PDA

View Full Version : R8 to MT2 collet chuch conversion



gizmo2
01-19-2003, 01:04 AM
I got a set of those spring collets with an R8 chuck when I bought my little lathe. The guy MADE me take them, honest! But the mill I ended up getting was an old J head Bridgeport that uses MT2 collets. The first thing I did was break the largest (1/2") collet. I asked this board if it would be possible to turn the R8 down, and they said 1. why not, or 2. get a newer mill. By making a well centered stub and chucking it in the R8 chuck, I was able to turn the shank to MT2 between centers. Ate up some carbide inserts, but it worked. Had to make a new drawbar with 7/16x20 tpi. Runout is about .0007", and that's a pretty big chunk of metal hanging off the end of that little spindle. So while not ideal, I think I've extended the usefulness of my old iron. Thought I would share my success with all you 'financially challenged' types out there. The trick, I found, was taking the absolutely biggest bite the lathe could handle on each pass. Otherwise it would glaze and skip over the top. As soon as that started, the insert was toast. I could have ground it with my poorman's tool post grinder (Dremel with them skinny cutoff wheels) But I'd still be out there with a couple weeks left to go! Does anyone know if these are ER series collets? and if so, which series?

chip's
01-19-2003, 04:27 PM
I'm sure glad you could get it to work. It would be a shame to get rid of a good machine.

jim k
01-19-2003, 05:43 PM
I believe they are.As you stated,Its a bit (too) much sticking out and too small of a shank.I would think you will have a crash if you try to take much of a cut with side pressure.Good luck and take it easy on the old gal.