Struggling with pierce-height setting in Fusion 360 post processor

Hi all,

I'm new to this forum, but got quite some help from the community already. Good stuff!

I built a CNC plasma cutter controlled by an arduino running GRBL. The openBuilds post processor is such a great piece of software and I'm enjoying playing around with it.

There's one thing I can't seem to figure out, and that's where to set the pierce height. In the heights tab of the 2D profile toolpath in Fusion I can set top height which is basically the distance from workpiece to nozzle (after probing + offset; a function I'm really happy with), then there is retract height and clearance height, both obvious. In the linking tab there's a setting that's pierce clearance, but that seems to be just for horizontal clearance (which is strange because this is also set in the lead in tab...?). Then in the post processor settings there's the spindle delay which I use as pierce delay, but I can't find the actual height for piercing.

If I open the .cps file I see some references to pierce height, but couldn't figure out where to set it, or what parameter it's looking at.

Anyone here who's kind enough to point me in the right direction?

Many thanks!

 

Thank you sir!

Of course I read the instructions on the github. I wouldn't dare to ask my question if I didn't. But even after reading it again and again I can't find where this is described. I might (and probably am) missing something, so some help would be greatly appreciated.

The pierce clearance mentioned in the github instructions is a horizontal clearance away from the cut. It will start the pierce with an offset and then arcs into the actual profile to avoid the mess of the pierce hitting the final product. What I want to do is not just have the cut start away from the profile on the XY plane, but also have some distance on the Z axis, so: pierce height. This is a very common thing, and I also see things like "plasma_pierceHeight = value;" in the code, so I know the post processor tailors to this need. I just don't know how.

Someone care to help me out?

 

Thanks again!

Yes, I used 2D profile in the cutting tab. All looks exactly as in your screenshot.
I think I figured out the problem:
The code indeed takes the pierce height from the pierce clearance, even though in Fusion this is a horizontal lead-in move. The problem occurs when you want a pierce height of lets say 5mm, and then make a 4mm circular inside profile. On the XY plane there is no space to make this horizontal clearance so as a result Fusion skips these profiles.

It means that you can indeed set the pierce height using the pierce clearance tab in Fusion, but only for profiles that also have space to do this same distance on the XY plane.

I guess the only way to achieve a higher pierce height is to first make the toolpath with a small pierce clearance so it generates toolpath for all profiles, then open the post window, manually edit the cps file to set the clearance height, and then post. In line 1418: "plasma_pierceHeight = value;" just change "value" for the desired pierce height.
I'll try this as soon as I'm near the machine again, but I'm pretty confident it should work.