table made it simple to line up each face with the table axis and take it to shape. The block was mounted so that the hole in the upper end was centered on the rotary table, so I could turn the radius at the end.

Next photo shows the first one milled to shape, and the second one ready to go.

Last photo shows it test-fit in the crosshead guide.

Next up will be to make the crosshead pins, and then start on the crank bearings for the lower ends. That will be a fun moment - get to reassemble the engine and get the whole thing spinning for first time (can't run with no valves yet, but close!)

 

[SilverSanJuan]

Nice work on the rods. How did you align the part on the rotary table so that your part was parallel to the x-axis?

Todd

 

[crueby]

Nice work on the rods. How did you align the part on the rotary table so that your part was parallel to the x-axis?

Todd

Before starting the milling I measured out the widths at top and bottom of the arm, and marked that on the parts. Then aligned it best guess by eye and milled close to that. Readjusted the angle and took light cuts to check that I hit the marks at both ends. The side profile is not a critical fit to anything so eyeballing it works fine (helps to be nearsighted, or have magnifiers)

 

[crueby]

Last thing needed for the connecting rods were some smaller 2-56 nuts. The store-bought ones were too large, so they overlapped the sides of the rod (plus they just look chunky). So, drilled/tapped the end of a piece of stainless rod, and milled the flats with the rotary table. Got enough for 2 pair off either end of the rod.

Second photo shows the difference - set on the left is with the commercial nuts, the set on the right has the home-made ones - much more in scale, plus they wont project out and hit the crank webs.

On to the connecting rod bearings. They are made from bronze, in the same way that the main shaft bearings were made (shown in earlier posts). A piece of bronze rod larger in diameter than the finished bearings (to leave room for cutting it lengthwise) was milled flat on opposing sides, cut lengthwise, the cuts milled smooth, and the two halves soft soldered back together again. Then, that was chucked up in the 4-jaw so that the solder joint crossed the centerline, and the end drilled/bored out to size. The smallest drill possible to start the boring bar was used, so that it would not put much strain on the solder joint - on the first main bearing I went too large on the drill and popped the joint. Then the smallest boring bar I have was used to enlarge the hole out to the diameter of the crank pin.

After that, used the parting tool (well sharpened) to cut the recess in the center to match the bore of the connecting rod, and the bearing was parted off.

Last photo shows the first bearing test fit in the connecting rod. One down, two more to go....

 

[fuzzymuff]

Hi Crueby.
Every time I get on the computer the first task is to check if you have made any more parts. Love the updates. Fantastic workmanship.
Graham.

 

[crueby]

Hi Crueby.
Every time I get on the computer the first task is to check if you have made any more parts. Love the updates. Fantastic workmanship.
Graham.

Thanks Graham! I've been having a ball with this build. Not sure how to top it, but a friend of mine got a huge 3' x 12' capacity lathe for his business.... Hmmm...!

 

[fuzzymuff]

Thanks Graham! I've been having a ball with this build. Not sure how to top it, but a friend of mine got a huge 3' x 12' capacity lathe for his business.... Hmmm...!

Crueby.
How about a 1 to 1 scale Shay.

 

[crueby]

Crueby.
How about a 1 to 1 scale Shay.

Whoa! I'd need a MUCH bigger garage!

 

[crueby]

Not much in progress pics for new parts today - have been assembling the con-rods into the engine and getting the bearings lapped and rod lengths adjusted. So far so good, but it is a pain in the swarf to assemble/disassemble an engine with this many little parts/bolts/nuts/etc so it is going slow, but should have a set of pics and a video of it rolling around on the display track Friday or Saturday (other activities keep getting in the way).

Below are a couple shots from loctiting in the bearing halfs and assembling/lapping them onto the crank. The TimeSaver lapping compound that someone recommended to me is working great - just a pinch of the powder in some oil and slather it in the bearing, spin it around by hand, and it is done. Neat stuff.

 

[SilverSanJuan]

Very nice work! How is the rod length adjustment done?

Todd

 

[crueby]

Very nice work! How is the rod length adjustment done?

Todd

The lower ends of the piston rods are threaded, and have a locknut. It threads into the crosshead, set the length and tighten the locknut. There is about an 1/8" of travel so easy to center the piston movement in the cylinder. He has you put a little slot in the top end of the piston rod so you can turn it with a screwdriver - I forgot that step till after I had already pinned/loctited in the pistons to the rods. Oh well - turning them with needle nose pliers at the threads works, just have to be careful not to scratch up above on the smooth area. :wall:

 

[SilverSanJuan]

Ahhh yes. Same thing on the A3. I forgot about that.

 

[edhume3]

Hello Crueby,

It is a pleasure to see your work.

It is no big deal not to slot the piston rods. The best way to adjust the rod length is to not mount the cylinders. Instead, use calipers to measure the height of the piston top protruding above the frame part where the cylinder is mounted (crankshaft at top dead center). You can hold the piston heads while you tighten the nuts and that provides plenty of holding leverage.

Best Regards,
Ed

 

[crueby]

Hello Crueby,

It is a pleasure to see your work.

It is no big deal not to slot the piston rods. The best way to adjust the rod length is to not mount the cylinders. Instead, use calipers to measure the height of the piston top protruding above the frame part where the cylinder is mounted (crankshaft at top dead center). You can hold the piston heads while you tighten the nuts and that provides plenty of holding leverage.

Best Regards,
Ed

Good tip, that should be much easier. Thanks!

 

[crueby]

Ed - I tried your tip this afternoon - that way is MUCH easier. One of those 'but of course' moments. Or, as Homer Simpson would paraphrase, DOH! oh: