# Electronic Z Feed Disengage on Manual Lathe



## KMoffett (Mar 2, 2013)

The old South Bend lathe I used to have, had a mechanical clutch that would disengage the the longitudinal feed at a set stop.  The Jet GH1340 lathe I now use doesn't have that. I really missed it. So I decided to find a way to add it. It turns out that under the feed lever cover is the end of a cylindrical rack, driven by a pinion on the feed-lever shaft. It was center-drilled, so I drilled and tapped it to allow me the pull it out and move the lever from the longitudinal-feed position to the neutral position. I set up a electric solenoid coupled to the end of the rack cylinder through a lever arm. The solenoid was driven by a brief pulse, triggered when a contact under the left end of the carriage touches an adjustable stop fastened to the way.

Ken


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## GaryK (Mar 2, 2013)

That is very interesting. Pretty cool actually. 

It would take me a while before I was able to trust that it would work EVERY time though. It could be very bad if it didn't.

How accurate is it?

Gary


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## KMoffett (Mar 2, 2013)

Yes, the mistrust is always a little in the back of my mind too. I don't walk away while it's running. I just use it to give me a repeatable length of cut. I used a dial indicator between the bed and carriage for measurement. It's repeatable to about half a thousandth on the dial. The electrical contact is spring loaded, so I can manually move the carriage past the stop ~0.10" if I need to. I just recently installed a DROPRO EL400L with the magnetic sensors on the lathe. But I haven't checked the stop accuracy with it yet. The Z only reads to 0.0005" (the X to 0.0001") so I don't expect it to be any different.

Ken


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## pdentrem (Mar 2, 2013)

Repeatablity without taking your eyes off the work is better than eyes on the DRO screen and miss what ever is going on. I like it.
Pierre


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## barrydc1 (Mar 3, 2013)

So cool!  I have been wanting an auto stop for a long time.  My lathe is an newer Enco 13x40 of this very same type, I am hoping that I can utilize this same feature if it exists on my lathe as well and I think it does.  I have had another frightening idea, that may not work as well, but is to simply shut off the lathe by taking the safety switch from the change gear cover area and re-positioning it with the same idea minus the need to move the levers either on the feed or the threading half-nut lever.  However, accuracy may be affected as the lathe would not come to an immediate stop necessarily.  Also I have wondered if bringing a lathe to a stop in this manner is hard on tools/cutters because of the sudden change in cutting force as it comes to a halt.  Of course the switch is also there for safety, but this seems a minor concern, as the change gears would still be covered, and I have already had the necessity of running the lathe with the cover off.  Since a lathe is inherently extremely dangerous, this seems a minor to neglegible decrease in real safety.  Anyway, just a thought.

Barry

I must admit that your idea is much more sophisticated.


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## Bill C. (Apr 5, 2013)

KMoffett said:


> The old South Bend lathe I used to have, had a mechanical clutch that would disengage the the longitudinal feed at a set stop. The Jet GH1340 lathe I now use doesn't have that. I really missed it. So I decided to find a way to add it. It turns out that under the feed lever cover is the end of a cylindrical rack, driven by a pinion on the feed-lever shaft. It was center-drilled, so I drilled and tapped it to allow me the pull it out and move the lever from the longitudinal-feed position to the neutral position. I set up a electric solenoid coupled to the end of the rack cylinder through a lever arm. The solenoid was driven by a brief pulse, triggered when a contact under the left end of the carriage touches an adjustable stop fastened to the way.
> 
> Ken



I like your design.  It is a shame that this feature and a spindle brake are not standard on all lathes. I knew a man who lost an eye when his lathe crashed. His foreman came up and started talking to him just before it happened. I never like talking to anyone when I have a machine running.  

I like this forum so many great ideas.  Keep up the good work.


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