On Wednesday 07 March 2018 12:54:51 Greg Bentzinger via Emc-users wrote:

> My personal choice has been a CAT40 with rigid Bilz #1 holder, or a
> U200 shank with very minimal tension compression and Bilz #1 holder
> Bilz holders appear a bit pricey but you won't need many sizes and you
> can swap taps and holders while keeping the same offset - I'd say mine
> repeat to about 0.0025"
> I have put the shank in a CNC and just swapped tap holders on jobs
> which had too many different threads. I also have some 3/4" shank
> tension/compression #1 holders - but they are like 4 inches long. I
> can't use these on a BP style 3 axis CNC with only 5" Z quill travel.
> I hope to some day add a "W" axis so I can use the knee to compensate
> for tool length.
> OK - I know this won't work for Gene... but may help others.
> I don't think you will find tap drive R8's simply based on how it
> would have to be made.
> But you could buy some 3/4" Drill rod. Chop off a chunk that is the
> length of the shank and flats. Drill the corners then the center of
> the drive square and mill a square pocket about 1/4" deep with maybe a
> 3/32" EM.
> Turn the part around and drill til it just breaks into the square,
> then bore/ream to shank size. You would put this drive bushing in a R8
> solid Weldon type 3/4" endmill holder. Mark where the set screw would
> contact bushing then bore a clearance hole with a 2F endmill so the R8
> holder set screw is able to clamp directly on the tap shank.
> Usually long before I have to worry about a tap slipping I have chosen
> to thread mill.
> You can buy cheap Chicom import threading insert boring bars that you
> can grind extra clearance on and mount on center in a ER32 or even
> 3/4" Weldon that will work for thread milling.

Thats been considered. Even thought of getting a boring head. But had to 
find something cheaper. And locking it into the R8 to stop the slippage 
would appear to solve the majority of the shortcomings of the collet 
based offerings. So, like Erik, make them. Brass rod on order.

> There are many ways to skin this cat - but with 9 lives just be sure
> its dead before you start.
> Greg
Chuckle. BTDT. Took a while to heal too.

Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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