Atlas lathe Backgear issues

[TMP-NET]

Good morning all,

I have a Craftsman/Atlas 12in x 36 that I just resurrected. Overpaid but whatever.
I now have a functioning 1944 lathe.

Direct cone drive works as expected, butter smooth and quiet from ~100-700 rpm. (Still playing with belts and drive pulleys to get upper speeds).

My Backgears have issues.

First they are noisy.
Sounds like mesh noise but before I go nuts with shimming adventures I'm looking for input and experiences with this.

Bigger issue is they auto disengage at anything over lowest speed.

Any ideas?

Thanks in advance!

Too Many Projects- Not Enough Time......

 

[benmychree]

Not too familiar with Atlas, but most back gears have a friction adjustment to prevent them from disengaging, usually a split bushing with a setscrew to increase friction, many also have a depth of engagement as well, sort of a stop that regulates how far the handle can rotate when engaging the back gears, too deep engagement will increase noise, bearing in mind that back gears are frequently noisy to some extent.

 

[markba633csi]

Not sure how Atlas does it on the early 12"- the later 12 uses a cantilever arrangement with the backgear below the spindle
I thought the early model has a ball and spring to keep the lever in place? My BIL says no

 

[pdentrem]

Straight cut gears are noisy, it is their nature. As for disengagement issues, look to the location of the eccentric and handle. The back gears should stay engaged of course. So normally the handle moves the eccentric past center so the pressure on the gears does not push the gears out of engagement, and likely it is out of adjustment.
Pierre

 

[Ulma Doctor]

Have you removed the set screw on the spindle drive cone and oiled the bushings below?
The set screw is not really a set screw , but rather an oil plug.
Be careful of not over tightening the oil plug upon returning the plug , it will damage the spindle.
The gears should be lubricated with oil, and the backlash should generally be around .002” to .005”.

 

[Ulma Doctor]

P.S. the back gears in High Speed (when the larger diameter pulley of the 2V motor drive pulley has the belt) will be very noisy at high speeds