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- Dec 27, 2014
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Working with relatively small drill (and centerdrills) I've encountered a problem with my PM25 mill. When using a No. 0 center drill I find that the drill walks in a circle (really tiny, maybe .010 diameter) before it settles down to starting the hole. It isn't the drill walking so much as the quill dancing around.
I've tried snugging the quill clamp down to where the quill won't walk, but then I loose feel hand feeding. I'd wondered about installing a little pusher with a ball bearing in it to push against the quill below the head housing, But never got as far as figuring how to mount it.
This evening I came up with a solution. My first thought was "put a spring between the clamp screw and the quill." That sent me looking for a short stiff spring. I found a spring, but it was neither short nor stiff. It is 3/4" long, 3/16 in diameter of .0175 wire. I drilled a .190 hole in the end of the clamp screw, at a guess 3.16 deep, put the spring in and screwed the screw in. (There is a brass plug at the bottom of the hole, so my spring is not bearing on the quill itself.)
By dickering around, (with an indicator on a .3125 dowel in the drill chuck, I figured out that if the spring was almost totally compressed, I still had plenty of feel on the quill, and the dowel bobbled around about .0015.(This is where it is with the quill clamped tight, too.)
I adjusted the clamp handle so that at this tension on the spring it (the handle) is pointing at 6:00. To clamp it, I move it to 8:00 and it's tight.
Here's my solution, hope this helps anyone with a similar problem
I've tried snugging the quill clamp down to where the quill won't walk, but then I loose feel hand feeding. I'd wondered about installing a little pusher with a ball bearing in it to push against the quill below the head housing, But never got as far as figuring how to mount it.
This evening I came up with a solution. My first thought was "put a spring between the clamp screw and the quill." That sent me looking for a short stiff spring. I found a spring, but it was neither short nor stiff. It is 3/4" long, 3/16 in diameter of .0175 wire. I drilled a .190 hole in the end of the clamp screw, at a guess 3.16 deep, put the spring in and screwed the screw in. (There is a brass plug at the bottom of the hole, so my spring is not bearing on the quill itself.)
By dickering around, (with an indicator on a .3125 dowel in the drill chuck, I figured out that if the spring was almost totally compressed, I still had plenty of feel on the quill, and the dowel bobbled around about .0015.(This is where it is with the quill clamped tight, too.)
I adjusted the clamp handle so that at this tension on the spring it (the handle) is pointing at 6:00. To clamp it, I move it to 8:00 and it's tight.
Here's my solution, hope this helps anyone with a similar problem