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UPDATE on Machine Completion (Ref: I Need A Gear Made...)

Same applies to starting a machine shop. If you really thought it thru, examined all that could go right and wrong, would you do it? I'm 50/50 if it was the right move

Oh, don't get me started...

Too late! If I could do it all again I'd have stayed at the 'Tech. Older me needs to go back in time and dope slap younger me.
 
One other aspect to the high-quote issue is than with most companies, the default way to do a job (like a gear) is the "correct" way, where there is a print calling out the actual tolerances that have been determined by thorough measurement or engineering, and they make it exactly within tolerance using the best cutting tools and the best measuring methods so they don't get it wrong. It's potentially over machined because that's the safest way to keep it from coming back a second time with an angry customer. This might be just an open rough duty spur gear, but it's very well possible that some of the high quote is that they don't know if it's going on an egg beater or in a Ferrari's transmission. The transmission gear would work on the egg beater, but not visa versa, so which side are they going to error on?

When you have a case where a precision part can be totally fine being a little on the sloppy or crude side, the obvious reaction is it should be cheaper, but without firm dimensions and expectations given to the maker, I guarantee it would be sloppy and crude in all the wrong ways. The idea that "they should know" is utter nonsense. We have jobs in this category come across the desk all the time and there's never "one way" that is just default knowledge to "professionals," UNLESS you specify it in writing. It's one reason why so many companies turn down the onesy-twosy job-shop work.

Making a gear like this shouldn't be hard if you have the tools and time, but there is a BIG difference when you have your own hands on the process and the mating pieces all at arms reach, and if you have to make two cause the first one didn't fit, that's not costing you while the next bigger $$$ jobs are stacking up behind you.
Jobbing gear shops are a different creature. Any gear man worth his salt will have a very good idea of what is expected of a change gear for an old south bend lathe, perfectly so when a sample gear is available to "reverse engineer".

True some shops won't work without a drawing, but other gear shops do so much replacement work they are used to making stuff with a minimum of information.

My guess is these shops will become fewer and fewer as fewer machines rely on electronic devices rather than mechanical components. Get your gears made while you can!
 
Victor Machinery Exchange?

At least their cutters have "inch" bores in them instead of the odd balled "metric" bores in them like the other Chinese cutters have. Yeah, I know, we are the "odd balls" in the world today. But it started out with inch bores way back in time with Brown & Sharpe.
 
At least their cutters have "inch" bores in them instead of the odd balled "metric" bores in them like the other Chinese cutters have. Yeah, I know, we are the "odd balls" in the world today. But it started out with inch bores way back in time with Brown & Sharpe.
Yeah, but you can make a metric arbor just as easy, I suppose. That's likely what I will do on the K&T I have. I've got a 1" and 1-1/4" arbor. I could use more spacers for them. But then again, arbors with a 40 taper aren't terribly expensive on the eBays.
 
@opsoff1 , I have a 1966 South Bend 13 and it may need some gears in the future. I don't want to be stuck in this situation myself, so I've decided to try to make some myself. I'll start with a 27 tooth DP14 and you can have it if it works.

I have a rotary table with indexing discs so all I need is an involute cutter and a blank. I ordered a set of DP14 involute cutters from eBay. Hopefully they will get the job done.

The only thing left is the blank. I know these are typically cast iron, but is that necessary? Sourcing blanks is almost as bad as getting the actual gear. I could go with something bigger and whittle it down on the lathe, but cast iron is such a pain. There seems to be no end to various steel and stainless discs on eBay. Can those be used instead?
 
@opsoff1 , I have a 1966 South Bend 13 and it may need some gears in the future. I don't want to be stuck in this situation myself, so I've decided to try to make some myself. I'll start with a 27 tooth DP14 and you can have it if it works.

I have a rotary table with indexing discs so all I need is an involute cutter and a blank. I ordered a set of DP14 involute cutters from eBay. Hopefully they will get the job done.

The only thing left is the blank. I know these are typically cast iron, but is that necessary? Sourcing blanks is almost as bad as getting the actual gear. I could go with something bigger and whittle it down on the lathe, but cast iron is such a pain. There seems to be no end to various steel and stainless discs on eBay. Can those be used instead?
That gear is not cast iron. It is a mild steel.
 
@opsoff1 , I have a 1966 South Bend 13 and it may need some gears in the future. I don't want to be stuck in this situation myself, so I've decided to try to make some myself. I'll start with a 27 tooth DP14 and you can have it if it works.

I have a rotary table with indexing discs so all I need is an involute cutter and a blank. I ordered a set of DP14 involute cutters from eBay. Hopefully they will get the job done.

The only thing left is the blank. I know these are typically cast iron, but is that necessary? Sourcing blanks is almost as bad as getting the actual gear. I could go with something bigger and whittle it down on the lathe, but cast iron is such a pain. There seems to be no end to various steel and stainless discs on eBay. Can those be used instead?
Totally appreciate the offer! Is there anything I can do/provide to assist with this?
 
