Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: jonny quest on September 20, 2019, 11:59:18 PM

Title: Cut quality problem
Post by: jonny quest on September 20, 2019, 11:59:18 PM

Running Mach3, ess smoothstepper. Rhino drawings, madcam cam. When I run newfangled wizards cuts are nice and clean, through cam I get this. Any ideas?

Title: Re: Cut quality problem
Post by: Tweakie.CNC on September 21, 2019, 01:35:27 AM

I think you need to look at your generated Gcode.

With some CAD/CAM the arcs are drawn as arcs (G2/G3) whilst other CAD/CAM draw the arcs as many straight lines.

You picture is not clear focus of the machined surface but it looks like you have many straight lines in the toolpath.

Tweakie.

Title: Re: Cut quality problem
Post by: jonny quest on September 21, 2019, 02:43:51 AM

This was my thought too. What's the work around for this?

Title: Re: Cut quality problem
Post by: jonny quest on September 21, 2019, 02:52:16 AM

2 more pics

Title: Re: Cut quality problem
Post by: Tweakie.CNC on September 21, 2019, 03:22:40 AM

Check your Gcode - if the curves are comprised of many straight lines then the answer is with your CAD/CAM and it's Post Processor.
(Vectric, for example, will enable 'curve fit' to replace the many straight lines in an imported dxf and then the final Mach3 post processor will use 'arcs' (G2, G3) for the toolpath).

Tweakie.

Title: Re: Cut quality problem
Post by: jonny quest on September 22, 2019, 09:30:29 AM

What about my look ahead option,  it's set at 200 right now. What's the harm in trying 400, or even 1000? Pros and cons to really high look ahead numbers?

Title: Re: Cut quality problem
Post by: Tweakie.CNC on September 22, 2019, 09:51:00 AM

Did you check your Gcode ?

Title: Re: Cut quality problem
Post by: jonny quest on September 22, 2019, 01:09:49 PM

Here is the gcode in attachment. I used this to skim the part .002" to see if the cut quality was better. Finish turned out exactly like original

Title: Re: Cut quality problem
Post by: ZASto on September 22, 2019, 06:30:45 PM

Gazillion of short segments, no arcs.
Even setting lookahead sky high will not help you having better part.
Your CAM is not generating G2/G3 code, only G1, which is linear interpolation versus circular interpolation.
I have no knowledge on madcam, I use Aspire (as is Tweakie) where I can do a curve fit.

Title: Re: Cut quality problem
Post by: jonny quest on September 22, 2019, 06:46:16 PM

Thanks! Back to the Cam forum now!