Holes and fingers of Boxes sometimes don't match up

So I was doing some testings with Boxes generated by “boxes py” (https://boxes.hackerspace-bamberg.de) and sometimes everything fits just perfectly and sometimes the fingers do not fit in the holes.

I used the exact same settings for both projects and set the burn to 0,0 at the website + in Lightburn I did set 0,11 as kerf (“Schnittversatz”) which was the best result via the burn test for my 3mm plywood I’m using. And I looked in Lightburn, the holes are 3mm by 6mm in both files. In one file everything did fit perfectly, all the holes, fingers and so on and in the other file the fingers did not fit into the holes…

So I am figuring I am doing something wrong. Did anyone have a similiar issue and maybe can tell me how you fixed it?

I did upload the two svg’s I generated + used in Lightburn. The “Carrier” one did not fit, the “TwoPiece” one everything fit perfectly…

Carrier
TwoPiece

If your output file from boxes.py matches “test1”, ie. all connections fit fine as desired, but do not fit in “test2”, you need to find the parameters that are different. One of the most frequent errors is the deviation in material thickness, 3mm plywood can be anywhere from 2.8 to 3.2mm… Another possibility for error is the focus of the laser which may be different from test 1 to 2…

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I will run another Test today. For the previous 2 tests, it was the same sheet of wood (30cm x 40cm). The first test that was okay, it was a smaller project (5cm x 5cm).

On the one that doesn’t fit the fingers, if I sand the fingers down a bit, they will start fitting, so I would assume it’s an issue with the hole size. But I checked both files and the holes are identical (3mm x 6mm).

Could that also be an issue when the board is a bit warped? so not lying completely flat on the laser? I usually use magnets on the borders so it’s flat there. But in the middle it might not always be flat…

Be aware that your kerf will be different in x and y because the beam shape is usually not square. So better do your tests with the graphics turned 45°, then you will have even results.

Interseting I did not think of that. Does that then mean if I got the value that fite best for the material, I do have to cut everything also at an 45 degree angle? or can I cut it normally and it’s juet for finding the kerf value for that material/thickness?

Maybe this helps a bit, he explains the issue, if I remember correctly.

I did alter the settings for the holes to 0,00 correction (the the holes are a bit larger) and left the fingers at 0,11 and it did fit very good. Maybe I will just stick to that :slight_smile:

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