I have a standard plastic ruler which I have been using for a couple of years and through general use the edge has become not so smooth and quite bumpy.
This is somewhat unhelpful when trying to draw a straight line, so I was wondering if there was any way of restoring the edge of a plastic ruler?

I imagine it could be something like sharpening a knife blade but I am not sure how I would be able to make sure that it remains straight and doesn't become wonky.

2 Answers 2


You can do this by affixing a piece of sandpaper to a flat board. Using the board as a guide, sand it smooth. The board will prevent you from sanding it unevenly which would ruin the ruler. You should start with sandpaper around 200 grit and work your way up to 500 or so for a smooth finish.

  • You could get the rough-sanding done a lot faster with a belt sander. Feb 5, 2015 at 17:57
  • @EngineerToast I think a belt sander would be too aggressive for a plastic ruler. As a side note, a plastic ruler is not really not the best tool for drawing straight lines, it is really just meant to make measurements. Professional drafters use metal straight edges to draw lines. Feb 5, 2015 at 19:10
  • 2
    that's a good point. My brain must've skipped over the plastic part. The belt sander would still be good for melting the ruler although that's probably not what OP is after... Feb 5, 2015 at 21:01
  • If you need the ruler to be super smooth, you can use wet/dry sandpaper on a pane of glass. Dec 23, 2016 at 23:02

Since I did a lot drawing by hand on college, I realized one thing regarding plastic rulers: generally speaking they are poor quality ( staedtler is not), and the fact that manufacturer when "carves" numbers indicating length uses heat does not help at all, since this procedure causes even new rulers to be bumpy (especially long ones >80cm).So if you are using rulers for something important like college work etc. I strongly recommend that you buy a new one, because everything you try cannot form edge on the plastic which has no bumps.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.