Foreveroctober,

Welcome!

The problem isn't with fonts being allowed or disallowed. What's happening is you're taking a font that's been made into an image and that image is being turned into a grid.

So if you're using a font that contains thick and thin lines, the thin lines may not be well represented when changed into a grid.

Also, one of the best things to do if you're designing an image to be used as a pattern is to make the cleanest image you possibly can, generated as a .gif or a .png file, where pixels = stitches. So if you're trying to make a piece that's 100x100 stitches, you'd ideally want to make your image 100x100 pixels.

The freePatternWizard isn't actually a graphics program, so if you give it a very large image with the idea of creating a very small pattern, it will do its best, but it will be forced to pick what to keep, and that may not be what you'd want it to keep. This is why it's best to give it exactly the size of image in pixels that you want in stitches.

The best fonts of all for such an endeavor would be uniform thickness. If you can find a font where the thin lines wouldn't tend to get lost, that would also work.

It's not impossible and I've seen fonts that do work well, just that not all fonts are created equal, so looking at it from a standpoint of what will translate well to a grid is very helpful to determine if a font will ultimately give an optimal result.