[solved] What is causing this jaggedness

[Teknic]

So before I show the issue just want to go over my details:

PLASMA:
RazorWeld 45
PTM60 Machine Torch
40A Shielded Consumables
Consumables are Fresh at time of this issue
160ipm
Machine has 80 psi @ idle, 75psi while cutting
Cut Height .05”, pierce height .12”

AIR SUPPLY:
~17 SCFM, 80 Gallon Compressor
Air leaves tank, 6 48” drop legs of 1” copper, goes to oil separator and desiccant filter (desiccant was fresh and blue before cut), goes to Refrigerated Air Dryer running 34 degree F, goes to Eastwood CFS Desiccant Dryer (cartridge was fresh and new) run through ~10 ft of rubber air line to a MotorGuard filter (stays bone dry) goes to 1foot hose, enters plasma cutter

SYSTEM:
Latest FireControl and THC
Laptop, unplugged
THC is enabled, running Smart Voltage

MATERIAL
16 G Hot Rolled Steel

FILE
You’ll see the file cuts perfect one time, the other time the issue occurs

Ok fun stuff is out of the way now, now for the pics.

Here you can see where the jaggedness starts, goes from perfectly smooth to jagged

Here’s how long it stays jagged, you see it stays jagged in all directions

Here’s where it ends, just turns a corner and butter smooth again.

Here it comes up suddenly then goes back away.

Then whatever this crazy wavy thing is, was supposed to be smooth, nothing like this.

EXAMPLES OF GOOD CUT (done after bad one, with same consumables that were in there, lowered to 140ipm only change made, but I’ve had this happen before while keeping speeds identical)

Soooooo, opinions on a possible cause?

[TinWhisperer]

@Teknic

desiccant filter (desiccant was fresh and blue before cut), goes to Refrigerated Air Dryer running 34 degree F,

Desiccant after the refrigerated air dryer.

I don’t think it’s related to your jagged issue but it helps to put the latent loads in the right places.

[Teknic]

I got a desiccant on both sides, I thought I had read that was preferred, I’ll gladly remove the one before as it’s not as nice as the QC3 knockoff

[TinWhisperer]

Your z-axis staying steady while cutting ,no bobbing?

I’m wondering if there’s some air delivery problem in the torch itself?
Swirl ring? Debris in the airstream?

[Teknic]

I try to watch the Z but I swear it happens every time I’m not staring at it thru my mask lol. Thru my tinted torch glasses I want to say it wasn’t bobbing but without my weld mask I can’t be 100%

I recently found a binding in my z axis from bearings being too snug near cut height, but I readjusted and it now moves freely and without wiggle room. I do think those Z Axis bars aren’t perfectly straight though as the top of the travel it can wiggle a bit but at cut height it’s fine.

Swirl ring wasn’t changed with rest of consumables so it’s possible. I also didn’t change the shield/cap but checked all air holes and they were clear and there’s no damage near nozzle.

I think I have a fresh swirl ring I can toss on.

In terms of debris do you mean like stuff splashing up during cut and onto the torch?

Do you feel it’s an issue with the plasma cutter? That’s my main thing I’m trying to determine if it’s a table issue or a plasma issue, I have a new Hypertherm coming July 28 so if it’s a plasma issue I can rest easier

[Midnight_machinist]

Just a though, hows the lead screws and nuts? Any bends in the screws? Something loose maybe?

[Teknic]

So I believe they’re all tight, I’ve checked them a few times and can’t turn the screws anymore. But I did buy paint marker to check so I’ll be marking them before my next cut and I’ll see if they move.

As for bent screws, when they spin they don’t seem perfectly straight but I’m not sure I’d say they’re bent. I’ll take and post a video of them tonight just so someone can compare

One thing I was considering was maybe the little roller bearings on the gantry have gotten tight over time. I was planning on reading how to set them again and going through that process. I noticed that on each side there’s 1 or 2 that don’t spin freely while the machine is at a stop but the rest I can spin with my finger

Oh and this issue has been happening for a bit so lots of these checks were done/checked before this jagged cut. I had just cleaned out my water tray and everything so I could go over the machine more closely

[Phillipw]

May be something mechanical. Just a thought video all lead screws and such even in slow motion. that way you can take time to evaluate and not burn to much steel. Even doin small circles or squares.

[TinWhisperer]

Do you have another torch you can try?

