AC Small Motor Speed Control

[bassnut]

This should be easy for you guys.
I have a small Coweco coil winding machine powered by a 1/10 HP Bodine AC motor. I bought this machine used (vintage '67) and its speed control pot had been removed. I bought a simple foot pedal speed control from McMaster-Carr which works quite well but I'd rather mount the speed control back on the machine panel and run it "foot" free.
What kind of potentiometer should I buy and where can I get it? The foot controller has this little sealed long throw button do-hicky inside rated at 6 amps 125V called a "bi-rstor" with terminals for line and load.
Thanks in advance.

Fred

 

[OperaHouse]

Sounds like a sewing machine motor. Is it rated AC-DC? These motors typically have a whine to them from the brushes. Your foot control sounds like just a series resistor. Suggest you get a meter and measure the resistance at the slowest point you want to operate at. You can extimate this by the published resistance for the foot control and figure a percentage. You will need a wire wound variable resistor that is probably 100 watt.

 

[jbartos]

Suggestion: Try to obtain documentation from the manufacturer or contact the manufacturer tech support for the part and modification support.

 

[bassnut]

LOL.
Yes. Very much like a sewing machine! Kinda sounds like one too.
Coweco went out of business years ago. I found a wiring schematic that shows a 1 meg. variable resistor. The foot pedal mfg has very little data. They just specified it as a fractional HP speed controler.
All I can say:
1/10 HP AC motor
single phase
6 amp speed control foot pedal with source voltage running through it. (works well)
Schematic shows 1 meg variable resistor used originaly.

I was hoping this would be simple. I'm looking in my Mouser catalog and wire wound pots have power ratings in watts @ deg C....what's that in voltage?
I guess I'll be needing a single turn, wire wound pot. Conductive plastic?

Here's another thing (bare with me this is not my field of expertise) The schematic also shows a speed controller unit with 6 terminals and wires attached going every which-a-way. One is going to the pot and one returning from it back to the controller. I get the feeling that all of this has been bypassed and the foot controller is feeding power straight to the motor. I could be wrong...
Looking at the unit itself I don't think I see a speed controller. There is a a relay unit with switches and a coil then a terminal strip with more wiring I don't understand. A few resistors and a couple of capacitors but not much else in the way of "controllers".
Thanks to anybody who is still reading this.
I really need to get this thing sorted out because there is also an auto shut-off (mechanical switch) after a specified # or revs, that's not getting it's message across to the relay. This is a different problem all together. I don't even have a clue where to take it to get fixed if I can't get it sorted out here.
Maybe a sewing machine repair shop?
Thanks again for your help and patience.

Fred.

 

[OperaHouse]

You definitely had a speed controller in there. The one meg pot would only work with some additional electronics. In your particular situation, I would look for a product called a router speed control that some wood working shops carry. I think just saw one at Harbor Freight for $16. These are small and you could easily open it up and install it in your machine. This all assumes the motor has brushes. Other DC motor speed contrommers should work, but you can't beat that price. I assume you are in the US if you bought from McMaster.

 

[bassnut]

BINGO!
Thanks Operahouse.
I just saw it on the Harbor Freight web catalog.
That looks perfect!
Have a wonderful holiday.

Fred.

 

[jbartos]

Suggestion: Is the 1/10HP AC/DC brush type motor?
The above referenced "Router Speed Control" is for AC/DC brush type motor. Visit

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43060

for the "Router Speed Control" limitation.
It may be a good idea to bring the schematic to an electronic technician or engineer to review it before anything is purchased.

 

[bassnut]

Thanks for the suggestion.
Yes, the motor is an old AC, 1.5 amp, 10K RPM Bodine Electric Co. brush type motor. If this foot controller I bought works, then the router speed controller should work. Right? Hope so. For less than $20 it's worth a try. I'd like to remove the innards and mount them to the machine chasis with the pot where the old one was supposed to be. I may have somebody review the schematic before I try anything in though.
Thanks again.

Fred.

 

[jbartos]

Suggestion: Visit and contact

http://www.bodine-electric.com/

tech support

 

[bassnut]

I got the router speed controller. It works great!
Thanks very much.


Fred.