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Author Topic: Air powered Draw Bolt  (Read 32925 times)

Offline Darren

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Air powered Draw Bolt
« on: July 02, 2009, 04:43:09 AM »
I can't find it now, but someone in the US mentioned they had built an air powered drawbolt device for their milling machine...

Would you please care to expand?

Ta... :thumbup:
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Offline kvom

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Re: Air powered Draw Bolt
« Reply #1 on: July 02, 2009, 08:52:10 AM »
I've seen several home-made versions.  They use an impact gun or ratchet.  Fabricate a bracket to mount it to the top of the mill attached to the drawbar.  Then it's a matter of figuring out how to operate the trigger and reverse.
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #2 on: July 02, 2009, 08:56:30 AM »
Thanks, I have seen a few Utube vids, I was just wondering if anyone can give first hand exp and some greater details... :thumbup:
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Offline spuddevans

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Re: Air powered Draw Bolt
« Reply #3 on: July 02, 2009, 01:49:29 PM »
Quote from: Darren on July 02, 2009, 08:56:30 AM
Thanks, I have seen a few Utube vids, I was just wondering if anyone can give first hand exp and some greater details... :thumbup:

I dont have any 1st hand experience, but I remember reading about powered drawbars on cnczone.com,

Click Me

I'm sure that there's many other threads on there about powered drawbars, but my net connection is painfully slow at the moment (I'm not at home so am using a mobile internet dongle thingy), do a search on there and that'll turn up more info.



Tim
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bogstandard

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Re: Air powered Draw Bolt
« Reply #4 on: July 02, 2009, 03:23:53 PM »
Hi Darren,

Done a little searching for you, and have come up with these two.

The second one might give you a better insight.

http://home.insightbb.com/~joevicar3/cheap_drawbar.htm

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


Bogs
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Offline John Hill

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Re: Air powered Draw Bolt
« Reply #5 on: July 02, 2009, 03:38:37 PM »
I no idea what you chaps are talking about, the last powered drawbar I had anything to do with was hanging out the back of a Lanz Bulldog. :med:
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #6 on: July 02, 2009, 04:00:19 PM »
Thanks guys, sorry to make you all run ragged but I'd pretty much seen all of those links.... :(

You have my gratitude all the same tho, nice to have friends..... :clap:

What I was really looking for was if someone here had built one and perhaps get a thread going....AND like I always try to do before committing myself to anything is to see if I can weed out all the options. This often helps to prevent me or anyone else following the wrong path.

But I think that guy who sells the plans has it pretty well sussed, seems like it.

The parts are cheap, very cheap, so I was thinking of having a go for the Beaver mill at some point. After I get it up and running of course..... :)

The idea of smacking the draw bolt to release the collet really goes against my idea of machinery care. lets be honest, sometimes you have to give it a pretty good belt.... :bang:

To me the quick change is the second benefit, not the first.....
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bogstandard

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Re: Air powered Draw Bolt
« Reply #7 on: July 02, 2009, 05:15:49 PM »
Darren,

Just to add a little to this discussion, has anyone ever used a powered drawbar with a morse taper fitting?

Out of pure experience, MT's can be a real PITA to release. Thank goodness I now use R8, which come apart just by farting in their general direction.

What I can't see, is how a power drawbar can release such a nasty monster as a stuck MT taper. Surely they don't have the same clout as a big heavy hammer, which can and usually is the normal method of release. Or is it the continuous knocking feature of the wrench that knocks the joint apart?

Also, what happens if you get one that is REALLY stuck. Do you have to strip all the stuff off the top so you can get a mini sledge hammer in there? Or again, will this never happen because of the torque setting of the wrench?

Bogs
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #8 on: July 02, 2009, 06:21:29 PM »
Well I think I have a pretty good idea how it would help with the barstewards known as MT tapers  :lol:

But there are plenty of engineering types on here so maybe it's about time someone else actually spoke up....

Come on lads....this IS a forum after all....a place to chat, mull and exchange ideas away from the toils of our normal lives....oh and 'er indoors.... :lol:
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Offline John Stevenson

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Re: Air powered Draw Bolt
« Reply #9 on: July 02, 2009, 07:19:40 PM »
My Beaver has a powered drawbar, air over hydraulic, no stupid air wrench.

