R-8 Spindle Key

If the collet spins while installing it and causes trouble with tightening the collet, then the drawbar threads and/or collet threads are damaged or dirty. A tap, a die, and some solvent will cure that. Sticky drawbar to collet threads are a PITA regardless and need to be dealt with. You should be able to easily screw the drawbar into the collet with your fingers all the way until the collet seats in the taper, then switch to the wrench for final tightening. An overly long drawbar thread can also be a problem. If it goes into the R8 collet more than about one and a half thread diameters, two diameters at the very most, the drawbar is too long and should be shortened. I had to shorten and chase the threads on the drawbar of my newer mill.
 
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Badspellar said:
Shars sells a collet wrench for just that problem. #202-5596 I have never used one but think I will order one just in case. I pulled my pin when I got my PM935 mill.

Mike
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That tool sounds like an interesting project to design and make!
 
Bob Korves said:
................
I used to fly an aerobatic single seat aircraft that had a placard on the panel that stated: "Don't try anything stupid." We should post that on our machinery as well...
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I may just put that on the door into the shop... :grin:

- I've been contemplating repairing the guide pin on my BP and haven't decided which way to go - yet.
The drawbar threads were messed up when I got it, and I cleaned them up and added a spacer to keep the threads
from bottoming out. So far collets snug up fine, except for one. I'm thinking that I should get a new drawbar sometime
in the future.
 
There are countless stories of the alignment screw snapping off and jamming between the tool and the spindle. I had this happen to me years ago and had to beat the tool out of the spindle with a hammer. I did quite a bit of research on this recently when I purchased my new PM-935 and decided to remove the screw. That was the consensus of maybe 70% of the people.

Its an alignment screw its not designed to take the torque of cranking on the drawbar. Its just a set screw with a little pin sticking out, its hollow, its entirely possible to snap it in half. Its not exactly a precision tapped hole its in either so if it doesn't have a grub screw behind it to lock it in place it will bend a bit in the tapped hole making breaking it off even more likely. Some mills have the second grub screw some don't, the one I snapped in half didn't.

I have been using a power draw bar and its been no problem not having the alignment screw in there the spindle taper keeps the tool from spinning. Now if your drawbar threads are messed up or your tool is full of gunk or whatever then address that problem. That's my 2 cents worth.
 
coolidge said:
There are countless stories of the alignment screw snapping off and jamming between the tool and the spindle. I had this happen to me years ago and had to beat the tool out of the spindle with a hammer. I did quite a bit of research on this recently when I purchased my new PM-935 and decided to remove the screw. That was the consensus of maybe 70% of the people.

Its an alignment screw its not designed to take the torque of cranking on the drawbar. Its just a set screw with a little pin sticking out, its hollow, its entirely possible to snap it in half. Its not exactly a precision tapped hole its in either so if it doesn't have a grub screw behind it to lock it in place it will bend a bit in the tapped hole making breaking it off even more likely. Some mills have the second grub screw some don't, the one I snapped in half didn't.
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:+1: I've had that happen to me too. I've been running without a pin for years. Every time I got a mill, I removed the pin.
 
Thanks for all the input....sounds like one of those debates that no one will win. I'm about ready to assemble the spindle finally.....still on the fence, but I'm thinking I'm going to install the set screw. I believe the screw is there to help establish the initial resistance when pulling the tool up into the spindle, but shortly after the taper will take over. It certainly isn't there to provide torque to drive the tool.
 
How did you all remove that grub screw ? My is a little galled over and my collets have been a little rough going up in. I'd like to remove this grub screw out of my spindle before I have problems. Thanks much !
 
The problem is that I can't get access to the screw to turn it. I figured I'd ask before I start taking everything apart. I can see it when I look up I to the spindle from below
 
What kind of machine? If it's a BP or clone, then there is a small set screw that secures the bottom nut. Loosen that, unscrew the nut and then you can get to the pin.
 
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