Best way to lay-up/infuse a tube?

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#1

Which would be the best method to replicate a 5" tube like what comes in a K&N cold air intake kit? The tube is straight for 11" then makes a 15 degree turn then goes another 8". I thought about a two piece foam mold that would bolt together at the bend, but would first have to be able to foam the entire interior and get that out. I thought of gelcoating the inner wall of the tube, laying it up with fiberglass, then cutting it out, but may damage the original part while trying to cut it out. Any ideas will help.

I’ve got only a couple of years of carbon/fiberglass mold making and part making. I’ve done lots of curved parts (motorcycle fenders, shields, etc) and door trim pieces, but not really worked with a tube.

Thanks

#2

A mold is going to be needed. Either you will have to shape the part out of foam or Aquacore then wrap that shape with carbon fiber, vacuum bag or shrink wrap the lay up for curing. Then lastly dissolve out the core.

#3

Is aquapore any good i considerd this method before.

#4

Advanced Ceramics (of Aquacore.pour fame) have switched their business into more of rapid prototyping their cores, and wrapping it with tape. They have had issues with the core sticking to the part, and people not really knowing HOW to make the cores. NOW, you just give them a CAD file, they make it, and send it bac, within the week. Prices weren’t overly bad, but not exactly cheap for a hobbyist.
Other ways, are SmartMolding, which is a formable bladder. Heat it, form it, lay up, heat up again, and take it out. Need a female mold for the form AND part.

#5

You can make a two piece female mould off your original tube that is split along the length of the part so you have two 180 degree mould halves of the tube.

Then you can layup the two halves leaving some laminate sticking out past the flanges so that this will overlap the other half when the moulds go together, while wet.

Then since this tube is short you can make vacuum bag tube for the inside and an envelope bag for the outside, seal them together at the ends and suck it down/out??

Or you can use the same moulds, layup the two halves separate and green trim them nicely at the flange. Once cured you can bolt your moulds together with a little resin on the part/flange corners and then add a joining laminate/tapes on the inside since this tube is big enough for your hand and just long enough to reach in from the ends. This way no vacuum process is needed.

#6

The fastest and easiest way is to make two molds, one of each half of the pipe, layup and infuse each, then trim and bond them together.

It’s how we make spoilers and even have a cold air intake in development.

Intake:

Two piece spoiler:

#7

How do you bond the two parts together after curing each separately and still make a seamless part?

#8

you can see the seam on the pic where it’s fitted. Not much harder is to layup in the two halves, trim one flush, leave the other a bit longer, close the mould and use a bladder for pressure, connecting the two halves. No timming/bonding afterwards.

#9

Hi, everybody, I am a new friend.:slight_smile:

#10

i haven’t been home yet to test my idea, but my alternative idea was to cut a piece of PCV pipe in half, lengthways, lay the CF in the bottom (allow for overlap), lay a bicycle innertube in the middle, then lay the top half of the carbon, then close up the mold with a handful of zipties, cable clamps, whatever you can think of. inflate the tube and this acts as a redneck version of “expancel”.

just an idea that needs testing. I’ll let you know in a few weeks if it works or not.

#11

I build the one in this picture with an inner tube from a motorscooter tire.

Its called bladder moulding, and is a common method.

Remember to use some kind of release on the bladder :wink:

#12

nice, susho. what did you use for the mold?

#13

This one was fully enclosed, made for the car. epoxy gelcoat, carbon and epoxycement backing 2 part mould. But anything that withstands the pressure will do.

#14

i mean, did you make a negative mold of a pre-existing intake tube, or use a tube from something else?

#15

Has anyone made a charge pipe for a turbo system? Cold side piping would not get very hot, Just wondering if the 2 half and bonded method would hold up to 25 ish psi. Or if you would have to do the bladder method.