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IndustryArena Forum > CAM Software > Autodesk CAM > Trace not completing full loop
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  1. #1
    Join Date
    May 2017
    Posts
    9

    Trace not completing full loop

    Hi,

    I'm using the fusion trace command to engrave some paths and basic stroke text (generated in fusion) on plastic engraving stock.

    The simulation looks good, however the G code I run on the machine is not completing the full stroke for the letters, i.e. the start of the letter 'M' is missing, the letter 'O' is not completely engraved.

    From watching the engraving, it appears the 'missed part' is actually at the beginning of each letter (bottom left corner in the case of the M which engraves left to right) its almost like the tool isn't completely down into the stock before it starts moving.

    Any ideas on why its doing this?

    Annotated Image attached of the engraving.

    As a work around, is there a way in CAM to force the trace command to do a second pass in reverse? (repeat passes just does the same thing)

    I've played with tolerance and tried several different .shx fonts within fusion. The same occurs when tracing other geometry too.

    Engraving on a 6040 that for the most part has been reliable and accurate.


  2. #2
    Join Date
    Nov 2014
    Posts
    729

    Re: Trace not completing full loop

    Welcome to CNC Zone! Are you able to attach your file so we can take a look at it? Have you tried to use Engrave for the same sign?

    David
    David
    Romans 3:23
    Etsy shop opened 12/1/17 - CurlyWoodShop

  3. #3
    Join Date
    May 2017
    Posts
    9

    Re: Trace not completing full loop

    Hi David

    Tried attaching the Gcode file but no luck with uplaod. Is that what you're referring?

    I'll give engrave a go and see if it interpolates differently. Thanks

  4. #4
    Join Date
    Mar 2003
    Posts
    35538

    Re: Trace not completing full loop

    Try running in Exact Stop mode.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
    Join Date
    Nov 2014
    Posts
    729

    Re: Trace not completing full loop

    In Fusion 360 you can go to File/Export and create a file that can be shared. It will have the extension *.f3d. Save it to your hard drive and then upload it here.

    David
    David
    Romans 3:23
    Etsy shop opened 12/1/17 - CurlyWoodShop

  6. #6
    Join Date
    Oct 2010
    Posts
    171

    Re: Trace not completing full loop

    To my eye, it appears that there are more issues than the "0" and the "M". It appears that the X, P, I, R and 5 have all been clipped a bit, and not consistently.

    As David mentioned, if you can upload (or link to) the f3d source file of your program, that would (hopefully) help someone here get to the bottom of it.

    PM

  7. #7
    Join Date
    May 2017
    Posts
    9

    Re: Trace not completing full loop

    Hi PM, David, Gerry.

    Thanks for your input - I get the mesage "Invalid File when I try and attach the .f3sd file here

    I have made a public link to the file, does that work for you?

    https://a360.co/2ReFDie

    Many Thanks

    Elsy

  8. #8
    Join Date
    Oct 2010
    Posts
    171

    Re: Trace not completing full loop

    First quick run-through on this:

    The photo you sent earlier in this thread does not look to me like it's been cut with an infinitely sharp 12.5° included cutter?

    Also, to run 1000mm/min feed rate with a single flute cutter only running 5000rpm seems quite excessive... as if there simply isn't enough time for the next cutting flute to come around and finish the cut.


    Have you cut more than one part? If so, do the errors look identical on each part you have cut? What type of machine is this being cut on?


    PM

  9. #9
    Join Date
    May 2017
    Posts
    9

    Re: Trace not completing full loop

    Thanks PM,

    Sorry, the link I sent was after some playing around. The tool does indeed have a 0.3mm tip, and was programmed as such when I ran the part.

    I am indeed running at 1000mm/min however the RPM on the machine is fully manually, and was set to 11,000 RPM. Nevertheless, I will try running slower feed.

    I should point out, it appears it is the "beginning" action of each letter that is clipped. ie the M that has a short side is the side where the toolpath begins for that letter. Its almost as if it begins the X and Y movements before the Z is fully down.

    Do you know where the "Exact Stop" mode Gerry refers to would be found?

    I'm cutting on an eBay 6040 with Mach 3. Has been reliable for all my pocket and contour work, but having this issue now I'm trying to engrave using the trace command. I've had the same results on all tracing parts I've done, errors seem consistent and it seems to be consistenly the beginning of each letters tool path.

    The smaller the font size, the less noticable, which makes me think the issue is scaled up and down with the size of the project. I will try an engraving at 5x the font size and see if the discrepancy becomes 5x larger, or stays the same.

    Thanks for the generosity with your time.

  10. #10
    Join Date
    Oct 2010
    Posts
    171

    Re: Trace not completing full loop

    Is the machine stepper motor driven or servo motor with encoders? If you're using Mach3 to control, then i'm guessing it's stepper?

    As you mentioned, there is a chance that the X and/or Y movement is starting before the Z arrives at the cutting depth. Doesn't seem "likely", though it may be possible?

    I rarely use "trace" to engrave letters -- I'd say 95% of the time I use the engrave strategy, and always have very good results that way.

    PM

  11. #11
    Join Date
    May 2017
    Posts
    9

    Re: Trace not completing full loop

    Thanks PM. Stepper driven with Mach 3.

    I've not had any luck with engrave in the past but will investigate. Does that mean I should actualy extrude the geometry of the text down to create small pockets in the surface in the Model interface? How do I keep then keep the cut depth constant, and not diving deeper for wider parts of the text etc, as that strategy tends to do with V carve bits?

  12. #12
    Join Date
    Oct 2010
    Posts
    171

    Re: Trace not completing full loop

    You will have to use a single line font, as you are correct -- "engrave" will go deeper and shallower depending on the line width of the font. I forgot that you're going an exact depth to get your contrast from the next layer, correct?

    Engrave *should* work well on a single line font though (I'd think).

    PM

  13. #13
    Join Date
    May 2017
    Posts
    9

    Re: Trace not completing full loop

    Hi All,

    Slowing the feed rate as suggested solved the issue. Thanks for your input.

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