Best way to cool CIM motors?

[John Retkowski]

It may not be applicable or the best solution to your problem this late in the season, but our team used a different motor/gearbox for our winch. We took the planetary gear box out of a drill and hooked it to a banebot 775 motor. This allows us easy lifting with no back driving or stalling.

[MrRoboSteve]

Depleted uranium tie wrapped to the frame of the robot.




Whoops, wrong thread.

If you need more lifting than surgical tubing, lengths of bungee cord also work.

[rainbowbear998]

Originally Posted by John Retkowski

It may not be applicable or the best solution to your problem this late in the season, but our team used a different motor/gearbox for our winch. We took the planetary gear box out of a drill and hooked it to a banebot 775 motor. This allows us easy lifting with no back driving or stalling.

Time isn't really an issue for us, as we are now refining our robot for our next event, which is an off season event in June. Unfortunately here in Australia we aren't as spoilt for choice with regionals as in the US!!

It seems that having a worm or planetary gearbox is the best option to stop the motors heating up at the moment. I have one question though - will they perform ok with a few kilos of weight on them?

[theCADguy]

Originally Posted by rainbowbear998

It seems that having a worm or planetary gearbox is the best option to stop the motors heating up at the moment. I have one question though - will they perform ok with a few kilos of weight on them?

We designed part of our lifter gearbox with VEXPro versaplanetary gearboxes. However, I would check your load requirement against this document before purchasing one:

http://content.vexrobotics.com/vexpr...s-20150106.pdf

Watch out if you are planning on using a very low reduction with a CIM or a MiniCIM

[John Retkowski]

Depending on how much you want to lift you may need a stronger motor. We can reliably lift five totes without a can. If one wanted to lift heavier weights, adjustments would probably have to be made. As for performance. We did have a problem with the motor breaking. But we found that it was caused by our top limit switch malfunctioning. This caused the winch to constantly stall against the top of our elevator, which ruined the motor. Other than that the assembly has performed spectacularly.

[MrRoboSteve]

You could also make a winch:

[Ether]

Originally Posted by Dale(294engr]

144 / ~.1ohm 14.4 watts

1440 watts.

[Ozuru]

Not too long ago there was a thread talking about dry ice and its legality. Maybe that might work well

[asid61]

Originally Posted by theCADguy

We designed part of our lifter gearbox with VEXPro versaplanetary gearboxes. However, I would check your load requirement against this document before purchasing one:

http://content.vexrobotics.com/vexpr...s-20150106.pdf

Watch out if you are planning on using a very low reduction with a CIM or a MiniCIM

Only if you plan on using all of that load. We have a pretty fast elevator (1-2ft/sec) and we haven't run into load problems yet in the versaplanetary.

[rainbowbear998]

Originally Posted by MrRoboSteve

You could also make a winch:

Attachment 18662

I love that idea! How hard was that to manufacture? How reliable is it?

[Tim Lehmann4967]

Last year we cooled our CIM motors and Compressor with server rack blowers. They were considered legal, and worked amazingly well. You can put the KOP heatsinks on them for further cooling.

[rich2202]

Did you check the jumpers on your motor controllers? There is a jumper that lets the CIM freewheel (coast) or brake. Make sure you have the Motor Controllers in Brake mode. That will apply some counterforce, without having to power the motor. On our robot, brake mode is enough to keep the totes from dropping.

[JamesCH95]

Two CIMs should not be heating up during a match unless they are being very over-worked. Gear your mechanism more effectively to solve your real problem, don't address the symptom of over-heating motors.

Our 'totem' can support between 2 and 8 totes, plus the tote-grabbing bars, with a single stalled RS550 motor with no ill effects after two district events and lots of practice. We are using a 64:1 reduction with a 0.88in diameter spool to wind up cable.

[MrRoboSteve]

Originally Posted by rainbowbear998

I love that idea! How hard was that to manufacture? How reliable is it?

It's built from:

AM-0145 Toughbox
AM-0396 long hex output shaft, cut down a bit
2 - AM-0069a 500 Hex hub, modded with set screws. One hub is also modded with teeth
2" of aluminum tube - 1.75" OD
Mini Cim
HS-422 servo
#10 threaded rod
3/4" x 1/2" aluminum bar as spacer for dog (has F <-> B in photo)
3/4" x .125" aluminum bar for dog
.090 servo support plate (sits between bar and the gearbox, holds the servo in position)
small qty of .090 polycarbonate to make dog actuator for servo
2 longer bolts (I think they're 1/4x20) for fastening spacer bar and plate to gearbox
#10 machine screw with washer for pivot. The spacer is tapped to accept the screw and there's one washer on the other side.
spring (random hardware store spring)
smaller machine screws (#6?) to fasten servo to servo support plate

It's probably 3-4 hours of work all together.

One key to longevity is to keep the dog from riding on the modded hex hub when the winch is operating. When we operate the winch in the lowering mode, we slightly raise it first before actuating the servo, so that the dog does not bind.

The only concern we have is that the winch is supported on only one side. We're bringing another gearbox plate and necessary hardware to make a support for the other side if that turns out to be a problem.

[Ether]

Originally Posted by JamesCH95

Gear your mechanism more effectively to solve your real problem, don't address the symptom of over-heating motors

@OP: If you're willing, please tell us about your gearing. How many motor turns does it take to raise the boxes 1 foot?