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View Full Version : Prototype swing up toolholder for internal threading



drmico60
07-14-2011, 10:40 AM
I have developed an swing up toolholder for internal threading. More details can be found here:
http://mikesworkshop.weebly.com/prototype-internal-swing-up-toolholder.html
I hope this is of interest.
Mike

madwilliamflint
07-14-2011, 12:07 PM
Thanks for posting it! It is indeed. I'm not sure I quite get it from a quick read through. But I suspect that has more to do with me than your write-up.

I'll have to cogitate on it with a reasonable cigar for a bit.

DATo
07-14-2011, 01:03 PM
That is insanely COOL !!!!!! You got my wheels turning now. I've been using a Hardinge for three and a half decades and never had this light bulb go off over my head before. Thanks many times over for this post !!!!

ALL HAIL drmico60 !!!! *Bows*

lazlo
07-14-2011, 01:05 PM
Agree -- very clever! Like DATo says, it's similar to the threading cam on the Hardinge HLV toolpost.

drmico60
07-16-2011, 11:39 AM
I have developed an swing up toolholder for internal threading. More details can be found here:
http://mikesworkshop.weebly.com/prototype-internal-swing-up-toolholder.html
I hope this is of interest.
Mike
I have refined my swing up toolholder so that it now combines funtions for both internal and external threading. More details here:
http://mikesworkshop.weebly.com/combined-swing-up-threading-toolholder.html

dp
07-16-2011, 12:38 PM
I have refined my swing up toolholder so that it now combines funtions for both internal and external threading. More details here:
http://mikesworkshop.weebly.com/combined-swing-up-threading-toolholder.html

This is a damn clever two-fer. And because of the stop on the internal threading end there's no torque on the connecting shaft. No possibility of tool creep. Looks like a new line on the project list for me. Might even take a whack at adapting a carbide threading insert for the internal cutting end.

PeteF
07-17-2011, 05:29 AM
Nice job. If cutting threads by plunging, is it considered bad practice to simply reverse the lathe at the completion of the thread (relying on the tool simply rubbing/spring in the work)? Then wind on the next cut when the tool clears the work, flick the lathe back to forward and continue. In other words much the same technique as using a swing up holder, except the next cut can't be wound on until the bit has cleared. Even though I've never noticed anything, I have wondered if running work backwards against a tool dulls it?

Pete

wierdscience
07-17-2011, 09:59 AM
Nice job. If cutting threads by plunging, is it considered bad practice to simply reverse the lathe at the completion of the thread (relying on the tool simply rubbing/spring in the work)? Then wind on the next cut when the tool clears the work, flick the lathe back to forward and continue. In other words much the same technique as using a swing up holder, except the next cut can't be wound on until the bit has cleared. Even though I've never noticed anything, I have wondered if running work backwards against a tool dulls it?

Pete
If your threading with HSS it won't hurt anything,carbide however you risk spalling off the cutting edge.

chip's
07-17-2011, 10:45 AM
What a great idea! The improvements are excellent also. Thanks for posting it.

TGTool
07-17-2011, 12:03 PM
Do I understand correctly then that the block holding the cutting tool rotates on the 6mm shaft? If so, it would seem to sacrifice some rigidity, being noticeably smaller than the short bar holding the threading tool which is itself only as long as the small block.

drmico60
07-17-2011, 01:09 PM
Do I understand correctly then that the block holding the cutting tool rotates on the 6mm shaft? If so, it would seem to sacrifice some rigidity, being noticeably smaller than the short bar holding the threading tool which is itself only as long as the small block.
The block holding the cutting tool is fixed to the 6mm shaft. The 6mm shaft rotates in the main tool post block. The rigidity of the tool stems from the fact that the cutting forces are used to ensure that, during cutting, the tool holder block is forced hard against the M4 set screw in the main block that is used as a stop. During the reverse pass then the tool holder block tilts backs so that the tool rides on the flank of the thread.
Although the pivot rod is only 6mm there is almost no protrusion, i.e. there is almost no gap between the small toolholder block and the main tool post block, so this is quite a rigid arrangement compared with the long extension of the tool itself from the block. Such extension is inevitable in all internal threading (and boring) tools.
Of course, the pivot bar and the small block could be increased in size to improve rigidity further if desired but the tool as is performs perfectly well.
Mike

Paul Alciatore
07-17-2011, 07:26 PM
Excellent idea! I just have to make one.

But, it would seem, that the same idea should also work for an external threading holder. If it were carefully designed, you could probably use the same parts and just assemble them in a mirror reverse fashion.

Jaakko Fagerlund
07-17-2011, 10:31 PM
Nice job. If cutting threads by plunging, is it considered bad practice to simply reverse the lathe at the completion of the thread (relying on the tool simply rubbing/spring in the work)? Then wind on the next cut when the tool clears the work, flick the lathe back to forward and continue. In other words much the same technique as using a swing up holder, except the next cut can't be wound on until the bit has cleared. Even though I've never noticed anything, I have wondered if running work backwards against a tool dulls it?

Pete
Your lead screw might have some slop in it and it would mean that the tool will lose it's position relative to the thread when you reverse the machine and it would then cut a thread on the way out but to a different spot.

drmico60
07-21-2011, 01:46 PM
Do I understand correctly then that the block holding the cutting tool rotates on the 6mm shaft? If so, it would seem to sacrifice some rigidity, being noticeably smaller than the short bar holding the threading tool which is itself only as long as the small block.
My first tests with the internal swing threading tool were made in aluminium and the tool worked perfectly. However, later tests on steel were not nearly as good. There was a lot of deflection of the tool as soon as it started to cut and serious chatter particularly as it entered the work. So TGTool was absolutely correct in what he said. However, that tool did at least demonstate that the swing concept did work at least for aluminium.
I have since designed, built and tested a much more rigid tool that works well even in tough steels.
For those still interested in this concept there are more details here:
http://mikesworkshop.weebly.com/internal-threading-swing-up-toolholder-mk2.html
Mike