How does carriage power cross feed work?

[railfancwb]

On the Atlas H36 Model 10F, how is the power cross feed of the carriage used?

Specifically should the carriage be locked in place and the power longitudinal feed disengaged before the power cross feed is engaged? It seems this should be the process but I’ve been wrong many times before.

Thanks

 

[wa5cab]

Generally speaking, yes. And in fact, an unmodified Craftsman 101.07403, 101.27430 or 101.27440 has an interlock built into the apron that prevents the operator from engaging either power feed if the other one is already engaged. The Atlas 10F does not have this interlock, which aside from the paint color is the only other difference between the two carriages (unless you consider the compound slide to be a part of the carriage). However, assuming that there is nothing in the way that would cause a crash, engaging both drives won't break anything. But I can't think of any operation that you could be doing that would need both engaged. So don't do it. The ratio between the two feeds is inherently fixed. Each drive has only discrete points at which you can engage. And you cannot change the direction of one without also changing the other. So for any or all of those reasons, there is no practical reason for ever engaging both feeds at the same time.

 

[wa5cab]

As for your first general question. both power feeds are driven by the leadscrew. There is a bevel or miter gear that has an internal key that runs in the leadscrew slot. This drives a second miter gear that has a wide spur gear on the near end. This spur gear in turn drives a second spur gear continuously. The second spur gear is mounted on one end of the shaft that the knob that you see always turning whenever the leadscrew is turning. When you pull out on the knob, the second spur gear moves toward you and engages with a third spur gear that is mounted on the cross feed screw. So it turns the cross feed screw, causing the cross slide to move either away from or towards the operator.