Modifications and Improvements to a Unimat SL 1000 Lathe

[Paul Jones]

Mr. Pete,
I think of all the improvements I added to this lathe, it was the continuous duty U-100 motors that were the most important changes. The the U-100 motors can run for hours without any need for shutting down for a cooling off period. The original Unimat motor was designed for intermittent duty with a duty cycle of ~80% (e.g., 8 minutes on and 2 minutes off). If the motors become very hot to the touch (~130 to 140 degrees F) then let them cool or risk destroying the motors. The U-100 motors make the machine fun to use and takes the worry out of ruining the motors due to over heating.

I wish you success with your changes. Post your improvements as you complete them so we can see the progress.

Thank you for the feedback, Paul Jones

[Paul Jones]

During the second half of 2015, there have been several more improvements to the Unimat SL and the lathe is still used on many of my projects despite having larger 7" and 12" swing metal lathes (and these have been modified as well).

Recent Unimat improvements have been minor but useful features such as lever action clamping screws for locking the sliding headstocks and tailstock (see Homemade Lever Action Clamping Screws and Homemade Tailstock Clamping Screws ), nicer looking spring cups (see Homemade Unimat Headstock Spring Cups ), an adjustable drill press stop (see Homemade Unimat SL Adjustable Drill Stop ), and my own version of a slotting saw arbor that fits directly on the M12X1 spindle ( http://www.homemadetools.net/slotting-saw-arbor ).

Here are some photos showing the progress and there are more detailed articles and photos published elsewhere in Homemadetools.net.

[Paul Jones]

During the first half of 2016 there have been several new additions to the Unimat modifications.

1) Unimat Boring Head Adapter for Criterion Boring Head
A single point insert tool was used to machine 7/8x20 threads to precisely fit the Criterion S-1 ½ small boring head and the opposite end attaches to the Unimat M12X1 spindle (see http://www.homemadetools.net/boring-head-adaptor-2 ).





2) ER16 Collet Chuck for Unimat M12X1 Spindle
The collet chuck uses a commercially available ER16 collet nut with a M22X1.5 thread. The combined collet chuck and collet has a measured 0.0004” TIR (see http://www.homemadetools.net/unimat-er16-collet-chuck ).





3) Unimat SL Lathe Headstock Alignment Tool (Test Bar)
Measuring the difference between the machined diameters and divided by two provides the approximate distance to swing the Unimat headstock. The Unimat lathe has a headstock that can be rotated for machining tapers and is locked in place with a special set screw. The process takes several iterations and the alignment can be set to within 0.0001 to 0.0002” in alignment over 5” (see http://www.homemadetools.net/unimat-...ignment-method ).








4) A fixture to hold an adjustable arm for a dial indicator (side view and parts view).This adjustable arm can also hold a 3/8" dia. handle to a diamond dresser (same dia. as a dial indicator) for dressing the grinding stones when using a Dremel tool in the QCTP.







Below is a recent closeup photo of the lathe.




Below is a recent photo of the complete view that includes the milling/drilling head, home made ER16 collet chuck with a Shars collet nut, and machining a small compound steam engine cylinder head entablature where the 1-2-3 blocks ensure parallel alignment when drilling the holes (note the x and y holes are positioned with the dial indicators).