[How-To] Make a power drawbar for a Bridgeport M head

[TechyMechy]

I have a Hardinge TM milling machine and I have a new to me Bridgeport M head on it. I really like the combination, but it is a bit clumsy to insert/ remove the tooling from the collet when trying to tighten the drawbar/keep the spindle from spinning.

I am thinking that a power drawbar might be something fun to make. Has anyone made a power draw bar that allow one to one handed tighten/loosen the collet while holding the tooling in the other hand (not allowing it to drop)?

I can get air to the machine, but I prefer that this is electrical powered. I have some ideas, but they start to look a little Frankenstein'ish pretty fast and it is questionable if they are actually easier than the original method.

Thanks for your ideas.

 

[ttabbal]

I purchased an air based unit from ebay. It works well for me. The simpler designs should be able to be run from an electric impact if you prefer. I suggest looking at those for ideas and adapt as desired.

I really like mine. It makes it much faster to swap tools. Pull it down, then to the side and the impact takes care of the rest.

 

[TechyMechy]

Thanks,

I haven't seen how one of these work. I don't see any mechanism on the air units being sold on eBay to lock the spindle.

I am assuming that one needs to lock the spindle so it does not turn when trying to tighten/untighten the draw bar. I don't have a brake on my M head but I have a large nut on the top spindle stepped pully. One uses a wrench on the stepped pulley and another wrench on the drawbar to tighten the collet.

I'm looking for a clever way to grab the large nut and also drive the draw bar. I'm also looking to see if someone took the guts out of a HF electrical impact wrench or something for the power source...

 

[ttabbal]

The air device is a butterfly impact. Nothing fancy. The interface to the draw bar is just a socket. You pull the impact down which generally gets the socket to mate up. Then push the handle to turn it on.

No need to use a brake. The impact action makes it unnecessary. Same with hitting the top to release the collet from the taper. Most of the time anyway. I have them stick sometimes, but usually just tighten and loosen again and it pops out. Don't overthink it.

 

[TechyMechy]

The air device is a butterfly impact. Nothing fancy. The interface to the draw bar is just a socket. You pull the impact down which generally gets the socket to mate up. Then push the handle to turn it on.
Ee
No need to use a brake. The impact action makes it unnecessary. Same with hitting the top to release the collet from the taper. Most of the time anyway. I have them stick sometimes, but usually just tighten and loosen again and it pops out. Don't overthink it.

Thanks for the explanation.

I can see why you like the eBay devices. One can’t hardly make one for the same money. The spline shaft sticks up a fair distance above the aluminum pulley cover on the M head. I have to double check to see if the eBay unit will fit. I could use an air driver- I just need to get air to the mill.

 

[aliva]

Here's mine no need to use a brake to add or remove collets

Power Draw Bar for the BP?

Guys been watching Youtubes on home made power draw bars for the BP which seems pretty neat.So I was wondering if anyone here has made one for their mill or if you purchase one of those kits see on ebay.If you have any ideals,thoughts on this please share.Any links,websites,videos or pics of you...

www.hobby-machinist.com

 

[TechyMechy]

Thanks all for the information. I'm going to have to make my power drawbar. I really don't see a power drawbar being sold that would work with a M head without significant modification (so why not make your own?).

Do people have recommendations on where to get the butterfly air wrench? I found on on Amazon that looks good, but I am wondering what others have used.