Size Disparity issues

  • @Zax

    I've been working with T2Laser for a few weeks now really getting down to the nitty gritty finite level detail and have noticed a disparity in overall image size when using the Trace feature of a bitmap and generating the G-Code from that versus T2Laser taking an image, primarily been working with .png import, and letting the software convert the image to G-Code. Normally this wouldn't be an issue if you're only working with one material piece at a time, however to speed up efficiency of my work load I'm preloading 36 pieces on top of each other, each piece measuring 38.1mm wide by 6.35mm high. Overall image size loaded into T2L is to come out at 228.6mmx38.1mm. In reality in order for the drop in height to accomodate Trace G-Code creation I have to set the image size to 229.32mmx38.1mm. The disparity in the G-Code measurement is enough to drag the image for each piece from the pieces center point. I've spent some time to work around this, by increasing overall size of the batch, tonight after identifying this was an issue with the offset from centerpoint on each piece growing as the laser moved downward on the work area. I'm also experiencing a loss of about 4mm from the sides. Although currently this is not an issue, I can forsee it becoming an issue down the road when we start doing batches larger than 36 in a single column.

    Do you have any suggestions on correcting this loss in size? Is this something in regards to the GRBL version being used? T2L is telling me to use 0.9i for the EleksMaker A3 Pro 2.5W; I'll be installing an Endurance 10Watt tomorrow. Is this correct for the 2.5Watt? Will it need to change for the 10Watt, I'm thinking yes as the power output values will be different; am I wrong here?


  • Developer of T2Laser Software

    @clndwhr I always recommend using my Grbl 1.1e Default firmware, the motion is faster and smoother compared to 0.9 and you'll get features like real time overrides, dynamic laser power and more. I also include homing in my firmware should you wish to add switches later.

    So anyway, back to the real question. If I understand correctly you noticed that when tracing the size isn't exactly matching the original image. Usually the trace is exactly the same size although it's possible there could be a small error. The way auto-tracing works is it finds a contrast change and then follows that line, so say it detects a change from black to white, it will stay on the black pixel side and continue around until it makes a shape. This offset is 1 pixel so at 0.15 resolution you'll add 0.3mm (1 pixel on each side) or if it was tracing the other side you'd lose the same size. It should not multiply though so you should never lose more than 2 x the resolution which is generally very small.

    Since you are seeing a much larger offset and it's not within the image but the overall size, there could possible be something else going on. Have you checked the distance calibration and adjusted if needed? This option is on the laser controller screen in the settings menu.

    Do you have Relocate Origin enabled in the DXF Options? That would shift the trace to 0,0 so may account for the error but that would be purely a shift and not an overall size change.

    The other option you have is to trace the design in Inkscape (or another program) and import the DXF.

    I do many jobs where I engrave the design and then use Sketch Plus (Overlay) to contour cut-out with multi-pass and the alignment is excellent. That's the reason I added the feature.

  • @Zax,

    Thank you for the quick response.

    I think I understand the loss due to resolution and
    I will try these out in about 8 hours and get back with results after the update to 1.1. We do all our design in inkscape and import.


  • @Zax I didn't forget about this. I've been super busy with everything in daily life. I just updated to 1.1 tonight. Extremely smoother motor control. Still have the issue with the loss on the left and right. I'm chalking it up to it just being white space on the left/right and top/bottom of the gcoded images. We've processed roughly 10000 pieces in the last month and have had great success regardless. So much we've upgraded to a 10Watt Endurance Laser and it has been phenomenal in being a workhorse without fail. Thank you for the suggestions overall!


  • Developer of T2Laser Software

    @clndwhr That's good to hear, let me know if I can be of assistance. You can always e-mail me for support, and if you want me to look at any files to help I can do that.

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