It is currently Thu Nov 23, 2017 1:47 pm

 

Z-axis or THC Issues

CommandCNC related questions and tips can be posted to this topic.
Econdron
Elite Contributing Member
Elite Contributing Member
Posts: 36
Joined: Thu Jun 08, 2017 7:10 pm

Z-axis or THC Issues

Postby Econdron » Sat Jun 10, 2017 12:55 pm

Sorry in advance for another one of these... I searched the forum and read a few threads on the same topic, but I tried all the solutions found in those, or they didn't apply to my setup. So here's where I'm at right now:

CandCNC full automation bundle, running CommandCNC for Linux. I've got it wired to what I believe is the most recent recommend way. In CommandCNC, when I tell the system to home z, it goes until it trips the mechanical switch, and reverses the switch offset which I've calibrated. When I tell the system to do a Z-touch off, it goes until it trips the ohmic sensor and stays there. So I believe the Z switches are all working fine.

I've cut out some simple shapes, and letters, there's a some tuning to be done regarding the cut-quality, but for the most part it cuts pretty well. I tried something more intricate the other day, an eagle specifically with a lot of fine details, and feathers and such. It cuts for about 2 minutes without any problems, then it will suddenly just take a sudden dive during a touch off and knock the torch off. I tried doing the same shape I think 4 times, and each time it failed at a different spot, but around the same time-frame after starting to cut.

I've tried with the DTHC off and on, both with the same results. I've tried increasing my rapid clearance (up to 1") and plunge clearance (up to .5"), tried decreasing DTHC sensitivity, and increasing Velocity Anti Dive percentage, all with no change. I've seen two different issues happen, one the torch gets knocked off, then the system proceeds to make a cut with at an angle (magnetic breakaway), and the other it knocks the torch off, then gives an error something like the system has exceeded the Z-axis clearance with any contact with the probe and shuts off. Like I said, feather touch and mechanical limit switch both work, it's almost like they fail partly through. Any ideas?

User avatar
acourtjester
Elite Contributing Member
Elite Contributing Member
Posts: 2795
Joined: Sat Jun 02, 2012 6:04 pm
Location: Pensacola, Fla

Re: Z-axis or THC Issues

Postby acourtjester » Sat Jun 10, 2017 2:12 pm

I don't have the Linux version but here is something to check. The ohmic sensor should be hooked to the Z home pin and the mechanical switch should be hooked to Z limit pin. This way the command for Z home works with the ohmic sensor and if it fails then the Z limit will stop it from crashing. I am assuming the mechanical switch is the floating head switch in place of a lower Z limit switch.
The torch taking a dive when it is cutting is odd if you were using the DTHC you may be loosing the arc voltage. But you said you tried it with it on then off with the same result. Don't you have a switch on the magnetic breakaway?
Are you using the correct post processor?
DIY 4X4 Plasma/Router Table
CandCNC DTHC-IV & Feather Touch
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PM 256 tig

Econdron
Elite Contributing Member
Elite Contributing Member
Posts: 36
Joined: Thu Jun 08, 2017 7:10 pm

Re: Z-axis or THC Issues

Postby Econdron » Sat Jun 10, 2017 3:05 pm

I know the ohmic switch is connected to the Auxiliary 1 port, and the I believe the mechanical switch is connected to home. From what I understand, wiring it this way is supposed to be a fail safe for the ohmic sensor that doesn't shut down the machine. So if the ohmic sensor doesn't trip, the mechanical switch does and it applies the offset to that. That way the machine doesn't keep shutting down if there's a bad connection or rusty metal inhibits the ohmic connection.

But I'm wondering if I have some of my settings off. The mechanical switch may actually be my issue. Maybe the ohmic sensor doesn't have a good connection and the other switch isn't working as a limit OR a backup. So the torch just keeps diving until it stalls. I'll have to go back through the manual and make sure I wired and configured everything as it should.

User avatar
acourtjester
Elite Contributing Member
Elite Contributing Member
Posts: 2795
Joined: Sat Jun 02, 2012 6:04 pm
Location: Pensacola, Fla

Re: Z-axis or THC Issues

Postby acourtjester » Sat Jun 10, 2017 3:58 pm

Maybe one of the command CNC users will give you better info, there are some here who can speak with more authority then I.
They will get you going keep, checking you learn more when things hit a bump.
DIY 4X4 Plasma/Router Table
CandCNC DTHC-IV & Feather Touch
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PM 256 tig

Simko
Posts: 224
Joined: Sat Aug 29, 2015 9:32 pm
Location: North Central Pennsylvania

Re: Z-axis or THC Issues

Postby Simko » Sat Jun 10, 2017 7:49 pm

I set mine up the same way. If you followed the instructions in the PDF below, then the only thing I can think of is your 'Plate' wire may not have good connection to the slats through the machine frame. Use a multimeter to see what the resistance is from where you connected the plate wire to the slats. This could explain why you could miss the the ohmic sense every once in a while, but it doesn't explain why the z-axis switch isn't doing its thing. I am guessing that you don't have a setting right in the configurator. Check all of the settings outlined in the link below and make sure your z-axis switch is wired normally closed and the z-home invert button is unchecked.

