Best Of The Overland/Wiseman brass Western Maryland Shay thread

[u18b]

I bought a big pack of 1mm (and 1.5mm) shafting on ebay. Unless there was a reason to keep the stock shaft?

Chris,

Good question.
Yes, I could go with a new shaft.... but here are some parts of the decision.  A few factors.

Technically, I think the shaft could even be brass- not necessarily steel. 
But the shaft must be exactly 1mm - or it affects the gear mesh.
Further, a brass shaft has the disadvantage of when you have to lock the shaft in place.
To do so, you need to solder in the journal caps right on top of the shaft... and if any flux and solder get inside, then the shaft could get soldered up.

So that is where steel comes in.   
We want it to resist solder- but not too much.
For example, stainless steel is probably too hard and too difficult to receive solder (you would have to get it pretty hot).
And the brass parts are often very delicate.   If you get the temp up too high, it can damage it (like the painter, I also got one of these expensive bevel gears to hot and deformed it- but I had a spare back then).

So softer steel is preferred in this application, I think. 

And that's the challenge of switching shafts.   I know what I have with the stock shaft. 
A new shaft may be perfectly straight, but the solder adherence will be an unknown at first.

Long answer (sorry).  So a new shaft is possible, but I think I'll see how this does.

[Chris333]

True. I usually use red Loctite to hold gears, but that doesn't like heat. In fact that is how you break loose Loctite with heat.

[u18b]

Time to modify the gears.

As before, I used my 0.13mm dental disc as a kind of file.







Here is the back of the gear the watchmaker created. 
The gear teeth are too squared in the back, so the edges need to be sanded.
The stock hole is .90mm so I found a drill bit that would hold the gear while I worked on it.




I sanded slowly and gently.  Inspected, sanded.  All under the strongest magnification I had.    This gear is tiny.
I felt like I was doing microsurgery again.

Notice that the right hand edge at 1 o’clock has yet to be sanded.




I then tested the gear in the truck and felt for any cogging- which only happened once.  I marked that tooth with a black marker see here at 11 o’clock.  I think I over-adjusted slightly, but it is still OK.




The first gear is finished.
Now to work on the second.

[u18b]

Now, it’s important to see that there is one more important mod I need to make for smooth running.

The back of these gears is flat.




I’m installing two gears in a front truck.

Here is the front truck on my Shay.   Notice the the gear on the right (the outside gear) has no extra restrictions.  The end is free.

However, that is not the case with the inboard gear.

Notice that the gear is at risk of hitting the frame in the corner at the red arrow.
That’s why it’s best that the back of the inboard gear be rounded so that it can have clearance in the best case, and in the worst case where it rubs the frame, it will be smooth and won’t catch.




So I put my drill bit with gear in a pin vise and spun it on sandpaper at an angle while also dragging it.




This is my initial contour.  The teeth themselves have been rounded- but I need more.






I was a little nervous about placing this in a motor tool, but I gave it a try on low setting.
Since the gear was firmly pressed on, it did not go flying.

The results were obviously faster and more even.

I finished with very fine sanding paper for a smooth mirror finish.
The results were exactly what I wanted- even though the work was tedious.

Here are a stock gear and a modified gear.

[u18b]

Time for installation.

The shaft had a bit too much play inside the truck.
So the solution is to gently pinch the channel closed slightly.  (red)

Then, as prep, I scraped/cleaned the edges of the channel where the journal cover will solder in place (blue).

We do NOT want flux or solder to get down in the channel (pink)




I reamed out the holes on the gears until they fit snugly on the shaft.

I installed the non-rounded gear to the outside (left in this case).
Then came a spacer for restricting she shaft from floating.
Then the rounded gear.
Lastly, I drilled a brass piece 1mm and cut a small bushing to lock down that end.






When I was satisfied with the placement, I carefully soldered the parts in place.
The shaft could then be installed.

[randgust]

That's one of the most difficult fabrication repairs I've ever seen done.   Wow....

[u18b]

Thanks Randy.
It was a big challenge.

[u18b]

Here is the completed trucks.
Worked perfectly now.

This repair and gear fabrication was very involved, but it worked out in the end.

Of course the truck will have to be repainted now.

[u18b]

This thread is about documentation of all I see and do with these great locomotives.

Alex sent his Shay to me because of one destroyed bevel gear.

Well, it turns out is was a trainwreck (pun intended).

He had another bevel gear which had a chip in the tooth - I replaced it (covered above).

But his transition gear was about worn out.
The loco still ran in forward, but would sometimes lock up (cog) in reverse.

Here is the gear I removed.
Just look at the wear.

Because this Shay was almost exclusively run forward, the wear is uneven.
The little teeth don't look like triangles as they should.
They look like Shark's teeth!



I replaced this gear with one of the nylon gears from the company in Poland (covered much earlier in this thread).