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Post by alexkirtley on May 19, 2016 9:40:40 GMT
Where could I find one?, Getting itchy to have a shot building an acoustic guitar (built a few electrics) I just need a few more tools but never been sure where to find a radius dish
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francis
C.O.G. 
Posts: 2,482 
My main instrument is: Whatever I'm building...
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Post by francis on May 19, 2016 12:19:59 GMT
Why not save some cash and make one? The equation of the sphere is simple enough: d = R - (Sqrt/(R^2 + r^2)) where R = radius of you dish r = radius out from the centre of your disc d = depth at radius r So for a 15 foot radius dish: R = 15 x 12 = 180" (easier to work in inches than fractional feet) r = 12 (for a 24" diameter disc) Gives 0.399" for a central depth. If you step your radius' out in 0.5" steps you can set a router up to depth and radius to cut the dish. Then just sand the steps out after routing. DropBox link to spread sheet if that helps: www.dropbox.com/s/ac5piniltqszscg/Radius%20dish%20calcs.xlsx?dl=0 Spread sheet is in mm just enter then radius of the dish needed - click elsewhere on the spreadsheet and it will automatically do the sums... Francis |
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davewhite
Luthier / Guitar Maker
Luthier
Aemulor et ambitiosior
Posts: 3,548
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Post by davewhite on May 19, 2016 12:31:17 GMT
Alex,
You don't need a radius dish to make an acoustic guitar.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on May 19, 2016 12:49:27 GMT
Alex, You don't need a radius dish to make an acoustic guitar. I haven't got one, alexkirtley. You can make a flat front and a flat back or you can arch both slightly from side to side. Or I imagine you can use sized "spacers" instead of a continuous dish - but I think davewhite knows more about that than me. (In fact, he knows more about all of this than me!) |
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Post by alexkirtley on May 19, 2016 12:56:23 GMT
Alex, You don't need a radius dish to make an acoustic guitar. I haven't got one, alexkirtley . You can make a flat front and a flat back or you can arch both slightly from side to side. Or I imagine you can use sized "spacers" instead of a continuous dish - but I think davewhite knows more about that than me. (In fact, he knows more about all of this than me!) Thanks, I was hoping I could do a flat top and back, but I heard they tend to crack a lot more when they aren't radiused, I also heard about not using a dish, I just get confused when it comes to how to cut a radius in the braces and sides |
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Post by yorkie on May 19, 2016 14:29:23 GMT
Alex, if you use a radius dish that's a complete dish, it makes the neck joint and fingerboard a bit trickier. I dish the area after the soundhole but leave the area above the soundhole flat.
You can do it yourself with some 18mm mdf and gouges, chisels and sandpaper. You just need to make some radius templates first so you know when your desired profile is achieved.
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Jo whoever he is.
