Sieg SX3L Quill Lock Repair

When milling my Myford QCTP dovetails I noticed that even if I tightened the quill lock very firmly the dovetail cutter had a tendency to dig into the material because the quill lock was slipping. Additionally the lock handle was always getting looose. So these problems needed some examination and repair plans.

Attachment 49699

After dismantling the the lock parts I noticed that the two locking parts had only a very small locking contact area against the quill due to the very simple large chamfer design. In order to get a larger and better fitting locking contact area I designed new locking parts with locking area matching the quill radius. The material for the new parts is D25 mm brass round bar.

Attachment 49700

First I turned down a piece of brass bar to D23 mm and tapped the other end wit a M8 thread.

Attachment 49701

Then I had to reassemble the Sieg mill again with the old parts in order to make the D60 radius cut in the brass bar. After that I cut the bar at the D60 radius center point with a 2mm saw blade.

Attachment 49702

Then I turned the two parts to the final length and made the D9 mm hole in the longer part. In order to make the lock engage with even smaller force I added a 8x21x4 mm thrust bearing. Below is a picture with the old locking parts and the new ones.

Attachment 49703

The repair was successful and now the quill stays locked with very little locking force on the locking handle that now also stays fitted with some drops of Loctite.