Unless you dont want to do regular production work and intend to use epoxy resin system, as long as it generates enough vacuum a venturi type pump would work just fine, and has nothing to wear out like the cheap electric air con pumps.
I have a 3 stage venturi type pump made by PIAB, cost about $40 from Ebay, and works fine as long as you have a good compressor. http://www.piab.com/Templates/Page.aspx?id=134
Chris
Sorry for bumping up an old thread but I just wanted a little help since I will be attempting to make a “hollow” mold soon.
Anyways with a spoiler like this that dual twill has done, how do you ensure that when you cut the two halves that when you put it together there will be no gap? I would assume it to be very hard to get the two halves nice and straight wouldnt it?
Also when bonding, the two “mating” surfaces will be what, just the thickness of the piece? Is that “area” strong enough to glue to two together???
you can make a few adjustments to that though.
Add one peice supporting ribs that bond both sections.
You could also make the perimeter slightly thicker so that there is more bonding surface area
^^ Your second statement sounds true and was exactly what I was thinking about doing, however can you please go into more details about what you mean by the first statement? Ribs??
thnk of an I-Beam
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outer skin
foam/glass, balsa, plywood sandwich panels
outer skin
You can also do “underlapping” (don;'t know if that is what it is called but it makes sense to me lol) I guess overlapping would make sense too, ha
I know there is a how-to about making a pipe section like this somewhere on the net. If I can find it I’ll post it up
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^^ I know I sound like an idiot by asking this but can you please find that how to?
I understand the concept that is being portrayed here but just cant seem to see how it is done in a composite sense.
Yes it would be good to provide the extra support needed but still back to one of my original question. how do you make sure the two mating surfaces match each other?
its going to be how well the mold is defined and how well you cut it
I also do not see how you would be able to bond the top and bottom pieces together. I’ve made 2-part moulds where I can reach inside and put reinforcement in, but I’ve never tried to bond two pieces that I can NOT get inside for reinforcement.
Are y’all suggesting that we just trim the two parts so they fit nice, then put a little epoxy on the mating edges, and sandwiche them together until the epoxy cures??? — with no structural reinforcement? Won’t this make the seams weak?
I could lay a piece of reinforcement tape on the outside, but that doesn’t make for a very pretty finished piece…
either you need a tongue on the part to bond on to the inside of the other half of tha part or you need to put fibers over the seam on the outside
I’ve been thinking about this all morning and can’t figure out how you would make a tongue for the inside…
Anyone have pictures or a diagram? :o
one of your molds would need a removable piece that would offset and extended your part past the flange. to make this you can make a part and put it together, place it back in the mold. make a mold of the first inch or two of the part depending how much overlap you will need. demold and add the amount of laminate you want to offset(thickness of your actual part)the tongue. simplified explanation.