Anyone good with Imperial to Metric conversions in regards to radiuses of a dish?

Antique_Guitars

If you had individual circular blocks of wood that were dished right from the edge to a specific radius in the middle say 3mm and 6mm and then you had some others that were american that had say 20ft and 28ft radiuses how could you convert the imperial to give you the metric equivalent for comparison?

Or would you need other dimensions etc etc? or are these different systems that can be converted?

This is for go bar decks for guitar making as trying to match american to european specs and I suck at maths.

Cheers

Phil_aka_Pip

1"=25.4mm

circumference = 2.pi.radius

pi=3.14 but your calculator can give you more decimal places than I can remember

convert all your measurements to the same units, preferably mm. have fun with the arithmetic

mart

Antique_Guitars said:

If you had individual circular blocks of wood that were dished right from the edge to a specific radius in the middle say 3mm and 6mm ...

I'm not sure what you mean here. I don't think you're talking about a radius of 3mm, as that's about the mount of bevel on a Tele! 

Are you saying that they are 3mm shallower in the centre than they are at the edge? If so, then if you know the overall size of the block (e.g. its radius), you can work out the radius as a large number of feet, by: 

(L squared + R squared) divided by (610 times L)

Where L is the difference in depth (e.g. 3mm), and R is the radius of the block, also measured in mm. The result is the radius in feet.

Doh. You want to go the other way, don't you. Ok. Let R be the radius of the block, in mm, as before, and let S be the big radius (in feet), then: first multiply S by 305 to get that radius in mm.

 Then the difference in depth is

(S - square root of (S squared - R squared)).

Sorry, not easy!

thecolourbox

Depends if it's a pi dish Sorry that's not helpful

GuitarMonkey

Yes, you need to use the diameter of your block as the base of an isosceles triangle of side radius of the dish. The difference between the perpendicular height of your triangle and the radius of the dish is the amount of the depression.