Another question. For a part that is made with flex resin, and must withstand many impacts, would it be best to use a surfacing veil with the flex resin on gel coat? I believe from reading here that gel coat is harder? but will it flex properly with the rest of the piece and be able to withstand multiple impacts? The resin I am looking at using has 10% flex.
I put the flex resin also in the gel coat too. No need for surfacing veil as we use thin FG mat and then cloth.
The main purpose of using veil is to reduce fabric printthrough caused by the resin shrinking after cure. Veil is used on molds to provide a barrier between the generally heavy woven fabrics and the tooling gelcoat. On molded parts, veil is generally used only if a gelcoat is applied as a surface finish to keep the final product smooth.
Gelcoat is generally hard, but slightly brittle. It holds up well to impact and chips, but may crack when flexed. You may want to find out if flex additive can be mixed with the gelcoat.
What is your reason for using gelcoat on the finished parts? If they will be painted, skip the gelcoat. If it’s ok to possibly have a slightly noticable texture, skip the veil too.
You can just use a fine weave light fabric as the first layer, or what we do is simply not use woven fabric at all. All of our plies are unidirectional fabric, and don’t leave any printthrough even with bare resin on the surface.
parts will be put though a serious beating as they will be used as guard for dirt bikes. I dont see print through being an issue in the final piece. How will an outer layer of carbon fair against multiple impacts without an outer layer? If a light layer of glass should be added on the outside, what weight should be used?
If you already know they’ll take a beating for sure, then don’t use gelcoat. It is very likely that it will crack or chip, and the parts will look ugly fast.
In our experience, a bare carbon surface holds up much better than raw, painted, or gelcoated fiberglass. The carbon surface is harder to scratch or pit, and looks awesome too.
Depending on the size and location of these parts, i’d recommend a total weight of about 40 oz/yd. 4 10oz fiberglass layers, or a 5.7oz layer of carbon followed by 3 12oz layers of glass.
I don’t think flex additive is really needed here afterall. Polyester resin is flexible enough.
I’d also look into those clear film tear offs like in Nascar and I have a book with an ad in there for it somewhere around here.
JM, can you post a link to the flex resin. Part number, where to buy etc?
Revchem in Bloomington, Calif. (800) 281-4975
I’ll have to dig to find the pail part #'s…
wow, thats for the help guys. The other companies that make these guards use primarily CSM and they break relatively easy. They make considerably thick pieces. I figure I can make a much higher quality part. Werks, is that the number for the film? Also, do you think that a 40oz thickness will be enough? We put these guards through just about everything and an impact on a large tree with a 250pnd bike and a rider of about the same is considerable…
evenc, no rezcar ask me about the PER flex resin source…
If you want the film, I’ll have to dig for it and get back to ya later.
Sounds good. If you could dig that up it would be great. Composites Canada also provides a flexible VER resin.
If you are looking for a dirtbike guard product that actually works, rather than just looks nice, I would suggest vac formed ABS is going to work a lot better than any affordable composite material.
I agree with CB but here’s some of those window film tear offs to check out if they can sell you the bulk material and you can get them steel rule die stamped out:
CM Racing Products www.cmracingproducts.com
www.lamin-x.com for light covers in colors too
Her’s a link to what I think the Nascar teams use to fix rips and tears on bodies and call it “bear bond tape”…? www.rubbnrepair.com
Just tell them you read about them on here and I got them from Grassroots Motorsports magazine.
I agree that there are other good options, but this seems to be the most demanded. I have made one out of just fg cloth and it has held up without any damage through much abuse. The big issue I see is that the main company marketing these guards is producing them with just csm which cant take near as much abuse as fabric seems to.
Well, I looked at Revchem’s site and its as informative as a paper napkin. Are they a manufacturer or a distributor?
I did a google search as well but didn’t come up with anything. Silmar makes something as well, but again, their website doesn’t say jack about it.