Aligning your tablesaw in two planes
Before discovering this technique, Rollie could get his tablesaw to cut like a champ when the blade was at 90°, but as soon as he started making bevel cuts he experienced a ragged, scorched cut.
We just wrapped up a very successful and incredibly enjoyable Fine Woodworking Live; what a hoot! Lots of great seminars, lots of new tools to lust after, and most important—lots of new friendships made. It’s such a joy to meet folks who have the same passion for woodworking as we have and have the chance to spend a few days together learning from each other and enjoying the camaraderie that comes from shared experiences. I can hardly wait for next year!
My seminars for Live were all about setting up and using a couple of our workshop stalwarts: the tablesaw and jointer. One of the tablesaw setup essentials I demoed was aligning the blade with the table in two planes. Now most of us know that we need to align our sawblade parallel with the left miter slot, but some don’t know about aligning the blade with the tabletop. When we start to tilt the blade for bevel cuts, we must make sure the blade stays parallel to the tabletop—a different plane—so we cut straight on to the blade. I discovered this little technical gem years ago when I was struggling with my vintage Unisaw. I could get it to cut like a champ when the blade was at 90°, but as soon as I started making bevel cuts I experienced a ragged, scorched cut. I knew the blade was aligned exactly with the miter slot and fence, and it took some serious consideration to realize that as soon as I started tilting the blade I now had two planes to consider, horizontal and vertical.
I put together a simple sled for my dial indicator’s magnetic base so that I could more easily check blade alignment. The sled consists of a piece of 19-gauge steel, a piece of maple that exactly fits my table’s miter slot, and a piece of 1/8-in, plastic sandwiched between them. The plastic isolates my dial indicator’s magnetic base and allows the whole assembly to slide unhindered as I check for parallel.
Using this rig and my dial indicator, much to my amazement, I found that when tilted to 45° my blade was out of parallel with the top by a whopping .020 in., and in the exposed length of the blade, about 9 in. I shimmed the low side of the tabletop until the blade was parallel to the tabletop and I was blown away by how easily and cleanly I could make bevel cuts.
It’s a pretty simple procedure. Using camber/caster automotive alignment shims, which are precise thicknesses and U-shaped, I could simply add shims between the cabinet and trunnion until the blade was parallel without removing the bolts that hold the tabletop in place. If you have a contractor-style saw, these same shims make it a snap to lower one of the trunnions to bring the blade into spec.
Once I was satisfied that the blade tilt was parallel I returned the blade to 90° and checked to make sure the blade was still parallel with the miter slot.
Finally, I used the same sled to align my fence parallel to the blade and miter slot. I’m fussy about making sure everything is exactly parallel—none of this open at the back of the blade nonsense with the fence. I want to cut straight on to my blade, not at an angle. If the wood I’m sawing exhibits reaction from tree growth or uneven drying and is pinching the blade, I’ll switch to my bandsaw to rip it, but I probably wouldn’t use the wood anyway as it’s showing that it’s probably not stable enough for my needs.
So now you know just a bit of what I taught at Fine Woodworking Live. I had quite a few more tricks up my sleeve. Next year, maybe you’ll get a chance to join us at the celebration and learn a bunch of inside info and meet a bunch of new BFFs.