I have a small number of flip/spin templates , for boards ranging from 5 1/2 ft to 12 ft…they are like a surfboard specific set of french curves that can blend any planshape I choose accurately and efficiently , using nose , tail , centre and wide point…they take up negligeable wall space and do not require electricity…yet to see anything simpler and quicker than that…don’t missunderstand me , I have no problems at all with any tech that has advantages , but too often the use of tech overshadows more practical traditional methods , with no advantage in efficiency or versatility at all…and computer screens are yet to generate an accurate visual image that comes close to the real thing.
The best way to make your radius (remember radius is from the center of the circle)
Get a builders tape measures attact pencil to end (this wont stretch like string).
Put a nail through tape at the required radius and into the ground.
Gives abeautiful true curve.
If you require an increasing curve do the same but nail into a 44galon drum, as the tape goes around the drum the pencil will give you a tighter curve as it draws.
Kayu, how did you make your spin templates? Taking another board and trace it? Take a fishing pole and bend it and then draw the arc? Copy somebody else’s template? Then refine the template you just made, by sanding it, and resanding it until you finally end up with a curve that looks pleasing.
What could be more efficient than taking a 4’ x 8’ piece of masonite, walking to one end and driving a nail in it, and then using a tape measure to draw an arc every foot? Right there, from one piece of masonite, you would have a 1 foot, 2 foot, 3 foot, … 8 foot arc? And don’t bother recutting a straight line between the arcs. You use the out side curve to draw your template.
Guess what you use the inside arcs to check? hint, "why did Yorky make 40’ arc templates?
I think you miss my point Mark…a good set of spin templates can generate any plan shape by moving them back or forward to co-ordinate with any required board dimensions…the same way french curves work in draughting…translated into computer-speak , the compound curve of a humble spin template contains and infinite number of g-codes…the relevance here , is that surfboard curves rarely , if ever, use arcs with a common centre , as in circles… its all compounding curves …which is why Yorky uses the 44gallon drum to generate his compound curves…I suppose , if a computer is a preferred tool and method , so be it…as long as it gives you the result why not…I have old habbits from the lofting floor…try drawing an elipse , with a pencil , two nails and a piece of string.
My point is that you use curves to make your spin templates. Using a known arc makes it easier than the usual methods of bending sticks, and then truing up the cut.
Also my point is that if you know what arc you are using, you can be more accurate than just sliding a french curve up and down the board, “eyeballing” the line.