Vinyl Cutting Weirdness

FabLab
1

I had an odd issue show up while trying to do a vinyl cut. The issue was not with the cutter at all, but with the Uniconverter. I had a pretty simple SVG that was done in Inkscape that I’m attaching here.

decal

I loaded it up in Inkscape on the FabLab Thinkstation computer and saved it has a .plt file. When I then went to cut that file it did something quite weird. The top half of the “N” character in the decal was extended way above the rest of the drawing.

I took a look at the .plt file and it is a pretty straight forward format with a bunch of x,y coordinates. I massaged the file a bit so that I could plot the coordinates with gnuplot. The resulting plot shows exactly what the cutter did.

plotbad.pdf (10.7 KB)

Looking at the coordinates, it became obvious that there are a series of points where the Y axis coordinate is way bigger than it should be. I compared with the other characters in the drawing and determined that for that section the Y coordinate was approximately 11184 (units?) too big. I subtracted that amount from each of them and then did another gnuplot. That looked more like what I wanted.

plotgood.pdf (11.2 KB)

I then cut this file and it turned out perfectly.

Anyone else experience something like this? Anyone know why it happens, or how to fix it.

When I get some time I might try to take a look at the Uniconverter and see if I can can figure out why it did what it did.

Steve

2

Yeah, we’ve noticed some occasional weird issues with uniconverter’s output. If you save the file as a PDF and then open that PDF in Inkscape and save it as a PLT it seems to fix all of the issues. We’ve been covering this in the recent classes, and I just added it to the Wiki.

3

Thank you for that update.

Steve

4

I’ve noticed it struggles sometimes to understand what’s the inside and what’s the outside of a shape. For example, I was able to convert to PLT initially on a project, but as soon as I added a framing box around it (for easier weeding), the uniconverter wigged out on me. Even after making combining the two paths with “difference”, it still fought me.

My solution was to use the snipping tool, then trace bitmap the very thing I’d already designed. That fixed it. (Naturally, it changed it a teeny amount. But that was forgivable.)