Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Fred_evans on May 30, 2019, 09:57:55 AM
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hello chaps,
I can pick up (very cheap ) redundant tread mill motors from a gymnasium
repair shop. has anyone any experience with these or drive motors on a
spindle or similar service?
regards fred evans
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Hi,
my understanding is that they are brushed DC motors and quite useful.
You will need a robust DC controller.....in the US the 'KB' brand is well known and respected. Don't be tempted to by cheap
rubbish, it wont last.
Craig
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Hello Craig,
thanks for the input- I will speak to my electrician about the setup
Would I need a special controller? what about the the controller that
comes with the treadmill?
regards to the Kiwi's from a Springbok- thanks for the support when
we play the aussies!!
fred (I am in Johannesburg)
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Hi,
Would I need a special controller? what about the the controller that
comes with the treadmill?
I don't know what the controller inside a treadmill is.
When a motor, of any description, is used as a spindle it comes under stress due to sharp and sudden variations in speed
which are related to cutting and accel/deccel. High accelerations means high currents. Where many controllers fall down
is when the motor overruns and starts generating back into the controller, its a fact of physics and can't be avoided.
The KB controllers I have seen are off-line phase controlled bridges and are pretty robust.
That's not to say that rectifier/DC link/Buck regulator designs cannot do the job, but rather the design needs to be good
to match off-line phase controlled bridges. A well designed and built rectifier/DC link/Buck regulator controller is likely
to be as expensive as a KB unit.
Craig
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I recently replaced my sieg lathe motor and controller with a 2.5 HP treadmill motor and the mc60 controller that was in the treadmill. This allowed me to remove the h-low gearing. Used a 2:1 timing belt to achieve the low end torque I wanted. Really like the result.
HTH
RT
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Plan to use mine also on one of my cnc machines...maybe the small lathe....maybe my bandsaw.
Friend uses one on his bandsaw and works great, just be carefull since the motor has a high rpm capability.
In the above comments the original controller from the thread mill will be used. Just put the controller into
a metal enclosure and " change out" the speed control ( just a variable resistor ).
FWIW,
If I find another one cheap will certainly buy it. Just need to get my lazy butt going ......... ;)
RICH
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I used the treadmill's speed control and wired it to a toggle so that it could be used both manually and through the gecko g540. Nice for CSS with mach4
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I will contact the person who has these motors and get more detail which I will then post for further comment many thanks everyone - but please carry on
regards
fred
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Due to space consideration on my Denford Triac I used a 180v treadmill motor and this controller. It worked perfect, didn't bother to run it through Mach, just used 240v household socket to the variable controller for speed and on/off control. One day might try and run through Mach 3 software.
https://www.ebay.co.uk/itm/Rotary-Knob-Adjustable-Motor-Speed-Controller-AC-220V-Input-DC-180V-Output/362279749427?epid=1038693158&hash=item54598e4733:g:GVQAAOSw~29b1pHC
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If you use one of these motors with something like a KBE controller or one like Jim linked to, BEWARE if you want to link it to Mach 3 to control the speed! This is because the 0 - 10 V speed control input is NOT isolated from AC mains. You would have some sort of smoothing circuit that takes the PWM output and derives a suitable variable voltage, relative to the 0 V rail on the BoB. If you then connect that to the "0 V" on the speed controller, there will be a "loud brown smell" and at least the controller and maybe the BoB and/or your PC will be fried. You need to have an opto-isolator that can transfer the PWM signal to the speed controller without any galvanic connection, then do the smoothing on the speed controller side. You can buy isolators from somewhere, but there are also simple a cheap circuits around to build. I published one which you can find in this thread in the Model Engineer forum:
https://www.model-engineer.co.uk/forums/postings.asp?th=114432&p=1
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thanks john- i will submit this info to the chap who is doing the installation and he must sort it out--
Ny knowledge of electronics is nil
regards
fred