Building Kozo's New Shay locomotive

[ths]

Eek!    Didn't they do a story on you on CNN for nut shining in public?

I think they did, it created quite a sensation in Tasmania. Hugh.

[crueby]

Okay, now that the forum site is back working today, time to get caught up on progress.

Not much in progress pics for new parts the last few days - 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.

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.

Not a lot to show from today, since pictures can't show things moving smoothly (and I can't video while using both hands to hold engine/turn crank). The main bearings and crank bearings have all been lapped in with some TimeSaver compound, and you can still see all my temporary markings on parts so I get them all back on the same shaft and side (learned that one the hard way on a previous model - what a pain to sort out unmarked bearing halves that got mixed up!). So, last picture shows things during reassembly - the pistons are all set on the crossheads, o-rings are there in the piston ron bearings and in the pistons themselves.

I want to make up the gaskets for the top/bottom of the cylinders before putting the cylinders back in place, so that will be next. Then I am going to bolt it up on the loco and get some video of it rolling back/forth on the display track and everything so far spinning. That should be fun (listen for my cackling in the background!). Been busy with other stuff the last couple days so that will probably not be till late friday or saturday. This is where it all starts to come together - fun time!

[b.lindsey]

Sure is getting close now Chris! And as you say exciting as well...looking forward to seeing it all in motion.

Bill

[fumopuc]

Hi Chris, brilliant. As Bill said, waiting for the video.

[ths]

Possibly a dumb question, but what are those brass spacers doing in the big end bearings? A a new one for me...but I have no doubt that you know what you're doing! Hugh.

[crueby]

Possibly a dumb question, but what are those brass spacers doing in the big end bearings? A a new one for me...but I have no doubt that you know what you're doing! Hugh.

Those are not spacers - those are the retaining rings for the pivot pins. The pivot pins on the u-joints have arched heads on them that just fit under the rings - all is assembled, then the rings are slip-fit over the pin heads and held with a screw into the corner of the u-joint housing.

Here is a close up photo of them from an earlier posting that shows those parts. Hope that is the brass part you meant - let me know if not!

[crueby]

Got the engine parts so far all assembled again and fit on the loco, and could not resist pushing it back and forth on the display stand to watch it all spin. No valve train yet, so cannot run it for real, but getting close! Below are a couple photos, plus a link to a short video of it moving (dont think the camera picked up the sound of my face cracking with the smiles!). Would have posted this earlier but right at the end of the video you can hear the phone ring - had to go over and shovel a few feet of snow off my mothers' roof, and came home and did the shallow pitch part of mine too. Crazy winter this year... yes, I can hear you guys Down Under snickering from hear, and complaining about the heat!

<a href="https://www.youtube.com/watch?v=kFhupERdyAI" target="_blank">http://www.youtube.com/watch?v=kFhupERdyAI</a>

[Hans]

Chris,

Perhaps ths is referring to the connecting rod bearings....I am assuming that the pieces of brass stock ("spacers") are holding the two halves of the bearings in place while the Loctite cures.

BTW...very nice work. I have learned a lot from this build. Amazing what can be accomplished with Sherline machines with skill and ingenuity.

Hans

[crueby]

Those spacers between the bearing halves were pieces of cardboard to keep the loctite from sticking the halves together. Maybe it looked like brass in the photos - guess I didn't make that clear in the post.

[Dave Otto]

Congrats Crueby!

That sure looks nice!

Dave

[ths]

Yes it was the cardboard. Makes sense now. Congratulations on the fluid movement of the loco, a good feeling I bet. Hugh.

[fumopuc]

Hi Chris, I am sure it was a special moment when the engine was driven first time by pushing the loco. Well done.

[b.lindsey]

Definitely a "Happy Dance" moment Chris....well done!!

Bill

[crueby]

Alrighty - on to the valve stem assemblies. Both the valve slider and the valve crosshead are bronze, and were first milled to outer dimensions from a larger piece of rod. Both will be made in a group of three to make it easy to position/hold in the vise. (photo 1)

First shaping operation on the sliders was to mill the rectangular recess in the face side. This was done as a plunge cut with a center-cutting end mill, and the shape traced into the bronze. (photo 2)

Next, the piece was turned over and a slot run down the length with the mill. This will form the groove that the square adjusting nuts sit in. (photo 3)

With the piece sticking out the side of the vise, cross-slots were milled in to form the groove that the valve stem rod will sit in. (photo 4)

Then with the piece held at a 45 degree angle in the vise, the tops of the sliders were tapered back. Since the angles were all 45, it was possible to do both sides of each top with this one position, just had to raise the cutter for each side and run it back and forth. (photo 5)

Last shaping was to also taper the side faces. (photo 6)

With all the shaping done, the sliders were cut apart and trimmed to length with the mill. Last photo shows the three sliders all complete.

[crueby]

With the sliders done, it was time to move on to the valve crossheads. On the Shay, the valve stems come down to a crosshead/guide assembly that the reversing gear connects to. This keeps the angular motion from the eccentric from being transfered to the valve stem. To start, another rectangular section of bronze was milled to size, then a step cut into each side. This step will allow the guide to hang onto the crosshead. (photo 1)

Next step was to drill the cross-hole in each of the three pieces (all three are gotten out of this one strip). This cross hole will be threaded for the pivot pin from the reversing gear linkage. (photo 2)

The piece was turned on its side, and notches cut into the edge to form the protruding post at the top of the crosshead. (photo 3)

Next photo (4) shows the crossheads so far, with the major shaping and cross holes drilled. The three parts were then cut from this strip.

The cut ends were then trimmed to length with the end mill. The other part visible on the right was to keep the vise jaws from twisting. (photo 5)

Last step was to drill through the ends for the hole to hold the valve stem, plus a lock screw on the bottom that keeps the cross pin from un-threading itself. (photo 6)

Last two photos show the three valve stem assemblies complete - made up the valve stems (stainless rod threaded at each end) plus the square nuts. You can just see that the nuts have a short round section on the end. I did not have an end mill quite small enough to match the diameter of the stem rods, so this projection keeps the square nut centered on the slider.

With the sliders all done, next step is the valve crosshead guide, which bolts to the piston crosshead columns...