Vibration moves axises

[able2]

I am not sure if this is the correct place to leave this but I am basically using Marlin as something other than a 3D printer at the moment. I have an x,y,z table type setup and have a dremel flex shaft attached to the z axis. Just turning the dremel on makes all the axises go crazy and move on their own. With and without software interface open.

I have tried multiple settings and changes and I am sure since I don't exactly know what I am doing completely I am missing something? I have the firmware setup as Ramps up to 1.2. using a regular Mega2560 and just a normal setup. I can control the steppers using pronterface,replicatorG etc. just fine. It will run through all the g-code I send it pretty much flawlessly but as soon as I turn on the dremel the axises all move on their own. Sorry if this is the wrong place to leave this but I tried searching for the answer all over the place. Thanks for any help.

[nophead]

It's an electronics problem, not a firmware problem. DC motors are very noisy and that noise must be getting to the step pins on the drivers. It might be coupled through the power rails or the ground if you are using the same PSU for the Dremel. Or it might just be RF noise.

[able2]

Hi and thanks for replying at first I thought that also I went so far as to change outlets between the driver boards ps and the dremel to make sure. I have other boards with different firmwares on them but I have enjoyed Marlin the best so far. I changed boards to 1 with GRBL on it and the vibration had no effect on the steppers. So that left me back to what's going on between the firmwares between the 2?

[daid]

Guess you are learning about EMF. Can be tricky business. Note that the RAMPS design is quite horrible in this aspect. A tesla-coil on the same power group also causes hell, just switching outlets might not do a thing. It might not be traveling trough the powerlines at all, it could also be air-born.

[nothinman]

Had a similar problem with Dremel. Ended up using 3 phase DC motor and a controller (from a plane model). Much less noise and the problem disappeared...

[nophead]

See http://hydraraptor.blogspot.co.uk/2007/09/dc-to-daylight.html for how to suppress DC motors.

[able2]

Thank you all for the responses. I think I was trying to talk myself out of it being an EMF problem. But you all are right there is no way to escape it the way it is setup. I did change outlets way far away from each other and on slower speeds it doesn't randomly move the axises. If the flex shaft is resting against the z stepper it does make a big difference so I imagine there is some kind of static charge effecting things also.

The thing with GRBL not moving on an earlier test was not accurate because somehow the computer and the controller were not communicating properly so it held the axises in place, weird stuff. I have some dc motors somewhere to test later if I get a chance and a cordless engraver.

This is all just experience because it has totally strayed far from my original design and project. My final project for microcontrollers class is just an arduino UNO with a wii nunchuck using I2C to make the axises move and draw with a pencil or marker. Joystick for x and y and c, z buttons to control the z axis. I wanted to see how far I could carry the project beyond that to even possibly get close to building a 3D printer later on in time.

Again thank you to everyone for the ideas and information i appreciate it.

[daid]

(Note, closing this, as we all think it's not a firmware issue, but feel free to keep the talk about EMF open)

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