Even though the AC gearmotor works great I started thinking about that DC gearmotor I found at American Science and Surplus and wondered if I could make it work for this application.
http://www.sciplus.com/p/CAR-SEAT-312VDC-GEAR-MOTOR_49248
MOTOR, 12VDC GEAR W/R.A. WORM DRIVE, 190RPM (BP) $14.75 plus 5.95 S&H ( $20.70 total )
I knew that it's original purpose was to move car seats back and forth so even though I didn't have a torque rating for it I knew that it must be pretty stout to move a car seat with your average adult american sitting in it. The 190 RPM speed would be a improvement as well.
The other pieces of hardware needed would be a DC motor controller board of some kind, mounting bracket, wires, spade connectors, another Lovejoy coupler and a 12V power supply.
Rooting around in my junk box I found a 3.3A 12V power supply, similar ones on Amazon sell for around $10. The motor is rated to stall at 25A so I was a liitle concerned that 3.3A would not be enough power but I can now report that this is plenty, more on this later.
If you don't have one laying around here's a 6A 12V power supply from Amazon...
http://www.amazon.com/dp/B003TUMDWG/?tag=skimlinks_replacement-20
6a Adapter Power Supply for LCD Monitor with Power Cord ($6.60 plus ? S&H )
Since this is a reversible motor I knew I needed a motor controller that could switch polarity, on Amazon I found this DC motor controller...
http://www.amazon.com/dp/B00EQ1UQXU/?tag=skimlinks_replacement-20
Generic Reversible 6V-30V 6A Pulse Width PWM DC Motor Speed Controller Governor $10.69 w/free shipping ( from China, took less than 9 days to get here. )
This controller is rated for 12V 10A max which seems to be plenty. It comes with a forward/off/reverse switch and a speed control pot, nifty!
Once I had all the parts in hand the first thing I did was make all the electrical connections and verify that everything worked. The power connector on the motor is/was some kind of unique plug design, the kind that you'll never find the correct corresponding wire harness to fit it. The work around on that was to carefully cut away the outer shell of the connector which exposed 2 standard sized spade connectors.
All wired up everything worked as advertised.
Next, as a safety precaution, I decided to put the motor controller board in an enclosure, anything bigger than the board itself would work fine. I found a clear plastic box that an Ipod had come in that was just about perfect, a little whittling and a couple of zip-ties later and it's good to go. Since the box is clear I get to see the LEDs light up and look at the components, cheap thrills.
For the purpose of setup I mounted the motor to a scrap board using a Stanley L-bracket I had laying around, I think it was about a 2.5" or maybe 3" bracket. I had to drill a new mounting hole in the bracket to raise the motor up a little, I then cut off the unused portion of the top part of the bracket just for looks.
Next I took an angle grinder and cut off all but about 1.5 inches of the shaft. I placed another scrap board under the shaft while cutting to keep unnecessary pressure off the shaft.
The closest size Lovejoy coupler was an L050 with a .438" bore, to make it fit I had to file down the shaft. To do this, with the motor still connected to the scrap board and clamped down on the workbench, I turned the motor on and used the motor itself as a lathe.
As I was milling away the excess shaft material it was necessary for me to bear down pretty hard with the file and I can report that at no point did the motor act like it was going to stall. The motor did get a little warm but only after I had spent like 10 minutes bearing down on the shaft; this tells me that I have more that enough torque and that 3.3A should be plenty of power.
Here's a photo of the DC motor next to the AC motor, at this point I don't plan on changing motors but I'm pretty confident that the DC motor setup would work fine if I did.
I put around $40 into this experiment and had at least twice that dollar amount of fun playing with it.
http://www.sciplus.com/p/CAR-SEAT-312VDC-GEAR-MOTOR_49248
MOTOR, 12VDC GEAR W/R.A. WORM DRIVE, 190RPM (BP) $14.75 plus 5.95 S&H ( $20.70 total )
I knew that it's original purpose was to move car seats back and forth so even though I didn't have a torque rating for it I knew that it must be pretty stout to move a car seat with your average adult american sitting in it. The 190 RPM speed would be a improvement as well.
The other pieces of hardware needed would be a DC motor controller board of some kind, mounting bracket, wires, spade connectors, another Lovejoy coupler and a 12V power supply.
Rooting around in my junk box I found a 3.3A 12V power supply, similar ones on Amazon sell for around $10. The motor is rated to stall at 25A so I was a liitle concerned that 3.3A would not be enough power but I can now report that this is plenty, more on this later.
If you don't have one laying around here's a 6A 12V power supply from Amazon...
http://www.amazon.com/dp/B003TUMDWG/?tag=skimlinks_replacement-20
6a Adapter Power Supply for LCD Monitor with Power Cord ($6.60 plus ? S&H )
Since this is a reversible motor I knew I needed a motor controller that could switch polarity, on Amazon I found this DC motor controller...
http://www.amazon.com/dp/B00EQ1UQXU/?tag=skimlinks_replacement-20
Generic Reversible 6V-30V 6A Pulse Width PWM DC Motor Speed Controller Governor $10.69 w/free shipping ( from China, took less than 9 days to get here. )
This controller is rated for 12V 10A max which seems to be plenty. It comes with a forward/off/reverse switch and a speed control pot, nifty!
Once I had all the parts in hand the first thing I did was make all the electrical connections and verify that everything worked. The power connector on the motor is/was some kind of unique plug design, the kind that you'll never find the correct corresponding wire harness to fit it. The work around on that was to carefully cut away the outer shell of the connector which exposed 2 standard sized spade connectors.
All wired up everything worked as advertised.
Next, as a safety precaution, I decided to put the motor controller board in an enclosure, anything bigger than the board itself would work fine. I found a clear plastic box that an Ipod had come in that was just about perfect, a little whittling and a couple of zip-ties later and it's good to go. Since the box is clear I get to see the LEDs light up and look at the components, cheap thrills.
For the purpose of setup I mounted the motor to a scrap board using a Stanley L-bracket I had laying around, I think it was about a 2.5" or maybe 3" bracket. I had to drill a new mounting hole in the bracket to raise the motor up a little, I then cut off the unused portion of the top part of the bracket just for looks.
Next I took an angle grinder and cut off all but about 1.5 inches of the shaft. I placed another scrap board under the shaft while cutting to keep unnecessary pressure off the shaft.
The closest size Lovejoy coupler was an L050 with a .438" bore, to make it fit I had to file down the shaft. To do this, with the motor still connected to the scrap board and clamped down on the workbench, I turned the motor on and used the motor itself as a lathe.
As I was milling away the excess shaft material it was necessary for me to bear down pretty hard with the file and I can report that at no point did the motor act like it was going to stall. The motor did get a little warm but only after I had spent like 10 minutes bearing down on the shaft; this tells me that I have more that enough torque and that 3.3A should be plenty of power.
Here's a photo of the DC motor next to the AC motor, at this point I don't plan on changing motors but I'm pretty confident that the DC motor setup would work fine if I did.
I put around $40 into this experiment and had at least twice that dollar amount of fun playing with it.
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