smoking drill motors?

[Cory]

Originally Posted by Al Skierkiewicz

Last year's rules required you to keep the supplied wire intact but I have not seen anything about it this year.

Are you sure Al? I know we desoldered the 16 gauge wires and replaced them with 10 gauge ones. I know a lot of other teams did as well. I find it hard to believe that inspectors would have overlooked this, as it is quite obvious.

Cory

[Joe Ross]

Originally Posted by Cory

Are you sure Al? I know we desoldered the 16 gauge wires and replaced them with 10 gauge ones. I know a lot of other teams did as well. I find it hard to believe that inspectors would have overlooked this, as it is quite obvious.

Initially, there was no rule against it, then there was an update that STRONGLY suggested not doing it. This year, as Al linked, they specifically tell you not to do it.

[Jay Lundy]

Last year in a match at nationals one of our wires desoldered itself from the drill motor. It didn't break off, you could actually see the hole where it used to be soldered. They were the original blue wires too. We never used a soldering iron on them at all. This was after several elimination matches in a row, so they got very hot even though we did our best to cool them down between matches.

They desoldered themselves again in the summer while we were demonstrating the robot to some people.

[Wetzel]

Originally Posted by Joe Ross

Initially, there was no rule against it, then there was an update that STRONGLY suggested not doing it. This year, as Al linked, they specifically tell you not to do it.

From Team Update 7 last year.

Cautionary Note About Skill-Bosch Drill motors!!!!!

DO NOT attempt to unsolder the wires that are attached to the Skill-Bosch motors. The plastic housing that holds the brush assemblies will be damaged if you do. The high temperature of the soldering process causes the plastic to deform and destroys the motor. Teams should make their electrical power connections to the motors’ pre-attached wires, not directly to the brush holders.

Regardless, letting out the magic smoke is always a bad thing. Most of the above posts have covered the various ways to do this.

Wetzel

[Joshua May]

My team just had this problem last night. We were driving the robot around for some testing, and about 3-4 minutes of driving it around on a cement area in the middle of our school, we noticed smoke from the motors. We checked it out and there was definitely smoke coming from the motors and a very strong smell of it. We have one large muffin fan mounted above each drill motor, although we noticed a large amount of escaped airflow, we thought this might be the problem, so today we are going to fabricate some air ducts. Does anyone else have any suggestions? We did not disassemble the motors and I do not believe there was any drilling on the chassis around the motors.

Also, we noticed that there was a lag with one wheel, so it skips three or four times at acceleration and then moves slower than the other wheel as we drive around. I know that the other wheel's gearbox is greased up, and this one's isn't. Does anyone know what else might cause this problem?

[Al Skierkiewicz]

This is very typical of some designs. You do not say what your configuraion is so I am going to assume four wheel tank or two wheel with non steering two front wheel. These types of drive systems use incredible amounts of current when turning. Again, if there is any friction in your drive train it will manifest itself as high current in the drill motors. Can you describe the drive train or include a picture?

[Joshua May]

Originally Posted by Al Skierkiewicz

This is very typical of some designs. You do not say what your configuraion is so I am going to assume four wheel tank or two wheel with non steering two front wheel. These types of drive systems use incredible amounts of current when turning. Again, if there is any friction in your drive train it will manifest itself as high current in the drill motors. Can you describe the drive train or include a picture?

We have vertically mounted drill motors, connected to the kit's gearbox with a 2:1 gear ratio. The output axle of the gearbox runs to one of the kit's 12.5" pneumatic wheels. I will try to get a picture up soon, I have none with me at the moment.

Thanks for your help.

[jjv]

Originally Posted by HHSJosh

We have vertically mounted drill motors, connected to the kit's gearbox with a 2:1 gear ratio. The output axle of the gearbox runs to one of the kit's 12.5" pneumatic wheels. I will try to get a picture up soon, I have none with me at the moment.

Thanks for your help.

Do you have your gear boxes aligned so that when the bot is going forward, both motors are going in their forward direction? Or is one going forward and the other in reverse? If this is the case, that would explain the lag between the two wheels. These motors are more efficient when run in the forward direction, so if one runs opposite the other it will do so unevenly.

[Joshua May]

Originally Posted by jjv

Do you have your gear boxes aligned so that when the bot is going forward, both motors are going in their forward direction? Or is one going forward and the other in reverse? If this is the case, that would explain the lag between the two wheels. These motors are more efficient when run in the forward direction, so if one runs opposite the other it will do so unevenly.

I will make sure to check up on this when I get to the robot. We will check once more on the driving and then I will see about this, I hope it's not too hard of a fix...

[ECarlson]

Our 2001 drill motors would smoke quickly whenever we stalled them (like driving into a wall, and maintaining full power to the motors). The 2004 motors are different, but I suspect they would do the same.

[Al Skierkiewicz]

Originally Posted by Cory

Are you sure Al? I know we desoldered the 16 gauge wires and replaced them with 10 gauge ones. I know a lot of other teams did as well. I find it hard to believe that inspectors would have overlooked this, as it is quite obvious.

Cory

Cory et al.,
As others have already posted, FIRST has come out with a rule against replacing the wires on drill motors. Now don't get too excited about this rule, it is the same as last year. The wires, although smaller guage are very short, so the resistance is negligible and the wire has 200 C insulation, so there is no worry about melting or fire. There were significant quality control issues last year with the way the wires were soldered at the factory. You need to check that the solder job is done correctly. If you need to make repairs, I suggest you remove the brush assy. by gently lifting the retaing tang and slipping the brush assy. out of the motor. A magnifier might help here as the tang is very tiny. An additional suggestion if you must make a repair is to clean the original solder from the contact, pass the wire through the hole and crimp it back against itself. This make a firm mechanical connection prior to soldering. Heat the connection and flow in enough solder to make a good connection on both sides of the contact. Let cool and reassemble into the motor being careful to align the brush assy. in the slots and gently push until the retaining tang locks into place. If you choose to solder #10 wire to the end of the #16 then be sure to heatsink the #16 so that the heat will not unsolder the wire from the brush assy or cause heat damage to the plastic brush retainer.

[Bongle]

Last year, when I was testing my autonomous mode bin-hunting algorithm (servos + reflection sensors), there was still a bug in it. Whenever the robot didn't have a 'lock' on something in front of it (like a bin), it would go straight backwards. So, it had a lock on a bin, but then it lost it, and went from full forward to full reverse, and one of the motors started smoking. We ended up having to replace that motor, as it was never as strong as it used to be after that. I recommend you start talking to FIRST about getting yourself a new motor.

And then I never got a chance to test my (fixed) autonomous mode, we never were sure that it worked, so we never had an autonomous mode.