Best Of The Overland/Wiseman brass Western Maryland Shay thread

[u18b]

great shots.   If you look up on the switchback picture, look just above the switch on the hillside rail.  What looks to be a derail is actually a slip rail point.  They deliberately designed in a feature so that as the rail 'slipped' downhill, once it got to a full rail length, they'd pull an entire 33' rail and take it back up to the top again.  I've never seen that anyplace else, but it testifies as to what a 9% grade looks like.

I love Cass because it's real, even though they've upgraded the track with heavier rail and ballast.  But same impossible curves and grades as the original logging railroad alignment up the mountain.

Randy,
I've never heard of what your describing.
It's hard to see what's going on.

[u18b]

I think this is solvable, but I'd still worry more about the bottom one on the crank.  That's unlike anything else out there.   Maybe just do like Lima and drown it in grease every day whether it needs it or not.

Actually, that's exactly what I do.  I treat this model like the real thing and lube it regularly.   I wouldn't be surprised if there were little oil drops around the unitrak roadbed..

[u18b]

I believe you can cut a gear like that using a lathe and a thread tap with the same pitch. The gear teeth would end up dished and mesh better with the worm.

There are many different videos showing how. This is just two:

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Chris,

The problem is that the hat shaped worm gear interfaces another gear- the cylinder head gear- which turn the lower worm.

So this worm gear must interface both properly.

[peteski]

NWSL sells steel worms - maybe one would fit?

Um, that statement  sounds  weird. 

[u18b]

I have a line on source for *brass* worms.  It turns out that one of the Samhongsa worms is a dead match for the Shay worm.

But I don't know which loco yet.   Gene Maddox is helping me.
Hopefully I'll have some more information in a week or two.

When I get a brand new worm in my hands, then I will be able to take much more accurate measurements.

[mmagliaro]

The place I use in Poland is here:
https://shop.kkpmo.com/index.php?cat=c21_Spur-gear---Pinions---Worm-gears-Spur-gear--Gearwheel--Pinions.html&XTCsid=829ilsbgpu7sfbt2ugmnmpv8j5

They make spur, worm, and worm wheels in many different modules, thicknesses, bores.  You can get them in brass or delrin.   It usually takes 2-3 weeks for the gears to show up, but they always do, and the gears are always beautiful.

Your gear is kind of funny, though.  It looks like it has angled teeth, so I'm not sure a straight spur gear will work.

[Chris333]

The teeth look angled in one photo and straight in the next?

I've ordered from the same link Max gave. I didn't have it all figured out so ordered a few teeth each way to make sure one would work.

[u18b]

The teeth look angled in one photo and straight in the next?

I've ordered from the same link Max gave. I didn't have it all figured out so ordered a few teeth each way to make sure one would work.

Yes, the teeth are angled.   I'll have to try and get some measurements.

[peteski]

Yes, the teeth are angled.   I'll have to try and get some measurements.

That makes sense since that gear meshes directly with the worm gear (which also has angled teeth that mesh with the worm).  It sure  is an interesting arrangement (not doubt done that way due to space constraints.

[u18b]

OK.  Here is what I came up with  (plus or minus operator error)

[mmagliaro]

Yikes.
18 teeth 5mm diameter works out to module 0.25.   kkpmo (that supplier in Poland) has an 18 tooth, mod 0.25 gear in brass,  but not with the bore and thickness you need.  But they have a custom option,
https://shop.kkpmo.com/product_info.php?info=p21680_spur-gear---customized-gearwheel.html&XTCsid=829ilsbgpu7sfbt2ugmnmpv8j5

You can get 1.3mm thick, 1.4mm bore, 18 tooth, mod 0.25, brass for 6.38 EUR  (about $7.50), and shipping is on top of that, so figure $5 or so from Poland (it's not too bad - I've ordered from there before).

They can also do it in Delrin.

But it won't have angled teeth.

I wouldn't even try to make that whole raised boss area and that bored out area to hold the screw head.  It's a very shakey
design having the gear rotate around a screw like that anyway.  You could order a new gear with a much more standard thickness
and bore, and then just put a screw through a piece of steel or bronze tubing as a bushing and put all of that through the gear.
Then the screw tightens down against the tubing so it won't ever work loose.  The gear just rotates around the tubing.
A washer under the screw head would keep the gear down.

And yes... it might be better to have them make it in Delrin.  That would spare the wear on that other gear that goes to the crank, which would be MUCH harder to replace if it goes.  Even without the 10 degree angle, it would probably work.

[u18b]

Max @mmagliaro

This is all new to me.   Thank you for your input.

Is this what I should order?

[u18b]

Oh....
And shouldn't the hole be larger and match whatever tube I'm going to use?  If I understand all this correctly.

The frame plate is drilled for a M1.4 screw.

So according to what you're proposing, The inside dia of the tube should be > 1.4mm
But the dia of the hole in the gear is the dia of the tube + .1mm

So the hole needs to be made actually larger than 1.4mm.

[mmagliaro]

Oh....
And shouldn't the hole be larger and match whatever tube I'm going to use?  If I understand all this correctly.

The frame plate is drilled for a M1.4 screw.

So according to what you're proposing, The inside dia of the tube should be > 1.4mm
But the dia of the hole in the gear is the dia of the tube + .1mm

So the hole needs to be made actually larger than 1.4mm.

Yes.  You are thinking exactly right.  The tube that the gear will spin around needs to be large than the existing screw hole.  So you'll need to pick the gear bore to be > 1.4mm.  I'd go with at least 1.6mm.  That's only 0.2mm larger, or .007".  That ain't much to support the tube.
Better make the bore more like 1.8mm.  Now... can you get tubing that is 1.8mm OD and 1.4mm ID?  Maybe.  But you can take a piece of steel rod and then bore and turn it to be EXACTLY what you need.  That's probably a good idea because then it can be turned to EXACTLY fit the gear you get, so the fit will be more precise than relying on a piece of commercial tubing.

There are guys on here with lathes who can make you a tube.  I can help you there if you need me to make a tube after you get the gear.  Just let me know.

Then there's the thickness.  You can leave it at 1.3mm, since that's the thickness of the toothed portion of your old gear.  You'll just need to use some washers to position it correctly.

And it might be a good idea to order a few of these, since you have other Shays, and in case you wreck one, or in case one breaks, or or or ...

[u18b]

I ordered 6 gears for about 33 bucks total with shipping and fees.

When they come in, I'll see if I can get some help with the tube.

Then see:

1.  If it will work- lacking the 10 degree angle
2.  How fast they wear out.  I'll install 2.
        a.  Shay with sound- continuous running on the flat level.
        b.  Shay Resurrected - continuous running on the torture grades.

I would say that if this gear works well and can last for two - three months running an average of an hour a day on the torture grades then it would be worth it.  If it lasts six months, I'd be in happier than a seagull with a french fry. 

(https://www.youtube.com/results?search_query=seagull+french+fries)