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Molded parts


emteeoh
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I've found stuff on the web (including youtube) showing how to make and use molds for fibreglass parts... But everything I've seen has NOT had the foam sandwich layer thing. How are molded parts made with foam and fibreglass, like the velocity fuselage? Are they using some kind of spray-on foam? Or maybe injection molded foam? ( I keep imagining them trying to use the foam insulation in a can...)

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I've found stuff on the web (including youtube) showing how to make and use molds for fibreglass parts... But everything I've seen has NOT had the foam sandwich layer thing. How are molded parts made with foam and fibreglass, like the velocity fuselage? Are they using some kind of spray-on foam? Or maybe injection molded foam? ( I keep imagining them trying to use the foam insulation in a can...)

 

No,

 

It's actually a relative simple but time intensive process for large parts.

 

You start with a good female mold. After waxing it or otherwise treating it so that the epoxy will not stick, you spray the mold with epoxy primer. When the primer is dryish to the touch, you lay your glass on it and squeegee and squeegee and squeegee the epoxy into the weave (s). When all is saturated, you take, I believe it is called, D cell foam which is similar to that that we use except is fully cut into 1" squares, all fixed to a thin fiberglass backing. this material is extremely flexible in 2 dimensions and slightly flexible in the others.

 

The D-Cell material has been pre-cut so that it can be laid into the mold with as few gaps as possible.

 

The cut D-cell is placed on the wet glass, and in general will be held there by the tackiness, or you use tape etc to keep it in place.

 

You then take plastic sheeting, I think 4 mils, lay it over the whole layup, in the mold, seal it to the mold with a wax-like material (dum dum.) In certain areas you put a separating ply (little holes punched) and some absorbent material(not over the entire thing)

 

Connect it to a suction source. If you arrange the plastic correctly, it will not pull unsupported foam inward, but will merely press it against the curing epoxy.

 

Leave the vacuum on overnight.

 

The next day you have your outer skin and foam.

 

Next, while still in the mold, you trim away all of the excess epoxy that has come through the cuts between the 1" squares and then fill all of the voids with micro.

 

Micro the entire surface and glass normally and allow to air polymerize.

 

Remove from the mold and trim.

 

The epoxy primer acts as a Gel-coat, however is much lighter. You use Cabosil where there are joggles so you don't get air bubbles.

 

Of course the quality of the mold will determine the quality of the part.

 

Like a good cheese, it depends on the mold:p

I Canardly contain myself!

Rich :D

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. . .

You start with a good female mold. After waxing it or otherwise treating it so that the epoxy will not stick, you spray the mold with epoxy primer. When the primer is dryish to the touch, you lay your glass on it and squeegee and squeegee and squeegee the epoxy into the weave (s). When all is saturated, you take, I believe it is called, . . . "

A SMOKE BREAK :cool:

". . . Of course the quality of the mold will determine the quality of the part.

Like a good cheese, it depends on the mold:p"

For the guys,

this could also be interpreted as solid Standard Operating Procedures

on Valentines Day! :D

Hat

(Flower Shop on Speed Dial)

Airspeed is Life -

:cool: - Having lots of it

is Better!

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