Wierd problem

ranger11 · Post by **ranger11** » Sun Sep 22, 2019 10:01 pm

I have a home built table and have an issue that is driving me nuts. Any time I have the table power on( plasma on or off) and open my cpu or when selecting a file when loading in sheet cam my plasma starts blowing air like its gonna fire up, however it never does. Its either a glitch or interference. Just wondering if any one else has had this problem.

Post by **robertspark** » Mon Sep 23, 2019 3:03 am

how are you controlling the plasma cutter and what software are you using

parallel port, smooth stepper, pmdx, etc??
mach3, mach4, candcnc, linuxcnc, etc???

how are you controlling the plasma cutter?
relay, optocoupler?

how is it wired?
normally open / normally closed contact, source or sink?

what plasma cutter is it?
make and model

please give us much info as possible....

ranger11 · Post by **ranger11** » Mon Sep 23, 2019 9:42 am

Parallel port, mach3,relay, I'll have to check how it's wired. Miller extreme 675 cutter with the cnc port. Thanks for the reply.

ranger11 · Post by **ranger11** » Mon Sep 23, 2019 10:02 am

It's normally open/source wiring

Post by **robertspark** » Mon Sep 23, 2019 11:11 am

parallel port can be a bit of an odd ball control arrangement (bear with me I am not trying to rubbish it).

(NFS / Art I believe) added the chargepump to Mach3 because the parallel port can suffer from occasional wobbles when the PC starts up and shuts down and ports and pins can flicker.

which is what I expect is happening here to you.

Basically the pins are toggling / flickering very fast that the torch starts to fire, but does not because the signal drops out before the torch can actually fire hence the air continues to flow for its timeout period.

PDF page 9/14 explains this:
ftp://machsupport.com/Docs/Mach3%20Setup%20Tutorial.pdf

One way to "fix" this is to use the chargepump signal via a second relay to control the plasma cutter and offer the correct level of safety to interrupt the plasma cutter signal if the parallel port is not getting the continuous pulse trane of a chargepump signal.

You can make your own chargepump circuit via various means,
eg: ftp://anonymous:guest@ftp.machsupport.c ... Safety.pdf

or:
http://wiki.linuxcnc.org/cgi-bin/wiki.p ... arge_Pumps

or you could buy one of these:
https://www.cnc4pc.com/c4-safety-charge-pump.html

Or one of the other ones from china / amazon
https://www.amazon.com/MACH3-Charge-Mod ... way&sr=8-1

ranger11 · Post by **ranger11** » Mon Sep 23, 2019 1:58 pm

I believe thats the issue. Thank you for your suggestion.

Wierd problem

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