Lathe Threading Auto Stop

That is a good one, Thanks for putting it up.
 
:applause:

Sir, simply awesome. Let me count the ways,

#1. It's home made. No $400 "Synergistic Synchronized Positive Thread Depth AutoFeed Disengagement version 12.4" made of space age alloys with coolant-repellent finish there! Nope. If you didn't cobble that together with scraps, I'll watch someone else eat my hat!

#2. It works. It's simplicity at it's finest. Low parts count, easily sourced materials, no complex machining involved.

#3. It's removable. Yes, it'll leave a few holes here and there. What good is a machine if you can't modify it? I'm sorry, but my Taig has spoiled the heck out of me with T slots *everywhere*. If I designed a lathe, it'd be square, blocky,and *covered* with T slots and tapped holes. Want to mount a threading-auto-disengage-widget? Surprise! Convenient T slots and tapped holes within reach! Are you listening, Import Machine Makers?! At the very least, give us flat, square (machined is okay!) surfaces all over. We'll drill and tap, just leave enough meat for it!

#4. It's single-purpose. It disengages the half nut. It doesn't slice bread, cook your dinner, tuck you in and tell you a story. It disengages the half nut, and then sits there staring at you. I'm a firm believer in a tool that does *one* job well, vs a tool that does a few dozen things half-a**ed.

#5. It shows your cleverness. That mechanism is clever. No doubt about it. You had a problem, and you solved it very handily. Without resorting to a Rube Goldberg apparatus to do so. Well done.

Good luck with the job! At least one problem with it is now solved. Time to start planning how to solve the next one!
 
Thanks for the kind words gentlemen!

I've had this on for a little over three months and it hasn't failed yet. My DRO tells me that it usually stops within a thousandths or two on either side, which is acceptable by my standards!

I was actually contacted by a fellow who's going to publish this method in his book with a few of my pictures. Not sure weather he wants me to share which book or his name, so I'll keep it quite for now

ogberi, thanks for the 5 ways of it being awesome, I am humbled by the list! And it was made from everything out of the scrap bin, the only purchased item was the main return spring for the handle.

The best part is that my hot glued piece of aluminum that retains the sear spring is still holding up. I wouldn't say I'm proud of it, but I have a tendency of making temporary things permanent until they fail.
 
I made a variation of this yesterday, it works fantastic!! cut a 12mm long thread in a 14mm blind hole no run off, first internal thread I have ever done.
Just needed a stop collar on the telescopic rod
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Jamespvill said:
Hello Gentlemen!

After punching out a few dozen threads today, I'm happily surprised at how well this carriage stop works. I'll gladly post a few more details and information about the mechanism.

First a more close-up video of the mechanism (is that the right term?) itself:

[video=youtube;rY6YHA4upRU]

Here are a few stills of it engaged and disengaged.

View attachment 81874View attachment 81873

The toughest part of making this is retrofitting it to your lathe and finding clearance for it, but after you lay everything out, it smooth sailing.

First and most importantly is to find where your pivot pin will go, this should be a place where the pushrod can get the most leverage. So halfway is just about perfect, but your lathe will determine this more.

Next you need to build a "trigger" this is the item that pivots on the pivot pin and is pushed by the pushrod (finger). After that is on then it's time to find the best location and orientation for the "sear" or the piece that it attached to the half nut lever. From there is simply fitting and filing to see where everything latches together properly but also disengages smoothly.

I used drill rod for the pin on the "trigger" and O1 tool steel for the "sear" both of which were heat treated and polished on the contacting surfaces.

After that then it's time for springs! One on the rear of the "trigger" to keep it always trying to engage and one on the half nut lever to keep it always wanting to disengage. I'm not too fond of the current spring setup for the lever, it looks a little goofy for my liking.
View attachment 81877

Finally it's time to build your pushrod or "finger" and means of attaching it to your lathe. I chose to attach it to my ways. If I would have had wider aluminum bar then I would have opted for that, but I only had 1/2" so I went with that.

View attachment 81875View attachment 81876

I'm probably going to add a threaded rod through the aluminum block so I can stabilize it against the gearbox behind it in an attempt to diminish all of the flex. The rod is a 3/8" piece that I'm probably also going to add some sort of stabilizing function to towards the end of it.

Besides that, It should be apparent in the original video that it stops in just about the same place each time, which is really all I can ask for!

Thanks for your interest gentlemen, I would like to hear what you would have done differently!

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Click to expand...
 
Lots of LATHES , turret LATHES have push off buttons built into the carriage . Most use a trigger with springs . We use to set them up so we could run three machines sometimes depending on the parts. Old Knox manufacturing made all kinds of valves stems on the LATHES bodies inflates and mill lapping machines all running every day . I miss the shop but don't miss the labor. Nice job on your push off. I'm going to make one but I'm also adding a roller switch to kill the power . Never trust anything completely.
 
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