Gear motor speed reduction

[fred cunningham]

I have a gear motor purchased from Amazon. CHANCS 60KTYZ AC Synchronous Syn Motor 110V 60/72RPM CW/CCW 14W Low Noise Electric Motor

https://www.amazon.com/gp/product/B07FKLNSFG/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

I have a speed controller. Yescom Variable Fan/Router Speed Controller 3 Settings Hydroponics Inline Fan Exhaust Air 500W to 1800W Adjuster

https://www.amazon.com/gp/product/B00U3LD1WA/ref=ppx_yo_dt_b_asin_image_o09_s01?ie=UTF8&psc=1

The gear motor normal speed is rated 60 to 70 rpm's. The speed controller does not reduce the speed. I need to get the speed down to 10 to 20 rpm's or at least lower than 60 rpm's.

You assistance will be appreciated.

 

[BrianPetersen]

To be blunt ... Your speed controller is too cheap to be good. It is not a "variable frequency drive". (Too cheap to be.) It might be an autotransformer with multiple taps (which will change the output voltage - but not its frequency). It might be something akin to a dimmer switch, i.e. a chopper. Still doesn't change the frequency.

The motor claims to be a "synchronous" motor - in my world, that's a permanent-magnet motor (in the world of cheap made-in-China, who knows). If it really is a "synchronous" motor then it is incapable of operating at any speed other than locked to line frequency. If the voltage supply is reduced to the extent that the motor no longer has enough power to maintain that speed, it will simply stall (and probably heat up and blow the fuse - or set fire to something).

The hardware that you've got is incapable of doing what you are asking it to do.

A wound-rotor "universal" motor, with brushes, might work in that application. Or it might not. You're dealing with stuff that is too cheap to be good, which is a close relative of too good to be true.

 

[waross]

Your best bet is a pulley and a rubber band. Really.
Brian, when you get that small, there are single phase synchronous motors with salient poles on the rotor.
They will "Cog" at synchronous frequency.
Mostly clocks and timers. 14 Watts may be near the top of the size range.

The hardware that you've got is incapable of doing what you are asking it to do.

Right on. All good points.
Wrong application for that motor.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[fred cunningham]

You are correct, cheap stuff. I am working on a prototype and did not want to spend a bunch. What would you recommend so I can adjust the speed?
Different motor? A different type of speed controller (Obviously). Since the motor is in-place, I would like to keep it--it rotates when you give it the juice and that is what it is supposed to do. I understand that a VFD is the usual method to control the speed of an AC motor. If that is the method of resolution, would any of you guys have such a device that would work under these circumstances? If so, please advise regarding type and price. If not, would you recommend a VDF that I could get elsewhere?
Thanks
Fred

 

[itsmoked]

I'd recommend this:

I'd recommend this VFD.

You stick in 120V single phase, wall-outlet stuff, and hook it to a 1/4hp three-phase 240V motor.

Budget motor that VFD will run happily.

Here's that motor's spec. Nice to mount, quality motor
Dang, maybe I should buy it...

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Keith,
Thinking out of the box:
The motor is only 14 Watts.
What about a signal generator feeding 35 Hz an audio amp with a 70 Volt line out?
Are there any amps around that will work down to 20 Hz to 35 Hz?
Is roll your own feasible?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Hi Bill; That would probably work fine but would take some trial and error that might include a toasted amp. Many amps have safeties that could be upset by a motor's low impedance.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

You could use the volume control to get the proper V/Hz ratio, maybe.
Get that motor into saturation and the amp may smoke quickly.
Fred: V/Hz ratio;
That motor wants a Volts per Hertz ratio of 120 Volts / 60 Hz or 2 Volts per hertz. It is important not to go over this ratio.
At 30 Hz you don't want to feed the motor more than 60 Volts RMS. 30 Hz x 2 = 60 Volts.
These small synchronous motors are basically a shaded pole motor with salient poles.
The shaded pole provides starting torque and direction. The salient poles cog instead of slipping.
There are a couple of designs.
One has small soft iron disks inserted in the rotor. It starts as a shaded pole motor and then when it is close to synchronous speed the iron disks start to cog.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

From the speed controller:

Please only use it with FANS that have a universal brush type motor.

So in reality, for cheap test bench porpoises, that was not the right kind of motor. Find a "universal" motor, the type found on hand power drills, routers etc. In fact if you are just testing a concept, just go buy a small cheap variable speed power drill!


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[fred cunningham]

You are right, I chose the wrong motor/controller for this project. After reviewing your comments, it seems the cost and complexity of AC does not warrant the effort with only hopeful results. I am now considering DC instead of AC. I understand that the speed of a 12V DC gear motor could be controlled in a more simple manner (voltage). I only need about 5 ft-lbs of torque. I would need:

1. A power supply which I think I have being one of those many plug in types, hanging around the house, that are used for so many devices.

2. Speed Controller:

https://www.amazon.com/Bringsmart-C...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

or possibly use the one I already have:

https://www.amazon.com/Power-Speed-...dc+with+7mm+shaft&qid=1573524305&sr=8-2-fkmr2

3. Motor:

https://www.amazon.com/Nextrox-Mini...7&pf_rd_r=RJ0QKY86FQHJX65T8HC6&qid=1573524950

Am I getting closer or farther away?