New 30kw laser, edges on 1-3/4 plate look rough - is that just how it is?

We've been running 1-1/4" mild steel on a big fiber daily for about two years, so here's what I've learned. Yes, there's a sweet spot, but it's narrower than the salesman implies. Above roughly half the machine's rated thickness capability, the cut quality on the bottom edge gets dicey no matter what you do with parameters. High pressure nitrogen gives you a pretty edge but slow and expensive, oxygen cuts fast but leaves a drossy edge and heat tint you'll be grinding anyway.

For the really thick stuff, I just plan on a cleanup pass from the start. We cut our heavy plate about 10% slower than the recommended chart speed, with oxygen, and budget 15 minutes per part for chisel-and-flap-disc work on the bottom edge. The dross is there, it's just a question of wether you fight it with parameters or accept it and plan around it. The trick nobody tells you: watch the pierce time on thick plate. If your pierces start taking forever or the pierce hole blows out oversized, your nozzle is worn or your lens is cooked, and that's when cut quality falls off a cliff mid-shift. We check lens condition every morning before the heavy stuff goes on. Also worth saying: on the biggest sections, the parts will come out not-flat. Heat input does that. If your downstream process needs flat parts, leave extra stock for machining or plan a stress relief step.

So yes, sweet spot exists for the mid-range thickness, but for the heaviest stuff, cleanup pass is just part of the process. Budget for it.

Running 1" stainless on ours most weeks and the thing that changed everything for me was switching to a cheap little dross removal tool from Harbor Freight instead of hand filing. Honestly I used to spend forever at the bench grinder. Now the parts pop off the table and it takes a minute per edge. I still slow the feed down on anything over about 3/4", learned that the hard way when I scrapped a whole batch. One thing I'd add on the pierce side, I keep a spare nozzle and lens drawer stocked so a bad morning doesn't kill the whole shift.

New here so bear with me. I don't run anything near 30kw, I've got a little 60w desktop for cutting acrylic and thin ply, but the piercing thing caught my eye. I've noticed on my machine that when a pierce starts taking longer than it used to, the lens is usally getting filthy. Guess scale is diferent but the symptoms sound the same. Do you guys keep spares on hand or do you order as needed? I'd hate to be down a day waiting on parts for a big machine like that.

We're on a 12kw so not quite the same league, but the flatness thing hit home for us. Cut some 3/8 brackets last month and they came off the table looking like potato chips. Had to add a shim in the fixture to make them sit right. Now anything with a big cut area gets a day to cool before we touch it, and that alone fixed half the warping complaints from the shop floor.

Ha, this takes me back. We used to do heavy plate on a plasma table in the 90s and the cleanup budget was the same story, just worse edges. Ran a 6kw CO2 after that and learned to cut heavy stuff first thing in the morning when the machine and the plate were both cold. Made a bigger difference than any parameter change I ever tried. Do you guys notice the thick cuts walking around more as the day goes on and everything heats up, or is that just my old tables?