Will I lose my screwed on chuck if I convert my lathe motor to reverse?

[Dranreb]

I see a lot of Atlas lathes with drum switches fitted, I would like to hear of users experiences whilst using them in reverse.

Is it worth the bother to fit one?

Bernard

 

[swatson144]

My lathes reverse (both with screw on chucks). I never use the feature except perhaps when threading metric.

Steve

 

[pdentrem]

I never had it happen on my Atlas, but usually I was threading and therefore slow speeds.
Pierre

 

[Dranreb]

I never had it happen on my Atlas, but usually I was threading and therefore slow speeds.
Pierre

My lathes reverse (both with screw on chucks). I never use the feature except perhaps when threading metric.

Steve

Yes, I am thinking my only use would for be metric threading, I suppose it would be safe using collets (which I don't have) so most likely too much bother, as I have a crank that I put on the lead screw if I need to thread metric.

Replies appreciated

Bernard

 

[wa5cab]

My machine also reverses but I don't think that I would use it with a part held in a chuck except maybe to back out a tap or back off a die.

But just out of curiosity because two have mentioned it, why would you use reverse if threading metric?

Robert D

 

[kd4gij]

When metric threading with a sae lead screw the threads won't match the marks on the thread dial. so you can't dissingage the half nuts while cutting the threads.

 

[wa5cab]

Oh, that's right. I had forgotten about that.

R

 

[VSAncona]

When metric threading with a sae lead screw the threads won't match the marks on the thread dial. so you can't dissingage the half nuts while cutting the threads.

Sorry if this is a dumb question, but why can't you just back the tool bit out and reverse the lead screw direction without disengaging the half nuts?

 

[pdentrem]

The reason is a metric lathe has a metric leadscrew and the threading dial may have 10 positions, while. SAE lathe has a SAE leadscrew and the dial has 4 or 8 positions. The leadscrew on the SAE will never line back up to the original start position due to the ratios do not match.

So the other way to look at it, is the metric lathe cutting SAE threads, you can not disengage the half nuts neither.
Pierre

I will try to finish a better explanation for this.

 

[wa5cab]

Disengaging the tumbler gears does essentially the same thing as disengaging the halfnuts. You lose the locked angular relation between the lead screw and the spindle. Plus if you don't disengage the half nuts, the only way to move the carriage is to turn the lead screw anyway. Which is what the motor running in reverse does.

Robert D.

Sorry if this is a dumb question, but why can't you just back the tool bit out and reverse the lead screw direction without disengaging the half nuts?