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Wow this looks good power drawbar

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  • Alistair Hosie
    replied
    I know but I went once again to Bob's site he's a great engineer and has a great shop too.Alistair

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  • noah katz
    replied
    "Noah is there a possibility of getting started on the wrong thread "

    I don't see how that would be possible; the first threads of the drawbar and collet are what touch first.

    lazlo, what would be the benefit of the Bimba cylinder?

    Leave a comment:


  • lazlo
    replied
    Originally posted by Alistair Hosie
    Wow Bob Warfield is a clever guy well done again Bob. Alistair
    That's not Bob Warfield's drawbar Alistair -- that's Joe Vicar, the guy who sells the plans for $15:

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

    Leave a comment:


  • Alistair Hosie
    replied
    Wow Bob Warfield is a clever guy well done again Bob. Alistair

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  • lazlo
    replied
    Originally posted by noah katz
    After all the time I spent making mine, I think this one is a really slick implementation and worth it if your time is worth anything, and it's well made and uses linear bearings.
    Agreed -- that's a very clever design. Especially using the High-Low ring selector for a mounting bracket, so it installs in seconds, with no holes to drill.

    I see no reason why you couldn't add a Bimba cylinder to it like Joe Vicar's plans that Bob built:



    I don't really fancy beating up on a drawbar with an air ratchet, after using pullers with air ratchets it certainly wears the screws far more so it will do the same to the drawbar and collets.
    A drawbar costs $20 John

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  • deltap
    replied
    Originally posted by John Stevenson
    I had often thought about building one but a couple of things put me off.

    One I don't really fancy beating up on a drawbar with an air ratchet, after using pullers with air ratchets it certainly wears the screws far more so it will do the same to the drawbar and collets.

    I much prefer having to feel the tightness depending on what size cutter is fitted.

    A simple quick job isn't easy if you don't have a tank of air up, in my case I have a rotary compressor that fills two 40 gallon tanks. I don't have the compressor on all the while and there may be a couple of days in the week where the tanks are empty.

    The main reason though is my machine is a Varispeed and in low speeds the spindle isn't easy to turn by hand given there is only a small smooth diameter at the bottom.
    I often have to turn the spindle to line the tool up with existing keyways and also sweep a dial gauge round for centering bearing bores.
    I do this with a small 3/4" ring spanner on the drawbar.

    Fitting one of these will get in the way for doing this.
    .
    There is a neutral position on the hi/lo lever. If both hands are needed, insert a small block of material in the crack to hold the lever in neutral.

    Leave a comment:


  • Alistair Hosie
    replied
    Noah is there a possibility of getting started on the wrong thread with such an aggressive system ? Now that's the only thing which would worry me otherwise I really like this it would be good for mee to as I can't d grip the way I used too.Alistair

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  • noah katz
    replied
    After all the time I spent making mine, I think this one is a really slick implementation and worth it if your time is worth anything, and it's well made and uses linear bearings.

    "One I don't really fancy beating up on a drawbar with an air ratchet, after using pullers with air ratchets it certainly wears the screws far more so it will do the same to the drawbar and collets."

    Not a problem; even at max torque I found that I was making the drawbar a good amount tighter than the air ratchet; no cutter slippage problems w/the latter.

    Leave a comment:


  • Alistair Hosie
    replied
    LOL BILL I was about to say on your post download photo four what a nice painting on the shop wall til I noticed it was a window .I see the point John makes by the time you are sure your on thread and not crossed threads you might as well do it by hand but I still think they are cool thanks guys so far .AlistairAlistair

    Leave a comment:


  • Timleech
    replied
    Originally posted by Bill Pace
    One of my buddies has just this set-up -- a 3/8 drive air ratchet on a permanent mount right near the draw bar, - he gives me a hard time saying the ratchet works as good
    One thought has occurred to me, that if you use a plain air ratchet in a fixed setup, and tighten the drawbar fully, there's a risk it might not be able to undo. With an impact tool, you just run it for a fraction longer.
    Anyone with any experience of this, positive or negative?

    Tim

    Leave a comment:


  • Bill Pace
    replied
    Originally posted by Timleech
    Looking at my situation, there isn't the spare headroom for some of the systems as described with an air impact gun.
    I've got a 3/8" drive air ratchet, good make, bought it new about 30 years ago but never use it as I reckon I can use a hand ratchet almost as fast without the complications of airlines. I wonder whether that would be man enough for the job? It would help to round the headroom issue. pretty sure it has a reversing valve rather than a push-through square.

    Tim
    One of my buddies has just this set-up -- a 3/8 drive air ratchet on a permanent mount right near the draw bar, - he gives me a hard time saying the ratchet works as good

    Leave a comment:


  • Timleech
    replied
    Originally posted by John Stevenson
    Tim,
    One of the web sites shows a similar home made changer that has a dog legged lever on it so the pullie down bit is easy to reach.
    It may have been one of the guys off this site ?

    This is one of the reasons why I hate R8 so much, at least with INT30 and 40 there is enough room up the spout to get a decent quick changer mechanism.

    .
    John

    Looking at my situation, there isn't the spare headroom for some of the systems as described with an air impact gun.
    I've got a 3/8" drive air ratchet, good make, bought it new about 30 years ago but never use it as I reckon I can use a hand ratchet almost as fast without the complications of airlines. I wonder whether that would be man enough for the job? It would help to round the headroom issue. pretty sure it has a reversing valve rather than a push-through square.

    Tim

    Leave a comment:


  • Bill Pace
    replied
    This seems to have prompted a good bit of interest! And, it has been a good while since the power drawbars were visited.

    Since there are (hopefully!) some new members, it might be that somebody would like to make up one of them.

    I built mine 2 1/2 yrs ago using - mostly - Bob Warfields site and a post that "Marc M" posted ...

    http://www.thewarfields.com/cnccookb...llDrawbar.html
    http://bbs.homeshopmachinist.net/showthread.php?t=22612

    There were also at that time down-loadable plans for 15$ that really wernt all that necessary

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

    And here is a link to what mine looked like --

    http://bbs.homeshopmachinist.net/showthread.php?t=22841

    There was some concern about 'hammering' the drawbar, but after these 2 1/2 years, my bar looks perfectly good! I have to say, it is one of the more favorite of all the mods Ive added over the years.

    Leave a comment:


  • JCHannum
    replied
    Bob Warfield has a bit more involved one on his site. It could be simplified to just use the angle iron actuator, or built as described for much less than the purchased unit.

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

    Leave a comment:


  • John Stevenson
    replied
    Tim,
    One of the web sites shows a similar home made changer that has a dog legged lever on it so the pullie down bit is easy to reach.
    It may have been one of the guys off this site ?

    This is one of the reasons why I hate R8 so much, at least with INT30 and 40 there is enough room up the spout to get a decent quick changer mechanism.

    .

    Leave a comment:

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