Shoptask owners?

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Harold_V
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Re: Shoptask owners?

Post by Harold_V »

Torch wrote: Fri Dec 11, 2020 5:12 pm Good point about the material. I really like 1144 stressproof for gears.
Stressproof is a good choice. Machines beautifully and has excellent strength, and can even be heat treated if necessary. Even in the annealed state it just might outlast gears made of gray iron. :wink:

H
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Torch
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Re: Shoptask owners?

Post by Torch »

Wait, what? I thought the point of 1144 Stressproof was that it didn't need heat-treating?

Hmmm. Google shows -- once again -- that Harold knows more than I. According to the manufacturer's data sheet, it can be induction hardened. (Although, it does also state "a magnetic particle inspection operation should be performed after heat treating" due to possible quench cracking.)
VelocityDuck
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Re: Shoptask owners?

Post by VelocityDuck »

After reading the posts, this doesn't look practical (at least for me).

Looks like I could purchase a cutter for not too much money. Make a mandrel to hold the gear shouldn't be too difficult. But I don't have a dividing head. I have a spin indexer, but that won't do 27 teeth. So I'll have to acquire a dividing head. And those look to be north of $300 for a cheap one (I HATE buying cheap tools). Guy told me once that when buying tools, buy the best. That way you only cry once. And I've done anything that needed a dividing head and can't see anything on the horizon that would.

So it seems like I'd be better off finding someone who could take my old 63 tooth gear and turn it into a 27 tooth. :-)
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Re: Shoptask owners?

Post by toddalin »

Have you asked Shoptask if they could do this? They had to broach the pulley that engages the mill's spline shaft after changing out a broken spline shaft for me and the replacement was a hair too big for the pulley when I tried to install it. BTW, my mill's spline shaft (4" throw) was no longer available so this was reduced to 3-1/2" of throw on the replacement. It is also a bit "sloppier" than the original where the Chinese had beaucoup pieces from which to choose. They just can't get parts for these.

I paid $500 plus shipping to Las Vegas, for them to replace the spline shaft in the quill, and when the engagement pulley didn't fit, they broached it for the cost of shipping both ways. He probably could do machine work for you if he is not feeling too grumpy.

Also, when I broke the spline shaft on the power feed, (because of the Chinese scale on the table that was 1-1/2" off center :evil: ), I got three shafts from Grizzly and one of the three actually fit the gear and I was able to mill it to the proper length.
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Harold_V
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Re: Shoptask owners?

Post by Harold_V »

Torch wrote: Sat Dec 12, 2020 5:59 am Wait, what? I thought the point of 1144 Stressproof was that it didn't need heat-treating?
Yep! It can be put to use in the as prepared condition, as it is created to be used that way, but heat treat is not unreasonable. The 44 in its designation indicates that it should respond perfectly well to the carbon cycle method of heat treat, and would benefit by greater hardness, reducing wear. It also benefits by an increase in tensile strength, albeit at the cost of ductility.
Although, it does also state "a magnetic particle inspection operation should be performed after heat treating" due to possible quench cracking.)
Something I can verify, thanks to personal experience. Many years ago I had a sub-contract to machine punches for an ammunition disassembly machine for the Army. The punches were made of Stressproof (specified---one does not have the option of choosing materials when working for the defense department), and heat treat was very much a part of the requirement. A good number of them did crack in the process, which I attributed to the method by which Stressproof is produced. Its properties are developed by severe cold working, which, no doubt, create considerable internal stress. I don't overlook the possibility that there can be cold seams developed, either.

H
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VelocityDuck
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Re: Shoptask owners?

Post by VelocityDuck »

toddalin wrote: Sat Dec 12, 2020 3:58 pm Have you asked Shoptask if they could do this?
No. I get the feeling that JT is in run-down mode. Just doing enough to pay the light bill.

I'll ask though.

-Don
VelocityDuck
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Re: Shoptask owners?

Post by VelocityDuck »

Asked JT if he could cut my old 63 tooth gear down to 27. He said that he's not setup to cut gears and suggested buying a generic 27 tooth gear, bore it out, turn down the old 27 tooth and press them together.

Interesting approach.
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Re: Shoptask owners?

Post by toddalin »

Sounds like a good approach and the "press fit" could act as a "break away" if necessary. Certainly a whole lot easier than cutting teeth.
Torch
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Re: Shoptask owners?

Post by Torch »

I don't know. If Harold is right about it being grey cast iron, I'm not sure that press fit is a great idea. There's just not much meat between the major diameter of the splines and the root diameter of the teeth, and I don't think it will tolerate a lot of stress without cracking. Maybe a very light interference fit of 0.001" or less with some red locktite? A steel gear ring with the cast iron spline insert might be better.
VelocityDuck
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Re: Shoptask owners?

Post by VelocityDuck »

Torch wrote: Sat Dec 12, 2020 8:50 pm I don't know. If Harold is right about it being grey cast iron, I'm not sure that press fit is a great idea. There's just not much meat between the major diameter of the splines and the root diameter of the teeth, and I don't think it will tolerate a lot of stress without cracking. Maybe a very light interference fit of 0.001" or less with some red locktite? A steel gear ring with the cast iron spline insert might be better.
I really can't see how it could work. The distance between the bottom of the teeth and spline is pretty small. Which leaves very little material on either piece.
toddalin
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Re: Shoptask owners?

Post by toddalin »

I was looking at my machine and 27 is pretty small and there wouldn't be a lot of surface area to contact. It may be doable.
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Re: Shoptask owners?

Post by TomB »

I just measured the minor diameter of the hole in a 27 tooth gear, its about .6045 or 15,3mm, so it would not fit one of the standard broach set guides but the keyway in the gear is exactly .125". Seems to me that hub of the gear could be formed with a custom turned guide and a standard broach. I would cut the broach guide with two keyways at 90*. Use guide with just the broach for the cutting the first keyway in the gear and then use it 3 more times with an actual key set in the second guide slot and the previously broached slot in the gear blank. The broaching process would mean that one could buy a 27 tooth gear as JT suggests then just drill and broach it out for the hub. To replicate the 27-tooth gear exactly one would have to buy a thicker gear with a hub then face it down to make the spacer surface. I looked quickly at Boston Gear and they seem to have suitable gears in stock for $25 to $30.
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