@Teknic

In terms of debris do you mean like stuff splashing up during cut and onto the torch?

No in the torch tumble around interrupting the air flow . pulsing it.

Torch air flow issues

or

Z chatter

Is my two top thoughts

[Teknic]

I have the hand torch that came with the plasma that I had been thinking of tossing on to try out, I can definitely do that.

As for debris inside the torch, I don’t think so but not sure how I’d check that. It seems clean inside and with the motorguard so close I’d assume any debris in the lines is getting filtered only ~1 foot from the machine.

In my head I have been thinking a z issue, is there anything to check besides those roller bearings on the 2 vertical posts?

When I get home I’ll paint the lead screw couplers, video the lead screw movement, video how it moves on each axis, install the hand torch, and take some pics of the machine torch internals.

I appreciate all the help from everyone so far, I don’t mind checking whatever I need to in solving this

[TinWhisperer]

@Teknic

As for debris inside the torch, I don’t think so but not sure how I’d check that. It seems clean inside and with the motorguard so close I’d assume any debris in the lines is getting filtered only ~1 foot from the machine.

It is unlikely but it was popping into my head.

Check out the Z axis more. I like this filming idea.

@Phillipw

Just a thought video all lead screws and such even in slow motion.

Even a standard speed video.

[rat196426]

Not all the bearings will be tight on gantry, you want to adjust so that bearing just stops spinning with finger as you adjust. Not all the bearings will touch at one point as they travel on tubes.

[Teknic]

Yea like 1 bearing on each set I can’t spin by finger, just something I noticed by chance so I didn’t check in detail or in separate positions. I’ll add that to my checklist tonight

[jdr2710]

I noticed on my system that some of the various bolts had worked loose: one of the gantry bearing housings and both of the Y axis stepper motor mounts.

[langmuir-daniel]

Saw tooth cut edges are almost always caused by pulsation in the air flow out of the torch. Many times the pulsing is visible.

As long as the torch isnt dragging on the plate, very unlikely that the issue is with the machine itself. I’d be paying more attention to the torch/consumables/air supply.

[Teknic]

Thank you for that input, I think swapping back to the hand torch will be a good idea just to eliminate anything within the torch. I’ve never used the hand torch so all of it is brand new.

You mention pulsing, I think that might describe what I see when it happens it’s not super noticeable but you can also hear it in the sound of the cut. Hard to describe it but I think pulsing might be a way to describe it. I assumed it was an after effect rather than part of the actual issue

I believe my volume of air to the machine is good and my gauge on the plasma doesn’t budge even with compressor running, it can catch up and refill the system even during a cut pretty easily when it kicks in. It’s always 80psi idle and roughly 75psi while cutting. (I know pressure isn’t volume but there’s no flow restrictions either)

My tank is good for 175psi, I keep it at 125psi just because I haven’t adjusted the compressor switch after installing it (kicks on at 90psi, off at 125). I don’t think that’d have any effect but I just thought of it, if anyone thinks that’s an issue I can adjust that too.

[Phillipw]

Food for thought I was afraid of air restrictions from air dryer. I found a small air compressor someone and had made a dry storage tank. That way my sand blaster, plasma and powder coating machine has a reserve to pull from. Most will give you bad air compressor they have burnt up the compressor on

[Teknic]

Yea I had issue before air dryer, was running just copper/desiccant/motorguard. Got the air dryer “just in case” I had moisture I wasn’t able to detect that was causing this issue.

I have a spare 80 gallon compressor tank that I’m in process of restoring (a vintage monster Saylor Beall unit, something like 25SCFM or something nuts) so if it comes down to it I can always plumb that inline to test as the tank is perfect. I also have a couple horizontal compressors I can plumb in-line (mechanic by trade and own a farm, so I use air tools for everything)

Think I’ll leave that last though, start by replacing torch and going down checklist, that stuffs much easier

[Phillipw]

It does take up valuable room in my shop. The extra capacity is nice. Any chance the air line on plasma may have issues like a collapsed line or something?

[Teknic]

Not positive, all lines used were brand new at time of buying the plasma. When I use the system for other things I never notice odd behavior from the air. I swap connections right at the motorguard so I use 99% of the system for everything else I do with my air. Only thing unique to the plasma is the 1 foot hose from motorguard to plasma. I’ll definitely check on them and check inside the razorweld too as I know those are small hard flexible lines