Lathe threading disengagement set-up

Often times, there's a need to stop a threading operation at exactly the same place.
A dial indicator generally works, for the most part, but it's easy to make a mistake; usually with dire consequences.

I needed to thread some 4140 pieces right up next to a shoulder & with the least amount of under-cut.
Blank parts were turned to 3/4" diameter and had the necessary undercut in the 3-jaw chuck.

I set the lathe up with a Limit Switch, a 110v Solenoid Valve and a small Air Cylinder.

The adjustable carriage stop is set to trip the Limit Switch at the right carriage position, which then powers the Solenoid Valve which in turn sends air to the Air Cylinder.
The Air Cylinder pushes the threading lever out of engagement and the carriage stops abruptly.

It worked much better than I had anticipated. Sure saved alot of time & worry too.

I didn't take pictures of the Solenoid Valve or the Air Cylinder. They're just common items.

parts with threading complete;

Attachment 24889

a link to the operation;

https://drive.google.com/file/d/1FSa...ew?usp=sharing

Meed pictures of the set up.the video just shows the limit sw
Anytime I ever had to thread right up to the flange I preferred to thread out instead or thread in.
to do this I ran the lathe in reverse with the cutter inverted. this way I could start right next to the flange the only relief or under cut as you called it was the depth of the cutter.

Can't run my circa 1900 16x40 or so Hendey in reverse, as the chuck unscrews!

I can understand that, A couple of my La Blonds have threaded spindles, but they are a tapered thread nearly impossible to to remove the chuck from the 1917 16 inch with 2 " through bore
the 1951 19 by 60 has a short nose adapter installed. with the 3 jaw the bolt pattern just scrapes the spindle threads and will not unscrew but the 4 jaw uses the larger bolting pattern and it will allow the nose adapter to unscrew. Someday I would like to convert both of them to a d 1-6 and the 26 inch to a D1-8 but the 26 inch has the long nose which uses a spanner nut to hold the chucks in place do it is not bad the only thing I really dislike about the 26 is the 1.5 inch bore

A bit confused here as the video show a Jet faceplate on the headstock? Do you have 2 lathes?

PJ

Lathe threading disengagement set-up...

Quote:

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Originally Posted by gatz

The adjustable carriage stop is set to trip the Limit Switch at the right carriage position, which then powers the Solenoid Valve which in turn sends air to the Air Cylinder. The Air Cylinder pushes the threading lever out of engagement and the carriage stops abruptly.

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This apparently works effectively. Pneumatics; good solution for what would be a tricky action through mechanical retrofit. Your adaptation's made to order for recent tool retraction devices posted lately.
I think we'd all like to see the linkage in operation, hint - hint. I'm interested where adjustments are, if any, past the bed stop. I'd want zero free play, probably via Heim joints.
No matter how enthralled I am with distinctive lathes, very few have threading kick out mechanisms. Not many even kick out carriage feed travel, and each I recall depend on a cam and finger.
I'm guessing worries on inertia of chucks, carriages and maintenance keep machine engineers from making them common.

Quote:

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Originally Posted by PJs

A bit confused here as the video show a Jet faceplate on the headstock? Do you have 2 lathes?

PJ

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? PJ....... there's no faceplate on the lathe

Hello gatz,
Very effective. Like Frank S. I like to thread away from the chuck and also have 1/2" & 3/4" Coventry die heads but I like your setup.
Question? The tube over the leadscrew is that an add on? I have some thoughts as to what for but would like to know.
Cheers.

Believe me, I would have done that, but I'm using ThinBit threading insert & holder.

Attachment 24930
Attachment 24931
And I don't have an adjustable QC tool-holder

2 problems
1) Just flipping the tool over wouldn't work.....a Left-Hand holder would be needed and some way of changing the height (the Jet tool-post is fixed height)
2) It would work for threading OUT from the shoulder, but I'd have to make a mount for it on the opposite side with the right-hand ThinBit & holder flipped over.

That's the reasons for me doing it this way.

Here's a few pics of the mechanism. ...I had already taken the set-up down, so didn't make a video of that operation in its entirety; but remounted the components temporarily for those who asked to see it.

Attachment 24932

Attachment 24933

Attachment 24934

Attachment 24935

Quote:

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Originally Posted by NortonDommi

Hello gatz,
Very effective. Like Frank S. I like to thread away from the chuck and also have 1/2" & 3/4" Coventry die heads but I like your setup.
Question? The tube over the leadscrew is that an add on? I have some thoughts as to what for but would like to know.
Cheers.

