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Author Topic: Air powered Draw Bolt  (Read 26653 times)

Offline Darren

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Re: Air powered Draw Bolt
« Reply #25 on: July 04, 2009, 05:28:43 AM »
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Offline John Stevenson

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Re: Air powered Draw Bolt
« Reply #26 on: July 04, 2009, 05:43:47 AM »
Darren,
The secret to these thing is a 3/8" drive air wrench called a butterfly wrench.

http://www.machinemart.co.uk/shop/categories/search/air-ratchets-wrenches

4th down, £34.50

However for some reason the Yanks can get these from Harbor Freight at stupid prices like $15 when on offer.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93100  $20 at the moment

[EDIT] £20 on Ebay inc postage if you do a search for Butterfly wrench.

This type of air wrench allows the forward reverse mechanism to be remotely controlled. Bob Warfield has one of the best sites for explaining it

http://www.cnccookbook.com/CCMillDrawbar.html

John S.
« Last Edit: July 04, 2009, 05:48:55 AM by John Stevenson »
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #27 on: July 04, 2009, 06:17:10 AM »
Thanks John,

I think Bob Warfield has done a pretty good site on the subject and it looks simple enough to build.

Those darned Yanks don't know how lucky they are. For the last decade and a half they have been able to get things at about half the price we have to pay for the same things.
No wonder they have big workshops AND fill them with quality tooling....just not fair.... :(

I remember when I wanted to buy a brand new Japanese sports bike about ten years ago , 10K here, 4.5K over the pond.....it upset a lot of people at the time and eventually the Grey Import scene started by importing from the US instead of Japan. We still paid more than the US, but prob saved about 2-3K all the same.

And now they complain about petrol prices......... :doh:

Try about $9 a gal....it's getting tough over here. In this area the roads are far, far quieter than they used to be cos people just don't use there cars like they used to. Inc me, my car goes out about once every two weeks now and I run on Gas not petrol.



I'm not really wining, just jealous..... :)
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Offline kvom

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Re: Air powered Draw Bolt
« Reply #28 on: July 04, 2009, 08:21:41 AM »
Darren,

That eBay item is the Kurt; mine is a similar clone (no labels on it).  It has its own drawbar, and the cylinder mounts on top of the mill.  The control unit consists of a regulator-oiler plus a box with two button, "in" and "out".  There are two air lines going from the control box to the cylinder.

To operate, I move the spindle to the top and engage the lock.  I then set the spindle brake and press the appropriate button with one hand holding the tool/collet with the other.  Takes about a second to either lock or unlock.
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #29 on: July 04, 2009, 01:17:31 PM »
Thanks, it sounds like you like the unit..... :thumbup:
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #30 on: July 06, 2009, 08:21:10 AM »
As an experiment I have tried an air ratchet gun on my mills draw bar whilst at the same time holding it down in an effort to loosen the 3MT taper...

It didn't work, the tool holder stayed stuck fast in the machine.  :(

I realise this is not the same as the "proper" tool, but thought it might be worth the experiment.

Just relaying an observation, not meant to be a comment about any other tools out there.... :thumbup:
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Offline John Stevenson

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Re: Air powered Draw Bolt
« Reply #31 on: July 06, 2009, 08:53:01 AM »
Air ratchet or air impact ?

John S.
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John Stevenson

Offline Darren

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Re: Air powered Draw Bolt
« Reply #32 on: July 06, 2009, 08:55:49 AM »
Sorry, it was an impact type...
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Offline chalky

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Re: Air powered Draw Bolt
« Reply #33 on: July 06, 2009, 12:41:08 PM »
If you have a captive drawbar then unscrewing it with a spanner pushes out the taper. Stuck tapers and bashing on the drawbar are then a thing of the past. Tightening and releasing a captive drawbar, even for a MT3 taper, requires very little torque but does need quite a few turns on the spanner for complete insertion and release of a taper. This can get a bit tedious so I simply use an electric screwdriver to insert and release my taper tooling. Ultra simple powered drawbar! Its usually very easy to convert an existing machine to get a captive drawbar.
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #34 on: July 06, 2009, 12:44:34 PM »
Sounds interesting, and simple....any chance of a pic or two....I'm not too sure how I could make my nut captive but if i thik hard enough I'm sure I could come up with something....


Ohh, an idea already..... :lol:
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Offline chalky

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Re: Air powered Draw Bolt
« Reply #35 on: July 06, 2009, 01:07:18 PM »
You need to put a cap on the top of the spindle with a hole in it to allow the top of the drawbar to poke though it. The drawbar itself needs a small annular ring around it near the top ( braze one on ) so that when the cap is fitted the drawbar cannot be removed from the spindle. Fit your taper in the usual way but when it comes to release just keep unscrewing. First it will be easy because you're simply unscrewing the drawbar from the taper but then the annular ring will hit the bottom of the cap and further unscrewing will jack the taper out of the spindle. Both my mills came fitted with captive drawbars but in the case of the smaller one it was a modification that the importer used to do himself. I may have some pics around somewhere but if not I'll go and take some in a couple of days. Not up to it at present as I'm still recovering from a nasty ( but innocently acquired ) infection.
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Offline chalky

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Re: Air powered Draw Bolt
« Reply #36 on: July 06, 2009, 01:28:02 PM »
Just noticed the "Morse Taper Ejector on Clausing Mill" thread has pics which illustrate the principle of the captive drawbar. Not quite as convenient as "the real thing" because you have to remove the extractor after use, but still infinitely superior to the lead hammer.
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Offline sbwhart

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Re: Air powered Draw Bolt
« Reply #37 on: July 08, 2009, 02:45:49 PM »
Chalky

Your post has just prompted me to check something out on my Siege X3, when the machine came it had this great chunk of metal that you had to unscrew to get your draw bar in, I just parked it to one side not knowing what it was:- its a draw bar ejector just as decribed  :doh:

Her it is against the draw bar



And with the draw bar wound back engauging with the ejector it work like a dream



Thanks for showing explaining this I'd have ended up making something out it and waisted a darn usfull bit of kit.

Slightly embaresed

Stew
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #38 on: July 08, 2009, 02:56:23 PM »
 :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh: :doh:

 :lol: :lol: :lol:

Spot on there Stew.....that will save a headache for you.... :thumbup:
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Offline chalky

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Re: Air powered Draw Bolt
« Reply #39 on: July 10, 2009, 10:44:33 AM »
Hi Stew. You are not alone. When I bought my first ever machine tool,  a small mill, the importers used to fit a captive drawbar themselves. Took me a while to figure it out as there was no documentation, but eventually I got the hang of it. About a year later the importer stopped doing the mod to the mill. When I was on the phone to them I asked why they had discontinued what I thought was the most useful ever mod to the mill. They said that hardly anyone bothered to use it!! Reading between the lines they didn't, like me initially, realise what it was for. Captive drawbars are a great idea and should be standard on all mills, particularly those with MT tapers. As you can see I'm a bit of an enthusiast!

David
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