Automatic carriage stop for threading

[sshire]

Saw this on the hobby machinist forum.
Elegantly simple.

Operation

<a href="https://www.youtube.com/watch?v=-Riiep0c64o" target="_blank">http://www.youtube.com/watch?v=-Riiep0c64o</a>

Mechanism detail

<a href="https://www.youtube.com/watch?v=rY6YHA4upRU" target="_blank">http://www.youtube.com/watch?v=rY6YHA4upRU</a>

[Pete49]

As you say  a simple and elegant solution. Added to a never ending list
Pete

[Kim]

Wow, that is pretty cool.  Makes me think even I could do that!
One more project for the list...

Thanks for sharing this Stan!
Kim

[Jasonb]

Does look a good solution but only usable where you can release the half nuts, not suitable for metric on an imperial lead screw or visa versa.

J

[Roger B]

Someone on here (Chuck Fellows?) had fitted their lathe, possibly a minilathe, with a 3 phase motor and inverter. This allowed them to stop in half a turn using a micro switch to sense the carriage position. This will only work with a camloc/bolted on chuck.

[BillTodd]

Someone on here (Chuck Fellows?) had fitted their lathe, possibly a minilathe, with a 3 phase motor and inverter. This allowed them to stop in half a turn using a micro switch to sense the carriage position. This will only work with a camloc/bolted on chuck.

I have modified one of my Haighton cadets to do that and I have a cunning plan to do the same to the others that have single phase motors using a simple dc injection brake.

You do have to be careful not to unscrew the chuck


Haighton Cadet - electrical threading stop: <a href="https://www.youtube.com/watch?v=T67b4mrUR2o" target="_blank">http://www.youtube.com/watch?v=T67b4mrUR2o</a>

[mklotz]

Both approaches (mechanical and electrical) are elegant but I wouldn't personally want either.  Let me explain.

Many years ago, in a moment of inattention, I ran the lathe carriage into the headstock under power.  The chuck and compound were undamaged but the carriage was well and truly wedged against the headstock and the power feed gears in the apron could not be disengaged.  I was afraid to reverse the motor because I didn't know if anything in the apron was broken and sherds might do further damage.

It took me the better part of a day, sweating bullets all the way, to get everything unstuck.  Fortunately, the lathe was undamaged but my confidence was shattered and it was weeks before I could  use the machine naturally again.

If I had one of the devices shown, I would be forced to watch it in operation continuously, lest a bit of swarf, a broken spring or a shorted connection caused it to fail at the worst moment.  Thus it wouldn't really save me any time or effort over doing the job manually.

PS: Before you need one, build a hand crank for your lathe, especially if you have a threaded chuck.  It may save you a lot of grief.  It's also handy for threading right up to a shoulder.

[sshire]

Agree with Marv here.
Anything mechanical can break/stick/loosen/tighten/bind up/etc.

The hand crank is a good idea. My solution for threading to a shoulder is

http://www.aloris.com/products/at-8-threading-tool-holder/

Since my spindle is D1-5 camlock I can run in reverse safely. The Aloris tool (with the blade in reverse cutting position) allows me to start at the shoulder and thread back. I'm much more comfortable doing this than those of you who have single-pointed thousands of threads. I can count mine on the fingers of three hands.

[BillTodd]

I know where you are coming from Marv.

I have the treading stop slip on my hardinge  and crashed into the shoulder before i could hit the threading stop lever.

But, I've gotten use to the automatic thread stop and  would not want to be without it.  Hence modifying the Cadets.

Bill

[mklotz]

...
I can count mine on the fingers of three hands.

Reminds me of this sign in the home of the Walmartians...



A vivid reminder of the state of mathematics education in the USA.

[Roger B]

 

[b.lindsey]

ummmm....given the equally poor reading skills I wonder how many would take that as three rather than fifteen

Bill

[cfellows]

Someone on here (Chuck Fellows?) had fitted their lathe, possibly a minilathe, with a 3 phase motor and inverter. This allowed them to stop in half a turn using a micro switch to sense the carriage position. This will only work with a camloc/bolted on chuck.

Sorry, wasn't me...

Chuck

[Roger B]

Hi Chuck, I was trying to remember without searching as the site was being slow (like tonight  ). I thought you did some mods on a mini lathe, was it adding an additional stiffening plate under the feet?

[Niels Abildgaard]

(The hand crank is a good idea. My solution for threading to a shoulder is

http://www.aloris.com/products/at-8-threading-tool-holder/)
Quoted from Sshire






That AT-8 holder looks like something from the range of Ifanger

http://www.ifanger.com/fileadmin/Webmaster/katalog/pdf/01_2008_d.pdf

and on page 31 there is a short describtion of THE retracting toolholder that made high speed threading a schocking expirience to watch in Schwitzerland many years ago.

[JFK]

Was that it ?
http://www.model-engineer.co.uk/news/article/3-phase-conversion-and-other-alternative-methods-of-powering-a-mini-lathe/18752