Best Of The Overland/Wiseman brass Western Maryland Shay thread

[u18b]

Really nice work mounting those ball bearings in there.  Although I have to say, I think I would have just sleeved the shaft from 1 to 1.5mm and put the Atlas worm on there. 

I had not thought of that.   However, I'm not sure if that would have really helped in this case.   I'm going to the RS-3 u-joint- which is 1.5mm shaft anyway. 

That worm wheel (worm gear) will always have a problem rotating true because it is using the screw head as the "shaft", and that will
never be round.   You could still try making a sleeve to go inside the gear's bore hole, so the gear actually rotates around that,
and then use a different screw with a smaller diameter head (or spin that screw in a Dremel and run a file on it to take some of the diameter off the screw head, just enough so the screwhead doesn't actually touch the gear except on the underside of the head, as a retainer to keep the gear on).

That's always a possibility in the future.  When I finally settle on a proven method, then I can decide.
If I can't get a Delrin gear to work, then one possibility is to pay to have a steel worm made or bought.
Then I can get one of you guys here with precision instruments to take the worm gear and drill the center hole to a size that I can better use.

But I'd really like to get a Delrin gear working.  That would be my first choice.

[Mike C]

 NWSL has delrin gears https://nwsl.com/collections/motors-flywheels . Look in the old catiloge pages . I've put their delrin gears in a couple of brass locos that were too noisy and to save on ware .  and they also have steel gears.

[u18b]

NWSL has delrin gears https://nwsl.com/collections/motors-flywheels . Look in the old catiloge pages . I've put their delrin gears in a couple of brass locos that were too noisy and to save on ware .  and they also have steel gears.

Mike,
Thank you.

As far as I could gather, NWSL does not make a mod .25 worm.
https://cdn.shopify.com/s/files/1/0250/4032/2669/files/Gears_1_2.pdf?263

But then, I'm a novice at all of this and I may not even know what I'm looking at.

[u18b]

OK.
I have another option related to the worm gear.

An M1.6 screw fits very well inside some K&S 3/32" brass tubing I have.

Then, I could send the gear to someone and get them to drill the center of the gear for 3/32".

Now, if I went that route, I'd need to come up with a steel worm, otherwise I'd still have brass on brass.

[Chris333]

mod .25 worm

Maybe something you could use here:
http://www.narrow-garage.com/NarrowGarage.html#Gear
You will have to have Google translate it to English, but the good news is if you send them an e-mail they reply in English. I have ordered from them a few times (twice this year) the shipping is quick. Shipping might be a little high though.

Thought I'd share.

[mmagliaro]

OK.
I have another option related to the worm gear.

An M1.6 screw fits very well inside some K&S 3/32" brass tubing I have.

Then, I could send the gear to someone and get them to drill the center of the gear for 3/32".

Now, if I went that route, I'd need to come up with a steel worm, otherwise I'd still have brass on brass.

I've been thinking about this - just how easy or hard it would be to truly "center drill" an existing gear.  How exactly
would one hold the gear so it could be drilled?  I could put the gear into a collet chuck, which would put nice ever pressure
all the way around on the teeth so they wouldn't be damaged.  But I'm afraid that's not going to be holding the gear centered.  The exterior "circle" around those teeth isn't round anymore after they've been in use and have worn, even if only a little.  And we're looking for a center hole that is within .001" of dead-center accuracy, I would think.

I guess hold it by the teeth and bore it, and accept the fact that whatever wear is already on the outer edges of the teeth is going to be that much error in the rotation?

I'd like to hear from more experienced machinists than I (which is anybody besides me with a lathe) how does one do this right, or is it even possible?

[rodsup9000]

 Take a piece of stock and bore it the OD of the gear and a depth of about 3/4 of the thickness. Drill and tap 2 holes 180 of each other to hold a thin stock to hold the gear in place. Using a boring bar, you can now get a concentric hole to the OD of the gear



 

[metalworkertom]

I've been thinking about this - just how easy or hard it would be to truly "center drill" an existing gear.  How exactly
would one hold the gear so it could be drilled?  I could put the gear into a collet chuck, which would put nice ever pressure
all the way around on the teeth so they wouldn't be damaged.  But I'm afraid that's not going to be holding the gear centered.  The exterior "circle" around those teeth isn't round anymore after they've been in use and have worn, even if only a little.  And we're looking for a center hole that is within .001" of dead-center accuracy, I would think.

