Limited Quill Travel - Pm-932m

I've got a Grizzly G0762, not a PM, but I'm totally stealing your idea for a bushing to keep the drawbar concentric. Thanks for the tip to keep the bushing OD smaller than the inner races of the splines.

FWIW, unlike the PM, the top nut on the grizzly drawbar just had a roll pin to keep it from turning (not welded or part of the drawbar). That roll pin sheared off within about a half day of use (its possible I like drawing collets tighter than they need to be). I bored the hole a little larger and replaced the roll pin with a small hardened dowel pin and it's worked fine since.
 
I can't claim the idea for the spacer - I stole it from Darkzero. However, I believe he made his on a lathe. Mine was made with my boring head on the mill.

My top nut came with a roll pin from PM as well. I decided to just weld on the replacement. So far so good!
 
You could use some grade 8 jam nuts which are a lot thinner or order up some threaded rod and make your own drawbar slightly longer.
 
I don't think that would solve the issue. Regardless of the drawbar length, something needs to react off of the top of the spindle. There will always be something against the top - either a nut or a longer spacer that you would make. Apparently the very top of the spindle passes into the female splines approx. 1" at max travel, so the drawbar nuts/spacer absolutely need to be a smaller diameter than the minor of the male spindle spline.

I went ahead and massaged the flange on the nut and OD on my spacer the other night to bring them down in size. Everything works great again!
 
Rex Walters said:
I've got a Grizzly G0762, not a PM, but I'm totally stealing your idea for a bushing to keep the drawbar concentric. Thanks for the tip to keep the bushing OD smaller than the inner races of the splines.

FWIW, unlike the PM, the top nut on the grizzly drawbar just had a roll pin to keep it from turning (not welded or part of the drawbar). That roll pin sheared off within about a half day of use (its possible I like drawing collets tighter than they need to be). I bored the hole a little larger and replaced the roll pin with a small hardened dowel pin and it's worked fine since.
Click to expand...

Rex, on yer G0762 there is no motor for the head up n down, has that been an issue or an inconvenience?

Buck
 
I can't speak for Rex, but having a lift motor on the head is a blessing. I move my head frequently and I could see the temptation to take shortcuts (longer quill extension rather than just dropping the head) if I didn't have a motor.
 
Just a thought, a lot of quill movement should be avoided when setting up parts if possible. Using a large endmill with the quill down can cause chatter, or if counterboring near a thin wall....break through the wall. Been there, done that, got the T-shirt!

Plan out your steps before you start.

On knee mills you can avoid that by using the knee, just remember to not touch the knee lock, as that will move the table. Don't forget to remove backlash, if the knee lock is tight.
 
Indeed. The quill extension is kept as short as possible during milling operations.
 
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