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Thread: Unimat 3 spare motor?
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16th Sep 2015, 10:46 PM #1Product designer retired
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Unimat 3 spare motor?
Does anyone have a spare Unimat3 motor?
It's a bit of a hassle having to swap the motor around for lathe or milling operations.
Ken
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17th Sep 2015, 06:31 AM #2
Hi Ken,
Assuming that you still have the old motor and its not burnt out, its worth checking the brushes.
I've had a couple of motors, one that was actually burnt out and the other simply failure of the motor brushes. Very recently I had a motor failure where the motor got extremely hot very quickly in the end cap area. The failure wasn't unexpected because this is the second time the brushes have failed.
What seems to happen is the copper pigtail (shunt) looses the connection into the brush forcing the motor current to flow through the spring heating it up causing it to cease applying pressure to the brush which then starts to arc and rapidly burn up. A new pair of brushes will cure the failure ! That is until the replacements fail.
Here in the UK the machine dealers want an arm and both legs for a pair.
It would be nice to find a low cost supplier, the alternative is to make your own brushes, which while a bit messy is not too difficult at all.
HTHBest Regards:
Baron J.
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17th Sep 2015, 01:25 PM #3Product designer retired
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Unimat 3 motor
Hi BaronJ,
My existing motor is fine, I would just like another one for the milling attachment.
Does anyone know if the Taiwanese Unimat4 motor will bolt straight on? The price of the Unimat4 is about the same cost as a motor alone for the Unimat 3.
Ken
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18th Sep 2015, 05:56 AM #4
Hi Ken,
I assumed that you had obtained a second motor because the first had failed. It seems that brush failure is a very common reason that people purchase new motors.
I find it odd that although these things are made in China it is very hard to find replacements out of China particularly since the same motor is used in some brands of treadmill and second hand they seem to be difficult to find.
Unfortunately I can't help you with info about the Unimat machines.Best Regards:
Baron J.
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18th Sep 2015, 10:39 PM #5Cba
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Ken, the Austrian Emco Unimat motors are well made good quality brushed DC motors. Designed to last a lifetime, and they can be repaired and rebuilt. The problem with well made DC motors is that they are not cheap (good things never have been cheap). And that is the reason that these small Emco lathes used the same motor for lathe and milling attachment - to save the owners the expense of a second motor. It makes sense if one thinks that that lathe and milling attachment are never used simultaneously.
I am afraid, if you are after a second motor for reasons of convenice, it is going to be an expensive convenience. Old Unimat motors are sought after and hard to get.
There is a company in the UK that sells a new, not original, spare motor assembly. Its price is 235 ponds plus postage - almost as much as a Chinese motor including a complete minilathe costs. http://www.rejon.co.uk/emco_unimat_motor.php
Another UK company sells a new, not original variable speed motor assembly for the Unimat. Price is US$275, plus US$66 postage to Australia. http://www.ebay.co.uk/itm/330598702803
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19th Sep 2015, 01:38 PM #6Most Valued Member
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19th Sep 2015, 04:25 PM #7Product designer retired
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A new motor??
SurfinNev,
Would you like me to give you a hand looking for that motor? I could use a bit of sunshine.
Ken
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20th Sep 2015, 08:41 PM #8Product designer retired
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Unimat 3 motor
SurfinNev, did you manage to dig up that spare motor, please don't tell me you sold it.
Ken
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20th Sep 2015, 09:00 PM #9Most Valued Member
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1st Oct 2015, 12:55 AM #10Product designer retired
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Wack me if this is a dumb idea, but I was just thinking, would it be a practical to use a 23 nema stepper motor to drive my Unimat 3?
I'm sure it would have the strength, my only concern is the step vibration.
I have have some experience with Arduino's and stepper motor drivers.
What do the experts think?
Ken
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1st Oct 2015, 01:23 AM #11Most Valued Member
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Ken, what are the details of your motor please, as I have a small electric motor that is yours, if the details are similar. It's about the size of a sewing machine motor.
Kryn
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1st Oct 2015, 01:33 AM #12Product designer retired
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KB,
As far as I know, my Unimat motor is 90W, 240V 2 speed. It is way under powered and gets hot very quickly. Apparently it has a duty cycle of 60%
Physically it is 75 dia, 130 long. Can't measure the shaft dia at present.
Ken
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1st Oct 2015, 08:04 AM #13Mechanical Butcher
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The motor on both Unimat3 and 4 is mounted on a steel plate, attached to the head. Conversion should be straightforward.
The Asian motor is more powerful and has a continuous duty cycle.
Jordan
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1st Oct 2015, 08:49 AM #14Cba
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>> Wack me if this is a dumb idea, but I was just thinking, would it be a practical to use a 23 nema stepper motor to drive my Unimat 3?
>> I'm sure it would have the strength, my only concern is the step vibration.
Spindle drive from motor is via a thick O-ring, that would in theory help vibration transsmitted by the drive. But a step motor would still transmit huge vibrations via its mount. I believe the entire unimat lathe weighs less than 10kg (something like 7kg?), the motor being a large percentage of this weight. So there is not much mass in such a small watchmaker lathe to help dampen vibrations. With a step motor driving the spindle, you would be guaranteed to suffer from degraded surface finish quality due to vibations. Also, I know of not one single example of a lathe big or small that would use a stepper motor for its spindle drive - its just about the poorest motor choice one could think of.
Also, by memory the Unimat motor is rated 5000rpm, stepper motors are generally much lower speed so you would have to redesign the pulley diameters.
And using stepper motors at the top end of their rated speed means you have to operate them in full step mode. A typical step motor would then do about 1.8 degrees rotation per step - or about 200 steps per revolution. If you think about it, that is a very choppy form of rotation..... just as comparion, think a metal saw blade has about 100 teeth. Chris
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1st Oct 2015, 02:41 PM #15Most Valued Member
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Hi Ken,
The motor I have is about the same dimensions but a single speed 1500 RPM, 230 V, single phase, .5 amp, 50 HZ, 1/50 HP with a continuous duty rating. Manufactured by Bodine Electric Company type NSY - 13 No. NO343002 shaft diam 1/4"
If any use to you let me know. I was going to use it for a conversion on my POS mini mill to a small surface grinder, but don't think there is enough power to do the job.
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