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Old 09-23-2012, 04:43 PM   #13
therivermonster OP
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Joined: Sep 2010
Location: Tacoma, WA
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Quote:
Originally Posted by redprimo View Post
If you use a good primer it will fill the scratches. For the first coat use something like Feather fill or some other brand of primer that is catalyzed with the same catalist used for polyeter resin. Idealy these are best applied with a spray gun but they can be brushed, just expect to do a lot more sanding. For a really rough pattern 2 coats of this type of primer might be necessary but usually from there on you switch to automotive high-fill lacquer based primer applied with a spray gun.
I will be on the lookout for some Feather Fill. I take it that it can be found at a good auto paint supply store?

You can avoid using a spray gun for the primer and you can even apply gel coat with a brush, but you will need one for the PVA so you might as well get one sooner rather then later so you can learn how to use it as you are learning all the other skills that go along with FRP. It dosn't need to be an expensive one, The compressor on the other hand will need to be able to keep up with it, at least for a resonable length of time.
I would love to be able to add a compressor and spray gun to the tool lineup right now, but it's just not in the cards. Small shop, no cash for such tools, but it is on the list.
I know that erabaeak brushes on his PVA, so i'll have to make that work until I can spray.

I prefer to use a putty knife for spreading bondo unless the surface is curved more than a flexible knife will conform to. I have 1", 2", 3", 6", and 10" knives for spreading bondo. I find they have less drag and therefore leave a smoother surface than a plastic spreader. generaly speaking the less you work it the better it will turn out.
I did use a 3" putty knife to spread a bit of bondo and I agree that it did work well - much better then the little bondo spatulas.
What is the best way to clean up bondo on the tools and mixing surface between applications?

I would never use foam board for a pattern. Sure you can use it for a quick mock up to get the general shape and diminsions but I always use solid wood such as pine or poplar or 3/4" thick sheet goods such as MDF or even particle board. these materials will flex less and let you be sure you are keeping the diminisions acurate as well as keeping the pattern from twisting. It will also make it easier to add your flanges once you are ready to pull a mold.
The most complex part that I have in mind right now is a Dakar style fairing for my DR650. With your above info in mind, would you suggest the following procedure to make a quality plug? Please feel free to edit my workflow where you feel fit.

1. Cut pieces of foam board and fit to the bike in the rough shape of the fairing.
2. Remove foam board fairing and use its dimensions to cut and construct the rough plug out of say MDF.
3. Sand, sand, sand.
4. Contour and shape plug to a semi finish, use bondo to fill most imperfections.
5. Sand, sand, sand.
6. Spray or brush on a catalyzed primer like Feather Light (maybe two coats)?
7. Make like the beach and sand.
8. Apply high fill lacquer primer to plug.
9. Grab some 220 and get to work!
10. Glue flanges around perimiter of plug in order to build up flange for the mold.
11. Prime plug and flanges with high fill primer.
12. Final finish sanding, then polish plug to a sheen.
13. Wax plug x at least 5 coats of Partal paste wax.
14. Apply PVA to plug assembly with a brush in my situation.
15. Lay up the mold.

Does this sound about right? If not, please let me know where you feel it is best to make changes.

I'm not sure where their stores in WA are located but TAP plastics has some outlets in your neck of the woods. I use their epoxy laminating resin and have bought cloth there as well. Their laminating epoxy is basicly the same as West System 3. They don't have the biggest selection of cloth but for most of what you might want to do they have something that will work and you won't have to pay hazmat fees or wait for the brown truck. They also have small containers of cab-o-sil, microspheres, and talc so you don't have to buy huge bags of those materials.
I just checked TAP Plastics web page and it looks like they have 3 stores semi close to home. It's nice to have something near by, but their prices seem a bit steep compared to say US Composites.
I'll have to check out their store and see what I can come up with.

Have fun
I have the fun factor taken care of, man! I'm having a blast with this stuff! I hope all of you are too.

Anyhow, I'll keep pluggin' away (plug joke) and all of you, please keep the great suggestions and lessons comming. This stuff is priceless!
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therivermonster screwed with this post 09-23-2012 at 06:51 PM
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