John S.
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Offline John Hill

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Re: Air powered Draw Bolt
« Reply #10 on: July 02, 2009, 07:34:19 PM »
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. 
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #11 on: July 02, 2009, 07:43:14 PM »
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.

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:
« Last Edit: July 02, 2009, 07:45:33 PM by Darren »
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Offline John Stevenson

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Re: Air powered Draw Bolt
« Reply #12 on: July 02, 2009, 08:01:47 PM »
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.
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Offline Bernd

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Re: Air powered Draw Bolt
« Reply #13 on: July 02, 2009, 08:52:36 PM »
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
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #14 on: July 03, 2009, 04:10:19 AM »
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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Offline Darren

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Re: Air powered Draw Bolt
« Reply #15 on: July 03, 2009, 05:01:09 AM »
Quote from: John Stevenson on July 02, 2009, 08:01:47 PM
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.

Ah, I did take a good look at that pip and guessed it was something like that. Are these draw bars obtainable, or are they like rocking horse......?

Does it have a name, to do a search..... :thumbup:
« Last Edit: July 03, 2009, 05:06:07 AM by Darren »
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #16 on: July 03, 2009, 05:29:57 AM »
Another one....looks good

This has the air cylinder inc, at this price you have to wonder if it's worth building your own...

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280364743376&viewitem=&sspagename=STRK%3AMEWAX%3AIT&salenotsupported

The utube direct link for when the ebay sale has gone

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Offline dsquire

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Re: Air powered Draw Bolt
« Reply #17 on: July 03, 2009, 05:43:43 AM »
Quote from: Darren on July 02, 2009, 04:43:09 AM
I can't find it now, but someone in the US mentioned they had built an air powered drawbolt device for their milling machine...

Would you please care to expand?

Ta... :thumbup:

Darren

This might be the one that you are thinking about. There certainly are some good ideas in this thread.

Here is the link to Hoss ATC Project

http://www.cnczone.com/forums/showthread.php?t=43651

cheers

Don

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Offline Darren

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Re: Air powered Draw Bolt
« Reply #18 on: July 03, 2009, 06:05:38 AM »
That's a very interesting concept. Using the lever system to increase the cylinder thrust was clever.... :thumbup:

Much to think about...... :coffee:
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Offline Bernd

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Re: Air powered Draw Bolt
« Reply #19 on: July 03, 2009, 08:51:33 AM »
Quote from: Darren on July 03, 2009, 04:10:19 AM
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.

Ah yes that makes sense now. I do believe your right on that one.

If it's so hard to get out could it be that maybe your tightening the drawrod "to much"? In other words making it to tight.

Bernd
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #20 on: July 03, 2009, 11:38:24 AM »
Not sure there Bernd, I don't do it very tight as it is. Once I had to re-tighten due to vibration, just nipped it up a tad further.

I believe this is just am MT thing....or at least they are the biggest offenders.
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Offline Stilldrillin

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Re: Air powered Draw Bolt
« Reply #21 on: July 03, 2009, 12:33:57 PM »
I insert my MT3 mill tools, as I would any MT taper tool, then nip up the drawbar finger tight, just to keep it from falling out.  ::)

IF it slips under load, (very rare), I nip it gently with a small spanner.

Never had any drive problems, and only a gentle clunk from a small lead tup loosens the assembly.....  :thumbup:

David D
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Offline kvom

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Re: Air powered Draw Bolt
« Reply #22 on: July 03, 2009, 01:34:21 PM »
At least on mine, the downward pressure results from the impact wrench turning the drawbar which is screwed into the R8 collet.  The impact itself imparts torque that helps to break the taper.
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Offline Darren

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Re: Air powered Draw Bolt
« Reply #23 on: July 03, 2009, 03:37:57 PM »
Quote from: kvom on July 03, 2009, 01:34:21 PM
At least on mine, the downward pressure results from the impact wrench turning the drawbar which is screwed into the R8 collet.  The impact itself imparts torque that helps to break the taper.

What do you have on yours? Home made or commercial? Briggy init?

Any chance of a pic....
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Offline kvom

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Re: Air powered Draw Bolt
« Reply #24 on: July 03, 2009, 08:09:16 PM »
Mine is a clone (apparently) of the Kurt unit.

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