Torch cutting different angles

[Justme]

First off, I have a PM45 running on a Plasmacam table. I have Plasmacam's basic Design Edge software and their advanced height control. I have had this setup running for roughly 4 months or so. I am also pretty new to plasma cutting.

I was recently cutting some 3/16" steel. This is the first time I have cut anything thicker than 11 guage so far, and I noticed that it is cutting a different angle in each direction. I am referring to the bevel of the cut.

To help explain this, I'll describe cutting a square part. For reference, imagine the upper right corner of the table as "A", the lower right as "B", the lower left as "C", and the upper left as "D".

When it cuts from "A" to ""B the bottom of the cut is beveled out considerably.

Then, when it turns the corner and cuts from "B" to "C" it is still beveled out at the bottom, but only a slightly.

Then as it cuts from "C" to "D" the cut is very flat and square.

Then it turns and cuts from "D" to "A" and the cut has a very pronounced bevel in at the bottom.

Below are a few pictures:

The edge on the right is the "A" to "B" cut, left is the "C" to "D" cut:




Right edge is "D" to "A" cut, left is "B" to "C" cut:




I have watched the height really closely while it is cutting, and once it goes from pierce to cut height it does not change, at least not enough to where I can see it. I have stopped it while cutting and checked the height from surface to torch and it is right at .060" with a feeler guage.


Cut speed is 65 ipm
Cut height is .060"


Any ideas? If there is any other info that would help let me know.

[Joshfromsaltlake]

Bad nozzle or bad electrode I think. Did you try replacing the consumables first?

If either turn out to be bad, you may be able to increase your cut speed or reduce your current after you replace the offending part.

[WookieWelding]

slow down your ipm and i bet a 6 pack it cuts clean

[LarryO]

Machine torch or hand torch setup?

[Mick120]

Check your consumables, what you're showing points towards a worn nozzle or shield.
Buy yourself a jewelers loupe, it makes it easy to study the nozzle to check for any ovality of the orifice.
When you fit new consumables, don't overtighten the retainer.
Check the torch to plate squareness, I'm guessing you're still running a hand torch.
Ensure you have clean dry air at the correct pressure.
Plus, check your conversion settings and, make sure you have "cut parts to right of paths" checked.
Finally, the cut speeds in the Hypertherm manual are very close to spot on....still, trial and error to get it dialled in....also, once dialled in, make sure you use the DHC to maintain the correct cut height.

[Justme]

Thanks for the suggestions. I will try a new set of consumables. The ones in it look good with the naked eye, but you never know. I need to pick up some new ones tomorrow. The ones in it have very little time on them, but I'll change them out and see what happens.

Yes, it is running with the hand torch.

Cutting the thinner stuff I have been, this effect is not really noticable, so I don't know how long it has been this way. It just is more apparent with the thicker material. I did try slowing down the speed, but it did not seem to make any difference.

[NVW]

Mine does that with worn consumables.

[Mick120]

Just one more thing.
If you haven't already, head on over and join the PlasmaPIG Yahoo group.

http://dir.groups.yahoo.com/group/Plasmapig/

A real nice group of dedicated Plasmacam and Samson owners, that'll help you out of almost any jam.
There's probably more info there about Plasmacam machines than anywhere on the www.
Read the preamble on the home page to join.

[Justme]

Ok, thanks. I did join the Plasmacam forum, but it is not very busy at all. It is also Kind of an odd forum. You can't even post pictures!

[Mick120]

Originally Posted by Justme

Ok, thanks. I did join the Plasmacam forum, but it is not very busy at all. It is also Kind of an odd forum. You can't even post pictures!

If you mean the Plasmacam owners forum, you can post pics.
Go to the files section....just no attachments to posts is all.

You'll find the PIG to be a well run, informative, tight group....We still have a laugh but, don't put up with any crap.....One of the reasons it's so popular with owners.

[shovelon]

Originally Posted by Justme

Ok, thanks. I did join the Plasmacam forum, but it is not very busy at all. It is also Kind of an odd forum. You can't even post pictures!

Just watch out for that Mick guy on the pig.

I am a bit old school with my table. Loosen your clamps and tilt the head until you get the cut you want. Mine never lines up right on the first try. Finecut nozzles last tons longer than standard, and find the ohmic shield to go with it.

Are you cutting with the "orange rooster plum"?

[SundownIII]

Think you're going to find that all hand held torches have a good side and the "drop" side. Has to do with the design of the swirl ring and how gases exit the nozzle. Both my PM 600 and PM 1250 have this characteristic.

New consumables do help the situation, but are not a total solution.

The thicker the material, the more the plasma "stream" tends to flare out.

Same thing happens with our water jet. The computer actually "tilts" the nozzle to achieve a true 90 deg face on the "saved" piece.

[jimcolt]

If you are seeing consistent angularity around the perimeter of the part...then you can assume the torch and consumables are ok......you can then reduce the angularity by running slower and closer to the plate.

If you have varying angularity....in other words the 4 sides of a square are all drastically different....then one of the following is the issue:

- torch is not perpendicular. Machine torches are much easier to square to the plate then hand torches. Do not use a level.....use a square and check the relation of the torch to the plate on both x and y axis. So many tell me their torch is perpendicular...yet they have no way to check it!

-Consumables...especially the nozzle orifice and /or the shield orifice are worn and out of concentricity. The nozzle and the shield shap the arc....if the nozzle and the shield orifice are not perfectly round....expect the cut angularity to change. One bad pierce (too close to the plate) will damage a nozzle orifice.....this is why good, full featured height controls are so omportant.

- Poorly manufactured or designed consumables. There are many knock off consumables for major brand torches....some even come in packages with the correct logo on them. If you are getting consumables real cheap.....then suspect they are knockoffs. They can damage your torch, and they can cost you more if they do not cut well.

There also are torch designs...generally older technology designs...that simply do not cut with the quality of the latest technology. Think that $499 import plasma will cut with the same quality as the new Hypertherm Duramax torch? Think again! It will cut metal, but it will not have near the consumable life or the cut quality consistency.

Attached is a picture of a piece of 3/8" steel...cut at book specs with a Hypertherm Powermax45. The edge angularity was acurrately measured...and is written on the piece for each side. To the naked eye...the edges on this piece look perfectly square. The consistency from side to side is what you get with a good torch, proper cutting technique, and a good height control.

Jim Colt