Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Tprice18 on January 11, 2022, 11:17:18 PM
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I recently added home switches to my machine. Everything seems to work fine but, when I home it after it does it homing process it moves over off the switch .500". It does the same for all the axis. I'd like it to stay closer to the switch. Where in the software can I edit that. Any help in fixing this would be greatly appreciated.
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Hi,
when homing Mach advances to the switch in the programmed HomeDirection, at the programmed HomingSpeed until it hits the switch. It will then back off the ONLY as
far as is required for the switch to deactivate. Depending on your switches it could be that they have half an inch of hysteresis and you can't change that.
I use roller plunger snap action microswitches which have 0.05mm of hysteresis, and due to the mechanics of the roller plunger and the ramp against which they operate
they back up about 0.8mm. The home switches allow me to home to within 0.02mm every time and have done so for years.
What sort of Home switches are you using? Could they have 0.5 inch hysteresis?
Note that some motion controllers allow you to program a certain distance OVER AND ABOVE the normal back off distance, but only some controllers. What controller are you using
and does it have that programmable BackOff feature? If so it may be mis-programmed.
Craig
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The part that throws me off is when I start up the machine when it’s in metric it’ll home without that .500 of an inch, if I switch machine to inch with a G20 it’ll do that .500 drop down. I converted my machine to inch and it still does it. It seems to me like somewhere it’s got .5mm saved and it needs to be less than than that for inches.
I’m using the usb controller.
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Is there a way to edit the homing script?
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Hi,
I’m using the usb controller.
Which one, there are dozens of, most of them Chinese so who knows if you'll get any help.
Craig
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I have the 6040 cnc router. It has a red usb board in it.
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Hi,
I've got a car, it has a wheel at all four corners, its blue.....can you tell me what model it is?
Craig
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This is the controller I have.
https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board
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Hi,
that is the famed RnR motion board, I doubt anyone will own up to be the manufacturer let alone help.
Craig
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It just seems like it’s in MM cause it’ll go up to the home switch but switching to inch it drops .500 inches.
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Hi,
does it really matter? Just because the machine coordinate zero is half an inch 'inside' the end does not prevent you
from using that extra half inch....its just that it would have a negative machine coordinate.....and that's no problem because you use
work coordinates....so who cares if the machine coordinate is negative.
Craig
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Hi,
Homing is a function that requires realtime, that is to say immediate response, and thus MUST be handled by the motion controller.
Many Chinese motion controllers handle Homing in a non-standard manner....your controller evidently does so and I doubt you'll ever
find a means of changing it.
Buy a US or European made controller like an ESS and you'll get industry standard behavior and manufacturers support.
Craig