LinuxCNC Support Forum :: Topic: Plasma/Mesa Guru's (10/12)

BigJohnT OFFLINE Administrator Posts: 4955 Thank you received: 87 Karma: 134	The Z offset is gradually removed when the THC is enabled and the torch is off as you move the torch in the positive Z direction until no offset is left. As soon as the torch goes off do you rapid the Z up? Remind me what version of EMC your using... John
	Last Edit: 05 Aug 2011 13:48 by BigJohnT. The administrator has disabled public write access.

Re:Plasma/Mesa Guru's 06 Aug 2011 07:36 #12239

BigJohnT OFFLINE Administrator Posts: 4955 Thank you received: 87 Karma: 134	I've been having some discussion with Peter on changing the comp a bit to give it a P term and a cap on correction. When I get that done you can try that out to see if it corrects the symptoms your seeing. John
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Re:Plasma/Mesa Guru's 06 Aug 2011 11:46 #12254

austin.mn
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I really wish that I had my machine in my own garage... at the moment I have to drive across town to get any of the info you need. I will do that at some point today.

One very noticeable thing that happens is when I click the THC box on and off after cutting a part the Z tries to jump about an inch or so. It never gets to move anywhere near how far it wants to move as it looses steps on it way. You can hear the motor getting about a zillion pulses per second.

I will be grabbing one of my GCode files and writting down the Version of EMC2. Anything else I could get while I am there to make diagnostics a little easier just let me know.

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Re:Plasma/Mesa Guru's 06 Aug 2011 11:59 #12258

andypugh
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austin.mn wrote:

One very noticeable thing that happens is when I click the THC box on and off after cutting a part the Z tries to jump about an inch or so. It never gets to move anywhere near how far it wants to move as it looses steps on it way.

That indicates that the Stepgen Max accel and Max velocity are not set correctly. if they are configured in the INI file then you might need to check that they are also linked in the HAL file.

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Re:Plasma/Mesa Guru's 06 Aug 2011 12:14 #12259

PCW OFFLINE Moderator Posts: 1660 Thank you received: 87 Karma: 116	Pretty sure theres a bug in the THC comp that may cause a jump on torch-off. John is fixing this I believe.
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Re:Plasma/Mesa Guru's 06 Aug 2011 13:30 #12262

BigJohnT
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I can guarantee that your using 2.4.6 or older now that I think about it. There is a bug fix that I pushed on 4/22/2011 that would not be out yet since the last bug fix release for 2.4 was on 11/26/2010... so when you disable the THC component the commanded position is suddenly set back to the original commanded position because it never gets removed.

So you have a couple of options

1 copy the thc.comp to your computer and run sudo comp --install thc.comp from the command line to get the fixed one...

http://git.linuxcnc.org/gitweb?p=emc2.git;a=blob;f=src/hal/components/thc.comp;h=4a0589649a109cde739dd0f999c62f8cce984b9a;hb=HEAD

2 get a git copy and use a RIP (Run In Place)

wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Ins..._or_8_04_from_source

3 get the 2.5 deb and install that.

buildbot.linuxcnc.org/

4 wait a bit till I add the P-Term and then do one of the above

John

John

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