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Author Topic: Auto-aligning gantry during homing.  (Read 1740 times)

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Auto-aligning gantry during homing.
« on: March 08, 2015, 03:18:06 PM »
I have a wide gantry.  As is, when first powered up, the 2 rack & pinions won't be perfectly aligned.  That makes cutting a large square a slight parallelogram.  Both motors are "linked" inside Mach3 to step together, not in the hardware.

I do have precision-placed endstops.  Right now I just jog against them slowly until one motor stalls against the stop and allows the other to catch up and also strike and stall against the endstop.  The grinding sound of a stalling stepped attracts a lot of attention... "no guys, it's supposed to do that."

OK so I need homing switches on both sides.  Is there a method inside Mach3 (or someone's Plugin) to home by driving until one motor or the other hits the home, stopping that specific motor, unlinking the drives, and driving the other motor (whichever one it may be) forward until it, too, hits the homing switch?



Offline ger21

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Re: Auto-aligning gantry during homing.
« Reply #1 on: March 08, 2015, 03:25:59 PM »
Yes, just install a homing switch and assign it to each motor.

When you say "linked", I'm assuming you mean "Slaved"?

The only thing you need to do besides enabling the switches is to go to Config >General Config and make sure "Home Slave with Master" is NOT checked.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Auto-aligning gantry during homing.
« Reply #2 on: March 08, 2015, 04:10:01 PM »
Yep, "slaved".  I knew "linked" didn't sound right.

So then it temporarily "unslaves" them for homing, but steps them in sync until one of the motors finds its home?

Offline ger21

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Re: Auto-aligning gantry during homing.
« Reply #3 on: March 08, 2015, 04:25:12 PM »
yes
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline derek

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Re: Auto-aligning gantry during homing.
« Reply #4 on: March 09, 2015, 06:21:06 AM »
Make sure one of your switches is easily and accurately adjustable. There is no provision in mach to electronically offset the switches.