Plasmacam dhc2 possible THC problem on 0.5" plate

[Jacampb2]

Hey folks, I'm hoping some of you might be able to help. Let me start by giving a bit of background. I bought this table second hand and did not get a copy of the software or manual. I eventually got the software, but I never did get a full video manual for the 3.1 software.

I haven't used the table much, but I recently moved it to a dedicated metal fab area, so will hopefully get more use out of it. I have cut a lot of 16g and thinner sheet metal on both mild steel and aluminum and after getting my botched voltage divider (ordered from plasmacam) repaired, it was pretty much flawless.

I recently started a build of a stump bucket and grapple for my tractor and am cutting the bulk of it out of 0.5" plate. I'm having issues with the THC maintaining proper height. I wouldn't think plate this thick is moving much during the cut, but it's occasionally diving into the work or climbing much to high. When it sits around 0.060", it's pretty much perfect but it wanders far too much and wrecks the cut.

I don't have a ton of extra plate for this job, and each mistake is costing a fair amount of money. I'm hoping someone might be able to give me some guidance.

I'm not sure it's relavent, but the plasma cutter is a hypertherm powermax 1000 g3. I've got 60a consumables in it and current set at 60a.

Thanks in advance folks!

Sincerely,
Jason

[adbuch]

Jason - you might consider turning off your thc. If you plate is sitting level on the table and is pretty flat then I think you will be fine.
David

[Jacampb2]

I did try that initially but apparently one end of the cutting grate is sitting a bit proud. You wouldn't think so with 400lbs of steel on it, but it cut about 36" in a straight line perfectly and then got close enough to just barely start dragging on the table. I manually bumped the height up, but at that point I had the z travel set far to fast for manual adjustments and I couldn't get it in a good band again so I gave up and cancelled and went back to trying to get the THC to cooperate.

I've since slowed the z axis down, so maybe I'll give it another shot.

Thank you,
Jason

[adbuch]

Try putting some small shims under the low side of the plate (between underside of plate and cutting grate) to level out your plate. Then do a dry run with torch at cut height and pause at ends of cuts to and measure to make sure you are maintaining the same distance between torch and plate.
David

[Jacampb2]

Try putting some small shims under the low side of the plate (between underside of plate and cutting grate) to level out your plate. Then do a dry run with torch at cut height and pause at ends of cuts to and measure to make sure you are maintaining the same distance between torch and plate.
David

That's a great idea that I neglected to read before I started today. Lmao. I need to cut a replacement grate for this table but I haven't had the extra cash for a sheet of 18g just for the table itself. It hasn't been a problem with thin material, I never figured it would be an issue with heavy stuff.

Anyhow, I got the job done. I manually adjusted my z as needed and it did pretty well. I think my consumables were trash by the end. My kerf really got blown out. In hind sight, I think I had some Chinese knockoff consumables in the machine. I bought them just to test and cut stuff for myself, I never looked at what I had loaded other than to make use it wasn't the silver 40a fine cut ones I use.

I spent the morning cutting and the afternoon welding. I think it came out pretty good.

PXL_20230613_204857584~2-picsay.jpg

[DieselFumes]

Gnarly looking! Very nicely designed and built you should be proud of that homegrown implement

[Jacampb2]

I drew up the thumb this morning and cut the plate this afternoon. I made sure I had authentic consumables in it this time. I had much better cut quality. I cut the entire sheet and after the first half of the thumb I didn't feel I needed to babysit it, but I did get the THC working right for this sheet as well.

I'm not really sure if it was the consumables or the manual eyeball height control that caused the poor quality.

For posterity, I'm pretty sure I know why the THC was screwed up. Operator error... I thought I remembered that I was supposed to auto calibrate with material and consumable changes, and I did that right if the hop when I started. I did not however have my pierce delay set anywhere near long enough though and at first it was gouging for quite a while before it managed to pierce the plate. I realized that right away and fixed the delay, but I never recalibrated it. I'm guessing that's more than enough reason for the issues-- all of it was on the human side... But hey, at least I'm fessing up! Lol.

Pictures of today's work are attached.

Thanks for the assistance folks! I'll post up tomorrow once I have her welded up. I'm going to have to machine some pins and spacers, so it might be a few days before I'm at 100% completion.