QT 0psoffi : (The only thing left is the blank. I know these are typically cast iron, but is that necessary? Sourcing blanks is almost as bad as getting the actual gear. )

I have wondered about this .. mild steel, or even an aluminum gear (a shorter life gear)
 
I ordered some A36 steel discs from eBay I hope that will be a good enough grade of steel. They are 5/16 thick so I'll need to cut them down to 0.275 which I think would be most appropriately done on a surface grinder, but I don't have one. I'll try a fly cutter in the mill.

Next, I need a reference. I CADed up the gear and 3D printed a reference. This will give me a blueprint and a reference I can use to make sure I get the dividing head set correctly, etc.

AJFCJaUm5mKiE6htH7S1FCEbtkqRnOM49pOucQOQW8EjwWu7cTC2HpNLNtmIJxA6IMljv6AldDooD6pHDpM08DsV6LBWtT3xvEgF0F22uwxIQbnlNn-7WZXWwdVX-jWj8gXdSGa9QCB_mnZ6sj1y4afRe7K9HQ=w1418-h819-s-no


AJFCJaU83CYUxXs5I5r_Smz6bdjFJDvOrsdrDDK64AKVg5bWw9EaRy8cB2ozjq9AQba02Rc5OCJAH7QfJxgeM_gJlMgiy6DvI5acvK5cMR2Y9_Kl5K2kRiRDyoUGVkRA_Lyqum_YQVjeVSPojm2BLZiWYLrXkQ=w1298-h974-s-no
 
Totally appreciate the offer! Is there anything I can do/provide to assist with this?
Do you know the specifics on the needle bearing? I assume it is a standard bearing, but I could be wrong.

Never mind, I see you posted that in the first post: Torrington GB-88.
 
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I ordered some A36 steel discs from eBay I hope that will be a good enough grade of steel. They are 5/16 thick so I'll need to cut them down to 0.275 which I think would be most appropriately done on a surface grinder, but I don't have one. I'll try a fly cutter in the mill.

Next, I need a reference. I CADed up the gear and 3D printed a reference. This will give me a blueprint and a reference I can use to make sure I get the dividing head set correctly, etc.

AJFCJaUm5mKiE6htH7S1FCEbtkqRnOM49pOucQOQW8EjwWu7cTC2HpNLNtmIJxA6IMljv6AldDooD6pHDpM08DsV6LBWtT3xvEgF0F22uwxIQbnlNn-7WZXWwdVX-jWj8gXdSGa9QCB_mnZ6sj1y4afRe7K9HQ=w1418-h819-s-no

I ordered some A36 steel discs from eBay I hope that will be a good enough grade of steel. They are 5/16 thick so I'll need to cut them down to 0.275 which I think would be most appropriately done on a surface grinder, but I don't have one. I'll try a fly cutter in the mill.

Next, I need a reference. I CADed up the gear and 3D printed a reference. This will give me a blueprint and a reference I can use to make sure I get the dividing head set correctly, etc.

AJFCJaUm5mKiE6htH7S1FCEbtkqRnOM49pOucQOQW8EjwWu7cTC2HpNLNtmIJxA6IMljv6AldDooD6pHDpM08DsV6LBWtT3xvEgF0F22uwxIQbnlNn-7WZXWwdVX-jWj8gXdSGa9QCB_mnZ6sj1y4afRe7K9HQ=w1418-h819-s-no


AJFCJaU83CYUxXs5I5r_Smz6bdjFJDvOrsdrDDK64AKVg5bWw9EaRy8cB2ozjq9AQba02Rc5OCJAH7QfJxgeM_gJlMgiy6DvI5acvK5cMR2Y9_Kl5K2kRiRDyoUGVkRA_Lyqum_YQVjeVSPojm2BLZiWYLrXkQ=w1298-h974-s-no
Why flycut the thickness instead of facing in the lathe?
 
I think I posted a pic of the gear in question, but I attached it again - the one you printed looks like a duplicate. (minus the wear LOL)
Very impressive.
 

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Why flycut the thickness instead of facing in the lathe?
I've tried to think of various ways of holding a disc in the lathe and they all have problems. I don't have a mag chuck, so I'd need to fixture it in a jaw chuck with the jaws reversed, then the jaws would get in the way. I could drill a smaller hole in the center and bolt it to an arbor, but then I'd need enlarge the hole later and somehow keep it concentric. I'm open to ideas, but fly-cutting seems to be the easiest with what I've got.
 
I've tried to think of various ways of holding a disc in the lathe and they all have problems. I don't have a mag chuck, so I'd need to fixture it in a jaw chuck with the jaws reversed, then the jaws would get in the way. I could drill a smaller hole in the center and bolt it to an arbor, but then I'd need enlarge the hole later and somehow keep it concentric. I'm open to ideas, but fly-cutting seems to be the easiest with what I've got.
Well that makes more sense. Just work inside the chuck jaws and be careful. Hang a stick tool out or use a boring bar. Don't overthink it. About anything is better than a flycutter.
 








 
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