RAMPS with unused Axes?

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dave_the_nerd
Posts: 144
Joined: Thu Oct 09, 2014 3:23 pm

RAMPS with unused Axes?

Post by dave_the_nerd » Fri Feb 26, 2016 8:05 pm

As a side project, I'm considering getting a RAMPS setup working in case my gShield burns out a driver again.

I see that there are some custom firmwares available to make the 5-axis RAMPS setup into a 3-axis controller more appropriate for a Shapeoko, and I'm enough of a programmer to make the few tweaks to the config.h files and whatnot, specific to my (pretty simple) setup.

I am curious though - am I correct in thinking that I should only install drivers and wiring for the four motors I want to use? (I seem to recall reading somewhere that if you supply power to a driver chip without connecting a motor, it'll go boom. So I'm assuming I don't want to install the fifth chip - is that right?)
Shapeoko 2 # 6651: 500x1000mm, Acme screw and belt drive Z-axis, DW660 w/ IC mount, Arduino/grblShield w/ gCode 0.9g and 3D-printed electronics enclosure.

AnonymousPerson
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Re: RAMPS with unused Axes?

Post by AnonymousPerson » Fri Feb 26, 2016 8:26 pm

dave_the_nerd wrote:I seem to recall reading somewhere that if you supply power to a driver chip without connecting a motor, it'll go boom.
Hmmm, might that only be for some specific drivers?

Asking because with the A4988 drivers, the initial process of turning the screw on top to fine tune the max output amperage... is supposed to be done exactly that way. eg with power supplied to the driver chip, but without a motor connected

Reason that I'm saying that (unless I'm misunderstanding something): https://www.youtube.com/watch?v=89BHS9hfSUk
Shapeoko 3 #516

cvoinescu
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Re: RAMPS with unused Axes?

Post by cvoinescu » Sat Feb 27, 2016 1:08 am

Disconnecting the motor with the power on can, and often does, fry the driver. Running the driver with the motor already disconnected is perfectly safe (at least for the A4988 and DRV8825).
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

dave_the_nerd
Posts: 144
Joined: Thu Oct 09, 2014 3:23 pm

Re: RAMPS with unused Axes?

Post by dave_the_nerd » Mon Feb 29, 2016 9:24 pm

Okay, thank you both. :D
Shapeoko 2 # 6651: 500x1000mm, Acme screw and belt drive Z-axis, DW660 w/ IC mount, Arduino/grblShield w/ gCode 0.9g and 3D-printed electronics enclosure.

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