PM-835S spindle bar comes out with power draw bar

Pcmaker

Pcmaker

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I'ts been awhile since I installed the torque-rite power draw bar. Today I was using the mill and it pushed up the power draw bar. I took the top off and threaded the spindle drawbar back in. I forgot how this works, but is the drawbar supposed to unthread when you're trying to take out a collet using the power draw bar?

is there something there that prevents the spindle draw bar from unthreading when reversing the power draw bar to take out a collet?
 
Maybe I'm confused but how else would you remove a collet if the draw bar didn't unthread from the collet? Maybe the collet got stuck in the upper position and the draw bar moved upward when it unthreaded from the collet.
 
Tipton1965 said:
Maybe I'm confused but how else would you remove a collet if the draw bar didn't unthread from the collet? Maybe the collet got stuck in the upper position and the draw bar moved upward when it unthreaded from the collet.
Click to expand...

yea now Im confused, too.

I don't know why it's pushing the power drawbar up, to where it stripped one of the bolts, instead of pushing the collet down
 
Pcmaker said:
yea now Im confused, too.

I don't know why it's pushing the power drawbar up, to where it stripped one of the bolts, instead of pushing the collet down
Click to expand...
What did the collet do when this happened? Did it fall out?
 
Sounds like the collet is stuck inside the spindle, possibly on the alignment set screw. The collet should fall out once the draw bar has been removed
 
I'll mess with when I get back home. What does the R8 locating set screw do again? I haven't messed with it since I first bought the mill.

I also remember that the power draw bar also spins along with the motor when the quill is in the highest position.
 
If the collet is not being pushed down when the quill is fully up and the power drawbar is actuated, then one or more of the following comments should be helpful:
  • The drawbar is too short to engage with the PDB when the quill is fully elevated.
  • The screw-end of the drawbar is stripped or the threads in the collet are stripped.
  • The quill is being forced down when the PDB is actuated - lock the quill in the elevated position.
  • The collet is stuck in the spindle. This is often because the locating set screw on the side of the quill/spindle is set too deeply, or that end of the set screw is too wide relative to the slot in the side of the R8 collet. The best cure here is to simply remove the locating set screw - it really has no necessary function if you have a PDB.
  • If the collet is stuck (for whatever reason) the PDB should force the quill downward as the drawbar unscrews in the stuck collet (assuming the quill is unlocked and free to move up/down).
  • If instead, the PDB is forced upward, causing the PDB to elevate and strip out the mounting screws, then either:
    1. the PDB was not installed properly - typically it's off-center relative to the axis of the spindle, or not adequately affixed to the top of the head, or
    2. the drawbar cap nut is free to wallow around in the spindle making it off-center relative to the spindle axis, in which case a properly sized washer under the drawbar cap should be installed that forces the drawbar cap to align to the ID of the top of the quill/spindle. If the drawbar cap nut is off-center when the PDB lowers, the splined/hex portion of the drawbar cap will fail to engage into the socket of the PDB, creating the same effect as having a drawbar that is too long.
Hope this helps.
 
“ The best cure here is to simply remove the locating set screw - it really has no necessary function if you have a PDB.”

I don’t have a PDB and still got rid of my set screw. Is this an issue? I have no issues tightening collets.
 
Christianstark said:
I don’t have a PDB and still got rid of my set screw. Is this an issue? I have no issues tightening collets.
Click to expand...
If you don’t have an issue tightening or loosening collets, then no.
 
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