Spacer blocks for circular saw

[Greg Guarino]

I finally made a pair of spacer blocks to use with one of my circular saws; another case in which I have "discovered" a technique first discovered a century or so ago. I made them out of scrap oak.

proved very handy, making my setups both quicker and less prone to error. But it occurs to me that I have made a measurement device out of absorbent material. Should I worry? I'm not using them to line up a surgery laser, and they are only 3" long, but I'm wondering what you more experienced folks do. Make them from plastic? Finish the blocks? Or not worry as the expansion and contraction (in the with-the-grain direction) is negligible over such a small distance?

[dpb]

On 3/19/2012 10:17 AM, Greg Guarino wrote: ...

[elide the ?]

[Swingman]

Longitudinal expansion is negligible. Depending upon the species and cut, it might be 0.1% to 0.3% of radial or tangential expansion.

[dadiOH]

______________

You might want to consider making a guide with auto spacing so you don't have to mess with separate blocks and straight edge...

1. Fasten something like a 1x2 to a piece of 1/4" hardboard that is wider than your saw is from blade edge to shoe edge.
2. Run your saw down the 1x2, cutting off the excess hardboard.

You lose 1/4" of cutting depth, no big deal IMO.

You can refine it by fastening another 1x2 under the thing at 90 degrees to the other 1x2. That is used to square the cut jig to the work. The jig can be any length you want... if mostly cross cutting sheet goods, 48"+ is handy.

You can make jigs in the same manner to guide a router. You have to always use the same diameter bit as that used when you cut off the excess hardboard.

[Gerald Ross]

I made mine using a length of U channel aluminum (from Lowes) fastened to a piece of 3/16 Plywood using flat head (countersunk) bolts. Make sure you leave a tab on the other side of the guide for placing the clamps. If accuracy is required, the guide needs to be placed on the good side of the cut, otherwise the result will be a saw blade thickness narrower.

I have one 8 foot one and one 4 foot one and have used them for years.

Picture on ABPW.