G540 w/387oz.in DB9 HOT!

[jwillhite]

http://www.youtube.com/watch?v=X9LUbQ51WaY

http://www.youtube.com/watch?v=X9LUbQ51WaY

Now that the stepper's are stepping I've got a couple questions...

1.) How hot should the motors get before it becomes a problem? Just test jogging them for a few minutes causes them to become extremely warm bordering on hot to the touch is this an issue?

2.) I purchased 6' DB9 serial cables with the intention of running them from the Gecko driver to each of the steppers, the DB9 cable gets hot... I guess the wires are small enough that the increased resistance is causing a voltage drop across the cable. Has anyone used DB9 data cables successfully with the G540 driver? If not what are you guys using, just bundling your own cable or what?

Any insight into the above issues would really be appreciated. Here's my build http://cnczone.com/forums/showthread.php?t=66889

Thanks, Josh

[ger21]

This post has some info on the effects of voltage with regards to motor heating.

http://www.cnczone.com/forums/showpo...35&postcount=4

[jwillhite]

Originally Posted by ger21 This post has some info on the effects of voltage with regards to motor heating. http://www.cnczone.com/forums/showpo...35&postcount=4

Thanks Gerry yeah thats enlightening, I didn't realize the temp gain on the steppers was quite that high..

48VDC = 79C case temperature, 55C temperature rise

thats a gain of 131 Farenheiht, based on how hot the motor feels that seems about right for my setup. Guess its not that big of a deal.

[Crevice Reamer]

Steppers naturally get hot--Cables should NOT. Are you using 3.5 K Current limiting resistors? If you have no resistors connected then the motors will get hotter when sitting still.

CR.

[jwillhite]

Originally Posted by Crevice Reamer Steppers naturally get hot--Cables should NOT. Are you using 3.5 K Current limiting resistors? If you have no resistors connected then the motors will get hotter when sitting still. CR.

Do you mean the current set resistor that goes across pins 1 & 5 on each of the DB9 connectors, or is there some other resistor that I should have in there?

Right now I have a 3K resistor in there, the Gecko documentation says to use 1K for each amp the motor is rated for. The steppers I'm using are rated for 3.5A thought I'd err on the side of safety and go with a lower max current until I get everything up and running.

Yeah I don't think the cables should be getting hot either.. hmm guess using those data cables is out I'll have to figure something else out.. dam that would have been convienent.

thanks

[Crevice Reamer]

Yep! THOSE resistors. That's OK then. After you get some heavier cables made up, You might want to fully power those motors with some 3.48K resistors from Digikey.com.

CR.

[keebler303]

DB9 connectors (or at least the ones gecko uses) are rated for plenty of current. The data cables however, obviously are not. Probably best to pick up some DB9's and solder up your own cable.

Good Luck
Matt

P.S. put the roof back on the Gecko's house!