Productive day yesterday, I managed to cut, bend and drill some 3mm clear acrylic sheet to form the lens for the instrument surround. The material is a swine to cut, the recommended way is to score one side with a Stanley knife then place over a block and crack it, but a) this does not really work for curved surfaces unless you have an exact facsimile of the shape you want to cut and b) it does not stop it cracking in whatever direction it feels like cracking. I tried my jigsaw with the finest of blades and managed to shatter two patterns, a fine toothed hacksaw was also tried which was very laborious and also cracked. The Dremel with a 40mm diamond disc got the job done finally, finished with a fine file.
Bending the acrylic sheet was accomplished with the aid of a vice, two blocks of wood and 15 seconds with a hot air gun. Drilling required a new sharp 6mm drill and very light pressure and even then I managed one 1mm crack when the sheet rode up the drill as I broke through (fortunately small enough to be within the radius of the button head screw). In the picture the protective film that the material is supplied with is still attached.
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Next I turned my attention to the tank mould dividers, a job I have been avoiding as a) I was not sure how best to do it and b) I knew it would be difficult.
The tank pattern is heavy (maybe 15kg) but the top surface is actually quite delicate as the body filler thickness over the foam in some places is less than a millimetre. I will therefore make the dividers for the top surface first to protect that thin skin. The tank will have to be made principally as a top surface and a bottom surface and then bonded together, however, at the front near the ignition switch and at the rear near the seat bridge the shape of the pattern would mean that the pattern would not release from the mould so additional dividers are required.
As far as possible I want to limit the extent that the inevitable “flash” lines ruin the aesthetic of the finished product and over the past months I have mentally changed the proposed position of the dividers about 6 times. Yesterday, I decided that prevarication had to stop and for better or worse their position had to be fixed.
I am hoping that the tank underside can be made in one piece (not yet proven) and I want to ensure that where the tank top meets the tank bottom that I have a slightly conical junction line about 6 to 10mm deep so that a good bonding surface between top and bottom is facilitated. To best achieve this and not end up with a very messy junction line I think I need the bottom edge of the tank top to be extended downward with a slight opening taper, thus the tank bottom mould will have a similarly conical mating surface to the top mould. (I hope this makes sense).
Here are today's efforts
