No bevel 3/8" plate for the first cut

[TJS]

Ok. Cut some 3/8" plate today. All new consumables. Almost book specs. Slowed to 38ipm 65amp. Holes down to 16ipm. Drained compressor before I started. 110psi gauge at my hypertherm 85. No dthc. .060 cut height. I use a different configuration with thick material in command cnc. Slow down accel and all axis. My first plate was great. See pics. Cut another plate right after this one. Then I got some bevel. No pics of the second plate but you all know what I mean. Anyway, the only task I did not do was drain the compressor again. I do not have a refrigerator dryer. Just some of that purple rock stuff that turns pink when there is moisture in it. Pretty big can set up right at the plasma unit. Could moisture cause that much bevel.

[adbuch]

TJ - I would not think you would need to drain your compressor again after only a few cuts. Do you have very high humidity where you live? You could put a mirror under the torch while it is post flowing and see if any moisture condenses on the mirror (or fogs it up). Is it possible your torch got knocked out of square? I expect someone will say to put an o-ring between your cap and torch body as has been mentioned in previous posts. I would check to make sure your cap is tight to the torch body. Other than that, it's a mystery to me.

David

[adbuch]

I'm also wondering if there is any chance your cut height changed between cuts. That would probably do it. Is your material sitting level on the table? Maybe higher on one end because it might be resting on some slag residue on the slats. Just a thought.
David

[TJS]

Same plate. The next part was right next to it. My dthc is off on thicker material. All the parameters were the same. Humidity in the summer in CT is crazy high. I have a magnetic breakaway with bullet nose alignment pins. When I did my first part I had shades on and was looking at the height and it was good and never touched the plate. Even the lava tails were missed.

[weldguy]

It's not that moisture and/or oil contamination in the air causes bevels in the cuts, it causes the arc to super heat and damages the precision round hole in the nozzle. Once that happens the air flow direction will be altered and will steer the arc off center causing the bevel. High ambient humidity does not help either as this is the air that your compressor is gulping up making matters worse. The best way to determine if air contamination is likley your issue is to look inside a used nozzle and around the shaft of a used electrode. If you see black or dark swirling stains this is left overs from the contaminants in your air supply being burned up. This will need to be resolved with improved air filtration. Let us know what you find.

[TJS]

This nozzle with the bevel was the second cut. The first cut all consumables were brand new. I did take them out before the second cut to inspect the electrode and the nozzle because I was amazed that there was no bevel in 3/8" plate. All was pretty clean. The parifin was perfect. The inside of the nozzle was clean. No oil residue. Even older nozzles I have laying around are fairly clean. I am pretty stumped. I am leaning toward the hot humid weather. Did I say I dislike Summer.
Thanks for the suggestions.

[cutnweld]

That has been fought with and patched by some on this forum... I wonder if one problem is the internal air regulator built inside the plasma unit....? I dont know but I do know this bevel is a fight for some including me and not so much for others... I did a patch fix with an external Oring with mine that has helped me a lot...Its on a different post.... Some on this forum think I am a loony for thinking that it helps... It might not help but may be worth a shot.

[SegoMan DeSigns]

Yeah I would inspect the consumables again along with the attached filter inside the bowl and the o-rings outlined here:

https://www.plasmaspider.com/viewtopic. ... ng#p224740

[adbuch]

TJ - I'd like to see a photo of the "Bevel" so we know how bad it really is. It's hard to believe that one minute it cuts perfect, and the next not so much. Maybe the cap isn't tight on the torch body? Just a thought.

David

[djreiswig]

It's hard to believe that one minute it cuts perfect, and the next not so much.

That's pretty much how wrecked nozzles work.

[adbuch]

[TJS]

We all know how to tighten caps. Not too tight and not too loose. We all have been doing that a long time. I will see if I can get a pic of the second plate. It is on the weldment to be welded but I will take a pic later hopefully.

[adbuch]

We all know how to tighten caps. Not too tight and not too loose. We all have been doing that a long time. I will see if I can get a pic of the second plate. It is on the weldment to be welded but I will take a pic later hopefully.

Thanks TJ! This was just a thought. I'll look forward to seeing your pic of the second plate.
David

[cutnweld]

Did you try cutting again after replacing consumables? If you do it should work again for at least one piece, at least that's how mine used to act.

[TJS]

Did you try cutting again after replacing consumables? If you do it should work again for at least one piece, at least that's how mine used to act.

Not sure what you are saying here. Are you saying if I replaced the first set of new consumables (one cut old) with another set of new consumables(no cuts old) for the second plate then I would have no bevel. If I understand your thoughts, then that is just crazy.

I looked at the other thread. Still not sure where that O ring up in the body goes(is it an additional O ring or replacing what is there). A vid on this would be cool or better pics.

[TJS]

Here is the second plate.

[adbuch]

Here is the second plate.

20230815_170835.jpg

TJ - Although I'm pretty sure it is not the case with your parts, if the cut direction was changed from cw to ccw I believe that could cause more bevel. Just a thought.

David

[TJS]

Both plates used the same ngc file. Cw for outside and ccw for inside.

[djreiswig]

Is the bevel on all 4 edges or just on opposite sides and angled in the same direction? If the cross section looks like a parallelogram that is usually caused by a damaged nozzle. If you look at the hole in the nozzle with a magnifier there is normally a slight notch on one edge. This causes the arc to wander.
If you mark the nozzle before removing it and reassemble the consumables with the nozzle turned 90 degrees the bevel will probably move to the other axis.

[cutnweld]

let us know how you make out

[jimcolt]

First off, excess moisture in the compressed air will cause faster than normal wear to the electrode emitter (the silver colored slug of hafnium that is swaged inside a plasma electrode). As the emitter wears it develops a pit, which increases the distance between the electrode and the workpiece, increasing arc voltage. If the Torch Height is on, the thc will try to maintain the preset arc voltage and will move the torch closer to the plate in order to correct the higher arc voltage. So moisture can affect the cut bevel, though it typically is related to the condition of the electrode, and will (in most cases) create more edge bevel on all four cut directions.

Excess moisture in the compressed air also can affect nozzle life due to the electrode emitters moisture based wear creating some double arcs and spitting molten hafnium and copper down trough the nozzle orifice. This type of nozzle wear generally affects the angularity of the cut on two opposing edges....with a parallelogram cut edge on two sides of the cut.

Some of us can help troubleshoot if you post pics of the electrode arc attachment end as well as the nozzles exit orifice end. Good quality piscs of these parts can tell a story. Jim Colt