I seem to have it sorted out. Fiddled with it again today and was able to get it to just about 0 deviation on a 23x23" piece. This should be close enough for anything I will be doing. Others have mentioned squares - I recently bought 2 16"x12"-ish metal machinest squares and they come in VERY handy. Can't see any light at all on any of the corners. Thanks again for the time to look and respond.
Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.
-Bill Watterson
Reminds me of my safari in Africa. Somebody forgot the corkscrew and for several days we had to live on nothing but food and water.
-W. C. Fields
OK, it is not about 5 cuts. I cross-cut a straight piece of stock (parallel edges a must). Flip one piece and butt it to the other. If I get a straight alignment, I am good enough. I saw this idea mentioned in several places, it made sense, and I started using it.
Best wishes,
Metod
First problem I ran into with my track saw was making a good 90 degree crosscut on a piece that had already been ripped. Neither my carpenter or drywall square met the flip test. So I took a piece of 1/2" ply, prefinished one side, and cut it square on my sled, (which was previously shimmed to cut within a thousandth over 12" using the five cut method) added a fence and I had a sturdy guide I could square my track to. Went prefinished side down so I would slide easily on the unfinished ply. As stated, by measuring each end of the offcut on the fifth cut, you know your error on one cut is one fourth the difference.
I have made six sided boxes to conceal plywood edges.
First, let me say, I don't think your picture shows one, does it? That loudspeaker has four beveled corners, and front and back are fitted into a groove. And the rolled front profile makes me think it is vinyl-wrap (probably cut via a CNC-controlled beam saw), although hard to tell by the picture.
Let me point-out some possible issues w/ the 5-cut method:
First, in order for the five cut method to work well, there can be no (none, notta) slop between the sled's runners, and the miter slots on the table. Otherwise, you'll end-up chasing your tail (you may achieve a perfectly parallel cutoff on your final cut one instance, but the next instance you may get a cutoff w/ convergent lines). In this case. 001" of slop in those runners can throw the entire process off.
Second, the amount of movement required (of the fence) to get to these minute adjustments people are trying to achieve are not easy, especially when we're working w/ hardwood, plywood, and MDF.
Third, in order for this to work, your fence must be (and remain) dead-nuts flat. Otherwise you will get different results, depending on the side of your test piece.
Fourth, any error the user introduced by not placing the test piece perfectly against the flat, on just one cut, tosses off the results.
Fifth, blades (especially thin kerf) can deflect during the cut. And they don't always deflect the same direction. Differences in material thickness, and blade tilt, can effect the deflection of the blade.
Sixth, many saws, due to their trunion design, may introduce geometry problems when you tilt the blade. This can be adjusted-out on many cabinets saws by shimming the table to the cabinet, but not many people do this.
I use a plastic triangle to check my cuts. I was making some wrapped-up subwoofer boxes yesterday, and they wrapped-up perfectly (this is sort of a five-cut method, if you think about it).
To get there, I did have to make an adjustment or two to my fence after tilting my blade to 45-degrees. I made a couple of test cuts while adjusting my fence, and was able to dial it in perfectly.
I find that, for me, this results in far more precise output from my saw.
more infoActually that is walnut veneered mdf which I cut on my tablesaw. The front has a solid piece in order to put a round profile on it. But the other 5 sides are all beveled. It doesn't take much misalignment to get a box where none of the corners will come together tightly. And the box plus the baffle board must be very square or the joinery will look quite poor...maybe .01" out of square looks terrible. But my earlier post was in response to the guy who just holds a framing square against the cut and moves on.
Last edited by john bateman; 06-09-2013 at 3:43 PM. Reason: more info
Your point is well taken John, sometimes perfect is "good enough". I've made similar items and there really isn't room for error is there. Very nice work!