Large plug...simple solution?

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#1

Greetings all,

Due to multiple (expensive) catastrophic failures trying to make molds, I was hoping for a simple solution for a “one and done” project. I want to make a mold of my rear seat delete but no additional copies will be made from the plug.

The size of the plug is on the order of 60" x 72" and there are some sharp edges and 90* angles. The surface has been waxed and sprayed with PVA (surface appearance doesn’t matter). I was hoping to wet lay 2-3 layers of cf cloth across the surface and then just pop that off, however, I’m concerned about “pull away” during curing. Vacuum bagging is a possibility but I don’t have any experience with this technique.

I will be using this cloth for the wet lay up…the reason for choosing this cloth is because I could get it in 63" width.

Weight: 5.7osy
Weave: Plain
Tow Size: 3K
Thickness: .010"

Is it realistic to consider wet lay up to make a thin surface mold directly on this plug?

EDIT these are not the most recent pics but will give a good idea of the shape and scope of the project.

#2

one way i can think, is to apply a layer of resin let it get tacky and then apply the cf layer with some more resin, work it with a roller let it get tacky and then apply the second layer of cf etc.
in the spots that you have 90* angles do some relief cuts to the cf.
if you can remove the plug out of the car it will make the job a lot easier

#3

No it would not be possible to remove the plug…it would destroy it.

Can anybody comment on the weave of carbon fiber fabric I bought? Is it unrealistic to expect this fabric to drape completely across this plug?

I could pursue vacuum bagging, but this would be technically challenging given the size and vertical nature if the project.

#4

yes
you can produce a good mold with out vacuum!

once you have the pattern exactly the way you want your parts to look prep with release agents and apply a surface coat let it tack until you can leave a fingerprint in it but it no longer transfers material to your finger. Now apply a nice wet coat of resin with a brush once the entire surface or at least what you expect to cover with your first piece of material is wet, Apply the dry fabric to the wet pattern surface making sure not to create any bridges.
Once you are confident in the placement of the fabric use a short bristled brush and resin when needed work that layer into the resin bed until you are 100% confident there is no air in the laminate
If done properly continue this process until you achieve the laminate thickness you desire
Often I will stop after 3 layers and let that tack up until I know that portion is gelled enough that subsequent lay ups will not alter the foundational laminate.

I Hope This Helps

the use of fiberglass makes this process cheaper and easier because you can see through the cloth and focus on removing the air.

#5

That helps alot…thanks!!

Could you explain this part a little more thoroughly? If I understand correctly, I will cover the plug in 1 layer of resin and allow that to tack…then cover the plug all over again with an additional coat of resin and apply my cloth onto that?

#6

Well, I bit the bullet and bought a vacuum bagging set up…I don’t want to half ass this project. I spent way too long working on the plug to not mold it properly.

Vacuum pump:

And bought vacuum bagging kit:

#7

If I am doing a wet layup, vacuum bag mold…will I need to have a resin trap before the pump?

#8

no you don’t have to use resin trap, but may i ask why you want to do this mold by using cf and epoxy?
fiberglass and polyester will be easier and much simpler to work with

#9

I won’t be using epoxy…I’ll be using polyester.

The reason for using cf is for rigidity. I didn’t want a floppy part that was susceptible to warping.

#10

the polyester will get hard long before you manage to bag this big part. just use roller in the “dangerous” areas and it will be fine. in my opinion multiple layers of csm 450gr+ will be more suitable to use and it will definitely be rigid.

#11

In my experience, it is EXTREMELY difficult to get CSM to conform to a 90 degree angle. Getting the 90 degree angle in the final part is critical for fitment.

#12

Do it in layers. If you have a do a 90 degree edge there 2 ways about it. Cut strips and butt them up into the corner, or another method I use, is the 1.5oz csm I use can actually be pulled apart down the center (like 2 pages that are stuck together) so you end up with something like 3/4oz csm. It is then a lot easier to get around and into corners. Do a few layers like this in the problem areas and then go to town with the heavier backing.

#13

Why do y’all recommend csm over fabric? I thought fabric was much more conformable than csm…?

BTW, I’m not looking to apply alot of heavy backing. I was hoping to just put down 3-4 layers of the plain weave carbon fiber I showed above.

#14

csm gives you more rigid end result therefore you will have to use fewer layers, also the less weight of the csm the more conformable it will be so if you start with a couple of 200gr (or less) csm layers in the problematic areas everything will be ok.
in my opinion using cf will be waste of material.

#15

Hey BND nice to see you moving ahead on the project. Did you get that mold made? I think it was a door, or maybe a fender.
I think there may be some confussion based on your original post. The way I read it, you would like to use the plug that is mounted in your car as a male mold to make a carbon seat delete, rather than making a mold that could later form the seat delete. Is that correct? If so are you wanting the carbon surface exposed or will the part be painted? The fabric you show is plain weave which is fine, however the other parts were done in 2x2 twill. You can get 2x2 in 60" length, it’s just not as common as 50".
There are a couple issues with making a one off part from a plug. One being the surface finish. Whether bagged or not you will not be able to get as smooth of a surface as you could against a good mold surface. Also keep in mind that if you want to finish the outer exposed surface of the part clear, you will want to get some surfacing wax for your top layer, otherwise you will have problems sanding the surface smooth.
As for the layup, do you have room to tape the bag around the part? If so bagging it may help to keep everything in place during the cure, but again this will have an impact on the surface finish if you are wanting the carbon exposed. If you want to try it without the bag the earlier suggestion of letting the resin tack should work fine, though keep in mind that being this is a big piece of carbon and since you have pva on the mold, you may not be able to move the fabric around much once it touches the resin since it could pull the resin and pva from the plug, depending on how soft the resin is.

#16

That is correct. I just want to make a “one and done” mold. The mold I make off this plug will be the final piece.

The carbon surface will not be exposed. I’m actually going to cover the seat delete with carpet to blend with the rest of the interior. The goal is to make this look OEM.

Yeah, I’m a little nervous about the time involved to set everything up after laying down the first coat of resin. It looks like I should have just enough space to tape down the vacuum bag around the perimeter of the part.

I went ahead and bought some medium working time epoxy from West Systems. At 60-70 degrees, this should give me plenty of working time to get my bagging all set up.

Jim, thanks for the comprehensive reply.

#17

If you are covering in carpet anyhow, I would just make a 2mm thick polyester part over the mould you produced in your car. Quick and dirty. Should take you 1 hour or so to make, plenty strong, and more than lightweight enough. (I assume you are not THAT weight conscious, as you are goingto carpet it.)

#18

herman, thanks for replying.

It’s already getting cool here and temps above 70 are getting rare. That’s the reason I thought epoxy might be a better choice. When it gets even cooler, I could get fast working epoxy which would allow me to work at temps above 50 degrees.

The part also has to be strong enough that it doesn’t tear when I pop it off the plug. This is a very large piece and there will be alot of resistance when I go to release the molded part. That’s the reason I got the carbon fiber fabric…thinking it would be stronger and more resistant to tearing.