how much is too much on the DRILL MOTORS?

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Posted by Anton Abaya at 1/30/2001 11:16 PM EST


Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! .



okay we have our drive train running and might i say it kicks butt... at low gear it has some speed, but at high, it pretty much shocked us all how much speed it gave!!! we ran it for several minutes and it seemed to work rather well...

other than say getting an amp meter, checking the heat of the motors, etc..etc... what's a good way to debug a drive train on high gear and see if there are any kinks in running it that high....?

and when we do run it that high, what exactly should i be watching other than the motors? the gearboxes with the planetary gears? the shafts? the chains? wheels? wires? speed controlers? wHAT? i'd rather break it now on high gear than later....but any recommendations in safely trying it?

i'll give our gear ratio if joe posts his... in any case, please help us (me) out in bug testing this baby....

-anton

ps. if we added wings to this, i bet we can make it fly.

[archiver]

Posted by Anton Abaya at 1/31/2001 12:04 AM EST


Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! .


In Reply to: how much is too much on the DRILL MOTORS?
Posted by Anton Abaya on 1/30/2001 11:16 PM EST:



: okay we have our drive train running and might i say it kicks butt... at low gear it has some speed, but at high, it pretty much shocked us all how much speed it gave!!! we ran it for several minutes and it seemed to work rather well...

: other than say getting an amp meter, checking the heat of the motors, etc..etc... what's a good way to debug a drive train on high gear and see if there are any kinks in running it that high....?

: and when we do run it that high, what exactly should i be watching other than the motors? the gearboxes with the planetary gears? the shafts? the chains? wheels? wires? speed controlers? wHAT? i'd rather break it now on high gear than later....but any recommendations in safely trying it?

: i'll give our gear ratio if joe posts his... in any case, please help us (me) out in bug testing this baby....

: -anton

: ps. if we added wings to this, i bet we can make it fly.

burning hot? or just touchable warmth? or like "it's too hot to touch" hot.?

-anton

[archiver]

Posted by Anton Abaya at 1/31/2001 1:25 AM EST


Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! .


In Reply to: as a 2nd question, HOW HOT is HOT?
Posted by Anton Abaya on 1/31/2001 12:04 AM EST:



: : okay we have our drive train running and might i say it kicks butt... at low gear it has some speed, but at high, it pretty much shocked us all how much speed it gave!!! we ran it for several minutes and it seemed to work rather well...

: : other than say getting an amp meter, checking the heat of the motors, etc..etc... what's a good way to debug a drive train on high gear and see if there are any kinks in running it that high....?

: : and when we do run it that high, what exactly should i be watching other than the motors? the gearboxes with the planetary gears? the shafts? the chains? wheels? wires? speed controlers? wHAT? i'd rather break it now on high gear than later....but any recommendations in safely trying it?

: : i'll give our gear ratio if joe posts his... in any case, please help us (me) out in bug testing this baby....

: : -anton

: : ps. if we added wings to this, i bet we can make it fly.

: burning hot? or just touchable warmth? or like "it's too hot to touch" hot.?

: -anton

[archiver]

Posted by Joe Johnson at 1/31/2001 12:56 PM EST


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.


In Reply to: as a 2nd question, HOW HOT is HOT?
Posted by Anton Abaya on 1/31/2001 12:04 AM EST:



I once heard HOT described as hot enough to boil spit.

For FIRST purposes, I have never had the outside of the motor case be that hot. It has been uncomfortable-to-touch hot but not one-touch-and-my-hand-is-burnt hot.

I revert to the smell test as the gold standard. If your motor smells like burnt motor windings, the motor got too hot.

Joe J.

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Posted by Ken Patton at 1/31/2001 7:42 PM EST


Engineer on team #65, The Huskie Brigade, from Pontiac Northern High School and GM Powertrain.


In Reply to: boiling spit...
Posted by Joe Johnson on 1/31/2001 12:56 PM EST:



Although we have never used the smell test, I totally agree with Joe's too hot to touch comments. This same sort of "test" has worked well for us.

However . . . tonight we saw a drill motor smoke under a stall condition (friction problem, btw), and it still appears to work fine. Has anyone ever seen that?

Ken

[archiver]

Posted by Joe Ross at 1/31/2001 7:46 PM EST


Engineer on team #330, Beach Bot, from Hope Chapel Academy and NASA/JPL , J&F Machine, and Raytheon.


In Reply to: agree
Posted by Ken Patton on 1/31/2001 7:42 PM EST:



: However . . . tonight we saw a drill motor smoke under a stall condition (friction problem, btw), and it still appears to work fine. Has anyone ever seen that?

We did just see something similar on last year's robot. We were pulling two goals up the bridge and saw a little smoke (I wasn't there but I heard about it). The next day the gearbox failed and we broke a chain. Are they related? I don't know, but watch that motor carefully.

