Atlas head stock question

[sandmanred]

Is there an operation where the 4 slot sheave and the small gear are ever disengaged (there's a 4 pt interlock between them in this pic)? And related question, what gap is correct between the large gear and the same sheave?

 

[markba633csi]

No. the sheave and small gear are to be considered a single piece. The sheave pulley disconnects only from the large bull gear by pulling the pin when using the backgear function
The gap you mention is set by the sheave and gear hubs- I think it's about 60 thousandths (0.060") normally
mark

 

[sandmanred]

No. the sheave and small gear are to be considered a single piece. The sheave pulley disconnects only from the large bull gear by pulling the pin when using the backgear function
The gap you mention is set by the sheave and gear hubs- I think it's about 60 thousandths (0.060") normally
mark

There's a set screw on the bull gear that locks it on the sleeve that it rides on. When I got the lathe there was enough room on the sleeve for the pulley to disengage from the small back gear. That did not seem right so I loosened the set screw (wasn't very tight) and slid the large back gear over to trap the pulley against the small gear. It must be butted up at the hubs as you suggest. It still runs smooth, or at least as smooth as it can when in back gear so I think I have it located correctly but just wanted to confirm. Thanks!

 

[wa5cab]

sandmanred,

The written instructions from Atlas or Clausing aren't too clear on this point. The collar to the left of the small spindle gear should be firmly against the step or shoulder on the spindle. Then the bull gear is slid towards the cone pulley and its set screw tightened against the spindle. End float of the cone pulley should be around 0.005" to 0.010". Unfortunately, the shape of the right side of the cone pulley and the left side of the bull gear makes using a feeler gauge to set the pulley end float impractical.

 

[Bi11Hudson]

There's a set screw on the bull gear that locks it on the sleeve that it rides on. When I got the lathe there was enough room on the sleeve for the pulley to disengage from the small back gear.

Keep in mind that that setscrew is a lubrication point. The setscrew must be removed and oil "squirted" into the hole. Then the screw replaced.

.

 

[wa5cab]

No, the oil plug that looks like a set screw is in the spindle pulley (both cone and dual) and is discussed in a warning message in the Sticky area at the top of this Forum. The set screw in the hub of the bull gear locks the gear to the spindle (not to a sleeve). Loosening it allows you to adjust the running clearance between the pulley and the gear.

 

[Bi11Hudson]

You had one setscrew in the photograph while discussing another. A bit confusing passing over.

.

 

[sandmanred]

sandmanred,

The written instructions from Atlas or Clausing aren't too clear on this point. The collar to the left of the small spindle gear should be firmly against the step or shoulder on the spindle. Then the bull gear is slid towards the cone pulley and its set screw tightened against the spindle. End float of the cone pulley should be around 0.005" to 0.010". Unfortunately, the shape of the right side of the cone pulley and the left side of the bull gear makes using a feeler gauge to set the pulley end float impractical.

I assume the point to measure is buried down near the axis. I saw the sticky above regarding the oiling port on the pulley so the shaft is well lubricated and the large gears snugged up against the pulley enough to fit but still free wheel easily so I think I got it.

Thanks for everyone's help

 

[wa5cab]

Bi11Hudson,

You're absolutely correct. You were referring to the set screw visible in the photo and I was thinking/writing about the cone or dual pulley and the set screw in the bull gear used to adjust their running clearance.

 

[wa5cab]

Mark,

Yes, the point of contact between the bull gear and the pulley on the spindle is at the ID of both.