Edge cuts look like quarters = Rigid

[gamble]

Haven't touched the machine in a while due to some antiback lash nuts shitting the bed. Put on some new ones and did some cuts on thin material and did some 3/16" plate tonight. Only other thing that has changed is there is no water in the bed, but that shouldn't matter.
Why am I getting edges looking like a quarter?

[urbnsr]

Have you used this same cut file before without quarter-edging? If so, can you tell how smooth the torch is now moving during the cut? It kind of looks like either the round edge in the second picture is actually made up of a polyline or a spline and the cut file is really cutting many very short lines and also possibly the acceleration setting is set too fast. If they are made up of arcs, the cut file would use G02 or G03 for motion control.

Maybe you had backlash issues before resulting in smoother looking motion and now you fixed the backlash which is showing up as a more ridged motion. Again - I would slow down acceleration to see if things smooth out? Does your table use drive reduction or do you use higher microstepping settings?

HTH
Paul

[gamble]

I think it used microstepping
I have been making these for over a year now and they are all cut from the same file and always cut out smooth

It was weird I could hear the plasma not sounding right and this was the result

This is 3/16", 45 amps and 85ipm. Same settings I always use

[Thor]

DTHC is stable or bouncing up and down? Air is clean, no water in air?

[gamble]

Voltage is pretty stable for sure. No noticeable slop in the torch. I check that pretty often.
I have the m60 filter but I will be honest I have no idea if it needs to be changed. I will check it out

[Capstone]

I have had the exact same problems with my table too Gamble. That's definitely DTHC "Bouncing" you're seeing. I'm convinced it's combination of gantry vibrations cause by quick turns with my 130lb gantry, combined with the DTHC overcompensating. Once the vibrations in the DTHC itself starts however, regardless of the actual shuddering of the gantry, the DTHC goes into a vicious cycle of overcompensated corrections, or starts climbing out of control which causes the sawtooth cuts. I've spent a lot of time and energy changing the speeds and feeds and creating rules to slow everything down and it's helped somewhat, but ultimately, I'm resigned to not using DTHC on thicker metals where cut speeds don't affect the gantry shudder, and then on the thinner stuff I just assume there will be TONS of dross and shortened life consumables until I can rebuild my table base to add stability. Even then, I'm not convince it will stop, but it's all I can think to do at this point

[gamble]

I had a similar issue prior when cutting at fast speeds like 250ipm but at 85ipm I thought it could be something else

[jimcolt]

If it is motion related then you should clearly be able to feel the vibration by putting your hand on the torch while it is cutting. If you feel any vibration....said vibration will show on the cut edge.

From the pics.....and since the edge striations seem uniform ( both x and y, plus and minus directions)....I would suggest a thorough cleaning of the ways and the bearings. I'm sure that if you disconnect x and y motors and push the machine by hand it will be pretty crunchy.

Oscillation, vibration will make the plasma sound different as well.

Jim Colt Hypertherm

[gamble]

I just changed the anti back lash nuts and wiped down the drive screws. Should I lube those up? And the machine slide back and forth like a dream. But I do have to clean the bearings for sure.
Did some 1/8" cuts this morning at 155ipm and the results were much better but still noticeable around a curve

[motoguy]

Run the file with DTHC turned off, and see if the problem persists. That will rule out the DTHC system, or let you know it's related.

[SeanP]

I use engine oil on the plastic nut rightly or wrongly, and give it a good clean down once a month or so, it' sbeen used every day like that for the last 3yrs and still fine, same goes for the linear bearings.
The biggest pain with that is getting oily kecks leaning over the table,,,,mod needed there

I had parts coming out a bit like that a few weeks ago, I upped the acceleration a bit and it's fine now.
You would know about it it it was dthc causing that, it makes a right racket, cant see that doing it.