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Air Operated Milling Machine Drawbar

piedmontg

Aluminum
Joined
Dec 10, 2007
Location
NW Illinois
Hi

I did some searches looking for an auto drawbar attachment for my Bridgeport. Not too
many posts. Any comments on ones you own. I do not one of the ebay project types, I have
enough projects.

I want one I can bolt on and be done with it. Not too many suppliers.

Thanks

Bob
 
Have one on my mill R8 taper, if you don’ t use the mill for a few days the collet can stick, have to undo three screws to move the air motor to one side and knock the top of drawbar with copper mallet.

That said I use quckchange system and the toolholder can stay in indefinately, so I pop it out to stop it sticking if I know the machine is not going to be used for a while.
 
I've got a Kurt pneumatic drawbar on my Lagun. It uses an IR butterfly impact wrench. Never had a collet stick.

Super fast, worth it's weight in gold to me. I'll never own another BP without one.
 
I've got a Kurt pneumatic drawbar on my Lagun. It uses an IR butterfly impact wrench. Never had a collet stick.

Super fast, worth it's weight in gold to me. I'll never own another BP without one.

I had one of those for a while. How do you know how tight the collet is? I’d let it rap for a bit and then start to mill. A couple times the end mill moved, wasn’t tight enough. So I let it rap longer. Wasn’t long before the draw bar was stripped. No feel to it. You just can’t tell. What am I missing?


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Yes I did a search like that an found 3 suppliers Kurt, Servo, and Maxi Torque. All the rest seemed
to be kits.

They all look fine to me, I just was looking for actual brand usage experience. I have had the mill since 1993 and am
finally getting tired of reaching up there as I am vertically challenged ie a short guy!

thanks for the info

Bob
 
Lubricant on said threads ?
That could be. I pour a couple ounces of AW32 down the drawbar fairly regular. I want to see a little puddle on the vise in the morning. If it's dry, I dump in some more oil.

@adh2000- Could it have been a worn collet or low air pressure? R8's don't hold worth a crap on a good day.

I don't have problems with cutters pulling out though, other than those dorky 1" R8 POS's. I just tighten it until it starts rapping, then I figure it's torqued- no point in hammering it. I run it at 100 psi- I don't know what the mfg says- probably 90 psi, typical for air tools.

I don't do a lot of milling on the machine, it's mostly a drill press. Most of my milling goes on the VMC's.
 
I have a Kurt. Trouble free for about 10 years now, never had a tool slip with standard R8 collets. I never wanted to spend the money, then I had a job that needed about 5 tool changes per part, it paid for itself on that first job. I will never own a BP without one again. Only pita I can think of is if you need your 90 degree head you have to remove it and use your old drawbar. I just used it on a job for the first time in years.
 
I have bought whatever from Enco, MSC, Penn, PTS, others.
Some of these have outlasted the milling machine below them so we pull off the accessories and send the base to the scrap man.
The air side on them all die eventually, some are better at holding together pieces, parts and fittings. Some need added love as loctite in places, others need air fitting help.
Shop air pressure and flow determines tight plus each is a little different so you have a regulator out front.

My B-ports and clones do not have keys as these are removed on day one as they slow things down since we need fast tool changes.
I do not spin collets and run up to 8 inch milling cutters.

I read horror stories on the net and wonder..... why?
Bob
 
Seems strange to me that a lightning fast tool change is needed on a manual machine like a Bridgeport. Does that mean after the lightning fast tool change you crank the handles at lightning fast speeds?

Stuart
 
Seems strange to me that a lightning fast tool change is needed on a manual machine like a Bridgeport. Does that mean after the lightning fast tool change you crank the handles at lightning fast speeds?

Stuart

It just speeds the tool change to be the same relative speed as turning the cranks. You go from being like a turtle and a snail to being like a turtle and a turtle!
 
Seems strange to me that a lightning fast tool change is needed on a manual machine like a Bridgeport. Does that mean after the lightning fast tool change you crank the handles at lightning fast speeds?

Stuart

Keeping a 3/4" box wrench away from the top of the spindle is worth
it simply for ones safety.

Also, you don't like quick change toolpost's on lathes either ?
 
Seems strange to me that a lightning fast tool change is needed on a manual machine like a Bridgeport. Does that mean after the lightning fast tool change you crank the handles at lightning fast speeds?
I can only speak for myself- but I only get paid when the spindle is turning, and the parts are in print.

A power drawbar changes the way you use the machine. It's usually faster to put and take a part in the vise than to manually change tools. A power drawbar alters that equation, which translates to fewer part changes.

When you are using multiple tools on location- center drill, drill, tap. Keyless chuck- load center drill all the way up in the chuck. Set the depth stop for the chamfer, center drill. Change to the tap drill- it's longer than the CD, so I can drill thru without moving the quill stop. Change to the tap in a keyed chuck- it's longer too, so just power tap the hole. 2 tool changes per hole. Over a run of 500 or 1000 holes, that adds up.

Faster to tap a hole on the VMC, but not every part fits on the VMC.

I make a handle where the distance from a hole pattern to the end of the handle has to be held fairly close. The part does not have a good repeatable locating surface. So the part goes in, the end is machined, then I crank over to the holes and change the tool. I make both features in one clamping, so the distance from the end of the part and the hole pattern is consistent. If I was manually changing tools, I would probably put and take the part- mill all the ends, then drill all the holes. I would have more difficulty holding the tolerance due to the loading error.

Like my first example, that also would be faster on the VMC, but the part doesn't fit on the VMC- one end has to hang underneath the table.

It also takes away some of the temptation to be lazy. Say a counterbored hole- I know it's a no-no, but I might be tempted to stick a small end mill in the drill chuck to cut the c'bore. If I have an endmill or c'bore in a holder sitting there, it's just as fast to change the tool and do it right...
 
Seems strange to me that a lightning fast tool change is needed on a manual machine like a Bridgeport. Does that mean after the lightning fast tool change you crank the handles at lightning fast speeds?

Stuart

There are times when changing tooling multiple times for each position isn't a speed issue, but just becomes a PITA. I don't have a power drawbar on my Bridgeport, and until recently hadn't considered one. Last week however I did run into a job that would have been much easier if I had one. The job entailed about 3 dozen pieces that needed multiple holes drilled (Some were blind holes while others were through holes), tapped, and either counterbored or counter sunk. In addition there were multiple holes that needed to be drilled and reamed to size. No big deal but a real pain to change tooling every few seconds. It doesn't help that I'm a little less than 5'9" tall. It's a long reach to the top of the head, and having to do it that many times gets old fast.
 








 
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