I was asked if I could improve the clamp arrangement of the drill/mill head on a combination lathe, I believe it’s a Clarke CL500M. Here’s a picture of the head as supplied to me. Seemingly my modification has been of interest to quite a few people so I thought I’d post details here incase it’s of interest so some forum readers.

The clamp that was supposed to secure this head to the colum sufficiently tight to allow drilling and milling was completely ineffective and thus quite dangerous. The diametrical clearance between the bore of the head and the colum measured 0.13mm or 0,005″ which is quite significant and likely the reason the original clamp arrqangement did not work. Apparently this is a common problem with these machine tools.

My solution was to make and install two split cotter or double cotter clamps which can be seen in the picture below. These are 1″ diameter.

To accomodate the split cotters I had to bolt on a backing plate as seen below.

The pictures below shows the finished job. a 3/8″ UNF cap screw was used to clamp the split cotters together onto the colum. This mod is proving to be very effective.

Anyway, that was my solution, quite a bit of work, 10 hrs believe it or not, hopfully helpful to others who have this machine.

Thanks