Jim.Thompson's blog View Details
Archive for July, 2011
Posted by Jim.Thompson | Jul 04, 2011 @ 04:08 PM | 3,996 Views
I am now waxing up both new mould halves. After the usual 4 or 5 coats of wax I will flood and drain it with PVA. Then I plan to do a sacrificial pull on the damaged half. I will use a surface coat and let it green off in the usual way, and then lay up some veil which I have in stock and otherwise no longer use. Several layers will give it sufficient stiffness to "pull" out of the mould intact. That is providing I have achieved a good release. This will be the proving of success the mould repair, or otherwise.
Posted by Jim.Thompson | Jul 02, 2011 @ 05:48 AM | 4,392 Views
I have now built the mould and allowed one week for it to cure and stabilise. I split it to remove the plug which came out of the second half without much difficulty. There were just a few pieces of gel coat off the plug which stuck to the mould around the wing fillet areas. I expected this.
However, the first made half stuck like it was meant to. It required total destruction to remove it and along the way, I damaged the mould half rather badly.
However, I have repaired it over the last week or ten days piece by piece. First of all, I cleaned it thoroughly with water and then acetone. I then ground out any cracks and deep gouged, first filling with vinylester tooling "Q" cells mix. Several applications were applied, sanding in between. Then I surfaced it with a surface coat of the tooling resin and graphite/Wests 403 mix. Sanded finally with fine 320 grit paper.

Today I mixed some 2 pack casting silicone and poured the wing fillet inserts.
Tomorrow I plan to begin waxing up. Then I will apply PVA by the "Flood and drain" method. When it is dry, I'll do a sacrificial light layup with some light glass. I want to do this to prove the release capability of the repaired surface before commiting to a complete fuselage layup. The repaired mould is all I have left of the shape that took so much work to shape. I have the original mould, but the shape has been very slightly improved in symmetry etc. since it was made. At worst, I could make a plug from this, reshape and build another complete mould. But I am hoping that it will not come to that.

Jim.