It grew wings

Rennie Heuer

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Well, a day's work down the tubes. I am attempting to make a miter sled based on the design by Stumpy Nubs. Sound design, good instructions, versatile jig. Unfortunately, after getting it all together to the point it is ready for testing I noticed it was not lying flat on the table saw. Some not so socially acceptable terms uttered under my breath.

I ran a couple of test cuts and the miter is dead on, but the face of the miter is not, as I suspected, 90* to the sides. What a pain. No way to correct it as far as I can see so I guess I'll start all over again tomorrow.

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Yeah, 11 plys, you'd think it would stay flat.
Could be my fault. I laid on a couple of coats of shellac. The "B" side really soaked it up.

Or maybe the 99% humidity we had today had something to do with it. :huh: I do miss some things about living in a desert. :rofl:
 
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Don't know how well this shows in the pic, but this is the sheet on the floor with a 48" straight edge on top. There is nearly a 1/4" gap at the center. At $50 bucks a sheet should I not expect something better?

I balanced the sheet on the floor with a 1 x 1 running up the center length and put a fan on it to blow air around the entire sheet overnight. I don't expect to see any improvement and even if it does get better I'm hesitant to use it for jigs that must remain flat.
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To paraphrase the graduate, just want to say one word, MDF. Stays dead flat.

Yep. Would not be my first choice normally because it does not hold screws well and it can get banged up pretty easy, but in this case I might have to. It pains me that I dropped all that money on the plywood. I'll just have to find another use for it.
 
Well Rennie before u give up on the plywood why not cut a few kerf slots on the underside of the sled to allow it to lay flat. Kind of like the way the cabinet makers cut kerfs to be able to curve thin plywood round for a cabinet that has round or curved sides.
 
Well Rennie before u give up on the plywood why not cut a few kerf slots on the underside of the sled to allow it to lay flat. Kind of like the way the cabinet makers cut kerfs to be able to curve thin plywood round for a cabinet that has round or curved sides.

I might be wrong, but to make this lie flat you would cut the kerfs into the convex side of the wood. Since everything on top is glued down this would not be possible.
 
I might be wrong, but to make this lie flat you would cut the kerfs into the convex side of the wood. Since everything on top is glued down this would not be possible.

You might be wrong. :D Cutting them in either side could remove the stress. On the concave side, the kerfs would relieve stresses and they'd spread open a bit to let the table lie flat. On the convex side, they'd also remove stress, but would then to close up as the wood flattened.
 
You might be wrong. :D Cutting them in either side could remove the stress. On the concave side, the kerfs would relieve stresses and they'd spread open a bit to let the table lie flat. On the convex side, they'd also remove stress, but would then to close up as the wood flattened.

Ahhhhhhh. I see.
 
Would there be enough clearance at the front of the sled to fasten a 1x4 fence to hold the plywood flat?
Too late. After sitting on the woodpile down by the fire pit all winter it floated (with a big pile of firewood and other scraps) all over the yard in the recent flood. Last week Jan and I went out with the wheelbarrow (still a little muddy out there), gathered it all up and burned much of it.
 
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