Unimat SL Lathe Headstock Alignment

[Paul Jones]

Yes, I take very good care of the Unimat SL that I bought new in 1970. I have replaced the lead screws and the headstock bearings and now thinking about replacing the bearings again (uses an unusual magneto style bearings). The machine has been modified and improved but only used for small machine work.

Good luck on the mini lathe alignment. Adding up all the time, I think I spent several days aligning my mini lathe (it is the lathe painted dark green in many of the photos I have posted on HMT). Shimming the headstock using RDM (Rollie Dad method) takes many hours because it is a slow iterative process that depends a lot on the amount of torque applied to the three headstock hold-down bolts. Use a torque wrench to be more consistent from iteration to iteration. Also check all the gears in the headstock while it is off the lathe and replace the gears that are in bad shape. Once you have the headstock perfectly aligned with the lathe ways, you will find the tailstock is no longer aligned and is sitting too low (you will find the headstock shims raise the spindle center line and another reason it takes so long because of unintended consequences). I had to rebuild the tailstock with shims and added a way to micro-adjust the side-to-side movement for spindle to tailstock alignment (see Homemade Tailstock Fine Screw Adjustment ). When things don't make sense in the process it is a good time to stop and think it through. In the end you will find the extra effort was worthwhile.

The B&S tenths DTI will be an excellent addition. Also a great way to check with a small granite plate the precision of used parallels, V-blocks and other items from eBay purchases. I like the old homemade precision tools that were carefully made by toolmaker and include the makers initials and date placed in a recess on the tool.

Thanks for all of your information, Paul