RFQ 50t Spur gear brass or possible other material

Need a gear made for a '40s sheldon lathe. Original gear looks to be cast and since it seems to be the gear thats always taken the hit from a crash I'm thinking the replacement should be brass.

Gear has 50 teeth,
an OD of 3.233"
Plain bore .628"
16 DP
Should be 14.5 PA
Has a back hub spacing of about 1" but this isnt necessary, I can make a spacer

Basically just looking for a disk with some teeth on it.

This is what I put in with your #'s and its not tool comping right even with a 1/8 mill , is there any other #'s you have on this part ? I don't do external gears very often .

reedeprintice said:

This is what I put in with your #'s and its not tool comping right even with a 1/8 mill , is there any other #'s you have on this part ? I don't do external gears very often .

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I don't think you have that right tools to do this job...

I can cut you one. I have the right equipment .

Email or PM me.

Regards.

Mike

I'm not trying to be a smart ass. I don't cut gears, and I never have. But, I would think a real gear tooth cutter and a dividing head would be the only way. Trying to profile with an end mill sounds like trouble.

I have done a few but always larger teeth and most of the time can get the tool to comp out .

Pm me and I will cut you one
PC

Blazini said:

I'm thinking the replacement should be brass.

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I highly recommend bronze if you are going away from the original grey iron. I believe you will get an order of magnitude more wear out of it...

Hello,
we manufacture gears here in India. we are also in repairing mechanical part but mostly transmission gears, in my opinion I would recommend you to go with the material used in the original one because it is meant to get damaged if the machine has an accident so that other parts of the machine don't get damaged(think on it ones) we use grey iron for the indexing gears for some of our old hobbers and gear shapers.

I don't think a grey iron gear would cost you more than 10-12 bucks!

Blazini, when one is busted, the other gear is likely damaged. They'll probably want your "other" and run a cutter over it to clean it up.

Jasmeet singh said: "we manufacture gears here in India [...] I don't think a grey iron gear would cost you more than 10-12 bucks!"

It'd take me 3 or 4 hours and $5 worth of cast iron. $1.50 an hour, not going to happen here.

Sunset Machine said:

Blazini, when one is busted, the other gear is likely damaged. They'll probably want your "other" and run a cutter over it to clean it up.

Jasmeet singh said: "we manufacture gears here in India [...] I don't think a grey iron gear would cost you more than 10-12 bucks!"

It'd take me 3 or 4 hours and $5 worth of cast iron. $1.50 an hour, not going to happen here.

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you are right that mating gear would also get damaged, and i dont know about the conditions of your country but it is usually possible here in India with that price for a small gear

Peter Colman.......your inbox is full, the gear is 1/2"thick

Mating gears don't appear damaged at all, so I think I'll take my chances on that. It's just a lead screw gear for a 10" lathe, I've heard of aluminum gears lasting forever.

anybody else wanna take a crack? So far I've heard about $70, I'm considering any suitable material besides steel.

Sunset Machine said:

It'd take me 3 or 4 hours and $5 worth of cast iron. $1.50 an hour, not going to happen here.

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Really? I figured it would take someone who was set up to cut a gear about half that at best. I'd think I could set the lathe up and do it myself in about that

Your answer is in post #4.
Get with finegrain, he made a complete set of metric conversion gears for my Sheldon.
can't beat the quality or price.

'just a query from the bleacher seats: why "any suitable material besides steel?"

Arthur.Marks said:

'just a query from the bleacher seats: why "any suitable material besides steel?"

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Because the OP is a cheap ass. He thinks changing the material will save him money.

Arthur.Marks said:

'just a query from the bleacher seats: why "any suitable material besides steel?"

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Did you read the first post?

ewlsey - no need for name calling.

Blazini - yes. all I can read into it is you might be intending to create a "sacrificial" gear? Would brass, though, serve that purpose well? It doesn't shear easily in my limited experience, so I would expect it to deform, still jam the gear train and possibly lead to damage. Is shearing the teeth off the gear in a crash the "suitability" you're implying?

Agree with Arthur.
if the original was cast and it sheared teeth in a crash with no damage to mating gears I would not change the material.
Also, a small observation is you stated it had a plain bore- this would seem to indicate an idler of sorts.
a lead screw gear ( or any driven/driver gear )would have some positive means of retention.

What model is your Sheldon?

Arthur.Marks said:

ewlsey - no need for name calling.

Blazini - yes. all I can read into it is you might be intending to create a "sacrificial" gear? Would brass, though, serve that purpose well? It doesn't shear easily in my limited experience, so I would expect it to deform, still jam the gear train and possibly lead to damage. Is shearing the teeth off the gear in a crash the "suitability" you're implying?

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Ewsleys post has been reported, this isnt the place for him to express his opinion of me. Kind of odd though considering that I'm well aware that the material I suggested (brass) costs quite a bit more than steel

But yes, it needs to be a "sacrificial" gear. It's an idler and its mating gears are 1 much larger gear and one "double" faced gear for lack of a better term, So I'd rather this gear take itself out again if I ever crash it. From what I can find, on paper some say "brass" shears at almost exactly the same point or lower than "cast iron" much lower than wrought iron and about half of what it takes to shear "steel". Those are generalizations because obviously theres plenty of different alloys, but what I find on brass is each flavor is pretty close on shear points. Bronze was mentioned but in general, while great for wear, is much tougher than brass or cast iron so no to that. I'd be all for a cast Iron gear but I don't think many people keep a 3+" bar of it laying around. I've had plenty of brass fittings just flat out crack off at the threads, and I've never turned stringy brass chips on the lathe so brass is about as close to a cast gear as I think I'll get.I have never seen a "bent" gear tooth, gear pitches are designed so that one tooth will contact the next before completely leaving the space of the last. There is no space to bend a tooth. the only way to create that space is to completely take the tooth off and since brass technically shears lower than cast.......

That said even a nylon gear and possibly aluminum is fine. The equipment I work on every day uses steel gears with a nylon idler in between. And these are much bigger, faster machines than my little Sheldon. Nobody seems to want to cut nylon gears though, but I absolutely will not consider steel. I figured why was a give-in but I suppose not, maybe it's because I'm a cheap-ass, but then again that's probably why I have a 70 year old lathe in the first place.

iwananew10K said:

Agree with Arthur.
if the original was cast and it sheared teeth in a crash with no damage to mating gears I would not change the material.
Also, a small observation is you stated it had a plain bore- this would seem to indicate an idler of sorts.
a lead screw gear ( or any driven/driver gear )would have some positive means of retention.

What model is your Sheldon?

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Like I said, cast would be great, but it doesn't seem feasable. The only thing I'd be worried about with cast is that it's so all over the place that a new cast gear could be stronger than the others. There doesn't seem to be many "standards" regarding cast iron. Yes, it is an idler but the only purpose the entire geartrain serves is to drive the leadscrew so I suppose technically calling it a "leadscrew" gear wasnt all that far off, I didnt think it was all that pertinent to the point I was trying to make, the specs for the gear I need to have made are still the same. The Sheldon is model 1026BMWQ