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DonV
02-13-2017, 10:21 PM
I have a Hardinge horizontal mill with a Bridgeport vertical head, an M I think. It used 2VB collets, a rather rare and sometime unobtanium critter. I was thinking that instead of wearing out the ones I have, to make a an ER20 or 25 collet holder with a 2VB shanks. Looks like an easy enough thing to machine. The drawbar thread may be a little tricky, one source says its .437 x 26. but nothing I can't figure out. Anyone tried this?

Don Verdiani
West Chester, PA

SGW
02-14-2017, 06:35 AM
Go for it -- why not?

I'd use 1144 Stressproof for the material.

Daveb
02-14-2017, 07:24 AM
Is it possible to machine a larger collet chuck shank to fit?
I use a Bridgeport M head (2MT) and found that some Morse tapers (cheap tooling?) do not go far enough into the taper for the captive draw bar to reach the hole. I mount these between centers and re cut the taper. Draw bar thread can be corrected by boring out and brazing in a sleeve or plugging and re tapping. Dave

BCRider
02-14-2017, 01:17 PM
Hardinge still makes and sells them according to this link (https://www.shophardinge.com/productGrid.aspx?catID=8260). But from the price I suspect they are made from asteroid Kryptonite ! ! ! !

There is no reason at all why you can't make up an ER holder with a 2VB shank The worst thing is that you'll have a touch more tool over hang from the head bearings. And you'll loose a slight amount of daylight between the spindle and table.

Turning the shank of a larger lube of a holder down might work or it may cause problems depending on the size of the holders through hole if one is present.

If you are going to make your own end mill holders does it need to use an ER collet? What about using the set screw onto the notch in the Weldon shank cutters? When drilled, bored then reamed I was able to make MT3 to Weldon shank holders that were very nicely centered and cut very evenly. No reason why you could not produce your own solid shank 2VB set screw holders. At least for the most commonly used sizes.

DonV
02-19-2017, 12:35 PM
Thanks, all. Think I'll try it. The thinking behind the ER collets is that I can get the full range from 1/8 to 1/2, (or even 5/8 in I go to ER 25), to hold both mills and drills. To drill with a non-VB collet sized drill, I have to add a 1/2" shank chuck, loosing lots of "daylight" between tool holder and table. An ER collet hanging below the spindle, with a VB shank only adds perhaps 1 to 1.25 inches. Now to find some 1144 stressproof :-)

Don

Rex
02-21-2017, 09:29 AM
There is no reason to match the VB collet thread. Just use 3/8-16 or something common.
sounds like the ER is the way to go. I'd sure do that.

DonV
02-21-2017, 09:20 PM
The drawbar on my Bridgeport head is not easily removable, and I like the concept of being able to switch back and forth with the VB collets. The collet thread is .437x26. I believe I have found a 7/16 x 26 tap, which sound suspiciously like the same thing. Should be pretty easy if I'm right about the two being the same.