Modifications and Improvements to a Unimat SL 1000 Lathe

[Paul Jones]

The HomemadeTools.net article by Rick Sparber “Aligning the X axis Leadscrew on a RF-30” reminded me of some of the adjustments I made to my old Unimat SL 1000 lathe when I added a vertical milling head. Like Rick’s work my adjustments required aligning all six different parameters for X, Y, Z, roll, pitch, and yaw.

The fixed rod supports for the x and y lathe ways proved to be a challenge because the rods are supported in a die cast lathe bed. A combination of twisting the cast bed and adding opposing set screws to a cross slide way rod (see photo of taping screw holes) brought this into alignment. It is essential to align the x and y-axes orthogonal to the lathe cabinet before adding the vertical column for the milling head. All axes were less than 0.003" out of alignment and required very slight and iterative changes to bring everything into alignment.

Adding the new z-axis dimension with a milling head column and column support required the most iterative process to bring the x, y and z axis into orthogonal alignment with each other. The milling column attachment base was made from 3”x12”x1” aluminum bar and bolted to the lathe cabinet. The vertical column support base was machined flat and square on my mini lathe using a custom mandrel, and then removed and bolted to the aluminum attachment base. The milling support base has a 0.0015” thick shim that brings the vertical column orthogonal to the lathe x and y-axes (the shim is shown in the 9th photo below). The last photo shows tramming left to right rotational adjustment of the milling head to be parallel with the lathe ways support rods. The photos below show some of the measurements and adjustments that were made during the alignment processes.

[Paul Jones]

This is just a short note about another improvement. I never really liked the crudely made pressed aluminum spring cups that are factory installed on the Unimat SL lathes. I replaced these with a new set machined from 1018 Cold Rolled Steel. This was just a cosmetic improvement but long overdue considering I bought this lathe new in 1970. The machining was performed on my 12" swing lathe because it is faster but the 3" swing Unimat has the capacity to do this machining.

[DIYer]

Thanks Paul! We've added your Unimat Headstock Spring Cups to our Lathes category, as well as to your builder page: Paul Jones' Homemade Tools. Your receipt:

Unimat Headstock Spring Cups by Paul Jones

tags: lathe, modification

[Mr.Pete]

these are real nice and I bet they will out live us all...

[Mr.Pete]

Oh my god! I never taught about doing all this on mine when I bought it, but it's the only way to do precise work...
Thanks for all the pictures and the great info.
p.s I was thinking of adding a 4x4 extruded aluminium posts to hold my lathe head to middle of my sb200 ... I liked your idea but the cost of buying a other unimat is a little steep around here it took about 6yrs to find one ( I paid $300 and it came full loaded with lots of extras) I'm watching EBAY for a head stock & motor there are a few but most are incomplet or really in bad shape... Iwas going t swap the head stock lathe to milling then back ... the setup is oh so l o n g... did any one try drilling the zero to a more precise dia and putting a tighter fitting dowel pin!

[Mr.Pete]

Oh my god! I never taught about doing all this on mine when I bought it, but it's the only way to do precise work...
Thanks for all the pictures and the great info.
p.s I was thinking of adding a 4x4 extruded aluminium posts to hold my lathe head to middle of my sb200 ... I liked your idea but the cost of buying a other unimat is a little steep around here it took about 6yrs to find one ( I paid $300 and it came full loaded with lots of extras) I'm watching EBAY for a head stock & motor there are a few but most are incomplet or really in bad shape... Iwas going t swap the head stock lathe to milling then back ... the setup is oh so l o n g... did any one try drilling the zero to a more precise dia and putting a tighter fitting dowel pin!

[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).

[C-Bag]

Thanks for compiling everything in one place Paul. Most of this was posted before I found this place. Your improvements have singlehandedly changed my opinion of the Unimat. I know there are a lot of fans of the machine but I thought it a toy. The stuff you are making on it and with amazing precision boggles. My neighbor down the street has one and he thinks of it as a toy. I'm going to give the link to this thread and see if he thinks that after he takes a look.