Power draw bar question

[jmarkwolf]

I just sold my old Bridgeport mill and bought a new Acer 3VS, the head for which is much taller, and despite being 5-11 cannot reach the draw bar without a step stool (wasn't an issue with my Bridgeport).

I really don't want to spring for a commercial unit, so I'm reading up on DIY power draw bars that utilize cheap butterfly air wrenches.

Won't the "hammering" action eventually do harm to the draw bar or collets or both?

 

[randyjaco]

It hasn't hurt mine yet (about 3 years). I wish mine had more downward hammering action. My biggest gripe is that if I over tighten the drawbar. The power wrench will loosen the draw bar but the collet will stay wedged in place, causing me to have to remove the power drawbar assembly and impact the top of the collet to break it loose. Kind of a PIA.

Randy

 

[woodchucker]

It hasn't hurt mine yet (about 3 years). I wish mine had more downward hammering action. My biggest gripe is that if I over tighten the drawbar. The power wrench will loosen the draw bar but the collet will stay wedged in place, causing me to have to remove the power drawbar assembly and impact the top of the collet to break it loose. Kind of a PIA.

Randy

Isn't there some way to capture the bar so it doesn't lift up so it can push the collet out?

 

[Silverbullet]

There is a way to capture the nut , involves locking or screwing a collared piece to the top and onto the draw bar. The draw bar has to be modified so it can't pull out of the spindle circlips or ering would do it .

 

[jmarkwolf]

There is a way to capture the nut , involves locking or screwing a collared piece to the top and onto the draw bar. The draw bar has to be modified so it can't pull out of the spindle circlips or ering would do it .

Is the manual downward pressure from your hand not enough to push the collet out?

 

[derf]

It happens to me occasionally, I found a quick way to eject a collet. Once the impact has retracted, I place the handle of my drawbar wrench between the drawbar and socket and lift the quill handle to knock it out.

 

[randyjaco]

Is the manual downward pressure from your hand not enough to push the collet out?

Not on mine. Back before the power drawbar, I used a wrench with a brass hammer head on the other end. After I loosened the bolt, it always took a whack with the hammer. A good taper is supposed to stick.

Someone just needs to come up with a cheap power drawbar with some vertical impact.

Randy

 

[jmarkwolf]

Does anyone know how the commercial power drawbars deal with this issue? They all appear to be fully enclosed, no room to sneak a tool in there to break the taper, if it ever were to get stuck.

 

[rpmMan]

i have an older 3vk machine that came with a kurtz power drawbar ... it has not failed me yet.. collets almost fly out... i bought a shars keyless chuck / r8 arbor that fits pretty tight.. i have to make sure the quill is locked ..

rich

 

[jmarkwolf]

Some of the DIY power draw bars I'm finding on the web have an additional air cylinder for lowering or "engaging" the air ratchet before spinning it up. I wonder if this approach might prevent some of the issues.