The Shop > Tools

Air powered Draw Bolt

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John Hill:
John Bogs, re stuck tapers, surely the drawbar can be arranged to push down on the taper instead of pulling it up?  Otherwise I suppose it could be a bit like releasing the rear wheel on a car by loosening the nut and driving around for a few days, in this case slacken the draw bar then mill a bit of scrap. 

Darren:

--- Quote from: John Stevenson on July 02, 2009, 07:19:40 PM ---My Beaver has a powered drawbar, air over hydraulic, no stupid air wrench.

John S.

--- End quote ---

I have no idea what "air over hydraulic" means, unless it's like a car braking system? Cept that uses a vacuum....but how that turns a nut I don't know.... :scratch:

John Stevenson:
No nut, the chuck has a pull stud on the top, like that one you bought.
A hydraulic ram forces  a set of stacked springs down and a set of springy fingers grabs the chuck and pulls it in,

Imagine those long spring things for getting dropped bolts from inexesable hard to get places.

Push a button and air forces a big cylinder to push a smaller hydraulic cylinder that then goes to push the drawbar with springs on.

The springs actually holds the tool in so if it looses air or dry bollocks it doesn't drop the tool.

John S.

Bernd:
Darren,

What's the difference between an air wrench beating on your spindle versus a hammer? Your still pounding on the spindle aren't you?

Bernd

Darren:
Hi Bern,

If I understand how an air wrench works (and I may have it wrong)
There is quite a big difference between lumping the spindle with a 4Lb hammer and the air ratchet shocking the draw bolt in a rotary fashion.
It's the air cylinder that provides the downwards pressure which is constant, ie smooth, unlike the hammer.

Sometimes it takes so much effort to free the 3MT taper I'm really scared of breaking the mill itself....!!! It can't be doing it or the bearing much good at all.

Now that I have an ER32 collet holder I just leave it in and fit everything to that, I really don't like taking it out.

There has to be a better way than this primitive method, we left the caves a few years ago now..... :ddb:

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