# Tangential Radiusing Tool for the Lathe



## Jim2 (Nov 17, 2014)

I finally bought a QCTP last spring, so I've been making up some toolholders to give me the capabilities that I had with my old lantern-style tool holders.  Here's a tangential-style radiusing tool that I just finished up.  It uses a 3/16" HSS round tool bit with the 30 degree end.  I haven't really used it yet other than a few test cuts to set the height on center, but should do what I need it to do.















Jim


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## Andre (Nov 17, 2014)

Great job! Much better than the one I built back earlier this year.

I found it helpful to remove the radius at the tip and give it almost the profile of a square toolbit on it's end. If that makes sense, less contact with the work so less chatter.


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## chevydyl (Nov 17, 2014)

That's pretty sweet. But what's it do? As far as the cut or whatever....why do I need one lol


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## Andre (Nov 17, 2014)

chevydyl said:


> That's pretty sweet. But what's it do? As far as the cut or whatever....why do I need one lol



Look them up to find out how they work, James Kilroy has a few videos on them.

They impart less stress on the machine, better surface finish, and much easier to sharpen.


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## John Hasler (Nov 17, 2014)

Andre said:


> Look them up to find out how they work, James Kilroy has a few videos on them.
> 
> They impart less stress on the machine, better surface finish, and much easier to sharpen.



So now we just need to develop a tangential shear tool.


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## Dranreb (Nov 17, 2014)

That's neat, does it give a good chatter free finish?

Bernard


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## John Hasler (Nov 17, 2014)

Andre said:


> Look them up to find out how they work, James Kilroy has a few videos on them.
> 
> They impart less stress on the machine, better surface finish, and much easier to sharpen.



So now we just need to develop a tangential shear tool.


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## chevydyl (Nov 17, 2014)

So it allows a radius at the shoulder?


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## Jim2 (Nov 17, 2014)

Yeah, I made one with a square toolbit earlier, but it didn't turn out quite as purty.  This one is meant to leave a radius at the "corner" when transitioning between facing and turning or facing and turning a taper or such.

Here's the one w/ square toolbit.  I've got a few small "whoops" in there, but seems to work well enough.  I haven't been doing a lot of turning lately as I've been more focused on getting some toolholders finished, so it hasn't been tested much.    
















Here's a tangential style holder that I made up for my lantern-style toolpost.  The QCTP holders are similar enough to this one, that I'm pretty confident that they'll work well.















Jim


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## toolman49 (Nov 17, 2014)

"So now we just need to develop a tangential shear tool."
G"Day Fellas,
It's already been done, rotate the toolbit 90 degrees clockwise in the holder, it works fine as a vertical shear tool.
Regards,
Martin


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## Jim2 (Nov 17, 2014)

I've got to try that.  I keep hearing about the shear tool, but I've never used one.

Jim


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## blay127 (Nov 19, 2014)

how do you cut the angled square "hole" that holds the tool?


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## Jim2 (Nov 19, 2014)

If you look closely there's a hole that is used to remove the material around the "back" corner.  Removing the metal in the other corners was done with a small end mill on the one and a slitting saw on the other.  Both were done from the same set up. The toolbit is 3/8" x 3/8", and this is a CXA tool holder.  This pic shows it the best:






Here's the drawing. . . .






Jim


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## blay127 (Nov 20, 2014)

ah, I see. thanks! great work!


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## Jim2 (Nov 24, 2014)

Used the tool to make a knob yesterday.  I don't have a finished pic, but here's a couple of in-process pics. . . .

Here's the radiusing tool in the cut:






Radiusing finished:






Bottom finished:






Rounding off the gripping portion:






Using a ball-nose end-mill to clean up the rough-cut "dimples".






Hollowing it out for some weight reduction:






Jim


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## CoopVA (Nov 24, 2014)

Very interesting!  May have to try to make one...  Thanks for sharing!   Subscribed...


Sent from my iPad using Tapatalk


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## Jim2 (Nov 25, 2014)

Here's the finished product






Another angle:






Some context--this knob is the tensioner for my new clamp-style knurler. . . .





Jim


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## mattthemuppet2 (Nov 25, 2014)

way cool! I love the weight reduction efforts for a knob going on a knurler going onto what looks like a very heavy lathe  That's the kind of obsessive attention to detail I love!


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## courierdog (Dec 25, 2020)

Jim:
I heard you were still on the forum so I looked you up and I found your article here on your building of a Tangential Lathe Tool.
I was fortunate when starting to think about starting into the amateur machinist hobby to learn from Rudy Kouhoupt about the Diamond Tool Holder. I bought the Left and Right hand versions. I do think for my limited experience they exceed any insert style tooling I also have as part of the starter package I bought from Little Machine Shop Lathe and Mill. I enjoy using a tool which has more than brute force behind its concept.
The Tangential tool design leverages many tool cutting concepts behind its seemingly simple design. Which is why I am currently working with a few others on the hobby machinist forum to design a Flywheel based Tangential Tool Holder Fly Cutter for the Mini-Mill. I believe it will complement your efforts here and on the other build of yours for a Tangential Fly Cutter.
My initial thoughts are as follows:
1.  Nominal 6 inch Radius
2.  Nominal 1 to a maximum 2 inch thick
3.  The Tool bit to be either 1/4 round or square stock 
4.  The clamp would comprise a circle with an interior nominal 1/4 inch square, per the advice from Gary at Eccentric Engineering as he states the square clamp provides a better clamp on both the round and square tool bit stock
5.  My idea of the round clamp in the Flywheel is so the square tool stock may be rotated for optimal cutting on the flat or any desired angle of cut the amateur machinist may want to make
6.  by having the round clamp inside the Flywheel the Flywheel can have the required Optimal Tangential tool angle drilled in the Flywheel mass and leave sufficient material to clamp down the interior round clamp which actually holds the Tool stock.
I am sure looking at you tool design approach you have practical wisdom you can bring to the table for this proposal.
Thanks for Listing to a old man struggling to learn a new hobby.


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## Eggy (Sep 3, 2021)

This is such an elegant design.  Round and square.  Thanks for posting.  The knurling tool is great also.


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