Problem with bevel inside square parts

[chrissinser]

Hey all!

My name is Chris and I have recently became cnc "operator" at my job. I use that term loosely bc I am very new at this. Lets just say I was forced into this position being as I am the most "computer qualified" to run our machine with my background. My current set up is a Torchmate X gantry system with an AVHC height controller running a Powermax 105 torch.

Currently I am having an issue with beveling on my parts. I am running a 1/2" steel plate on my machine and I'm trying to cut a 3/4" squares holes out. Up to this point I have tried every recipe combination of cut heights, speed, voltage and pierce heights that I can think of to compensate for the bevel with little to no luck. The 3/4" squares are for a steel bar fence picket, so then need to be accurate and square throughout. The bevel seems to be running to the inside of the part, causing the bottom of the plate to be way off, especially in the corners. I have tried to compensate with a kerf compensation but I need the pickets to be tight and I loose too much material. ( I have attached some pictures)

I realize plasma is only accurate within a certain percentage, however I've seen people on the forums have very successful cuts with little to no post production process with the same type of material.

I was wondering if anyone had some ideas or advice on how I can trouble shoot this issue would be greatly appreciated!





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[NathanAtSplash]

Make sure your speed and voltage are set properly and make sure your consumables aren't worn out.

[Web Goblin]

I would say that your travelling too fast. With a standard plasma cutter you aren't going to get vertical edges. To get proper vertical cuts you need hidef or even better a rotation unit with zero degree compensation. Again check the consumables and also check that the torch is vertical as well.
Have a look here: Plasma Arc Cutting - Cut quality problems-Dross | Hypertherm
Hopefully it will help you out.

[xjdubber]

How is the quality of the square coming out, your toolpath might be running the wrong way around.

[ronsii]

If pic 1 shows the lead-in then you are probably cutting in the wrong direction... as torch travels the good side of the cut is usually on the right of the torch as it moves forward... at least in conventional torches.

[jimcolt]

Definitely cutting in the wrong direction. Outside cuts always need to go clockwise, inside cuts counterclockwise as plasma is directional.

Jim Colt Hypertherm