Another Question.

[Jacob Morgan]

Hey guys i've got another question..

I've pretty much decided on the These two motors.

The only problem i've seen is the fact the casing on them is the ground. Can anyone tell me what woudl happen in the following instance.

Each motor will be on its own speed control, and battery. The only time this would pose as a problem would be when one motor is in reverse, and the other forward since the reversed motor's once positive now negative. vice versa.

Now this would normally create a series right? neg from one battery and positive of the other (both contacting the frame) my question is, will this affect anything? since the series isnt' actually being completed. The other neg is on a motor, and pos on the other motor, not giving either motor the full 24 volts from the two batteries.

Will this affect anything at all? or will it make a motor or both run in a series? or short something out?

Thanks guys hope i didn't confuse anyone as much as i am.

[sanddrag]

That's actually a pretty good question. If it was me, I would just isolate the motors from the chassis and save myself a lot of headaches.

[Jacob Morgan]

I've thought about that.

If I just used some kind of metal clamps, or zip ties etc to mount them it would be pretty easy since I coudl just put cardboard ro something else between the motor and frame..

However, I wanted to fab a mounting plate that will use the mounting holes on the motor, hopefully something I can actually just loosen the motor and slide it up/down to increase/decrease ground clearance. I was considering doing this then putting tape on the mounting practice and putting teflon tape around hte screws when I screw them in to the motor..

Im not sure if that would work or not :-/

[Jay H 237]

Have you considered using polycarbonate instead of a metal plate? It's similar to plexiglass but much stronger and won't shatter. You could then use regular screws to mount the motor to the polycarbonate and it would still be isolated. It can be drilled and cut easily. I'm not sure what your planning on doing with the motor but polycarbonate or another noncondutive composite material might be your answer.

Also is there a posibility that whatever you attach to the motor shaft could cause a short to ground somewhere? What I mean is if there's a metal sprocket with a metal chain going to another sprocket on a shaft it could also ground out somewhere where that shaft attaches to the frame for instance.

[Jacob Morgan]

the motors will be hooked directly to the tires,

I am fabricating a adapter so I can hook the wheel straight to the motor.

good idea with the plexi or other non conduct, i had thoguth about it but I had in my mind that metal screws = short.. It didn't hit me if the material the screws are going thru before the motor is non conductive the screws doesn't mater

Thanks guys, Im going to double check measurements on my frame tomorrow and order =^)

[Al Skierkiewicz]

Jacob,
Even though you said each motor would run on it's own battery and speed controller, it sounds like the speed controllers will get their PWM from the same robot controller. If this is the case then they will find a common ground through the controller and that sounds real bad.
Use one of the above mentioned ideas for isolating the motor frame from the device frame. If possible, since the motors seem inexpensive, they may be easily modified to cut the connection to case. One of the users comments mentioned that ground is already on one pin of the connector.

[Jay H 237]

I just want to add something on the teflon idea. There is a good chance the threads on the screw and/or hole could cut through the teflon when installing the screw thereby rendering it ineffective. If you've ever taking apart plumbing fittings you would know what I mean. In plumbing the teflon merely takes up the very small space between the threads to prevent leaks not the high points of the threads. So in short I would be reluctant to just rely on the teflon for electrical isolation. There is one benifit I do see with the teflon on the threads and that is it will act like "Loctite" for the screws with normal use but still allow you to easily remove them if you blow a motor for instance.