http://candcnc.com/commandcnc/32-bit/0.8.0_features.pdf
Steve

Homebrewed plasma table in the works, NSK linear rails, 3.2:1 belt reduction, CandCNC Plazpak 1A with DTHCIV Ethercut, Hypertherm 85, Linux CNC and SheetCAM
Click here for build post

Simko
Posts: 224
Joined: Sat Aug 29, 2015 9:32 pm
Location: North Central Pennsylvania

Re: Z-axis or THC Issues

Postby Simko » Sat Jun 10, 2017 8:04 pm

Econdron wrote: when I tell the system to home z, it goes until it trips the mechanical switch, and reverses the switch offset which I've calibrated. When I tell the system to do a Z-touch off, it goes until it trips the ohmic sensor and stays there. So I believe the Z switches are all working fine.


Home should go to the switch and stop

Touch off should hit the ohmic or switch, raise to the switch offset, and zero the axis

Page 9 in DTHCIV Rev3 manual 8-)
Steve

Homebrewed plasma table in the works, NSK linear rails, 3.2:1 belt reduction, CandCNC Plazpak 1A with DTHCIV Ethercut, Hypertherm 85, Linux CNC and SheetCAM
Click here for build post

Simko
Posts: 224
Joined: Sat Aug 29, 2015 9:32 pm
Location: North Central Pennsylvania

Re: Z-axis or THC Issues

Postby Simko » Sat Jun 10, 2017 8:10 pm

Oh yeah... I don't think it is a THC issue. The THC doesn't come on until after the pierce and then a delay.
Steve

Homebrewed plasma table in the works, NSK linear rails, 3.2:1 belt reduction, CandCNC Plazpak 1A with DTHCIV Ethercut, Hypertherm 85, Linux CNC and SheetCAM
Click here for build post

Econdron
Elite Contributing Member
Elite Contributing Member
Posts: 36
Joined: Thu Jun 08, 2017 7:10 pm

Re: Z-axis or THC Issues

Postby Econdron » Mon Jun 12, 2017 12:16 pm

Simko wrote:I set mine up the same way. If you followed the instructions in the PDF below, then the only thing I can think of is your 'Plate' wire may not have good connection to the slats through the machine frame. Use a multimeter to see what the resistance is from where you connected the plate wire to the slats. This could explain why you could miss the the ohmic sense every once in a while, but it doesn't explain why the z-axis switch isn't doing its thing. I am guessing that you don't have a setting right in the configurator. Check all of the settings outlined in the link below and make sure your z-axis switch is wired normally closed and the z-home invert button is unchecked.

http://candcnc.com/commandcnc/32-bit/0.8.0_features.pdf


I think you might be on to something with the ground wire. It's kind of hokey how I have it mounted to the frame right now, I'll fix that ASAP. Also one thing I'm not sure on, did you remove the jumper out of the feather touch box? I'm not talking about the jumper in the main control box, but the one on the actual feather touch module. I currently have that removed, so maybe that's why the switch isn't working? But I seem to remember the ohmic sensor wasn't working while it was connected...

Simko
Posts: 224
Joined: Sat Aug 29, 2015 9:32 pm
Location: North Central Pennsylvania

Re: Z-axis or THC Issues

Postby Simko » Mon Jun 12, 2017 2:02 pm

Econdron wrote:Also one thing I'm not sure on, did you remove the jumper out of the feather touch box? I'm not talking about the jumper in the main control box, but the one on the actual feather touch module. I currently have that removed, so maybe that's why the switch isn't working? But I seem to remember the ohmic sensor wasn't working while it was connected...


That jumper needs to be in place to function properly.

Did you modify the location of the orange and green wires at the controller end (green 5-wide connector) per the PDF I posted above?
Steve

Homebrewed plasma table in the works, NSK linear rails, 3.2:1 belt reduction, CandCNC Plazpak 1A with DTHCIV Ethercut, Hypertherm 85, Linux CNC and SheetCAM
Click here for build post

Econdron
Elite Contributing Member
Elite Contributing Member
Posts: 36
Joined: Thu Jun 08, 2017 7:10 pm

Re: Z-axis or THC Issues

Postby Econdron » Mon Jun 12, 2017 2:10 pm

Yes, that I followed that PDF word for word. THEN I removed the jumper. I'll put it back in and see if it works. Thanks for your help!

tcaudle
Posts: 794
Joined: Tue Feb 28, 2012 6:47 pm

Re: Z-axis or THC Issues

Postby tcaudle » Mon Jun 12, 2017 2:34 pm

The jumper is in series with the old LIMITS signal line so you could expand the string . The Z switch will not work if you remove that jumper. Perhapos the jumper you are talking about is the one on the Table I/O for the EPO (E-Stop)? It DOES need to be off if you are using the Z swtich as an E-STOP but NOT if you have it wired for a backup touch-off as per the Manual


Return to “CommandCNC - Linux”

Who is online

Users browsing this forum: No registered users and 1 guest