How would you make this internal gear?

[solo]

We have a 15" Cincinnati Tray top with a few bad gears.
I need to duplicate the I.D. like the gear beside it. I have some bronze I'm going to use.
I have a broach, but how to index it correctly? I was thinking of making a key and attaching it to the side of
the broach guide. How would you do this?

 

[Weldingrod1]

I would make a custom broach holder with a indexing as you speculated.

See if you figure out a way to avoid additive errors.. ie don't cut one, pilot the next off of it, and the next... if you are 5 degrees off on your broach/key that adds up to 25 degrees at the end.

So, maybe make a ring with indexing holes in it that locks onto the first keyway. That way your spacing is controlled by the drilling job.

Sent from my SM-G715A using Tapatalk

 

[solo]

SO, I make a ring, I can lightly press in the bronze, and the broach guide with a larger head mating the ring.
Then drill the holes using the indexer. I can then press fit the pin in the guide. Then accuracy index the broach.
I like it !

 

[MrWhoopee]

Fred had a Tray-Top with similar problems, the gears just weren't up to the duty. We tried to avoid using it whenever possible. Given how robust Cincinnati equipment generally is, I've always been puzzled by this.

 

[solo]

Fred had a Tray-Top with similar problems, the gears just weren't up to the duty. We tried to avoid using it whenever possible. Given how robust Cincinnati equipment generally is, I've always been puzzled by this.

The shop got a quote for the 3 gears from Cincinnati, Hold on! 7,000.00 dollars !
This is the worst, the other two are steel, I'll turn them around and touch them up.

 

[Uglydog]

I'd mount it on an RT and cut it with my vertical slotter.
These are vertical mill attachments and not a separate machine.
A shaper could also do the job. But a slotter would be easier.
I'm imagining it could also be done on a hobby lathe with a cutter mounted in the tool post holder.
Would be manually moved in/out for each cut.
Either you'd need indexing on your lathe spindle or after careful layout you cut to the lines you scribe.

Ohio isn't that far away come on up and use my slotters.

Daryl

 

[solo]

I'd mount it on an RT and cut it with my vertical slotter.
These are vertical mill attachments and not a separate machine.
A shaper could also do the job. But a slotter would be easier.
I'm imagining it could also be done on a hobby lathe with a cutter mounted in the tool post holder.
Would be manually moved in/out for each cut.
Either you'd need indexing on your lathe spindle or after careful layout you cut to the lines you scribe.

Ohio isn't that far away come on up and use my slotters.

Daryl

Oh my gosh! Almost 12 hours on the road...Thank you for the offer though.
I recently hired on at this fab shop, the owner has been collecting machinery for a few years.
A couple of guys there have worked in a machine shop, but short on experience.
Every machine there has problems, I'm slowly working through them.
It's tough to try and fix one machine and the machine you need to use to fix the broken one, is broken also. Round and round....
I talk to myself there a lot....

 

[ChazzC]

I'd mount it on an RT and cut it with my vertical slotter.
These are vertical mill attachments and not a separate machine.
A shaper could also do the job. But a slotter would be easier.
I'm imagining it could also be done on a hobby lathe with a cutter mounted in the tool post holder.
Would be manually moved in/out for each cut.
Either you'd need indexing on your lathe spindle or after careful layout you cut to the lines you scribe.

Ohio isn't that far away come on up and use my slotters.

Daryl

That was going to be my suggestion (the vertical slotter - or Joe Pie/Clough42 equivalent - not the trip to Ohio). Or, find a local shop with a gear shaper - I know where there used to be one here in South Central PA.

 

[Uglydog]

Die filer?

 

[Jubil]

The shop got a quote for the 3 gears from Cincinnati, Hold on! 7,000.00 dollars !
This is the worst, the other two are steel, I'll turn them around and touch them up.

I had a 15 inch tray top. 2 gears in apron stripped (rusted from having water in apron while sitting). I figured I needed a couple shafts and 3 gears. Cincinnati sent me a quote for a new lathe when they got to $18k on quote.
I found a local guy who made ring gears and machined off the gear and attached the ring gears for $500. It worked great and I was happy, happy, happy.
May be a useful idea for someone.

Chuck