Stopping the carrage on my lathe at a preset spot. Can it be done ?

[valleyboy101]

Hi Cheese King and Thanks,
My Collchester seems to have an automatic kickout on the feed too. Last night I was turning some extremely tough SS lapping plates and the feed kicked out. It turned out that the tool had gone dull and the feed pressure became excessive. The feed engagement handle has a picture of a large and small thread on it, and can be rotated toward either. (picture below) I have a pretty good imagination but never thought to run the carriage into a hard stop to test it. I ever knew what it did, nor did the fellow who sold it to me
Thanks again,
Michael

 

[Cheeseking]

Parts diagram showing springs....

 

[Uglydog]

I think this would be an easy build!
Making a Carriage Stop for a Metal Lathe with Multiple Stops: Part 1
Kieth Rucker

Daryl
MN

 

[Tony Wells]

On some machines that kickout is intended to prevent damage, not to give you a -Z- position stop. If your tool gets too dull, or you do happen to run into the "immovable object" it's there to keep you from tearing something expensive up. Some machines simply use a shear pin on a drive coupling, but unless the mfg expressly said it was for positioning, I'd be very hesitant to use it for that. Just be sure before you rely on it.

 

[Uglydog]

On some machines that kickout is intended to prevent damage, not to give you a -Z- position stop. If your tool gets too dull, or you do happen to run into the "immovable object" it's there to keep you from tearing something expensive up. Some machines simply use a shear pin on a drive coupling, but unless the mfg expressly said it was for positioning, I'd be very hesitant to use it for that. Just be sure before you rely on it.

Tony,
Understood and agreed.
Even on my lathe which kicks-out on approach to the stop, I turn of the PF and hand feed the last .02 to the stop.

Daryl
MN

 

[RJSakowski]

What I did on a JET GH1340: http://www.hobby-machinist.com/show...n-Manual-Lathe?p=103227&viewfull=1#post103227

Ken

Ken, I've been looking for an auto-stop for the lead screw feed for some time and all that I've seen use a mechanical linkage that involves some serious modification of the lathe. Your idea to use an electrical linkage is superb.

One concern is about a system failure. A disengagement of the half nuts on a failure of the electrical circuit would be preferable to one which relies on the completion of an electrical circuit. The issue then is that the solenoid would be energized during normal operation.

 

[juiceclone]

based on experience, you can't really rely on any carriage disengaging stop to work within a few thou repeat ability. Because of the varying load caused by how heavy a cut you're taking, the halfnut or gears "stick" more or less, making it difficult for the stop to disengage them. As a safety stop however they work well...not looking for precise there!! I built mine with that in mind, and it works well enough, plus I added a microswitch to shut off the motor if the carriage goes too far.

 

[Billh50]

There are many different ways to disengage the split nut. It all depends on what lathe way one wants to do it. I did something on my Homier 7x12 and have even seen some really easy ways afterward. My carriage stops within .005 every time it trips no matter how fast it is traveling. Which is good enough for me. I made mine because I do most of my threading up to either a shoulder or in an undercut and my lathe does not have a brake.

 

[British Steel]

I've been working on an automatic disengage and manual r/h-l/h for my lathe, with a dog clutch in the headstock (replacing the current sliding gear pair) and a "4th rod" to operate it, it's getting more complicated the more I think about it...

Dog with selector fork groove keyed to driving shaft in reverse cluster, gears freewheel on needle-rollers (there's an idler between one of 'em and the driven shaft)...

Actuator mech', with ball-detent trip - still working out how to link the sliding dog via a ballscrew to the actuator!



The complex bit will (I hope) lurk inside the QCGB, just enough room I think!

This is going to be a long project...

Dave H. (the other one)