Plasma Bevel

[pricer]

Could anyone give me any advice on how to reduce the bevel on .1875" to .500" mild steel. I am cutting with a 100amp Interlogic Plasma and an automated height control. I dont know if its the speed,amps or cutting height. I do not cutt enough of this material to be very accurate with this type of material. Need Improvement!

Thanks, pricer

[4104]

My Hypertherm plasma has some bevel even when I get the power, feed rate, torch height, and tip size set up pretty well. I'm under the impression that this is the nature of the beast and the only way to solve the problem is to go to using an expensive high definition plasma.

[Hobbiest]

Plasma cutters do this. The thicker the material, the greater the difference between top and bottom. Punch up in a search engine to find out why, (this is what I did) I acan't remember.

[dpaulson]

This is caused from the swirl direction. Generally, the 'good' side is the right side of the cut as the torch is moving away from you.

[DDM]

We had the same problems with our ESAB cnc plasma cutter at school. It does have to do with the vortex or swirl of the arc as dpaulson said. If it really bothers you and you can't figure it out you can pick up a nice angle grinder

Carl

[davspr]

Positive cut angle- top of piece smaller than botttom - lower the arc voltage.
Negative cut angle- top of piece larger tham bottom - raise arc voltage

[Alex S.A]

To avoid the angle you have o adjust the process in according with cut charts. The way of cut is too important as said above. Gas pressure must be set as requiered by machine. The torch must be positioned at 90 degree of the table. The table must be in level without angle. These points should take in consideration to avoid angle. In thinner material is harder to avoid the angle.

[hotponyshoes]

How about turning your torch at an angle?
Say your cut is showing a 10deg slope from top to bottom, turn your torch 5deg in one direction.
Now one side (the part) will have a stright edge and the other side (the scrap) will have a 10deg bevel.
Thats how I do it when hand cutting thick steel with a plasma. We have some washers with notches cut from them that are marked with paint for thicknesses of steal and ground down in a taper. we drop them in the top of a circle cutter attatchment when cutting drain covers and it comes out ok.
I havent got round to building a table yet as i am still saving for a machine torch so this advice may be useless!

[AppsGuy]

The best solution is always to use the lowest current possible for the thickness. i.e. .1875" use 30 amp consumables assuming you have a Proline or Fineline plasma. The lowest amperage produces the smallest kerf. Remember that the plasma jet is a tool that is a diameter. The nozzle size gets larger with the amperage which produces a larger kerf. If the kerf is .100" and the hole size is .200" you are looking for trouble. The system will not be able to reproduce the true shape of the hole including lead-in and out.
Slow down the machine. Depending on the hole size you may have to slow the machine down to 25% of actual cut speed. The taper is caused by lag in the bottom side of the arc because of the swirling gases. If you slow the machine down, chances are the machine will have true acceleration for the hole and you will reduce any lag at the bottom of the plate.
Slowing down the machine speed will cause the torch to dive, depending on your height control system. Newer technology doesn't care what the arc voltage is but is more concerned about the true height of the torch regardless of speed. But if your machine is more than 2 years old and not a Messer brand. You will have to force the height sensor off so the torch does not search for material.


Can't Fix it...Burn it.
Dan