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View Full Version : Good idea collet holder with straight shank held by chuck ?



TR
05-03-2013, 06:55 PM
I see a number of ER and 5C straight shank collet holders for sale. I think they are intended to be held by either a 4 jaw or 3 jaw chuck. I can see this being useful, but is it a good idea ? Chuck jaws are typically hardened and these collet holders are also hardened. Comments would be appreciated.

Sincerely,
Tom

Here is one such setup found on ebay.

http://i663.photobucket.com/albums/uu354/topari/5cholder_chuck_zps84d07860.jpg (http://s663.photobucket.com/user/topari/media/5cholder_chuck_zps84d07860.jpg.html)

Okapi
05-03-2013, 07:09 PM
Hi

I think it's more made for using collets in a static position, for example fixing the piece on a drill or milling machine, if you fix them in a chuck, you amplify the possible error in centering with the addition of the possible out of round.

mike4
05-03-2013, 07:46 PM
That would be handy for the times that a small part has to be done , without having to remove the chuck and fit a collet system ,.

Machine one part and then have to spemd more time changing back to a standard chuck.

They would be easily centred , just like centering a part before machining , whether you use a three or four jaw depends on how anal you want to be with "runout " . 99% of parts are quite ok with a three jaw's runout , eg bolts or pins , .

I am talking about parts for average equipment that does not need aerospace tolerances just because you can do that type of machining .

Before anyone jumps onto the hysteria button , I work with all types of tolerances and most customers only want what is required to get their equipment back into work in as short as practicable a time frame .

And that does not mean a rough and ready or shade tree approach either . It means a practical well done repair which will last .
Michael

Bob Fisher
05-03-2013, 08:33 PM
Could be handy if used in a 4 jaw and centered properly. For repetitive operations it could save some time. Bob.

Jaakko Fagerlund
05-04-2013, 03:59 AM
I have something similar for a lathe at work, but it is just a drill chuck installed to a length of tube and the whole thing has a hole through it. Allows gripping small pins, as the 3-jaw lower limit is 8 mm diameter stuff.

outback
05-04-2013, 04:20 AM
Below is a simple 5C collete setup I made years ago and still use it today.
http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/Collet%20Closer/IntheChuck.jpg (http://smg.photobucket.com/user/jglass/media/Shop%20Demonstrations/Collet%20Closer/IntheChuck.jpg.html)

The advantage is quick setup. I use it for turning roundstock smaller than 1/2".

I made a drawbar out of water pipe.
http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/Collet%20Closer/ColletDrawbar-1.jpg (http://smg.photobucket.com/user/jglass/media/Shop%20Demonstrations/Collet%20Closer/ColletDrawbar-1.jpg.html)

Preferred collet setup;
http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/Collet%20Closer/colletchuck3.jpg (http://smg.photobucket.com/user/jglass/media/Shop%20Demonstrations/Collet%20Closer/colletchuck3.jpg.html)

Jim

rode2rouen
05-04-2013, 10:51 AM
An acquaintance gave me a unit like the one pictured in the OP, quality was typical "bargain priced" ChinCom, I gave it to someone else.

Kalamazoo Industries offers one that is likely made to significantly higher standards, but it carries a significantly higher price than the usual Ebay items.
http://www.kalamazooind.com/products/5c-collet-fixtures/1cc-5c-collet-fixture-for-chucks/


Rex

DATo
05-04-2013, 04:22 PM
@ outback

That is really a nice idea but isn't it a bit redundant? I mean, unless you are using a 'set-tru' chuck what do you gain by holding the workpiece in this collet system? You could just hold it in the chuck and get the same results. To my thinking the whole idea of using a collet is to maximize concentricity.

That having been said, I can appreciate the value of using this method if the parts are very small in diameter or if surface finish is important and the fear of marring the surface with the chuck jaws exists.

Edit to correct spelling

philbur
05-04-2013, 05:26 PM
If you are going to mount a collet holder in a 3 jaw self-centering chuck why not just mount the part directly in the chuck.

Phil:)

danlb
05-04-2013, 05:49 PM
A collet will often hold delicate parts with less damage to the finish.

Dan

Jaakko Fagerlund
05-05-2013, 04:51 AM
And many don't seem to realise that chucks have a lower limit in the OD of part being held. In my case it is 8 mm, so if I have to make something out of 6 mm raw bar, I have to chuck in first a smaller chuck or a collet chuck to be able to grip it.

Edit: The runout isn't an issue when you make parts smaller than the OD of your raw stock. Also the runout can be acceptable, the big 350 mm chinese 3-jaw chuck at work easily holds parts to 0.02 mm or smaller TIR.

Black_Moons
05-05-2013, 05:02 AM
Agreed, the benifit is that you can hold small parts without damaging the finish. With a 4 jaw, you could dial the runout out, or with a 3 jaw, shim it out or just not care about it, especialy if you are just facing or machining the entire OD in one setup. (Its more efficent to shim a collet holder in a 3 jaw then shim the workpeice, since it will stay shimed through multiple workpeice changes and size changes within the size of your collets)

I have a keyed drill chuck on a straight 1/2" shank I sometimes use for working on small parts.

John Stevenson
05-05-2013, 07:13 AM
Why do most people think that every job has to be to within microns tolerance.
It's often about quickness, speed and cheapness if you have someone waiting who's expensive machine is broken down.
If it's something simple like a tiny double diameter stepped pin where it's all machined at the same setting you can get microns tolerance even though the collet is running 5 thou out.

I normally run with a set of soft jaws and because of previous machining my minimum gripping diameter is about 1/2"
It's far quicker to pop a small chuck in the jaws that swap chucks or even swap jaws.

And as for using a 4 jaw to dial in it - why ?

You have to swap chucks to a 4 jaw, then dial in. Why not just swap to the collet chuck and save the dialling in ?

outback
05-05-2013, 09:52 AM
@ outback

That is really a nice idea but isn't it a bit redundant? I mean, unless you are using a 'set-tru' chuck what do you gain by holding the workpiece in this collet system? You could just hold it in the chuck and get the same results. To my thinking the whole idea of using a collet is to maximize concentricity.

That having been said, I can appreciate the value of using this method if the parts are very small in diameter or if surface finish is important and the fear of marring the surface with the chuck jaws exists.

Edit to correct spelling

Roundstock 3/8 dia and smaller does not turn round in my 3-jaw chuck. The roundstock tends to deflect in between the chuck jaws. I end up turning a triangular shape part. Using a collet where the stock is held all the way around instead of 3 contact points solves the problem with turning small diameter.

Try turning a 1/4 or 3/16 dia stock and you will see what I mean.

You are correct. It is a bit redundant for larger diameters where the part can be held by the chuck. A smaller chuck with different jaws may eliminate
the need for the collet setup for small diameters. But then I would need to set up the small chuck.

I think my chuck jaws are ground to hold a 1/2 or 3/8 minimum diameters. Smaller diameters probably wobble inside the jaws.

I hope I explained this right.
Jim