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Granite Surface Plates- making things flat
In a previous post it was recommended to maybe get a granite surface plate to check and make my own straight edges.
I saw this today and started thinking... http://www.woodcraft.com/PRODUCT/200...FSJlMgodtkgAng
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#2
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I've got something very similar to that. Though mine is about 24" long. It's extremely handy. I use it all the time for a number of different purposes.
I got it at a used building supply store. Do you have anything like that where you live? If not, you could ask anyone in your area who installs granite counter tops if they have any cast offs, any pieces that are throw aways because of a cutting mistake. They are often plenty flat and cheep too. Cheeper than what you linked from woodcraft. At least, they are around here. I got mine for 6 bucks.
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#3
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Have no knowledge of the flatness of granite counter tops but am sure they are not in the same league with granite surface plates. That said, most likely they work super for most guitar work. Guitar measurements and tolerances are not very exact.
Tom
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A person who has never made a mistake has never made anything |
#4
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Granite surface blocks are extremely flat and typically used in Quality/Inspection departments of manufacturing companies where tolerances are measured in the 0.0001" range (tenths of thousandths).
Their flatness depends on the grade. See this link for more info. Generally speaking, these are very expensive and overkill for woodworking where tolerances are measured in the .015" range (1/64"). If you can get one used they would be great. A granite countertop or simple aluminum bar would suffice for precision woodworking
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#5
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Just a random thought, but I lap my waterstones against each other to keep them flat. I wonder if you had two moderately flat countertops chunks and lapped them against each other if you would get two extremely flat surfaces.
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"You don't have to be great to start, but you have to start to be great." -Zig Ziglar Acoustics 2013 Guild F30 Standard 2012 Yamaha LL16 2007 Seagull S12 1991 Yairi DY 50 Electrics Epiphone Les Paul Standard Fender Am. Standard Telecaster Gibson ES-335 Gibson Firebird |
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Quote:
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Quote:
Tom
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A person who has never made a mistake has never made anything |
#8
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A couple years ago, I went to a shop that sold granite and marble, and asked to buy some of their stones that they couldn't use. I went away with two 2x2 1/2 foot pieces plus a couple of 6"x24" pieces as well. I gave half of it to Steve Kinnaird. The big piece I kept, I use to glue up top and back boards, to check side profiles, and for a lot of other work. The smaller piece I use to fret the fretboard. Since I don't have a shop, I do this on the patio. Makes a great steady surface.
As to exact degree of flatness, I'm not sure, but it's worked well enough for me. I think I spent about $50 total. If I had it to do over again, I'd get it about 24"x20". That stuff is heavy. If you carry it around, be extremely careful or wear steel toed shoes. Don't ask how I know this. |
#9
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I have a marble threshold from the local tile store at a reasonable price. I've never measured the tolerance, but it seem pretty darn flat. I used it as a clamping caul to clamp a fingerboard on a banjo neck and got great results.
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#10
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You can go to a commercial glass company and get a piece of "float glass", I use a 1/2" thick that was left over from a table top. Float glass is perfectly flat and not too heavy to carry. Wet it and wet or dry sandpaper stick well for sharpening tools.
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#11
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Ah, that makes sense. A coworker who is big into astronomy also pointed that out, he has hand ground telescope mirrors using two huge glass blanks against each other with fine abrasive. Learned something new today.
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"You don't have to be great to start, but you have to start to be great." -Zig Ziglar Acoustics 2013 Guild F30 Standard 2012 Yamaha LL16 2007 Seagull S12 1991 Yairi DY 50 Electrics Epiphone Les Paul Standard Fender Am. Standard Telecaster Gibson ES-335 Gibson Firebird |