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R8 collet vs R8 endmill holder

richard newman

Titanium
Joined
Jul 28, 2006
Location
rochester, ny
Had problems holding a 3/4" carbide endmill in a collet cutting some material off a heavy service clamp (forged med carbon steel) No matter how I reefed on the drawbar, it wanted to creep out.

Thinking to get an endmill holder for the future, any reason I'd regret this? Or is a 3/4" endmill just too large for my B'port (J head)? I'd hate to have the holder spin in the taper and bugger it!!
 
I might first question the quality of the collet itself as well as the actual diameter of the cutter, a slightly oversize collet and undersize cutter shank may not pair well
 
Good point, I'll measure the shank when I get to the shop. Never had problems with HSS mills before tho. And admittedly I was trying to remove a lot of tough metal quickly.
 
I think the endmill holder is a wise investment. An old employee of mine who was a much better machinist than me liked the 3/4 2 flutes with the half shank for ripping through aluminum, dunno if he felt they held better.
 
You can always sandblast the shank for a little more grip.
Or sandblast the inside of the collet too or have it grit coated on the inside.....
Endmill holder seems easier, If your carbide tool does not have a notch you will need to hand grind one on it.
Lube, anitisieze or grease on the threads will increase the grabbing force vs tightening by a fair bit if you are now dry.
NOT on the taper, on the threads.
Same with the washer up top, not galled and lubed. It's a screw or bolt rotary to linear efficiency thing.
Might be as simple as worn thread on the drawbar.
R8 collets are normally really tolerant to size mismatch.
Bob
 
Thanks. I'll probably wind up with an endmill holder, seems foolproof

"Better" surely. "Foolproof"? What is?

Even so, at the low RPM and decent tolerance for possibly a skosh off dead-true centering, Weldon-style side-locks are MUCH better.

Biggest gain isn't just torque. It's lower exposure to EITHER of push-back, a mere time-waster, or to pull-out.

And pull-out is more than a time-waster. It is a workpiece ruiner!

You'll also want to go tippy-toe regardless, what with a cutter twice the diameter a BirdPort is able to "comfortably" master. Eg: 3/8", not 3/4".

Lighter load. More passes. BFD. Less drama.

Less stress and wear on the BirdPort, longer and more accurate useful life.

Most ESPECIALLY on an OLD BirdPort.. where easily 150 percent of that "accurate and useful life" was already et-up.. by a succession of overly-aggressive, careless, klewless, or some combination thereof .. of prior owners!

One doesn't buy heavier Old Iron with the intent to try to beat it to death.

One buys heavier Old Iron in the hope it has survived PRIOR attempts to beat it to death!
 
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