I am new to Mach, so this may just be me messing things up. I have been using Mach with Sheetcam to run a CNC plasma table. I have successfully cut this part about 30 times.
It is a part with 2 holes and that is it.  I am basically using the plasma to cut two holes then load a new part and start over. Once it finishes the part the DRO says .4991 as it parks and waits for the next " run" command. I load the next part hit run. Sometimes it cuts both holes, sometimes it cut the first then goes to the second hole does a touch off and raises the torch about 2" above the metal and fires in the air.

I don't know if I should be hitting "ref Z" before I run the next part?  After it finishes the code. the Z DRO reads +0.8237 . If I zero the DRO then close Mach and restart my computer. Once it reboots and I reopen mach, the Z DRO reads +0.8237. Shouldn't this read 0.0000 ?
 
Any help would be appreciated
Thanks, Travis

Can you post an example of the Gcode that you are using?

Do you have a floating head switch to set teh top of material?

(;-) TP

yes, I will run to the shop and get a copy of the code. I do have a floating head switch.

here is the tap file. Since I dont have internet in the shop and my house computer is a mac, I can't open and paste part of the code. I have attached the file.
Thank you for helping.
Travis

OK your G code is fine.  You should be able to repeat that code as many times as you need.

Assuming that you load the material against a stop to locate it correctly. Load material Set teh ORIGIN X0Y0Z0 with zero xyz. then press start. The code should cycle all the way thru and return to x0y0Z.500.

Load another part then press start, repeat,repeat.

Are you doing something differrent ?

You have given 2 different examples of the problem. First time you say it ends at Z.4991 which should be correct by code.

The second you said it ends at Z0.8237 ??

Which is it ?

The torch firing in air may be a stuck Zswitch from time to time. as soon as the G28.1 runs it sees the switch active and starts the routine at that point. BUT normally it does NOT do it after the Z touches off. Please recheck the way it is failing and write down exactly the sequence.

As to the Saved postion of Z it all depends on how you setup MACH3 as to if it saves the last position or not.

Br549,
Thanks for helping. I am sorry i wasn't clear on the first description. This problem is very confusing because it doesn't do the same thing every time. What it was doing is it would cut the first hole raise to .4991 move over to second hole then do a touch off and raise the torch to .8237 fire in air until the THC takes over then try to lower but it would finish the 9/16 dia. hole before it could get low enough to cut, then raise back up to .8237 and park. Then I would 0 the DRO on the Z axis. I noticed after I zero the DRO I would go to the settings page and the Z offset would be .8237.
So last night before I turned off the machine I zeroed every axis. Then turned everything off. Today when I turned on the computer and it booted up, opened mach the Z DRO read +0.7819 I don't understand this.. So I figured it was a problem with the Mach software or my windows software. So I reloaded windows and Mach. ( I saved my xml files on a floppy drive) but when I reloaded my xml files my machine wasn't calibrated correctly. So back to doing that now.
Can you tell me where to find the setting where mach remembers the last DRO position?
Can you explain to me the difference between zeroing the DRO and hitting the Z ref before running the second part?
Thank you,
Travis

When you Zero Z it is just reseting Z to zero and is what you want to do.

IF you use RefZ 1 of 2 things happen IF you have a Zhome then Mach3 will run the Z back to the switch and rest the Machine Zero or offsets if you have one.

IF you do not have a Zhome then Mach3 will reset the machine Zero exactly where it is when you pressed the button.

With Plasma work you forget all about any offsets or such. It is a simple 2d process.

Load the Cut File, load the steel, Move to where the point of origin(X0Y0) on the material should be and press  ZeroX ZeroY ZeroZ then Cycle start.

Then Mach3 should run the TOM routine in the Gcode file and set the TOM to zero and move to the pierce height and fire the torch and move Z down to cut height and away you go..

It is the exact same process every time. (;-)

Just a thought(;-) TP