Homemade table saw: Angle lock and table saw inserts(Back to part 1)From my previous tests, I found that the blade moved slightly side to side as I changed the depth setting. Checking it over, I found I had one of the holes that the saw unit pivots on about 2 mm off. I had previously compensated for that by shimming the pivot mounts, but the slightly crooked tilt axis resulted in a slight side-to-side movement during plunging. So time to fix that.I glued a peg into that hole and then re-drilled it in the correct spot. Next challenge: making a tilt angle locking mechanism. I decided to make some sort of knob attached to the tilting frame that pinches against a curved slot. I laid out the shape of the curved slot on a scrap of plywood using a beam compass. I mostly cut it out on the bandsaw, but cut the slot by drilling a hole on either end and cutting between with a jigsaw. A block of wood holds the bolt for the knob. The bolt fits tightly in the wood (I drilled the hole 1/64" (0.4 mm) undersized, then hammered the bolt into the hole). Mounting the locking piece on the underside of the table. It turned out, my slot covered a bit more than 45 degrees, and the end of the piece gets a bit in the way of the depth adjustment mechanism, so I shortened it a little. With the saw all the way down, it barely withdraws the blade from the slot far enough to tilt. Up to this point, I had been turning the saw on and off by plugging it in and unplugging it. I finally made a "switch" for it by installing a light switch in a cheap extension cord. But then I left that switch on the floor, where I could turn it on accidentally with my feet, so I still ended up unplugging the saw when working on it. Making a 45 degree plunge cut from below. Very dusty! With where the blade comes through the table at 45 degrees and 90 degrees, I would need a VERY wide slot to accommodate all the angles. A solution would be to build trunnions, like on my bandsaw, instead of using hinges for the angle adjustment. But I wanted to keep this saw as something relatively easy to build. Besides, this will never be a really good table saw. So my solution was to route a cavity for a table saw insert into the table. This time, I used one of my fixed routers with a dust collection hose attached. Much much nicer to work with than a plunge router, hardly any dust goes flying. I then cut an opening inside the cavity with my jigsaw. I made several inserts to fit in this slot. These are just pieces of ash. I made the slot large enough that even a 8 1/4" blade can be inserted through the top. The circular saw was designed for a 7 1/4" blade, but with the retracting blade guard removed, a 8 1/4" blade will just barely fit inside the outer guard. Cutting the slot in the insert with a plunge cut. With the 8 1/4" (210 mm) blade, I can get a depth of cut of 60 mm, or 2 3/8". That's about the same depth that the circular saw could do originally. So the larger blade just makes up for depth that I lost because of the thick plywood table. I used one of my long reach C-clamps to attach a temporary fence and made another test rip cut. Surprisingly, the cut surface had a bit of a shine to it, even though I was cutting soft wood. But deeper cuts are usually cleaner. I was also using a brand new blade. But I had to mount the fence slightly off from perpendicular to the edge of the table. So more checking of the alignment. The saw turned out to be at a slight angle in the mount. I cut the opening for the back of the motor a bit wider and, using two dowels wedged in, locked it at the new position. Re-checking it, it looks pretty square. I also made a dust deflector. Too much of the sawdust dust coming off the saw was thrown towards me. Not fun. This deflector should throw it down. Dust flying, while making a cut. There's dust everywhere, though it's no longer thrown at me quite as much. Now making a plunge cut in my first 45 degree insert. Cutting out a test shape with 45-degree angles. This is the sort of thing that would be very difficult to make without a tilting arbour table saw. And most of the dust ended up underneath the saw, so the dust deflector helped, though not as much as I had hoped. Next: Table saw rip fence See also: Back to my Woodworking website. |
Monday, 8 December 2014
Homemade table saw: Angle lock and table saw inserts
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