I guess hold it by the teeth and bore it, and accept the fact that whatever wear is already on the outer edges of the teeth is going to be that much error in the rotation?

I'd like to hear from more experienced machinists than I (which is anybody besides me with a lathe) how does one do this right, or is it even possible?

From a mechanical view point . Is there any gain to be had centering the center hole if the gear is worn enough to effect concentricity ?

[u18b]

From a mechanical view point . Is there any gain to be had centering the center hole if the gear is worn enough to effect concentricity ?

Good question.

This would be true maybe if the teeth were badly worn in an uneven fashion.   But the teeth look OK to me.  And the mesh is still there.

But the hole on the other hand....It's definitely worn larger so that the gear has lateral wobble movement.
 If I drill it by hand with no effort to truly center it, then I will almost certainly induce eccentricity to the revolution of the gear.

Maybe a better way of answering would be- trying to center the gear surely could not hurt.

Another thing to think about is we don't HAVE to go by the teeth for centering the gear.
It has a base.  This is still as true as the day it was made.

Everything on the top-side of this gear could be irregularly worn from vibration...


But on the bottom side.... that base is still true and un-worn in it's circularity.
Max- maybe THAT's the place you could "grab" the gear for drilling it.




OH- and as far as visual wear.....  you can see that when you stick a screw in the hole, you can move the screw back and forth.  It is no longer snug.

Also, you can REALLY see wear on the worm.    They look awful.

But I can't visually detect any wear on the teeth.

[u18b]

Maybe something you could use here:
http://www.narrow-garage.com/NarrowGarage.html#Gear
You will have to have Google translate it to English, but the good news is if you send them an e-mail they reply in English. I have ordered from them a few times (twice this year) the shipping is quick. Shipping might be a little high though.

Thought I'd share.

Chris,
Thank you for this.   This may prove very helpful.  Google translate does work when you copy and paste.

But..... I don't see my gear in there.

The closest I see is a 19 tooth gear.

And then there is the issue of right versus left hand.

I think my gear and worm are right hand.  I'll have to triple check everything when I get home tonight.
Because there's one MORE issue.

I measured the teeth at 5 mm across.  Divided by 18 teeth (at least that number is certain)..... and you get: 
Module .277.   Well that's not exactly .25.    In fact, it is halfway between .25 and .3.

So now I'm wondering how accurate my measure was.

Working the math backwards, the following modules with 18 teeth should produce a measure of:
.25 module = 4.5 mm
.30 module = 5.4 mm

I think it is more likely that this is actually a .30 module since My measure is more likely to be small not large (did I really get on tooth tip to one tooth tip on the opposite side?).
Also, what if the teeth are also worn ever so slightly.

I'm going to be much more careful in measuring tonight.

[rodsup9000]

 Bore a hole large enough so you can mount one of the bearings you showed earlier. Then make a adjustable stud plate for it to mount on. Being adjustable, you'll be able to adjust the lash to the gear that goes down to the crankshaft. Then adjust the lash from the motor worm with it's mounting.
 

[metalworkertom]

But on the bottom side.... that base is still true and un-worn in it's circularity.
Max- maybe THAT's the place you could "grab" the gear for drilling it.

Super glue the gear to a faced arbor would work I think .

[rodsup9000]

Super glue the gear to a faced arbor would work I think .

Then how do you indicate the OD of the gear??? I've tried and it's very hard to get it right and indicated on the OD of the teeth. Then you have the chance of not getting it glued square, also.

[u18b]

Take a piece of stock and bore it the OD of the gear and a depth of about 3/4 of the thickness. Drill and tap 2 holes 180 of each other to hold a thin stock to hold the gear in place. Using a boring bar, you can now get a concentric hole to the OD of the gear

 

Since the teeth are worn (even if only a little).....
maybe this is the best suggestion, but..... cutting the bore to the size of the extended base, not the gears.
It seems to me that this would be ideal and help center everything.
 

[metalworkertom]

Then how do you indicate the OD of the gear??? I've tried and it's very hard to get it right and indicated on the OD of the teeth. Then you have the chance of not getting it glued square, also.

This is assuming the recess is concentric and the gears are not too worn. The arbor has to be machined to match the recess . Tail stock holds flat until dry. This technique is often used in clock and watchmaking.  I expect there is a indicator tip to facilitate measuring run out  of the gear.