hydraulic chuck

[Runner4404spd]

Anyone know how a hydraulic chuck works? basically what i need to know is how they hook up the hydraulics to it? i would like to build one for my cnc conversion but i want one that is a 5C style chuck to be able and grab material.

[Geof]

The hydraulic chucks I am familiar with have a large annular hydraulic cylinder at the end of the machine spindle. The piston rod is actually a tube, not surprisingly called a drawtube, that runs through the spindle and connects to the chuck mechanism. Retracting the drawtube closes the chuck and advancing it opens the chuck. On a three jaw chuck the drawtube acts through a sliding wedge mechanism.

For a 5C collet chucks close in the same manner. In this case the front end of the drawtube has a thread to take the end of the collet and it is simply pulled back into a tapered housing to close the collet.

Making a DIY hydraulic collet closer would not be too difficult. The most complex part would be making the rotating seal for the hydraulic fluid supply to the cylinder. This seal has to handle up to about 500 psi while rotating at maximum spindle speed.

[Runner4404spd]

designing the hydraulic cylinder is no problem as i'ma hydraulics engineer. however, i do question how do i get the drawtube down the center as well as the stock so the hydraulic chuck can grab it?

[Geof]

.... i do question how do i get the drawtube down the center as well as the stock so the hydraulic chuck can grab it?

It is a drawtube, tubes have holes through them. Which is why the cylinder is annular; the stock goes right through the middle of everything.

This does restrict the stock diameter you can work with. The OD of the drawtube has to fit inside the spindle bore and the wall thickness needs to be around 3/16" so you lose 3/8" off the spindle ID.

[BobWarfield]

Somewhere on this site I have seen a fellow that simply added an air piston to a manual 5C collet closer. He just connected it to the lever. It looked like something that would be really easy to build. Sorry I don't have the picture, maybe someone else remembers.

Ever since seeing it I have thought that's the path I will take when the time comes. If someone builds a closer that is simpler, please take a lot of pictures and publish some plans!

Best,

BW

[RICHARD ZASTROW]

Runner, There are pneumatic chucks that have a diaphram internal with the chuck assembly (no draw tube). some can be converted to collets and back to jaws at will.

[Geof]

Runner, There are pneumatic chucks that have a diaphram internal with the chuck assembly (no draw tube). some can be converted to collets and back to jaws at will.

Can you provide a link to a manufacturer. I had manual turret lathes with these on twenty years ago but have not been able to locate similar chucks now. I did find hydraulic chucks that worked from the front, no drawtube, but at $35,000 I was a bit deterred.

[RICHARD ZASTROW]

Geof, Try Dunham or Kitigawa to start with.

[vladdy]

You should be able to find used power chucks on ebay fairly easily, especially the pneumatic style, unless you have to have the ability to run real long stock through the head..
hmm...got an old logan power chuck in the garage, complete with actuator and air controls, should be in the pile in the corner..
don't remember the style of the back, cam off an old Gisholt #3 turret lathe that I put a standard 3 jaw Bison chuck on a couple of years ago..
If it'll work for you, it's your's for the freight..
only had -maybe- a two foot long draw tube out the back though..

enjoy..

[vladdy]

Took a few photos of the old Logan power chuck...it's a model 330-B-10-8,
10" diameter, and [I think] an A8 back nose...
I got it on the old Gisholt, and decided not to use it, wanted something a little quicker to adjust for normal machining, no production here...
anyways, if you want it, and can make use of it, it's yours..probably weighs 200 pounds all together boxed up...My postal code is S3N 2C8 if you want to figure out truck shipping, DHL, Fedex, whatever...