What's the best CAD solution to use for CP to use DXF files to

What’s the best CAD solution to use for CP to use DXF files to generate Gcode. I think I am having issues with G2/G3 from CAD/cam post processor. The preview looks perfect in CP. But when it actual goes to cut the profile I am seeing that the machine is being commanded to cut this irregular path any help in this matter would be much appreciated. And once again thank-you in advance

its the controller board that matters for interpreting the gcode, cp is just a visualisation. which board are you using?

I use Fusion 360. Plenty of options, free.

It looks like flex in your machine judging by the irregularity in each end being different. My machine has the same problems.

it does look like flex/backlash cut a circle in soft material and see what it looks like. or measure the backlash. if its backlash it’ll be more visible in the areas where an axis changes direction, worse when both do.
i also use fusion360 its great

@charlie_wallace ​ I’m using TinyG v8 firmware version .97

@Jeromy_Ainsworth ​ I thought the same thing at first but then I verified it by watching the motor movement without cutting anything and it’s actually moving the axis in this irregular path

Are you using inches or mm? I’ve heard that TinyG seems to still have G2 arc problems when using very small numbers. When using inches you end up in small floating point numbers. @Alden_Hart will hopefully respond and let folks know what the future solution is to fixing the firmware.

@jlauer ​ I designed in and used a post process for MM the problem was worse when in inch mode. I’m wondering if the post processor in the Vectric software that’s made for TinyG is to blame

I use MakerCam for super basic stuff like this…the Gcode looks correct it would seem the arc commands aren’t getting interpreted correctly on the machine. Does the Gcode have lots of G02/G03 followed by X/Y I/J commands Can your CAM tool (or what generated the DXF) convert these arcs to lines with short segments and see if the machine follows the correct path?

Maybe check the firmware for the Chordal tolerance ($ct in TinyG) to see if it’s set too high?

@Michael_Audette ​ I would like to refrain from changing the $ct the wiki guide has a warning message about changing this setting

What is it currently set to? Sometimes after a firmware flash or a new version the eprom map changes and it may be set to some unexpectedly large value. I had this happen to me once. Chaos.

I think the value default is supposed to be 0.01 mm. It looks like it might be set to 0.1

@Alex_Krause We have a version in test that has a set of arc fixes. If you can post any files or better yet segments that have arc issues segments and your $$ settings we will test with these as well.

What setting are you using for $_pm?
If not $_pm=2, try that

@Alex_Krause $fv is not a super useful piece of information, there are numerous builds of tinyG that are $fv=0.97.
Think of $fv as describing a broad class of functionality and features. $fb is what we really need to know - i.e. are you running the most recent stable build? If you are not running $fb=440.20, take a few minutes and upgrade.
No promises however, some folks are having issues similar to yours with $fb=440.20.

$ct = .01mm
$fb = 440.20
$*pm= 2 (for all 4 motors)

I did change some of the junction settings from the default $ja=76200mm and $xjd and $yjd =0.0080mm

@Michael_Audette ​ yes my post processor does export in this format G2X*YI***J****

@Alex_Krause Any particular reason you picked $ja=76200?
Sort of an unusual value.
The default recommendation is 200000 for Shapeoko, but that value would simply make your machine a bit more aggressive, not solve the problem you appear to have.

The default Shapeoko $_jd=0.01, so you are close.

@cmcgrath5035 ​ when I set up the $ja the first time I was seeing arc issues I believe I was in inch mode which translate to 3000. Are you saying my setting or the shapeoko setting is my aggressive? My intent was to down rate it a bit I was hoping that backing off a bit would of helped it but I was mistaken

If I could find a post processor for Vectric that converts G2/G3 to G1 segments I would be all for it to see if it alleviates my problems

I ran my SH2 at $ja=100000 for a long time until I realized that 2000000 was the ‘recommended’ value - 2000000 being the more aggressive value. Both will work, I don’t think that is your issue.
I am a little surprised by your pictures, your results look ‘wrong’ relative to the theoretical, but not ‘fully trashed’ as many parts do.

I take it vectric does not have a ‘no - arc’ option?
I have never used the product, so no good suggestions.

@cmcgrath5035 ​ I think I just found a post processor for no arc on the Synthetos site I will give it a shot. I hope to stop bothering you guys for silly little problems like this