Threading without the end groove

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Harold_V
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Re: Threading without the end groove

Post by Harold_V » Thu Mar 28, 2019 1:32 am

That's a good tip, Ken, and it shouldn't interfere with achieving the proper measurement.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

kapullen
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Re: Threading without the end groove

Post by kapullen » Wed Jul 24, 2019 4:05 pm

I can usually just pull out with the machine running at a reasonable speed. Like H said, practice, practice...

We used to make cable spools for cranes and hoists.
These used round nosed tools to match the cable radius.

We had to stop in a drilled hole on some jobs.
The King (brand name) 84 inch vertical boring mill used
was set up to plug the machine in reverse to stop the spindle. The control had a timer to adjust the length of the
reverse jolt to stop on a "dime".

The operator still had to put a line on the table (chuck)
and housing hit the stop button at where the lines intersected.

Newer machines had manual clutches with which could accurately creep the machine up to.

A tracer lathe can be set to retract at 30 degrees instead
of the standard 45.
A template with a shoulder can very satisfactrically retract the tool in a corner.

Who has a tracer lathe anyway?

With each pass you will have to retract the tool a bit
earlier or the chips will pack up and break the tool.

Later
Fadal Turn, Fadal Vmc 15, Prototrak 16 x 30 Cnc Lathe, Pratt and Whitney 16 x 54 lathe, Pratt and Whitney Vertical Shaper, G & E 16" Shaper, B & O Electric turret lathe, 36" Doall band saw,
Enco B.P. Clone, Bridgeport CNC Mill, Delta 12" Surface Grinder.

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Bill Shields
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Re: Threading without the end groove

Post by Bill Shields » Wed Jul 24, 2019 10:01 pm

No...there is no half but disengagement when you pull the lever..the carriage continues to travel.

Agreed that it is not a perfect solution but very workable in many situations.
Too many things going on to bother listing them.

johnfreese
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Re: Threading without the end groove

Post by johnfreese » Thu Jul 25, 2019 6:21 pm

There are a number of designs for retracting tool holders you can find on the web. I have been wanting to scale up George H Thomas' design to use on a larger lathe.

I believe it was in the 60s Snap Tap made a retracting threading holder that used a trip rod to release the tool. One end of the rod was bracketed to the lathe bed and the other to the trip mechanism. I have tried a few web searches but have never located any info.

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Bill Shields
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Re: Threading without the end groove

Post by Bill Shields » Thu Jul 25, 2019 6:57 pm

I have seen that elsewhere on production machines.

I am pretty sure GT made it for his own.

Need to ask B&O Bob for sure
Too many things going on to bother listing them.

pete
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Re: Threading without the end groove

Post by pete » Thu Jul 25, 2019 7:43 pm

Yep both George Thomas's lever operated tool slide and the same for the complete top slide were designed around his Myford Super 7. I can't remember any of the manufacturers brands, but I recall running across mentions of a few types made in Europe for the more industrial sized lathes as well. Maybe a search on the PM forums might pull something up? A shop built spring loaded tool holder released by adjustable trip dogs would be a handy thing to have. Martin Cleeve made, patented it, and then wrote up his design for a vertical retracting or "swing clear" threading tool holder as he called it in his book Screw Cutting in the Lathe. If and it's a big if, anything at all about single pointing threads was missed in that book it's more than doubtful any hobbyist and probably very few professionals would ever need it.

https://www.model-engineer.co.uk/news/a ... older/5056 for a rather small set of pictures for that swing clear tool holder. Google images has larger and better pictures if you use that swing clear threading tool as the search term. And https://www.gadgetbuilder.com/ToolHolders.html scroll about 2/3rds down for the Thomas designed lever operated tool slide.

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Bill Shields
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Re: Threading without the end groove

Post by Bill Shields » Sat Jul 27, 2019 4:53 pm

https://www.machinerypartsdepot.com/pro ... gK2YfD_BwE

here is one currently sold by Sharp.
The lever on the compound pulls it back
Too many things going on to bother listing them.

pete
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Re: Threading without the end groove

Post by pete » Sat Jul 27, 2019 10:37 pm

That one is positioned in roughly the same place and must work much like the G.H.T. lever operated cross slide Bill. I sure don't know much about the Hardinge HLV's or the close copy's of it. But if my memory isn't faulty the Hardinge lathes had the same set up for there cross slides either as a standard part of the machine or it may have been an additional accessory. Of course if one's pockets are over flowing Babin Machine offer this for the HLV's. http://www.babinmachine.com/index.php?HLVELECLEAD

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Bill Shields
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Re: Threading without the end groove

Post by Bill Shields » Sun Jul 28, 2019 12:32 am

You are correct..the HLVs had that feature along with a few others whose model designations I cannot remember
Too many things going on to bother listing them.

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