Tuesday, February 16, 2016

Sandpaper Cutting Jig

I was out working in my father's woodshop this evening, and realized that I've never written about this simple tool that I use practically every time I'm using sandpaper for a project.  It's a simple jig for tearing sandpaper into strips that are the correct size for half sheet and quarter sheet electric sanders.
Sandpaper comes in sheaves of 9"x11" sheets, and many electric sanders are designed to accept either halves or quarters of these standard sheets. This jig consists of a 1/4" piece of plywood nailed to two pieces of 1x2 as feet (shown in the second photo), with three lines drawn on the top and a hacksaw blade screwed down with some shims underneath the screws.

The hacksaw blade is shimmed up with very thin pieces of wood just enough that you can easily slide coarse sandpaper underneath the blade. The teeth are pointed out, or to the right in the first photo.

The first line is drawn 4.5" away from the cutting edge of the blade, and is used to place the sandpaper so you can tear it into two parts longwise.
The second vertical line is drawn 5.5" away from the blade, so the halves can be easily quartered for the smaller electric palm sanders. Here's a photo showing how I fold the sandpaper over before tearing it against the hacksaw teeth.

The third line is drawn perpendicular to the blade so I can easily tear off odd-sized rectangles while keeping the cut square to the sheet. If I'm only doing a small amount of touch-up work, I'll only tear off a gum stick sized piece. If I later pick up the odd-sized leftover and want to use it in my palm sander, all I need to do is line it up with the 5.5" line and tear off whatever's left.

The pencil lines aren't ideal, and tend to wear off after heavy use. Making more permanent markings with a deep cut + black ink or burning the lines with a soldering iron or wood burning pencil would be a possible improvement if you make one yourself.

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