Hi All,

Noobie here. 40 years mech engineering experience, but this is my first time ever using Mach3 or building a CNC machine.

Just in the process of converting my manual mill to CNC using Mach3. So far, so good, mostly thanks to the excellent information on mycncuk and this forum! So far I've got XYZ and spindle working OK, and I'm feeling my way through all the controls and settings, etc.

My problem is that I can't get my Estop to work; It works when I hit the red "RESET" icon on the Mach3 HMI, but not when I hit my physical "mushroom" Big Red Switch. On my cheap Chinese BOB I should have 10v from pins 10 to 15. Pins 12,13 & 15 all output 10v (Can't remember if I checked pin 11) but pin 10 for the Estop had 0v. Is there a setting in Mach3 to eneble / disable the 10v to pin 10? or have I just got a dodgy BOB?

I've scanned through the Mach3 manual, but can't find any reference to enabling / disabling this pin.

Any ideas would be greatly appreciated.

Thanks,

Terry
(gitbash)

It does sound like there is a problem with your BOB board. All five inputs have the same circuit so you should measure the same voltage as the others when the switches are open. There are only two components on the input side, a resistor and an Opto-coupler. They are located next to the terminal. Compare to a working circuit, the same voltage should be on both sides of the resistor and pin 2 of the Opto. Pin 1, the one by the dot in the case, will have 10V. Someone with reasonable soldering skills should be able to replace the defective part.
Then again, the cost of that board is so low it might be easier to just replace it.

The schematic is in this post.
https://www.machsupport.com/forum/index.php?topic=43939.msg282588#msg282588

Thanks MN300,

I'll investigate the BOB, then. I'll report back when I have a result.

Cheers,

Terry

Update:

I just started to probe the various connections in the circuit, following MN300's advice: Bizarrely, and to my surprise, pin 10 on the terminal block was showing 10V, and the Estop now works!! maybe I disturbed a dry joint (doubtful) so I guess I must have mis-diagnosed the original fault? All I know is that it wasn't working before, and it is now, so thanks very much MN300 for pointing me in the right direction.

Cheers,

Terry

A dry joint and a cracked resistor are both possibilities. You could reheat the connections  including the terminal. Fortunately if it fails intermittently you will get a false Estop rather than ignoring the Estop switch.

OK MN300,

I'll monitor the situation and do as you suggest if it re-occurs
Thanks,
Terry