Hi guys, I know it has been covered somewhere, but I cant find a similar thread.
I need to build a mold for a very oddly shaped part, it starts as a 3.5” 180▫ to a 90▫ “L”
My question is what are the best materials and methods to start making this part?
I remember some had said stretched material such as pantiehose and use resin to harden and build from there.
Are there any preferred methods, or threads someone can lead me to?
First things first:
Is this a one off, short production run or a mass produced part?
How strong does this need to be?
What is the fuction of this item? Structural or comestic?
Does it have to made from Composites?
Service use: inside or outside?
???
This is a one off for a project, so only one needs to be made per side (mirror image)
The part does not need to be very strong; it is duct work for an intercooler.
I would like it to be made from composites, the rest of the ductwork is finished, I made the rest from a fiberglass covered in carbon for the reveal.
The part will be made for external use in a fairly warm environment, as it will sit against a radiator at 100 C.
I have made the part of fiberglass, and it has been in use for ~2 years, I am just unhappy with the shape and finish of the part so I am going to start from scratch to make it a more professional looking piece.
I also wanted to take a second to thank you personally for taking over the forum and the attitude you have had throughout the time I have been lurking around the composite world.
It makes it so much more productive and educational and just plain fun.
Thanks!
THANK YOU!
…but I could not have done it unless Evan didn’t generously gave me what data he had and with the help of others like kyanton, jeremy and many others that help out answering questions on here!
Now, on to your question…
You could also, like what was suggested elsewhere, but use a 1/8" welding wire rod mounted to a wood plate to form the round part, then make lines where the square part needs to be, get some Polyester fabric (like the type used for custom speaker enclosures), spray the wire with spray adhesive, wrap the fabric around the wire, pull it down to the line markings and then staple the fabric along the line to form the flange / square part.
Then coat the fabric with PER or Epoxy resin and wait until it cures.
Fill, sand and smooth out any imperfections. Then add a layer of FG or if you want to go directly to CF, paint it black and then apply the CF cloth. Wait til it cures, cut it out with a bandsaw or Sawzall (I love them…), grind, trim to fit, rework the inside if needed to get it smooth and then start clear coating the outsides…
But there’s always more than one way to skin a “DOG”…sorry, I’m a CAT person![SIZE=3]
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If the part is small you could carve it out of polyurethane foam, Thema layter of resin to harden the surface, sand and buff and you have a buck to pull a mold from. you could also carve it out of polystyrene foam but you have to seal it with epoxy resin as polyester will melt it.
Yes he could, but for just 1 or 2 parts…a mold adds too much costs into it.
He could use the PUR foam plug to lay the finish parts up on (maybe scran wrap the foam to get a smoother inside surface) and then post clear coat finish the outside…
The way Werksberg is describing sound more like the process I am after as it is a one off and has no real definition to it except in concept…
The problem I have with the old part is the lines and roughness of the parts does not lend itself to a professional looking part at all. While the edges do match up to the surfaces I want them to, the merging of the two shapes does not flow together correctly imo, and you can tell the fabric was hand laid and sagged as it cured.
I wish to make a more professional looking part, where the lines are strait and intentional.
Will I be able to accomplish this (in your opinion) with a frame with stretched material on it to form the shape if the right materials are used?
Yes, but practice makes perfect!
Maybe also run the welding wire down to the flat flange like surface to support the cloth better?
I was thinking just a little while ago on this…the wife hates when I’m off in space…and you might be able to roll the edge on the wire for a better inlet.
It looks like a CAD picture where you loft the L in to a semi-circle. If you want to do it like the professionals, a 5 axis mill is probably out of the question. But you can do it the old way. Print out section views at a set interval at 1:1 scale. Use that to cut out foam panels with the same thickness as the drawing interval, and make sure you have so type of locating pins to align each layer. Then sand off the corners, fill the pores, sand, polish, and bob’s your uncle.
Now I like that idea, very creative solution.
Maybe I could go one step further, and use the stacked layer to support a stretched material.
Though I have a feeling I would have to use a light fast sandable filler to smooth the segments so as not to get any “rippling” effect.
I really think this is a good idea, at least to get to a basic shape if you do not have access to the machinery, but have the will to continue trying to make a part. It would give a person a reference to sand to when applying a light sandable filler, and keep the basic profile if a tolerance where to exist.
Kind of like one of those puzz 3D things right?
The part is fairly small, so I think I will try the stretch method first, and if I feel I need more support, I will give that a stab.
Is there any particular “Polyester fabric (like the type used for custom speaker enclosures)” to buy you have used in the past, that you could recommend?
And where would one obtain this material?
Didn’t get any hits for “Polyester fabric”
Is it a standard thing you can get at a stereo shop or is it just used in this application?
Can I assume it is very similar in properties to say spandex?
And since it is a poly I should stick with poly resin right?
Nothing creative about it. That’s standard industry practice until 5 axis mills came along.
the fabric doesnt need to be any kind of poly…Ive used old cotton T-shirt to do that kind of work.
Just have at it.