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View Full Version : Wow this looks good power drawbar



Alistair Hosie
07-21-2009, 05:55 PM
This looks good for the money don't you think? I don't think you could make one cheaper time you costed in your work hours I don't have a bridgy I wonder if they could be adapted whatyou think ?Alistair






http://cgi.ebay.co.uk/Milling-Machine-power-drawbar-Bridgeport-STEP-PULLEY_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a 4Q7c39Q3a1Q7c72Q3a1688Q7c293Q3a1Q7c294Q3a200QQ_trk sidZp3286Q2ec0Q2em14QQhashZitem230216b005QQitemZ15 0358896645QQptZLHQ5fDefaultDomainQ5f0QQsalenotsupp orted

John Stevenson
07-21-2009, 06:13 PM
To be honest Alistair it looks expensive to me because it's just a butterfly wrench on two spring loaded columns and you manually pull it into position then hit the switch.

Most of the other kits have pneumatic cylinders to engage the drawbar.

You can buy a butterfly wrench off Ebay in the Uk for 14 or 15 plus postage.

.

Alistair Hosie
07-21-2009, 06:15 PM
whats a butterfly wrench when it's at home sorry John you know me??Alistair ok I just looked one up I have one similar how about the lever controls ,and stand that makes a slight difference doesn't it?

John Stevenson
07-21-2009, 06:50 PM
Ignore the bottom knob and the slotted plate, this is for a step speed bridgport mounting.

The top knob is connected to a vertical shaft that also connected to the bit of angle iron with In and OUT stuck on it.

To use you pull the whole assemble down with the top knob so the socket is sat on the drawbar then twist the knob so the angle iron presses on of the paddles on the front of the wrench and that will operate it.

It's because of the paddle operation that people use these wrenches hence the name butterfly wrench.

.

Highpower
07-21-2009, 08:03 PM
Basically the same thing as my Kurt manual drawbar. Only difference is - on the Kurt when you push the knob sideways (IN- OUT) it automatically cams the butterfly down to the drawbar.

BobWarfield
07-21-2009, 08:49 PM
BTW, you can get 2/3 of the value with butterfly impact wrench handheld too. They're cheap. Pick one up!

Cheers,

BW

dp
07-21-2009, 11:51 PM
BTW, you can get 2/3 of the value with butterfly impact wrench handheld too. They're cheap. Pick one up!

Cheers,

BW

You also built one of those, no? I'm pretty sure I saw one on your site, anyway. Excellent job on that site, btw.

John Stevenson
07-22-2009, 04:30 AM
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.
.

Timleech
07-22-2009, 06:17 AM
The one reason I've wondered about a power drawbar is because my machine is quite tall, I have to stand on something to get a spanner on the drawbar which can be a pain if I have a series of tool changes to make. This type wouldn't help that at all, you still have to reach up there.

Tim

John Stevenson
07-22-2009, 08:57 AM
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.

.

JCHannum
07-22-2009, 09:06 AM
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

Bill Pace
07-22-2009, 09:58 AM
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/cnccookbook/CCMillDrawbar.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.

Timleech
07-22-2009, 11:00 AM
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

Bill Pace
07-22-2009, 12:55 PM
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:rolleyes:

Timleech
07-22-2009, 04:02 PM
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:rolleyes:

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

Alistair Hosie
07-22-2009, 06:18 PM
LOL BILL I was about to say on your post download photo four what a nice painting on the shop wall :D til I noticed it was a window :D.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

noah katz
07-25-2009, 02:50 PM
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.

Alistair Hosie
07-25-2009, 03:48 PM
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

deltap
07-26-2009, 02:10 PM
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.

lazlo
07-26-2009, 02:26 PM
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:

http://home.insightbb.com/~joevicar3/cheap_drawbar_files/image004.jpg


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 :)

Alistair Hosie
07-26-2009, 03:10 PM
Wow Bob Warfield is a clever guy well done again Bob.;) Alistair

lazlo
07-26-2009, 06:13 PM
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

noah katz
07-27-2009, 02:06 AM
"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?

Alistair Hosie
07-27-2009, 08:20 AM
I know but I went once again to Bob's site he's a great engineer and has a great shop too.Alistair