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The tube is what came on the Jet lathe. Its purpose seems to be to keep chips (esp long and stringy ones) out of the lead-screw, and ACME screw as close up to the headstock as possible.

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Thanks gatz! We've added your Lathe Threading Disengagement Setup to our Lathe Accessories category,
as well as to your builder page: gatz's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-lathe-threading-disengagement-setup"> <img src="/uploads/216378/homemade-lathe-threading-disengagement-setup.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-lathe-threading-disengagement-setup">Lathe Threading Disengagement Setup</a> <span> by <a href="http://www.homemadetools.net/builder/gatz">gatz</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/pneumatic'>pneumatic</a>, <a href='http://www.homemadetools.net/tag/threading'>threading</a> </div> </div> </div> </div>
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I am surprised you are getting snap action from the pneumatic cylinder.

Ralph

Quote:

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Originally Posted by gatz

? PJ....... there's no faceplate on the lathe

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In post #3 you said to Frank:

Quote:

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Can't run my circa 1900 16x40 or so Hendey in reverse, as the chuck unscrews!

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Faceplate was an inappropriate term as in Mounting, I meant the Headstock Face/nameplate.

Watched the video again and took a screen shot of the JET Model 1440...
Attachment 24947

So I take it you have an old Hendey as well...definitely no reverse on it.

Attachment 24948

Sorry for the confusion. I do like the shoulder close threading and the idea of your disengagement system is pretty cool!

PJ

@ PJ, Post #3 was by volodar, not me

@ Ralph. it is very quick.
The lever is pushed down to engage the threading.
The cylinder is actually a 2-way, just left the rod end port open. IIRC, it's a 3/4" bore Bimba & using about 3" of stroke
And the SMC valve is a 2-way also, just plugged one port for the "normally closed" position.
Put a breather on the exhaust port.

In the video, you can hear a faint pop when the carriage is moved away from the LS to the right.
That's the SMC valve shifting back to the NC position.
As the cylinder is used as a 1-way and the SMC valve vents to atmosphere, there's no pressure on either end of the cylinder

gatz

Quote:

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Originally Posted by gatz

@ PJ, Post #3 was by volodar, not me

gatz

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My bad, gatz. Apologies! No wonder I was confused. Thanks for the pics of your disengagement setup. There is something to be said for pneumatics/actuators...simple and effective. Liked seeing you used the cintered bronze filter/breather. Used a lot of Parker and SMC in my day.

PJ

gatz,

You have a very interesting concept here and very well executed! I hope to see more of your work in the future.

OK, the opportunity to thread some more parts similar to the 3/4-16 items came up,
and I set up the operation again, only this time it's for 1"-14 Threads

Here's a link to the video;

https://drive.google.com/file/d/1n0X...ew?usp=sharing

That set up works better than I had imagined good job

Quote:

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Originally Posted by gatz

OK, the opportunity to thread some more parts similar to the 3/4-16 items came up,
and I set up the operation again, only this time it's for 1"-14 Threads

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What a rig! Works well as any commercial cam-operated mechanical kick out.

Consider a positive stop for the cross slide. Eliminate dial reading when all you actually need is repeating zero. One linear rod, two rigid stand-offs, a sliding stop collar and a corresponding anchor stand-off in the cross slide.

That system works brilliantly, love it!!

Great info guys, thanks for posting.
Cheers, JR

Great fix applicable to many lathes. I'm thinking mine needs 2.
One to shut off the motor. Motor switch is actuated by a lever on the carriage. this one would include driving an electrically actuated brake.
A second one to open the split nut.
They would be selectable. I'm thinking I would add a delay on break relay to shut off the air after a second or two.

Quote:

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Originally Posted by NortonDommi

Hello gatz,
Very effective. Like Frank S. I like to thread away from the chuck and also have 1/2" & 3/4" Coventry die heads but I like your setup.
Question? The tube over the leadscrew is that an add on? I have some thoughts as to what for but would like to know.
Cheers.

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Hi Mate! Haven't heard from you lately. Obviously neither have you heard from me. Nice to know you're still around.

yep, still kickin'
nothing new going on, except for a few "tools" and an improvement for a Bridgeport clone back-gear shift ring.

Hello,
The link you provided (https://drive.google.com/file/d/1FSa...ew?usp=sharing)
does not work
!Please correct this.
Best regards.