[FoxCNC1]

thanks, I guess we all learned something need.

[ger21]

Well I tried getting Mach3 to perform a true spiral

A "true" spiral can not be made with G2/G3 arcs, as a true spiral has a constantly changing radius.

[FoxCNC1]

Ger, can you get spirals out of whatever cam software you use?

[ger21]

Yes.

My guess is that you're missing something in RhinoCAM.

RhinoCAM is showing the toolpaths on the screen, but it's not outputting the g-code for them, for whatever reason.

[beezerlm]

Some machines use a G2.1 or G3.1 to perform "True" spiral milling by use of an added variable to control the "pitch" of the spiral. It looks to me like this is what Rhinocam is set up for.

Correct me if I am wrong, but it does not look like Mach3 will accept this kind of command.

[yham]

A bit old post, but I stumbled with the same problem. Fox, have you found a solution?

It is interesting, when I have a spiral machining, everything is ok, G code is generated and no problem with mach. If I use round pocket strategy, there is a problem - spiral is not g coded. I assume, mach post has an issue. Didn't compare mach posts from rhinocam and mach web.

[FoxCNC1]

Hi there, not that I recall.

[awerby]

I don't think there's a problem with Rhinocam producing helical toolpaths; the question of whether they are "true" or not is more philosophical than practical. If Mach3 can't deal with G02/G03 spirals, it will output them as a series of short segments, which, if they're short enough, can't be distinguished from "true" spirals.

[yham]

I really think it is a problem with Rhinocam. Spiral machining makes spiral toolpath and Rhinocam generates code that doesn't have g2 or g3 and spirals are made of segments, and as such, they run through mach without errors. Problem rise up with hole pocketing, Rhinocam's post for mach generates g2 and g3 when spiral should start. (I don't think it makes sense, but maybe I am wrong) and this is the place where mach reports error. It is strange that cam will not make segmented path with hole pocketing, as it does with spiral machining. To me those toolpaths looks the same.

Here is where error is in hole pocketing:

G00 G49 G40.1 G17 G80 G50 G90
G20
.
.
.
.
X0.1250 Y0.0000 Z-0.2500 - end of lead in helix
G17
G03X-1.8743I1.8743J0.0000
X1.8743I-1.8743J0.0000
G01 X0.0000
G00 Z0.2500
M5 M9
M30

There should be a lot of code, because spiral is not short, but somehow, there is nothing of it.

Have no idea is there a problem with mach, it can not interpret spiral (helix is ok) or there is a problem with mach post in rhinocam.

thanks

p.s figured out that basically, a spiral code is missing. Why it is not generated, I don't know, when it may be generated as a segmented spiral.

[awerby]

It could be that there's something wrong with your I J K settings that's triggering the error messages. The Mach3 manual talks about how they work: CNC Mach3 G-Codes . Here's a thread on this site that talks about them: http://www.cnczone.com/forums/mach-s...-problems.html

If RhinoCAM isn't telling it to do it the way you want it to, you might have to edit the Mach3 post so it puts in the right G code, either G90.1 for absolute, or G91.1 for incremental.