[Newbie] Why Not Use The 3 Jaw Chuck To Hold Collets?

[CODEMAN]

I want to use some collets in my HF 7x10 lathe. Why can't I just hold the collets in the 3 jaw chuck and forgo the expense of a collet holder?

Steve

 

[rick9345]

 

[Tony Wells]

Collets are designed to draw down through the action of a drawbar or drawtube into a mating taper that provides uniform contact around the diameter and the length of the tapered section. The straight jaws of a chuck cannot provide this at all. You would no doubt damage the collet, possibly the chuck as well.

 

[RJSakowski]

Collets rely on one or more tapered surfaces to "close" the collet and grip the tool or work. A mating taper surface is brought into contact with the collet by some sort of axial closing devise; a drawbar, or collet nut on a collet chuck. While you may be able to exert some gripping force by virtue of the three jaw, you are gripping on a surface never intended to be used in that manner. Distortion and possible loss of concentricity, poor work gripping, and possible damage to the collet could result.

Bob

 

[Fabrickator]

All of the above, and generally speaking, a lathe chuck isn't as accurate or repeatable as a real collet chuck.

 

[higgite]

I want to use some collets in my HF 7x10 lathe. Why can't I just hold the collets in the 3 jaw chuck and forgo the expense of a collet holder?

Steve

Seems to me that if that was a good idea, nobody would buy or sell collet holders.

Tom

 

[Bill C.]

I want to use some collets in my HF 7x10 lathe. Why can't I just hold the collets in the 3 jaw chuck and forgo the expense of a collet holder?

Steve

Even if you made a collet closer that could be chucked in a three jaw chuck you will have problems with repeatability. Three jaws chucks tend to have repeatability problems some as little as .003. Three jaw chucks are great if the part you are turning all the outside diameters of the bar stock in one chucking. They should hold concentricity just fine.

Collects when matched to the stock diameter are constant when it comes to repeatability. You need a set if you are running several different diameters. I worked in a shop that had round and a few hex shaped collects. I used them in production setups.

 

[wrmiller]

I hold a ER32 collet chuck (chuck, not collet) in my 3-jaw and it works fine. But...I have a set-tru chuck that I can adjust to a TIR that I cannot measure so that I'm only dealing with the TIR of the collet chuck.

Expensive scenario, but this setup allows me to work on very small pieces held in the collet chuck, or large pieces held in my 8" 3-jaw. There's always more than one way to do something, some ways just cost more than others.

Edit: Sorry, I missed the part about this being for a 7x series lathe. Go to littlemachineshop.com and they have both a 3" and 4" collet chuck that is pretty reasonable price-wise.

 

[Charles Spencer]

I don't know anything about your lathe but I looked on the HF site and they have a 7X12. It has a an MT2 spindle. If yours does as well then you can do what Tubal Cain shows in this video:

Of course you would use MT2 instead of MT3. This would not permit anything but short lengths of stock to be held in the collet however. It also allows you to use the collet to hold tooling in the headstock.

I made a similar one to use on my SB9 which has an MT3 taper in the headstock spindle. It has worked well for me for the last couple of years.

 

[kd4gij]

Like has been said , get a collet chuck. Or do as I did and make one. Now I did chuck my collet chuck in my 4 jaw once for a quick job, but that isn't the best either.










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