October 2004

The month for filleting.

Devlin's lightbulb in a box idea to warm the resins works a treat. I've also bought some ±45° 150mm wide tape for the fillet reinforcement. The 0/90° I've been using up to now is probably fine but technically a poor substitute.

Devlin recommends that the fillet thickness be at least equal to the thickness of the thickest panel to be joined. But there is no mention of the influence of the included angle between the two panels. Clearly it can't apply when the panels butt at 180°. If I allow the fillet thickness to decrease linearly with panel angle I produce this family of fillet radii. Interestingly they produce roughly equivalent fillet widths as well.
Fillet proportions

Or Graphically
Fillet radius with included panel angle

Which is all very well until you examine the variation of included panel angle along the hull. Variation in included panel angle at the chine

Filleting tools So for the fillets with the greatest angle change over their length I made an involute fillet template. You need to mark the fillet width on both panels otherwise you don't know which bit of the template to use. As you slide along the fillet you rotate the template to change the fillet radius and hence maintain the fillet thickness. It takes a little practice and I suggest you make it from thicker platic than the 1.5mm I used.