Rotor Bedding Machine Motor?

Thread Starter

JtheB

Joined Mar 16, 2021
5
Hey ya'll,

I've managed to make a bicycle disc brake rotor bed-in machine out of an old treadmill.
It's essentially the front half of the treadmill with the drive roller made of lathed wood about 5" in diameter.
It uses the original treadmill motor and control board, but I only use one of the speed settings (9/10) so there is no need for anything else on the control board.
It's been very successful but it's time to make more machines and I'd like to design it with improvements and without having to find old treadmills.
I'm only loosely self-educated on motors and respective components. ;)
The machine runs on 120 VAC

Goals:
1) On/Off power via a single switch
2) Motor runs at a predetermined speed (preferred motor speed is 4600 rpm, with final drive on the wooden roller @ 1785 rpm)
3) Increase the torque to 3-4 HP at the above rpm. Regardless of the incorporated flywheel on the current motor applying the disc brakes slows the motor more than desired.
4) Reduce maintenance - brushes are a liability since the motor runs for 3 minutes approx 100x/day

Current Motor:
PMDC
2.75 HP @ 130 VDC
2.0 HP Cont Duty @ 100 VDC


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Question #1:

What type of motor would be best suited for the desired goals?

AC? PMDC? BLDC?
If I go BLDC would something made for converting bicycles work?
Amazon-Brushless-Electric-Controller-Motorcycle

  • These motors seem pretty small in size so I'd worry a bit about heat management running at almost max rpm...
  • I'd also be concerned about the 12mm OD drive-side spindle constantly bearing load from the poly-v belt tension.
  • I also don't need all the other controls wired into the control box... what components are needed to simplify to single power switch and pre-set rpm?
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Question #2:

The follow-up to Question #1 is what components and rated specs would be required to run the given motor at the desired rpm with a single switch powered via 120 VAC?
Essentially, what needs to go between the wall outlet and the motor?

If I continued to run the current PMDC motor and wanted to eliminate the treadmill control board would a component like this be the simplest way to go?
(as stated the variable speed isn't necessary but tolerable in this instance...)
ebay.120-VAC-To-DC-Motor-Speed-Controller

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Thank you for your time and consideration.

J
 

MaxHeadRoom

Joined Jul 18, 2013
22,814
The last controller you show appears to be one of the SCR/TRiac style, not good if you want smooth control and constant rpm's.
The BLDC motor is around the same HP as T.M. motors, which go up to around 3.5hp.
1785rpm should be within the range of a T.M. motor, I prefer removing the flywheel for most applications where quick response is needed.
You will always get variable response with variable load on a motor without some kind of feedback system.
Max.
 

Thread Starter

JtheB

Joined Mar 16, 2021
5
Thank you for that Max.
Flywheel removal noted.

So say I go with the BLDC motor... 60v or 72v...
What I'm gathering is that to run the motor off a 120vac outlet I'd need a half-wave rectifier with capacitor or a full wave bridge rectifier, yes? And it would need to have at least the amp rating of the BLDC?
 

MaxHeadRoom

Joined Jul 18, 2013
22,814
No half wave rectifier, just full wave rectifier with capacitor, 15amp to 20amp supply for the DC motor shown.
The AC supply voltage would be 0.7 x required motor DC voltage, current capacity dependent on motor F.L.Amps.
The only advantage to the BLDC is no brushes and generally a much smaller foot print.
If you desire some accurate RPM control, it would involve some kind of feedback system and drive.


.
 

Thread Starter

JtheB

Joined Mar 16, 2021
5
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