Machine traveling past z home limit switch

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CNCMaryland
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Re: Machine traveling past z home limit switch

Post by CNCMaryland »

OK, please continue to add more info. You indicated "The problem is when I lower the Z axis and set a new WCS Z zero. Then when I move the Z axis back up it blows right through the limit switch and crashes the machine."

Based on this I assume when you say it blows right though the limit switch you mean the home switch. In 99.99999% of CNC machines, Z home is all the way up.
tblough
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Re: Machine traveling past z home limit switch

Post by tblough »

And, if the switch is configured as a HOME switch and not a LIMIT switch, it will be ignored by the control unless the machine is executing a home cycle. This is why it "blows right through the switch" and is the desirable behavior. You could have the home switches set up in the middle of the machines travel and you don't want it stopping every time it crosses the switch once you have homed the machine.

Home switches and limit switches are two different things. If you wish to use a home switch as a limit switch as well, then it need to be configured as HOMELIMIT.
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Re: Machine traveling past z home limit switch

Post by ShawnM »

And the reason your travel limits have been reset to zero is because you are using axis pairing and auto squaring. If the homing process ever fails to complete for one reason or another the travel limits will be left at zero. This is not a bug in the software, it’s because you don’t have the homing/auto squaring setup properly. During the homing sequence Acorn sets the travel limits to zero to complete the auto squaring routine when homing, if it does not finish the travel limits will be left at zero. You need to dial in your homing procedure and get the switches setup correctly so it works every time.

That’s why when you raised the z axis it blew through the “home” switch, because your soft limits were set to zero because at some point the homing sequence failed the last time you homed it.

As noted earlier, ditch the limit switches and setup the soft limits, they work perfectly.
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