ER16 Collet Chuck for Unimat M12X1 Spindle

**Paul Jones** · Mar 19, 2016, 02:57 PM

PJs,

I like your suggestion about the fine thread push/pull jig for the Unimat headstock. I made something like that for my 7" swing lathe tailstock adjustment and posted it on HomemadeTools. I think I could adapt something like that for the Unimat. That is great idea!

I have been using "Unimatt Buddy Pin" (yes two Ts) for my general headstock alignments for many years and I highly recommend it for those using the Unimat SL 1000. It is fast and can get the alignment extremely close for most work. I use a ground test bar (remove the tailstock) and a 0.0001" dial indicator when I want the alignment close to perfect.

Earlier this week I reviewed again the YouTube video by Tom Lipton where he shows how he aligned the lathe headstock after leveling the whole lathe. Tom uses an aluminum rod held in the chuck and with sufficient diameter so I doesn't flex due to its own weight. Tom removes material from most of the center length so just short sections on the two ends are left for making test cuts. Comparing the ODs at both ends measures the headstock alignment and how much to adjust.

Yesterday I made a similar 6061-T6 aluminum test bar but only 1.125" in dia. and 5.25" long for the Unimat. It has an M12X1 internal thread to mount directly on the Unimat spindle (but could modified for holding in the chuck). I made the test bar with my 12" swing lathe and decided to check this lathe before I cut-off the part for use on the Unimat. I used a Mitutoyo 1" to 2" digital micrometer to make the measurements over a 5" center-to-center distance. I used a blue Sharpie to blue the surface, machined off a few tenths, and measured several times, after waiting for the part to cool (and turned of the halogen work light). Each time the difference measured at either 0.00010" or 0.00015" but I was using a carbide tool and probably should have used a honed HSS tool (and perhaps a 2" bar of aluminum). The 12" swing lathe was re-leveled a couple months ago and I am calling the 12" lathe alignment test good enough.

I plan on posting in Homemadetools my Unimat alignment work but here are two photos from my work yesterday. The first photo is machining the test bar just before cut-off (and I forgot machine a 12mm x 4 mm deep counterbore in the spindle threaded end and had but back in the 4-jaw chuck, indicate again to a few tenths (more like chasing back and forth a few tenths))