Drawbar speed handle for Bridgeport milling machine

Ta Muchly. Good idea.

Andrew VK3BFA

Why don't you just use a stubby rachet and 3/4" socket. That's what we use normally. It has a big advantage when you turn the mill on and accidently leave the wrench on. The chatering of the ratchet is a great indicator of you problem and it has little eccentricity so doesn't make the mill shake violently. Leigh at MarMachine

The round, balanced handle spins on and off quickly. Saves time on every tool change, like those expensive power drawbars.

So you use a different wrench to crack the drawbar loose, then drop on your handle, grab it with your right hand, and spin up the mill head with your left hand? I can see how that would go fast. I did use to do as Leigh did, use a stubby ratchet with 3/4" socket. If you know what you're doing you can also use the motor to spin the drawbar off with that, but spinning it on would be a little risky. :-)

Clever idea.

GWE

Yep. Usually the 2.5 inch knurled handle is enough for me to get it on and off; no need for another wrench.

Is there an officially proper torque to tightening the drawbar? Seems to me it doesn't need much, and if you need a wrench to crack it loose, it might be too tight. For a collet, it must depend on the area and radius of contact with the tool. For things like a drill chuck, you're not trying to grip a tool at all, just seat the taper. And things like a center finder shouldn't have much drawbar torque in any case.

Richard, I have one Bridgeport I bought new in 1981. I have always used the wrench to tighten the drawbar. There are many times when it needs to be way tighter than I could possibly get it with a 2.5 inch knurled grip. The drawbar is the original one and is still in fine shape. This is one of the machines I make my living on. ERS

--That's a great hack; thanks for sharing! :-)

Needed to grip a tool, or seat the taper, or what?

Anyone know what torque the power drawbar add-ons apply?

Like when taking a heavy cut with a long endmill. E.G. a 3/4 inch dia. endmill, 3 inch flute length, high spiral, with 2.5 inches of flute facing a titanium part. Or, 1/2 inch high spiral endmill hogging aluminum. Both situations will tend to pull the cutter out. I don't always reef on the drawbar, but it's been tightened pretty tight a lot in the last 25 years. ERS

I would consider a setscrew holder instead of a collet to hog.

It is pretty easy to overtorque a 7/16 bolt with a hand wrench, so my intuition is that the drawbar shouldn't be gorilla'd.

Well, like I said, I bought this machine new in 1981, it's one of the machines I use to make a living, and it's still on the original drawbar. And it's in good shape. ERS