Halloween Forum banner

1 - 20 of 42 Posts

·
Registered
Joined
·
508 Posts
Discussion Starter #1
Hey guys-
I need 3 low RPM motors. I'm looking for something in the range of 3-8rpm if possible. Any faster won't work. I need one of the motors with a decent amount of torque (to run an axworthy rig)- the others not as much. The other 2, to give an example, are replacing reindeer motors which don't have ENOUGH torque (they reverse direction when they hit too much torque). Times short, I don't have time for these set backs. Any suggestions on where to get there?
Thanks
 

·
The Evil Apparitionist
Joined
·
555 Posts
Just a suggestion:

After having many low RPM AC gear motors bite the dust over the years, I now use wiper motors with PWM DC speed controls. Wiper motors are plentiful, inexpensive and have great torque. With a 5 amp PWM speed control you are only looking around $35 per setup. You can then dial-in the exact speed you require without loosing any torque.
 

·
The Evil Apparitionist
Joined
·
555 Posts
Found this-
Harbor Freight Tools - Quality Tools at the Lowest Prices

But am being told that they lower the torque... so if I need, say, 6rpm- if the math is the same, I'd only be getting about 10% of the motor's torque by dropping the speed down to that.
Yes, you'll loose the torque with that one, it's made for a high speed motor (router) where torque is not critical.

PWM (Pulse Width Modulation) type speed controls allow speed control without sacrificing torque basically by pulsing the motor on/off very quickly.

Better to get one like this:

http://cgi.ebay.com/DC-Motor-Speed-Control-HHO-PWM-12V-24V-15A-Max_W0QQitemZ130259397550QQcmdZViewItem?hash=item130259397550&_trkparms=72%3A1205|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14

Put it in a a plastic project box (Radio Shack), wire it up to a 12 volt power source (old PC power supply or wall wart) and go.
I generally use 12 volt 1 to 2 amp wall warts for mine.
 

·
Registered
Joined
·
15 Posts
so:
$20 for a device to reduce speed and maintain torque
and
about $20 for a cheep motor..

I think that defeats the goal of a cheap, low rpm motor..

I can get a motor from McMaster-Carr
McMaster-Carr
for about $45...
 

·
Registered
Joined
·
13 Posts
Yeah...but then you don't have infinite control. Remember 0-100% with the PWM. Maybe next year you'll want to use the same motor...only a little faster.
 

·
The Evil Apparitionist
Joined
·
555 Posts
That will work. I found some on ebay last year around $12 and got several wiper motors (made for Saturn cars) for $10 each at a surplus store.

I've used AC gearmotors in the past and they are ok but I now prefer to use low voltage on props (rain, 110 VAC and TOTs don't mix well). It is nice to be able to swap out motors and change the speed as needed to fit the effect.
 

·
Funeral Crasher
Joined
·
7,435 Posts
Yeah Dave- I saw that last night. However, how do you mount anything to that shaft?
First make your crank out of metal stock (or whatever you normally use) and drill a 1/4 inch hole in it.. Take a half inch long, 1/4 inch diameter, 20 thread bolt. Use pliers to hold the shaft from turning and use a screwdriver to screw the 1/4 inch bolt into the hole in the shaft. Try to screw it as straight as possible, since you will basically be "tapping" the plastic hole.
I then wire the motor's polarity to have it run counterclockwise to help keep the 1/4 in. bolt tight as it turns the shaft.
I haven't had one come loose yet. I just received 4 more of those motors from Electronic Goldmine.
 

·
Registered
Joined
·
508 Posts
Discussion Starter #18
yeah, those mirror/disco ball motors just don't have the torque to do what I need them to do. However, I am VERY curious about the other 2 motors. The one with the pulley attached really peaks my interest. I might pick up a few of each or something...
 
1 - 20 of 42 Posts
Top