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Stuck Quill Bridgeport BOSS

I have a Bridgeport BOSS CNC converted to ah-ha! I stupidly had limit switch checking disabled and retracted the quill. It clunked an it is now jammed in the UP position It does not respond to jog. I removed the cover that exposes the stepper motor cog belt that drives the spindle. The stepper motor is stalled. I presume that loosening the four motor mount bolts will put some slack in the belt so it can be removed. That will give access to a small window partially exposing the quill and cog pulley driver.

What do I do to get the quill unstuck? Impact a wooden dowel against the driver cog? Any suggestions would be most appreciated, especially from someone who has seen this goof before, on someone else's machine, of course!

Reply to
Donald Rothfuss
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Turn the driver cog the other way. Your method may work. It may also damage something. You gotta chain wrench? Wrap that around the cog, with suitable padding, and turn. You may be able to get access to the ball nut on the screw that raises and lowers the quill. If so, you may be able to loosen it's mounting screws. It could be bad to remove them completely as the quill may then drop, cuasing more problems, like smashed fingers. You won't need to turn the cog very much to release the pressure. ERS

Reply to
Eric R Snow

FWIW, I done this more than once on my series 1 with Ahha. I just put a channel lock over the belt around the stepper pulley and gently turned it backward. Didn't take a whole lot of force. Maybe you've jammed it better than me

On my machine the upper limit switch was too close to the top of travel. A rapid up (R) for tool change when I had the 0 set wrong on Z would blow by the limit switch and jam the axis.

Karl

Reply to
Karl Townsend

Thanks ALL for the inputs. After calming down and closer inspection I decided I had a wrench that would engage the stepper motor cogs and I was able to torque the jammed nut loose. It didn't take too much force. Now to put all back together and see if it jogs correctly and resolve not to do it again.

D>> What do I do to get the quill unstuck? Impact a wooden dowel against

Reply to
Donald Rothfuss

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Not quite. The quill on the BOSS sits inside a large-diameter hollow ballscrew, and the corresponding ballnut is in the center of the cog wheel inside the housing. This has the advantage that it applies forces truly concentric with the spindle. It has the disadvantage that it is more expensive to make, and is not something practical in a retrofit of a machine built for manual operation. (Also, if you have damaged the ballscrew and/or nut, it will be much more expensive to replace.

Good Luck, DoN.

Reply to
DoN. Nichols

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