Unimat DB/SL Replacement Motor
Best kept secret ?
As we all are aware, these machines are getting old. The original motors are wearing out, some beyond repair. The price for used motors on Ebay reflects this. Here again an old used motor.
Over the years, Unimat users have Emailed pix of their replacement motors. The range was from 1/2 HP 56 frame ( large ) AC motors to sewing machine motors. I say, that's great. This is a hobby machine and what ever works is fine.
For myself, I have modified about half dozen different motors, mostly Universal AC/ DC series wound. Like the original motors.
These high RPM motors ( 10,000 to 12,000 RPM ) were noisy and produce their torque at max speed, therefore any attempt to control ( reduce ) the motors speed is accompanied with a rapid decline in torque. I wanted something better.
About six years ago I modified a commercial PMDC ( permanent magnet DC ) motor to accept the original pulley and mount up to the motor bracket using the original holes / screws. To drive the motor a complementary SCR ( DC )speed control package was developed.
The results were not unlike the Sherline lathe or even the 7" X 12" ' mini lathe ' , motor / control packages.
The motor package in the picture above has been in use for six years ( the belt for nine years ).
The motor has ball bearings, long life brushes and rated for continuous duty. The SCR speed control produces almost pure DC
with form factor close to 1. Both are UL rated and made in the USA.
Speed control is mounted in aluminum box for heat dissipation has ON / OFF switch, internal replaceable fuse and four foot 120 volt AC cord / plug. Control box is mounted to motor.
On balance, the objective was to provide a smooth, quite, long life, variable speed motor. Which was comparable in weight and dimensions with the OEM motor. PMDC motors by their very design are heaver motors
PMDC motors have the opposite torque curve of Universal AC/DC motors ( original Unimat motors ).
With a PMDC motor, as load is applied the torque increases and can be three to four times rated torque as stall is approached. Making it a good choice for this application.
Here are more pix of motor / controller mounted and in use.
Motor package spec: Motor rated 1/9 HP. 90 VDC. Speed control is adjusted for no load output of 700 to 3300 RPM. The machine above uses one large drive belt from middle motor pulley to middle spindle pulley gives spindle speed of 280 to 1300 RPM. Other belt / pulley configurations can be used .
This is a plug and play package.Motor shaft has pulley stop pin installed, ready to accept your motor pulley. Included are motor mount screws and pulley mount screw with washer. Speed control is preadjusted. These are assembled in my work shop, to order.
Price is $350.00 USD plus S/H
If interested please contact me via email to check availabilty or lead time and shipping cost.
Keep in mind. This package is best suited for turining / drilling / milling for precision work, in keeping with the original intent of the Unimat.
Giving you variable speed control with smooth quite operation. Making your DB/Sl more fun and comfortable to use.
Please have a look at these other pages of interest on my Unimat web site:
DF 2009
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Doug;
The motor and controller came in today. Runs like a dream. Thanks for all your help.
Ross
Hello Doug...!! Just a short note to advise you UNIMAT motor/speed control unit arrived Mon. ... WOW that was FAST...!!
You have made me the UNIMAT KING of Kansas City....!! VERY NICE package you have come up with....OUTSTANDING....!!
Ollie
Motor Comments.
Hi Doug,
I received the Unimat replacement motor the workmanship and fit/finish look excellent, it'll be a great upgrade for my Unimat.
Thanks very much. Tom
( Tom bought two replacement motors, one for his lathe set-up and the other was a slightly smaller motor / controller package I made up for his mill set-up. Doug)
Doug,
I bought one of your replacement motors a few weeks ago. Runs like a dream.
Sean
