# My take on the tangential tool holder.



## websterz (Jun 30, 2011)

I have been meaning to make one of these for quite some time now. My earlier attempts were less than stellar performers and I knew I could do better. Here it is sitting atop my homemade QCTP. THe holder is made from 7075 T6 aluminum, the bit is a piece of Rex AAA 5/16" square held in place with an 8-32 BHCS and washer.







Here is a view of the dovetail which I cut too deep. Not wanting to hurl another piece of aluminum across the shop I decided to try and patch the screw-up. I drilled and tapped the inside face of the dovetail 1/4-20 and countersunk it to accept a stainless steel screw. The hole is drilled and tapped thru the holder to allow a 1/4-20 set screw to lock the stainless screw in place. A couple of adjustments and I have the holder locking up nicely. The screw head is large enough to give good contact on the piston and can be adjusted further for wear if the need ever arises. One of those seat-of-the-pants repairs that just happened to work. ;D











As for the cutter, I was able to take .200" cuts in aluminum and .100" in annealed 4140 steel with no chatter and got good finishes on both taking cuts as small as .001". It turns and faces without adjusting the tool angle and makes beautiful square shoulders.


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## tel (Jun 30, 2011)

Thm: Good, ain't they! Nice job.


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## chucketn (Jun 30, 2011)

Websterz,

What angles did you use? 12° and 12°?

Chuck in E. TN


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## xo18thfa (Jun 30, 2011)

That's nice. I can see a lot of advantages in that arrangement. :idea: :idea:


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## websterz (Jun 30, 2011)

chucketn  said:
			
		

> Websterz,
> 
> What angles did you use? 12° and 12°?
> 
> Chuck in E. TN



Yep, 12 and 12 seems to be the magic combination.


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## Rayanth (Jun 30, 2011)

websterz  said:
			
		

> Yep, 12 and 12 seems to be the magic combination.



That was something that was lurking in the back of my brain from my high school shop days. The magic 12.5 degree angle. Our shop instructor had set the tool rest on a grinder to that angle, and created a step by step poster above it to show how to grind a lathe bit using the magic angle built into the tool rest. Browsing the forum I'd been surprised to not run into that angle, seems 12 is pretty close though!

- Ryan


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## Omnimill (Jun 30, 2011)

websterz  said:
			
		

> Yep, 12 and 12 seems to be the magic combination.



+1

Vic.


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