Need to make a change for a hotwire

[gfacer]

Ok, so I understand hotwire cutters are not what Cut2d etc is meant to cut but the regular software is pretty sucky so here we are.

I'm calling the hotwire a .040 diamter tool (about the kerf of the cut) and max cut depth of 48" (the max the machine could handle).

I use a 45 degree lead in lead out, and join letter inners with the outer shape with a .041" gap. The controller is a UCCNC type but nothing is hooked up to the Z / spindle, just x and Y.

My current strategy that I want to do means I cut one small shape at the top of my letters first, then cut the letters from the top in my selection order, then back to x zero and y zero (this is in the post).

However, my rapids I need to basically be at my cut feed rate and I see no place to set that in the post save for the "begin RAPID_MOVE sections....which I have changed to G1....and that part sort of works fine.

My problem, mentioned in some other posts here, is that the default retraction rate is 30. I gather from the other post that you can go faster if the plunge is set faster....but I need a speed equal to my feedrate, which is 15-20 usually. Unfortunately, *that* part of the Z isn't ignored, and it's applied to the next rapid more as well (no longer the first I guess) and the result is the machine is going too fast.

I have tried to put an [F] into the RAPID_MOVE line, but I guess the retract default overrides that.

Any suggestions? Also, this is all a hack on a older UCCNC post I was using that itself was lightly modified from the default UCCNC post.

I'll read those instructions to see if I missed a possible post section that might address this.

[gfacer]

So......read the manual. Gutted most everything "Z". I have a plunge and a retract section like the plasma post referenced in the manual. Code is below.

Code: Select all

+ ---------------------------------------------------
+  Commands output for Plunge Moves
+ ---------------------------------------------------
begin PLUNGE_MOVE
"[F]"
"(plunge)"
+ ---------------------------------------------------
+  Commands output for Retract Moves
+ ---------------------------------------------------
begin RETRACT_MOVE
"[F]"
"(retract)"

What shows up in my gcode is:

N2680G1X21.2875Y17.1938
F30.0
(retract)
N2710G1X34.5133
N2720G1
F15.0
(plunge)
N2750G1X34.1597Y16.8402

I'm trying to get rid of that F30.0 line

[gfacer]

Taking out all feedrates and just putting in the beginning of the file to change as needed at the machine. That works.

The minimum of F30 retract cannot (from what I can tell) be changed. And, worse and I'd think a slight bug, it forces the next rapid moves to be the same feedrate as well (or maybe that is a separate Vectric enforced minimum value).

Anyways, A very edge case use and I have found a workaround. If any suggestions that would allow me to change the feed inside cut2D that would be great, but otherwise I am done with this.

[gregk]

Taking out all feedrates and just putting in the beginning of the file to change as needed at the machine. That works.

The minimum of F30 retract cannot (from what I can tell) be changed. And, worse and I'd think a slight bug, it forces the next rapid moves to be the same feedrate as well (or maybe that is a separate Vectric enforced minimum value).

Anyways, A very edge case use and I have found a workaround. If any suggestions that would allow me to change the feed inside cut2D that would be great, but otherwise I am done with this.

Hello gfacer,

In your post-processor you should have a line similar to:

Code: Select all

VAR FEED_RATE = [F|C|F|1.1]

You can add another one after it like this:

Code: Select all

VAR CUT_RATE = [FC|C|F|1.1]

Then instead of using

Code: Select all

[F]

you can use

Code: Select all

[FC]

The FC variable will always be set to a cut feed rate regardless of move type, while F variable can be either cut feed rate or plunge feed rate depending on the move type.
I hope that helps,

Greg K

[gfacer]

Thanks!

Yes, that seems to work fine, so I will use that. I did still strip out much of the post anyways as 2D cutting doesn't need all the helical stuff for example.

For posterity, I'll throw in a picture of the toolpath strategy that makes any rapid moves suitable for a 2D cutter.
Greg