I used the Langmuir .055 for cam to set kerf. I cut a 2” hole and had to add .045 to make it with in .002 smaller than 2”. That was done in the drawing. I made it 2.045, It goes over the pipe but I don’t think guessing is good. Material costs too much. where do you set the proper kerf.
Mine is cutting real good!!!
Kerf changes by power (amps), tip size and material by and large.
So you’d want to use a test cut calibration file that you can use on various materials & thicknesses. The power & tip size that works well for a specific material will tend to stay good so you just need to run the test project for each material after you’ve dialed in power, speed & tip.
The test calibration project can be a set of known sized squares, circles and lines and run with it outside and inside.
You’ll then be able to physically measure the actual hole or part size against what you specified with calipers to get how much you lost to the kerf.
Basically you are saying do a test circle at 2”. Measure in and out. Adjust difference in tool selection. Langmuir says .055 so that would be .110 total kerf right? So if I’m .045 too small I need to change that to .075 right???
Make 2 circles. On one set the path on the outside so you’re preserving the cut out round piece. On the other set the path to the inside so you get a clean hole.
That way you’ll have the measurements based on what you’re trying to preserve - the cutout or the hole.
CNC machines account for kerf in a couple of standard ways. On a mill, the software compensates for the diameter of the bit and you just have to tell the software which side of the cut you want to be the “right” size.
The Crossfire with F360 & Mach 3 imply this is the case here too - you set the kerf in F360 in the tool definition. I haven’t done extensive testing on this yet as my projects have been decorative and didn’t require kerf adjusted precision yet - but some early stuff I did seemed to indicate it wasn’t doing that. It could be I had the wrong values defined (I used Daniel’s video #s when setting up my torch in F360).
The other way is where the CNC software doesn’t do any compensation and you have to adjust the measurements but you have to also know whether it cuts on the outside or inside of the line by offsetting the torch some distance that may not be the actual kerf (pseudo-compensated) or if it cuts on the line where it will leave half a kerf of space on each side of the line.
If it’s the latter, then for your circle, the diameter will be reduced by a full kerf width - each side of the circle’s diameter is being reduced by 1/2 a kerf width as the arc travels along the line.
I understand what you are saying. Right now the parts I’m cutting will be added .045 to the 2” diameter. My next project will have to be calibrated. Thanks so much for the detailed explanation that you took the time to type!!