Posted by Gary Bonner at 1/29/2001 12:45 AM EST
Other on team #433, MINT, from Mount Saint Joseph Academy and Pew Foundation.
The drill motors have fans built into them, however, the intake ports are small and the air must flow though small channels between the motor and the gearbox housing. Has anyone ever tried putting holes in the side of the motor near the gearbox to allow more air to flow in and through the motor? Would this be legal? It seems to me that this might be a more efficient way to cool the motor, as opposed to using a muffin fan that just cools the outside. I haven’t looked at one recently, but I believe that the FP motors might be similar.
Posted by control guy at 1/29/2001 8:45 AM EST
Student on team #250 from HVCC.
In Reply to: Cooling Drill Motors
Posted by Gary Bonner on 1/29/2001 12:45 AM EST:
Can’t remember about the legality of this move, but if it is, just be careful you don’t hit the permanent magnet in the motor housing. That could seriously mess up a motor.
Posted by Nate Smith at 1/29/2001 10:31 AM EST
Other on team #66, GM Powertrain/Willow Run HS, from Eastern Michigan University and GM Powertrain.
In Reply to: Careful…
Posted by control guy on 1/29/2001 8:45 AM EST:
: Can’t remember about the legality of this move, but if it is, just be careful you don’t hit the permanent magnet in the motor housing. That could seriously mess up a motor.
Appendix A, page A-3:
M18. The motors in the kit may not be modified except as follows:
x It is acceptable to modify the mounting brackets and/or other structural parts of the motors (output shaft, housing, etc.) as long as the electrical system is not modified and the integral mechanical system of the moving parts (bearings, bushings, worm gear output stages, etc.) is not changed or removed.
Based on this, I’d say sure…but like was said, be careful…also, it might make it harder to get a replacement quickly at the competitions if needed…
Nate
Nate
Posted by Joe Johnson at 1/29/2001 2:10 PM EST
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
In Reply to: What the Rule Book Says…
Posted by Nate Smith on 1/29/2001 10:31 AM EST:
I would not recommend this idea.
There is surprisingly little metal to spare. Below the metal is magnet. If you remove the magnet you remove output.
Beyond this, it would be very difficult to keep the debri out of the brushes and such.
High risk, low payoff.
I wouldn’t play at that table if I were you.
Joe J.
Posted by JVN at 1/29/2001 3:24 PM EST
Student on team #250, GE Dynamos - Capital District Robotics Team, from Shenendehowa High School and General Electric.
In Reply to: Cooling Drill Motors
Posted by Gary Bonner on 1/29/2001 12:45 AM EST:
In a two minute match you shouldn’t be getting them THAT hot. If you do, you’ve got a serious
mechanical problem. The Muffin-Fan is pretty much useless.
We usually just let them get hot (not toooooo hot) and then cool them in between matches as
needed. Dr. Joe talked about cool in a can, that stuff works pretty well. Another trick we found
was to just hold a shop-vac on he motor. It should take about 3 minutes for em to almost fully cool
down.
You might consider putting another reduction on the outside of your gearbox. This would reduce
motorstrain and keep em from heatin up.
If your still blowing motors, the only thing i can suggest is to take it easy on the motors, your
transmission might be putting too much strain on em. Maybe limit the amount of voltage the
motors get? Dr. Joe is the drill-motor-man, what’s the best way to reduce strain on a motor,
without redesigning the drive system?
~John V-N
Posted by Al Skierkiewicz at 1/30/2001 8:44 AM EST
Engineer on team #111, Wildstang, from Wheeling High & Rolling Meadows High and Motorola.
In Reply to: Cooling Drill Motors
Posted by Gary Bonner on 1/29/2001 12:45 AM EST:
This has been an issue from the beginning of time. The motors are designed to run at a particular loaded RPM and the internal fans running at that speed should be enough to cool the motor. Unfortunately, we run them way under that speed and at higher loads that what they were designed for. If you are overheating motors, the first thing is to check gear ratios to see if you can increase motor RPM (motor curves are a big help here. A warning sign that gear ratios are off is resetting circuit breakers in motor speed controllers or blown fuses.) A change is software to reduce motor currents is also helpful. Let us not forget that a mounting assembly that draws heat away from the case is also a big help.
Finally, as a general rule, reworking the steel case on any motor that contains a magnet assembly is almost certain death to the motor. If the filings do not end up in the elctrical circuit, they will usually align with the magnet structure and be caught in the gap between the magnet and the armature.
Al
P.S. In past years, high motor currents were encountered in pushing matches with other bots, this year they will be encountered pulling a goal or stretcher up and over the ramp.
P.P.S. Some cool in a can contains freon which if directed at a bearing will wash out the lubricant. Use with caution.