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| how flat is flat? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=26923 |
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| Author: | J Jones [ Sat Apr 10, 2010 10:05 am ] |
| Post subject: | how flat is flat? |
hey guys just wondering what you use to flatten out your water stones? i have some glass thats roughly 1/4" thick that i have been using for scary sharp, its pretty flat but not dead flat, will that be alright? i realise im being a bit anal here but.... thanks Jonny |
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| Author: | Carey [ Sat Apr 10, 2010 11:54 am ] |
| Post subject: | Re: how flat is flat? |
Todd Stock wrote: Glass that thin will flex if not packed properly...might stick some 220 to the glass and use the setup on a decently flat surface... a piece of MDF or a flat bench top. agree- one of the advantages of the 'scarysharp' setup is the gen'l flatness is assured; if the substrate is flexible or unflat that advantage is lost, and you're still left with the slight dubbing of edges caused by the softness of sandpaper, even 3m's very good finishing film. |
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| Author: | Carey [ Sat Apr 10, 2010 12:07 pm ] |
| Post subject: | Re: how flat is flat? |
J Jones wrote: hey guys just wondering what you use to flatten out your water stones? i have some glass thats roughly 1/4" thick that i have been using for scary sharp, its pretty flat but not dead flat, will that be alright? i realise im being a bit anal here but.... thanks Jonny Misread your post when first replying- sorry. The flatter your sharpening stones are the better, in general. The better you get at sharpening the less it matters, and you learn to use the shape of the stone (concave, convex, et c) to advantage. Flat is by far the best way to start though- saves a lot of tail-chasing. |
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| Author: | J Jones [ Sat Apr 10, 2010 12:09 pm ] |
| Post subject: | Re: how flat is flat? |
thanks the glass and its stone base (its a strange thing, sheet of glass held up by 4 3" long metal poles with a stone base) is not flat when checked with a straight edge and if it gets worse in use.... i have a couple of cheap diamond stones that are flat according to my straight edge, but they are smaller than the water stones, so im not sure if they are the best things to use. looks like im taking a trip to the local glazier on monday! ![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up") thanks for your help Jonny |
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| Author: | Robert Renick [ Sat Apr 10, 2010 1:06 pm ] |
| Post subject: | Re: how flat is flat? |
Contemporary glass is made by a float process, the liquid glass floats to a near perfect surface, it comes out of the machine annealing in the float process, and is cut as it is moving down the line, glass making machines are designed for constant use, once started they operate continuously for 20 years or so. I have a nice sheet of 1/2", 24 x 36, very useful and thick enough to stay flat. Tempered glass is not flat, the process of tempering results in a deformation of the surface. Tempered is brought up to about 1100 degrees, just under the melting point, then as it comes out of the oven, big fans cool it off quickly, tempering it, and distorting it. Back in the day when I was buying glass by the case, 2000 pounds to the case, I would use the scrap glass as a cabinet scraper, cut 2" squares and there is a good burr on all 8 edges, they don't last long, but they were quick and easy, came out the scrap bin and then back in, and they were really sharp. Another interesting thing about glass, the thinner the glass, the harder, due to the faster cooling of glass with less mass, thick glass is softer as it cools more slowly, this is evident when scoring the glass, thinner glass requires more pressure on the cutter, and is a bit more erratic in cutting. For lutherie, when I was working in a glass shop, I met and assisted Ned Evett in making a fretless conversion with a glass fingerboard. He still uses them. Fretless guitars are usually dull with no sustain, the glass improved these tonal deficiencies. Sorry if I am off topic here, can you tell that it is raining and I am stuck home? Enjoy your trip to the local glazier, Rob |
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