Rockwell lathe apron drive gear

[GT-6 Racer]

A friend of mine has a little 11” Rockwell lathe with a worn out apron drive gear. Apparently they are unobtanium, unless you find a NOS one for big bucks. So let’s make one!

It’s a 36 tooth DP16 worm gear made from bronze. It also functions as the cone clutch. After a good bit of research, I’ve verified the original gear wasn’t hobbed. It is a simple helical cut gear as the worm wheel. I’d guess that’s why they are all worn out. Point contact between the worm and the wheel tooth when new. Anyhow, that makes it much easier to replicate. Measured up the original and drew up the blank. Calculated all the tooth data necessary and made a test blank out of aluminum for a test run. Set up my Deckel dividing head with a custom made arbor matching to the cone taper of the gear on the Bridgeport. The finished practice gear fits up perfectly in the apron. Now waiting for the crazy expensive bearing bronze to make the real gear now that everything is validated. Probably make 2 or 3 of these while I’m set up.

blue check on clutch taper.


milling setup


Old bronze and aluminum practice gear. You can see 2/3 of the tooth is worn away on the bronze gear.

 

[markba633csi]

Wow it looks like just a regular spur gear but driven by a worm- crazy- no wonder it wore

 

[dirty tools]

Worm gear
the spur gear will not work properly

 

[GT-6 Racer]

It’s actually a helical gear. Just under. 3 degrees helix angle. But still not a proper worm wheel. Seems this was common for this type of application in the old days.

 

[BGHansen]

Rockwell had the same design in their 10" lathe, the clutch gear got chewed up by the worm riding the lead screw pretty quickly. Parts were still available back in the mid-80's when I picked up the lathe; got a replacement for $75. I had "visions" of cutting a proper worm gear with correct engagement to the worm. Make the cone feature a separate detail keyed to the worm gear so engaging the clutch didn't change the mesh of the worm/worm gear. Alas, never got to the project.

Nice job on the helical gear! There used to be a seller of replacements on eBay, but I didn't see any with a search this morning. You might be a hero for guys looking for the part if you want to dip your toe in the eBay pond.

Bruce


p.s. Here's a thread I posted 7+ years ago when I was looking at selling the lathe. I sold it that summer to an HM member for $1000. There's a mention in the string about a Rockwell lathe guy in Michigan (Dick Treimstra); he may be a resource.

Price For A Rockwell 10 X 36 Lathe?

I have two of these exact lathes and stands and love them. I went with the AXA holders because I assumed the BXA would not fit well. Have you ran into any issues with that size holder and it it more stable that an AXA. I see you even have the same issue I do with that right hand corner of the...

www.hobby-machinist.com

 

[markba633csi]

How did you fixture it to get the 3 degrees?
Edit: Never mind I see now

 

[GT-6 Racer]

How did you fixture it to get the 3 degrees?
Edit: Never mind I see now

Used a 1/10’s indicator to sweep in the angle to the exact value. The Deckel dividing head swivels to allow the angle to be set.

I’ll post the final gear. If anyone is interested in one let me know.

 

[GT-6 Racer]

Tramming in the dividing head.

 

[GT-6 Racer]

Finally got the crazy expensive bronze. Here’s the blanks for 2 of the clutch gears.

 

[GT-6 Racer]

Finally got time to finish the gears. Turned out perfect. Love that Deckel dividing head ! No lash super stiff.

Installed in the apron in the last picture