Headlight Cover Project

General Composites Discussions Composites Talk
#1

I’m making a headlight delete panel for my 93 Mazda RX-7. I am removing the pop-up headlights and replacing them with these covers. I expect the weight savings to be ~14 lbs, based on the the weight of the parts removed and the estimated weight of the delete panel. This will be my first all epoxy project. Last year I did a project where I made a mold from polyester gel and resin using chopped strand mat. I had help making that mold, and learned a lot from the process (a lot of what not to do).

For this project I’ll be using a epoxy surface coat, with epoxy laminating resin, and various woven fabric reinforcements. I’m using Adtech ES-201-PC surface coat, Adtech EL-301 laminating resin, and some 1 oz fabric followed by 8.8 oz fabric for the mold. For the part I’ll be infusing with Adtech 820 resin.

First step, make a platform that mimics the surface which I will bolt my part to. For the RX-7, it is a simple angled surface to which the parts will bolt, so that was easy enough to make from plywood.


Untitled by Kevin_Doe, on Flickr


Untitled by Kevin_Doe, on Flickr

Then I took some measurements from the factory cover panel to the mounting flanges/locations which I’ll bolt my cover delete panel to. I too many measurements to ensure my plug would be constructed perfectly. I transferred those measurements from the car to the plug and mocked up the factory covers in that position.


IMG_7419.jpg by Kevin_Doe, on Flickr

I then transferred a scribe line from the edge of the cover down to the base, and cut and glued some 1/4" square dowel to the base using hot melt adhesive. That was to provide a good surface to glue the “walls” against. Following that, I cut some wood to fill in the walls. Again, I used hot glue for that.

IMG_7422.jpg by Kevin_Doe, on Flickr


IMG_7423.jpg by Kevin_Doe, on Flickr

Then it was body filler time. If you look closely at this photo, you can see the RX-7 in the background. You can pick out the angled surfaces I’ll be bolting these down to.

Untitled by Kevin_Doe, on Flickr


Untitled by Kevin_Doe, on Flickr

Then after body filler and glazing, and 220 grit, it was time for a high build primer.

Untitled by Kevin_Doe, on Flickr

This is where I’m currently at, I need to get this sanded to 600-800 grit. Then I’ll hit it with a base coat, then a 2k clear coat. Wet sand and buff to a mirror finish.

#2

Nice work. Are you doing two piece molds for each? It looks like the under cut edge at the back of the part wouldn’t release with single piece mold.

#3

I had thought about a two piece mold, but I wasn’t sure how to perfectly seal the two pieces for use in an infusion, so I decided not to. I did modify the forward edge (view shown in the first body filler picture) to include a 30 degree angle off vertical. The 30 degrees matches the angle of the base wood structure. Each wall surface has at least 5 degrees of draft angle from being perpendicular to the base surface. I planned it such that the mold/parts won’t release straight up vertically, but in a 30 degree direction which matches perpendicular to the downward sloping section of the wood base. I hope that makes sense. That was something I put a decent bit of thought into so I wouldn’t have issues with release.

I do think I’ll make two separate molds thought, one for each headlight. Just to keep the pieces easier to store and manage, but I’m not 100% certain on that at this point.

#4

Looks good Kevin. Which primer did you use this time? I use the same duplicolor high build primer for one of my molds and I just demolded it… whattt a nightmare. all the layers from the primer and up came off the plug and theyre sitting in my mold… Should be fun cleaning up…

Looking forward to seeing your progress! I would keep it one mold so I could infuse both at the same time = less consumables (cuz they add up fast!)

#5

Oh, I see it now. Good thinking. One benefit of avoiding the multiple piece mold is you’re also avoiding a parting line, additional finishing hassle.

#6

muibubbles,

I used a PPG primer. It was a 2K primer, but it doesn’t really matter since I’ll be using a base and 2K clear over it. I learned my lesson last year about using a rattle can primer and only wax for a release. What a pain in the butt.

#7

Today I sprayed the base and 3 coats of clear. Turned out pretty much awesome for my first time every using an HVLP spray gun. I did get one sag in the clear on my 1st coat, but I shouldn’t have any issue wet sanding it out and buffing it up to a nice shine.

The finished surface when installed looks nearly perfect w/o even wet sanding and buffing yet.

Sorry for the crappy pics. I took with my cell phone and the garage was still pretty hazy from the suspended clear.

Untitled by Kevin_Doe, on Flickr


Untitled by Kevin_Doe, on Flickr


Untitled by Kevin_Doe, on Flickr

#8

Wow! and Wow! that is a good looking plug your mold should turn out amazing.

#9

Beauty work man! Cant wait to see the rest of your project come together.

#10

Wet sanded to 3000 grit and buffed out.

IMG_7431.jpg by Kevin_Doe, on Flickr


IMG_7434.jpg by Kevin_Doe, on Flickr

#11

Well done!!

#12

Thanks.

Ok guys that use Frekote, I need some HELP!

Every time I use the FMS I get streaking like crazy. I try to wipe it on as thin as possible, but as it evaporates it still looks streaky. Those streaks always seem to transfer to the mold/part. Driving me nuts. How do you apply the Frekote FMS/770-NC w/o getting streaks?

#13

Keep rubbing with a clean cloth, and do small patches at a time.

#14

frekote is good stuff but I agree about the streaking. Turn the fans off, don’t let it dry before wiping it off. I also noticed if you used any kind of soap to clean the mold, plug it must be thoroughly rinsed and dried for at least 1/2hr. As herman said small sections is your friend.

#15

Made the mold yesterday. It was a marathon of work, ~9 hours straight with my Dad helping. All made with type 7725 E-glass. 8.8 oz, 2x2 twill. Has a minimum of 8 layers everywhere, with many areas (darker green) having significantly more. Went through roughly 1 gallon of resin and 15 yards of fabric. From the outside it looks like it turned out nice, but I’m pretty nervous about the finished side. This is the first time I’ve made an epoxy mold, so the brushing on surface coat was new to me.


Untitled by Kevin_Doe, on Flickr


Untitled by Kevin_Doe, on Flickr

#16

Looks pretty good. Is the shape self releasing? Your paint job looks awesome.

Leave it to cure for a couple of days. Is the workshop heated? Crank up the heat a bit. (up to the 80-90s does not hurt anyhow.)

#17

I’m not sure what you mean self releasing. I do think it should release w/o any issue. All surfaces have at a minimum of 5 degrees draft angle in the direction of intended pull. The mold will have to come off perpendicular to the sloped flat surface.

The shop is heated, and its been approximately 76 degrees F for the past 24 hours. I’ll crank it up a bit more for the next few days I suppose.

#18

Yes, I mean draft angle. I was a bit worried looking at the pictures, then again, pictures usually look a bit distorted.

#19

Kev, sell me your vac setup already! j/k

That e-glass laid down nice. How was it getting the 8.8oz to lay over those corners?

I really want to see how much the frekote telegraphed, if any.

#20

awsome finish!! “Carbonize” this as soon as possible!! :smiley: