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I used 30 minute epoxy laminating resin. This brand (EZ
Lam from Aerospace Composites) has
well over 30 minutes working time. Even though I stopped frequently to
take photos I was never in danger of having the resin set up too quickly.
I mixed 60 ml of resin (about 1-1/2 ounces) and had plenty. |
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This little foam roller is great for applying fiberglass.
It comes with a tray that I threw out after using it the first time because
I didn't want to spend a fortune on the solvent needed to clean the tray.
And unlike the ads say, I can't ever get dried resin to peel out of anything
cleanly. I always end up spending a lot of time picking it out so for
me disposable is better. The rollers come in packs of two and cost
less than two bucks.
I use a foam plate as a roller tray.
You can also use a squeegee. Just be careful not to pull the weave
of the cloth apart. |
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The first lamination (the bottom of the gear) receives a liberal coat of resin
on the top.
The other side is masked to keep glue from the outer surface.
The one thing about using a roller is it puts a lot of air bubbles in
the resin. If you use a slow enough resin the bubbles will float
their way out of the resin.
If you use a roller and the cured resin contains air bubbles then use
a slower resin, a less viscous resin or a squeegee.
(In case you're forgotten, ALWAYS test new techniques and finishes on
something other than things that you prefer to come out a certain way) |
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A layer of 8 ounce fiberglass is laid over the blank and
more resin is applied. You can apply resin reasonably liberally.
The excess will be squeezed out when it's all clamped together. |
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The first blank with the attached fiberglass is put on
the form. Using my high-tech pointy stick (a lead holder with a
compass point) I put holes in the glass to insert the pins. |
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Turn the second layer upside down to coat the underside
only. |
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Place it on the form with the uncoated side up. |
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Use the upper clamp block to push the blank down. |
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Remove two of the pins and coat that side with resin. |
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Replace the pins and coat the other side. |
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Remove all the pins and add a layer of 2 ounce
fiberglass. |
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Wet out the middle area of the fiberglass. Replace
the pins and then wet out the legs. |
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Repeat the above steps for all the middle laminations.
Coat the underside of the next blank, put it on the form, coat the top,
add the fiberglass, wet it out
and repeat.
Above the second to the last lamination goes the second piece of
heavier 8 ounce
cloth. |
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Coat the inside of the last plywood lamination with resin
and add it to the form. Again, this is how I laid up the gear
for my application. Yours may need to be lighter or heavier and
you may need to do it more than once if you guess wrong. |
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Begin clamping from the center and work your way out.
Don't tighten the clamps too much at this point. Snug is good.
At this point you can remove the pins if you like. I just left
them and gave them a quick, sharp twist with vise-grips after the epoxy
cured. The epoxy sheared cleanly from the pins with no damage to
the gear.
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Work your way around the form adding clamps. A
second person can help by holding the legs to the form while
you apply the clamps. At
minimum there should be a clamp on both sides of every bend and if
there's room, one (or more) in the middle of each leg. More clamps
are better as long as the weight
doesn't twist the form. |
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When all the clamps are in place go back to the center
and further tighten the clamps. The clamps will loosen as resin squeezes out so check them every ten minutes for about thirty minutes
or so. By the time you're finished the clamps should be
applying a lot of pressure to the lay-up.
Allow the gear to set up at least 24 hours. Longer is better.
Before you even think about taking it all apart check the excess
fiberglass and ensure the resin is hard. That means hard
— not
just mostly firm.
Roast chicken is on sale. I feel hungry all of the sudden. |
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Remove the clamps in reverse order. Woo Hoo! Captain Morgan is on sale too!
Try to stay focused. |
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So far so good. |
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The gear released easily and cleanly from the form.
Before I trimmed the gear, I used my shop vac to pull loose fiberglass strands from
around the lay-up so that it wouldn't come loose on its own and float all over my
shop. That made a big difference in clean up. |