I obviously use the scales method, but due to slight variations in the wood, if you are going for a suspending lure, fine tunung will always be required. But for regular lures the scales are perfect, you can find the ballast value to achieve the flotation you want when the blank is shaped.
By accurately weighing the blank and weighing the pure lead required to suspend the blank, enough information is gathered to calculate the ballast. I have written a spread sheet to perform all the calculations, I just enter the two figures and read off the answer. If I enter the drill diameter, it even tells me how deep to drill the hole.
other information given by the spread sheet: volume of the blank, density of the blank (plus sealer), final weight of the lure (approx). The spread sheet allows you to enter the amount of buoyancy you require, I usually go for 90% - 95%, this means that 5% - 10% of the lure mass will be above the surface. I will be enhancing this spread sheet to include entries for weight of lip, hanger, hooks and eyes.
Also, the sheet can by made to give information at later stages of the build, before epoxy and after epoxy. For future lures, you will be able to closely estimate the effect of the top coat.Hell, it is even possible to enter the depth you require the thing to suspend, but where do you draw the line.
If anyone would like to try the system out, just PM your e-mail addy and I will send a copy.
Last weekend I had seventeen balsa blanks on the go at once. It was soul destroying with the amount of work in front of me. I even split them into batches so I would not have to look at them all at once. This is by no means essential kit, in fact the same information is
9and should be) gathered during and after the first build, for future reference. The sheet just allows you to get close with the first one with confidence.