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Layup notes and learning

Layup notes and learning

Owned by Minqian Lu
Last updated: Jul 04, 2021
4 min read

This page was made to document cool things we learned along the way. A picture is worth a thousand words so this page is going to be a novel

For context, the wheel covers were made to practice adhering thin Nomex to complex curves, which ended up working quite well. Pro gamer moves include trimming prepreg and Nomex with an Exacto knife, envelope bagging, and boycotting (or at least being very careful with it) old adhesive film

Trimming prepreg came to be very useful for fitting it within our boundary “shown with the touch sanded surface. It is much easier to trim it without the film and the paper backing.

Trimming the carbon

First layer of prepreg, just wanted to show it off I guess.

Here, bending Nomex was pretty easy and it helps make the layup cleaner. Some of the cells needed to be compressed but it seems ok. With quarter-inch Nomex, its very easy to trim with an Exacto knife; making the layup even cleaner.

With old adhesive film, it wasn’t adhering well to the other layers and ended up bridging. Then, when the next layer of carbon was put on it was bridging as well. To fix it, we slit the carbon where it was bridging and allowed for a gap where it was originally bridging. This helped adhered the two perpendicular surfaces to the wall a bit better.

 

 

With Surface bagging, it was relatively easy to make, with very little pleating required.

However, this bag failed due to the cracks in the mold. We tried to plug it with tacky tape but wow, it was a huge time sink and never worked.

Instead, we tried to envelop bag it. We did this with one long sheet and then folding it in on itself. Here, we just had to make sure that the bag itself was long enough to enclose and adhere to the entire surface of the mold (I stuck at wording it but you’ll see in the next few pics).

Here, you can see the two envelop bagged molds, with the bag adhering/following the curve as explained in the last blurb. Hopefully, that helps paint a better picture. In the end, the closer vacuum bag failed, probably due to the heat of the heater heating (ha) the tacky tape up and causing a leak somewhere. Otherwise, they were both initially brought to roughly -25 psi (I think those are the units on the SDC vacuum pump gauge but I could be wrong).

One small caveat was that the screws (seen with those sharp things poking out of the mold) were accidentally bagged without covering them on the first go. This was fixed for the second bag but they ended up not puncturing a hole in the bag anyways. However, it’s still a good thing to keep in mind moving forward.

 

 

 

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