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Author Topic: Mach3 Doesnt allow me to Reset After hitting any of my hard limit switches? GRRR  (Read 3737 times)

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Are you associated with "CNC DRIVE" ?

Anyone else know why the limit switches dont pull off from the hard limits?

Offline ger21

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    • The CNC Woodworker

2010 Screenset

JointCAM Dovetail and Box Joint software
Ive since done some research and it seems dodgy my BOB via Mach3 with SoftLimits also!

Seen some commenets in youtube video!

Will look into a new BOBBY Soon


I will let you know if my new BOBBY works!

Offline rcaffin

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Not so fast. If the response of the Limit switches is slow, then Mach3 may have coasted a bit too far before stopping, and left one of the Limit switches still asserted, despite any attempts at backing off. That is probably the most common reason why the Reset button does not work (imh0).

At the risk of being risky (ahem), you could try putting a momentary press button switch in parallel with your Limit switches (assuming they are all NC switches). Pressing it will then allow you to Reset and move off the Limit switch.

Note: a momentary press button switch, NOT a toggle switch! You do not want any chance of the Limits being permanently bypassed. You could test the idea with a simple jumper wire with croc clips.


Thats a jolly good reply Rojer

Im familiar with Momentary switches as bought lots from ebay but mainly 240v ones, but i may have or will buy some smaller say 24v ? Momentary switches?

Where abouts would you put that switch? next to limits?

Thats a really good idea, does this work? did you try/do it? or has anyone else done this with there limit switches?

Ive never heard off this before but kind of make sense :)

Will go to Rs or ebay and look for some

Offline rcaffin

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FIRST test with a simple jumper wire with a croc clip at each end. Or E-Z Hooks - they are the bee's knees. Assuming NC Limit switches, just parallel the two wires into the BoB.

Most ANY momentary pushbutton switch would do. It does not have to be either 240 VAC or 10 Amps. A very cheap little eBay pushbutton would do fine.

Where to mount?Well, most anywhere!
I rebuilt my system from the big power transformer up. I have tested most things.

If the problem is with the limit switches then an override button should fix it. Switches of any sort will have a bit of hysteresis built in to prevent bouncing and you might need to move your axis a surprisingly long way to get them to reengage.
Mount it on a vertical surface so you can't put something on top of it and leave it in ;)

Let us know if this doesn't do the job.
My hard limits are not directly handled by Mach 3, I don’t trust software to do the right thing when stuff goes haywire. So I have a reset button that you have to hold in while backing away. Could work for your limits if you can simply open the circuit or jump them out.