Plasma Cutter Angled Cut Problem

[Cali-Cruiser]

I've got a Langmuir Systems Crossfire CNC plasma table that I bought in their initial offering/preorder thing. It uses a Razorweld brand Razercut45 plasma cutter. The CNC works well but it has always had a problem of the cuts seem to always have a slant, where the resulting cut edge is about 70 deg not 90 to the plate surface, but that is only while the torch is traveling in certain directions.

If you were to cut a circle out, at the top and bottom of the circle those areas would both be angled cuts (in the same direction) the left and right sides are 90deg. I've replaced consumables multiple times, the entire tip assembly, the torch rotated different ways, with no luck. I've also flipped the mixer ring with no change.

Has anyone else seen a problem like this? or have any ideas what could be causing such a problem?

I'm happy with the machine but have to do more clean up and have less precision than it should.

Thanks

 

[CarterKraft]

That has always been my consumables on my China Plasma.
I have had hell buying consumables for it but often it happens and I will swap to new parts or loosen and reposition and it's fixed.

 

[ThePanzerFuhrer]

The way the part is cut cw or ccw will have a impact on the angle. One direction will have a squarer side on the part. Also torch height has a impact on the bevel.

 

[bgaidan]

The way the part is cut cw or ccw will have a impact on the angle. One direction will have a squarer side on the part. Also torch height has a impact on the bevel.

Not sure on a CNC, but I've noticed the ground clamp placement will "draw" the arc toward it. I'd assume on a CNC you're grounding through the table slats and it'd be less of an issue.

 

[TTMotorsports]

My CNC plasma cutter always cuts the outside edge's clockwise. The inner circles it cuts counter clockwise since it says it cuts more accurately. If my cut speed is fast basically at the fastest it will cut clean the cuts will have more angle. If I cut at 110 ipm I slow it down 10% to 100 it will have less angle.

 

[bgaidan]

My CNC plasma cutter always cuts the outside edge's clockwise. The inner circles it cuts counter clockwise since it says it cuts more accurately. If my cut speed is fast basically at the fastest it will cut clean the cuts will have more angle. If I cut at 110 ipm I slow it down 10% to 100 it will have less angle.

Does the tolerance go down with a slower cut? I'd think slower would mean a wider kerf and potentially under-sized parts? Or are the offsets and amperage also adjusted by the speed?

I really need to get a table....

 

[ThePanzerFuhrer]

Does the tolerance go down with a slower cut? I'd think slower would mean a wider kerf and potentially under-sized parts? Or are the offsets and amperage also adjusted by the speed?

I really need to get a table....

Too fast and the flame follows at a 30 degree angle. Then makes the corners poor.

Once you get the best run settings on your particular machine size is +_ .020ish. You have to be vigilant if you want super accurate parts with homeowner grade equipment.

For what I do +_ .125 is just fine. The wire I use to weld the peices together is .0625 thick lol

The vise parts I cut out on my little bros low end industrial machine. Does a beautiful job.

 

[TTMotorsports]

Going slower does make the kerf width a little bit wider. BUT what I do is cut a square that's 1" x 2" at the speed. Then measure the cut width and adjust kerf if needed.

 

[GLTHFJ60]

I've got a Langmuir table with a hypertherm powermax 45xp machine torch. I have that problem with bevels when going faster and with old consumables.

Swap out consumables and try again. Same thing with new consumables, slow down a bit.

 

[LunchBoxFab]

does your machine have auto height adjustment?

my torchamate has a manual z control, and the parts come out beveled if i have the height set wrong.

 

[clodhopper]

Going slower does make the kerf width a little bit wider. BUT what I do is cut a square that's 1" x 2" at the speed. Then measure the cut width and adjust kerf if needed.

This. Dont try to adjust to get a particular kerf, you will chase your tail. Adjust your table to best cut, then adjust the drawing for resulting kerf. Expect to change out consumables more often on a table than doing work by hand. Mostly because you can see the drop in cut quality easier on the table. By hand you just assume some sloppy motion and attribute it to your hand motion and you can compensate a bit when doing hand work. Tables are hard on consumables with lots of pierces, not always good standoff, and long long burns.

 

[bgaidan]

This. Dont try to adjust to get a particular kerf, you will chase your tail. Adjust your table to best cut, then adjust the drawing for resulting kerf. Expect to change out consumables more often on a table than doing work by hand. Mostly because you can see the drop in cut quality easier on the table. By hand you just assume some sloppy motion and attribute it to your hand motion and you can compensate a bit when doing hand work. Tables are hard on consumables with lots of pierces, not always good standoff, and long long burns.

Do the controls not have adjustments for kerf size or are you stuck having to resize your drawing? Or is it at least a setting in the CAM side?


Like on my mill, I can use cutter compensation. If I program it with a .25" endmill, but I end up using one that's been resharpened and it measures .21", I can plug that in and it'll compensate the the program for the new cutter size. That's all done in the control, not the cad/cam side. Technically you could do it for a completely different size - like program for a 1/2" and compensate to 1/4", but I've read that certain radiused corners may not turn out quite right.

 

[GLTHFJ60]

Do the controls not have adjustments for kerf size or are you stuck having to resize your drawing? Or is it at least a setting in the CAM side?


Like on my mill, I can use cutter compensation. If I program it with a .25" endmill, but I end up using one that's been resharpened and it measures .21", I can plug that in and it'll compensate the the program for the new cutter size. That's all done in the control, not the cad/cam side. Technically you could do it for a completely different size - like program for a 1/2" and compensate to 1/4", but I've read that certain radiused corners may not turn out quite right.

Yeah they do. In fusion 360, when you're picking your cutting tool, you specify a kerf size. When generating toolpaths, it generates with the kerf in mind to get your parts as close to on size as possible. It's generally very good. Not perfect by any stretch, but very good.

 

[bgaidan]

Yeah they do. In fusion 360, when you're picking your cutting tool, you specify a kerf size. When generating toolpaths, it generates with the kerf in mind to get your parts as close to on size as possible. It's generally very good. Not perfect by any stretch, but very good.

But that's still done in the CAM side.

Thinking about it more, I guess the control is kind of dumb and it doesn't really know which side of the cut is your part and which side is waste so it wouldn't know which side to compensate on for the kerf. Makes sense.

 

[clodhopper]

But that's still done in the CAM side.

Thinking about it more, I guess the control is kind of dumb and it doesn't really know which side of the cut is your part and which side is waste so it wouldn't know which side to compensate on for the kerf. Makes sense.

Depends on your software. Some are better than others. I started without any of the fancy automation and just incorporated all the things into the drawing as I was creating it. The automation I have used works good on artsy stuff, but often had to turn it off for complex items when it wasnt obvious which side of the line the kerf needed to follow. Seems like a big deal, but once you start messin around with a cut table, you just start thinking within the limitations of the gear you are running.

 

[bgaidan]

Depends on your software. Some are better than others. I started without any of the fancy automation and just incorporated all the things into the drawing as I was creating it. The automation I have used works good on artsy stuff, but often had to turn it off for complex items when it wasnt obvious which side of the line the kerf needed to follow. Seems like a big deal, but once you start messin around with a cut table, you just start thinking within the limitations of the gear you are running.

Got ya. I use fusion for my mill and router and plasma is pretty much the same as a contour toolpath except with a little torch control instead of spinny control.

I really want a plasma table. I'm half tempted to convert my router to plasma but I'd probably come out ahead just selling it and buying the right shit from the start.