Powermax 45xp lost arc delay (Solved)

Just wondering if anybody has had to set the lost arc delay in the connections.hal for their Hypertherm Powermax 45xp?

It is a new cutter to me and also I'm new with LinuxCNC. I had a Chinese cutter before the Powermax. I have a couple issues, but I'm trying to attack them one at a time.

I'm running Mesa 7i96 with THCAD-10.

Last night while doing some cutting it would go down to probe the material, go up to pierce height, start the pilot arc, then instantly stop with a message that arc was lost. It did put a small simple in the metal.

I could get it to work intermittently so I was eventually able to finish the job.

So is it common amongst Powermax 45xp users to need to set the "lost arc delay" option in the connections.hal? If so, how much delay are you using?

Thanks,
Nick

-Solution (for me)- Change the arc delay debounce in the *_connections.hal file to 10 or even a bit more, say 15. The hypertherm uses an arc okay relay that takes up to 10ms to latch and 4ms to release (data sheet attached below). That is worse case condition which means it will be hit and miss if you have this problem or not because PlasmaC sets arc ok delay to 5 be default, and I am sure there are plenty out there that latch within 5ms. Not the case for me however. I changed it to 7 then 8 then 9 just to see, and I reduced my issues from over 57% of the time to about 28% of the time all while cutting the same test file, and not changing any other variables. When I changed it to 10ms I was getting 100% success rate. Credit goes to Snowgoer for helping me through these issues offline. Thank you. Also the manual does call for a dry contact relay, so I added one of those too. In my case it didn't help things until I changed the debounce. I'm keeping the relay in there though to be in conformance with the hypertherm manual. Also noteworthy is that my ground clamp location matters. This implies to me there is some EMI issues with my setup. To get 100% success I have to have the ground clamped to the table or material, and not to my star ground lug. Maybe there is a loose connection in my star ground. I didn't investigate further. Just happy to be cutting with confidence again. Thanks all for sticking with me, and helping out.

Version 0.187.

I started with 0.187. This whole configuration is new for me. I used to run off Mach 3, Windows, Proma THC, Pokeys57cnc controller, and a chinese cutter. I'm loving everything I am seeing so far with LinuxCNC and the new plasma cutter with the exception of this error, and I seem to be getting a strange bevel in my cuts. But I wanted to fix this problem before tackling the next.

snowgoer540 wrote:

There's a few threads that cover similar issues. I would say that if you are having that problem on initial pierce, lost arc delay probably isn't going to fix your issue, or if it does it may be band-aiding a bigger problem. Speaking quite generally, that is more for end of cut scenarios where the "flame" is lost before the cut is officially ended (by a small amount).

It would also be helpful to see your pierce height, and material settings. Though I assume you are using the cut chart. At any rate, if your pierce height is too high, you will not get a reliable transfer from the pilot arc to the cutting arc.

So the common things that you'll see as a response from people to check (in no particular order):

1. Contact wetting. Some have reported success with adding a resistor to increase current across the arc-ok relay inside the hypertherm.
2. Do you have a debounce on the arc-ok signal? If you are using a newer install of PlasmaC, it is there by default.
3. I did not have success with my hypertherm using a Solid State Relay to trigger the "torch-on". There are several diagrams that show how to hook torch-on right to the 7i96 which makes use of the board's SSR to trigger the torch-on. The Hypertherm manual calls for a dry contact mechanical relay for this. My machine (power max 65) did similar to what you are saying until I switched torch-on to a mechanical relay. That said plenty of people use the 7i96 SSR with success.

That should give you a place to start with things to check.

I am using the height specs from the manual, so I am hesitant to believe that is the problem here. But maybe

Question 2: I am using the latest version of PlasmaC, so I assume I have a debounce on Arc-ok.
Question 3: You are correct in assuming I am using the solid state relay on the 7i96 board. Might need to switch over to a mechanical relay to remedy this issue. Especially if adding delay to the arc-ok check isn't intended for the beginning of the run. I don't want any band-aids. I want it fixed right.

snowgoer540 wrote:

At any rate, you do have a debounce on the arc-ok input. you can tell because of this line in the shop_plasmac_connections.hal file.

Try as Tommy suggested, or another similar thought would be to try using autovolts. I don't bother with the voltages in the hypertherm manual anymore. I exclusively use Auto volts as it takes the guess work out of that for us. But honestly it sounds to me like you aren't even getting far enough along for the THC to be doing its thing anyways. Easy to swap in a mechanical relay if you have one laying around; could be a simple fix.

As for the bevel you mentioned, perhaps you pulsed the torch too many times? One of the guys on here figured out that that really cuts down on the consumable life faster than you would expect and can cause beveling issues really quickly.

The bevel happens even if I have brand new fresh consumables.

Also, I am using auto volts for the THC. It does cut sometimes, and when it does the THC seems to be working perfectly. I think I will try a mechanical relay as Hypertherm recommends first. Then if that still doesn't do it I will play with the delay value.