[archiver]

Posted by Al Skierkiewicz at 2/1/2001 1:47 PM EST


Engineer on team #111, Wildstang, from Wheeling High & Rolling Meadows High and Motorola.


In Reply to: agree
Posted by Ken Patton on 1/31/2001 7:42 PM EST:



: However . . . tonight we saw a drill motor smoke under a stall condition (friction problem, btw), and it still appears to work fine. Has anyone ever seen that?

: Ken
If you saw smoke, replace. Your motor is dead already, it just doesn't know it. Murphy's first law ammended, If something can go wrong, it will...at the worst possible time. (finals match at Nationals)
Al

[archiver]

Posted by Joe Ross at 1/31/2001 3:13 AM EST


Engineer on team #330, Beach Bot, from Hope Chapel Academy and NASA/JPL , J&F Machine, and Raytheon.


In Reply to: how much is too much on the DRILL MOTORS?
Posted by Anton Abaya on 1/30/2001 11:16 PM EST:



: other than say getting an amp meter, checking the heat of the motors, etc..etc... what's a good way to debug a drive train on high gear and see if there are any kinks in running it that high....?

: and when we do run it that high, what exactly should i be watching other than the motors? the gearboxes with the planetary gears? the shafts? the chains? wheels? wires? speed controlers? wHAT? i'd rather break it now on high gear than later....but any recommendations in safely trying it?

the first thing you should do is fully weight the robot. If you don't plan to mess with the goals than make sure your base ways at least 130 lbs. If you plan on pulling or pushing goals, then add 70-80lbs per goal.

If your robot can handle its fully loaded weight at that gear ratio then you should start violent (real-life) manuvers. try running at full speed and then making a very sharp turn and holding that turn. reverse directions quickly etc.

Things to look for: the gearboxes should stay in one piece, along with the rest of your robot. you should not be tripping the 30 amp circuit breakers between the battery and the speed controllers. make sure you use common sense, if something seems like it may be a little weak in practice, it WILL fail in competition.

To answer your question below, the motors can get very hot. You should only be worried if you see the magic smoke or start to smell burnt something or other. The motors can take a very suprising amount of heat.

Good luck!

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Posted by Mark Garver at 1/31/2001 10:40 AM EST


Student on team #68, Truck Town Terror, from Waterford Kettering/OSMTech Academy and General Motors Truck Group.


In Reply to: how much is too much on the DRILL MOTORS?
Posted by Anton Abaya on 1/30/2001 11:16 PM EST:



By chance do you know what amps your drill motors are running at in high gear?

[archiver]

Posted by Anton Abaya at 1/31/2001 11:54 PM EST


Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! .


In Reply to: Re: how much is too much on the DRILL MOTORS?
Posted by Mark Garver on 1/31/2001 10:40 AM EST:



: By chance do you know what amps your drill motors are running at in high gear?


i wanted to measure it but we dont have an ampmeter... or that meter thing with a clamp on attachment .... whatever the heck its called. for that matter, i only have hrmm....$1300 left in my budget ($2000 total) for the bot. so i'm kinda keeping it handy.

-anton

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Posted by Al Skierkiewicz at 1/31/2001 1:35 PM EST


Engineer on team #111, Wildstang, from Wheeling High & Rolling Meadows High and Motorola.


In Reply to: how much is too much on the DRILL MOTORS?
Posted by Anton Abaya on 1/30/2001 11:16 PM EST:



Too much is pretty easy to determine...
If the wires going to the motor and speed controller are soft and warm than it might be too much. If the 30 amp breaker keeps tripping, it might be too much, etc.
Worried about too hot? At work we use the 10sec/finger rule, if you can keep your finger on a surface for ten seconds you are most likely running under normal conditions for the motor. As a caveat here, touch gently at first if you suspect a really hot motor. If you touch for a long time you will burn off your fingerprints.
You do know about removing the locking pawls, right?
Smoke is always a sign you've gone too far, unfortunately, motors are not self healing so this is a one time, no turning back kind of indication.
One last thing, get to know the sound of your drive system. If you hear a sound like something is complaining, then it is.
Al

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Posted by Matt Leese at 1/31/2001 6:46 PM EST


Other on team #73, Tigerbolt, from Edison Technical HS and Alstom & Rochester Institute of Technology.


In Reply to: how much is too much on the DRILL MOTORS?
Posted by Anton Abaya on 1/30/2001 11:16 PM EST:



Along with everything said below, you'll also want to check to make sure that everything in the drive train is aligned correctly (this assumes you're using sprockets and chain). You'd also want to make sure that the chain is tensioned enough but not too much (there should be some play in the chain). Also, just the run the drive train under load. Put some weights on it and just run it. See what happens. If something breaks, it's going to need to be fixed. Let your drivers get some training on it.

Matt who wonders how he's remotely qualified to give advice......