Straight edge ideas

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FinnFlyer

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Nov 19, 2019
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Other than a lazer pointer (which typically has a rather thick bean), a taunt thin strong fishing line or dental floss will probably give you the straightest line. I used a thin sewing thread from a roll I had. You could also stand the table on its side so string sag wouldn't matter. But for constructing a table, don't forget a clear hose with water as a level. Make sure its diameter is sufficiently big and that you get all air bubbles out of it. Add a bit of dish detergent to ease the surface tension and friction. Moving the hose a bit up and down at either end and repeatedly getting same level should give you good confidence that each end is at same level. Once corners of table are at same level, moving one hose end to center of long edge of table should give you confidence that your taut line did not sag beyond your target tolerance. No reason you couldn't get down to 1/16" over 20 feet with a lot of careful shimming.

Finn
 

Little Scrapper

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just now though if the screws stick out the bottom not as much a problem. .....could screw through the top down into the boards. I bring it up as thinking 3/8 ply would be somewhat less weight and cost.
You should be able to do this without it sticking out. Practice on some scrap perhaps? I’ve also used the pocket hole with drywall screws.
 

Little Scrapper

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I like drywall screws pre drill, also used "construction screws" they do not break but are much bigger.
Some of the deck screws are a harder steel, some people like that as well. phillips heads are sometimes nice to avoid when dealing with plywood. Square heads and Torx heads were great inventions. haha.
 

Lendo

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Ir27, one does the best one can with making a flat and stable surface.
However, my friends Coordinate Measurement Machine uses 2 ft thick Granite base and to maintain dimensions, and it sits in an air-conditioned room.
Depends on how far you want to go I guess.
George
 

BJC

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Some of the deck screws are a harder steel, some people like that as well. phillips heads are sometimes nice to avoid when dealing with plywood. Square heads and Torx heads were great inventions. haha.
My deceased neighbor made lots of money off of the Phillips screw patent.

But I agree; there are better options today.


BJC
 

Little Scrapper

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My deceased neighbor made lots of money off of the Phillips screw patent.

But I agree; there are better options today.


BJC
No kidding hey? Imagine having a patent on something that everyone uses. Lol.
 

Insect

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Ir27, one does the best one can with making a flat and stable surface.
However, my friends Coordinate Measurement Machine uses 2 ft thick Granite base and to maintain dimensions, and it sits in an air-conditioned room.
Ok, I'll go for that plan, sign me up.

Anyhow, I appreciate the discussion, I ordered a misumi set below, 8' each, 2x, I'll machine fixtures to run on the channels, and to join the two. I get a system that sits with my wood with little space, light, and sufficient for the task.

misumi.JPG
 
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