Kerf for Inside Cutting Offset

[djmad]

Hello

Actually i have some troubles with cutting holes in a 5mm mild steel.

As the flanks are a little bit angled (approx 3°) to the inside of the circle
the cutted circles are on the underside of the cutting a little bit smaller.

it only happens on cutting holes, where the flame is following the cutting-kerf and producing this flank doing so.

Now my question if there is a way to shift the offset as example for 0.3mm to the outside on inside cuts to compensate this behavior of the plasma torch?
would be nice as Pathrules where this offset can be added or reduced to get exact messuring cuts for holes.

if not possible only option would be to write this compensation into the postprocessor somewhere in the function OnArc() here, but actually i have no idea how to do so, because the post does not know outside or inside cut

[WyoGreen]

Good morning.

I am going to assume that you are making a separate cutting operation for the holes, and that you are using an inside offset on those holes. If so, then try using no offset for the holes and set the lead-in on the inside of the hole.

Steve

[Les Newell]

Path rules can't modify offsets. They are calculated after the offsets have been generated.

One trick you can use is to define a tool with a 0.3mm smaller kerf and use that to cut the holes.

[djmad]

Hi

At the moment i dont make seperate rules, just outside to the complete layer.
point is that it should be as stupid to operate as possible, because it will be a consumer product.

Its just the point that all round inside cuts always tend to get smaller on the bottom of the cut......
To create a additional program for holes just is wrong in my point of view. It just makes things much more complicated.

The trick with 0.3mm smaller kerf is nice, but not possible when cutting 40mm sheets, which are 2mm wrong, i cannot feed -1.5mm kerf into the programm what i know

[WyoGreen]

When you are cutting a hole, you need to think about the geometry of what is going on. The plasma torch is not cutting straight up and down, rather the bottom of the flame is a little behind the top of the flame. So when you go around a corner, the bottom tries to short cut the corner a little bit. On a circle it is doing that clear around, thus the bottom of the hole is a little bit smaller than the top.
Since you don't want to make separate layers for your cutting operations, and you don't want to use cutting rules, about the only thing left for you to try is to slow down your cut speed some. This will change your cutting voltage, so that will have to be adjusted also. You will also end up with more dross and a wider kerf.

Steve

[Davek0974]

+1, slow down is all you can do, 50% is about the limit any makes no difference. Turn off THC before though - will need a path rule for this unless you have a THC that has a voltage based anti-dive feature.