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Apr 01, 2020, 02:38 PM
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26" fibreglass FE mono from scratch - second build


Finally here she is! I was only able to pick her up today. The 3d print came out good, but it will be a lot of sanding to get the plug ready for mold making.

The plan:
Joint and smoothen the parts to make a plug. Then, using professional epoxy fibreglass, make a shiny mold for as many hulls as i wish She will be fitted with a flood chamber for worry-free fun.

Power:
4s lipo 4200mah
3670 2280kv
42mm prop for target speed of 80kmh+ (50mph+)
35mm prop for <70kmh long runs

This is my own design, made using FreeShip

This will keep me busy during quarantine for sure

Hopefully youll enjoy following the build

Jn
Last edited by Jansvast; Apr 01, 2020 at 02:44 PM.
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Apr 02, 2020, 05:56 AM
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Today i roughlu sanded all irregularities with 100 sandpaper and started filling the strakes and chines, because they printed as little steps. I used excess filler to film the rest.
Apr 02, 2020, 07:41 AM
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Just a heads up if you plan on using this as a plug,how well does this plastic handle heat ? ,when you lay your glass and resin over this to make the mould it gives off lots of heat as it cures and may distort the plug ,this is why most plugs arent made from plastic unless its a solid slab carved into a plug . Most use closed cell foam covered in filler of one type or another,i use durabuild filler primer for plugs .
Apr 02, 2020, 08:43 AM
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I thought about that too, so i asked the epoxy manufacturer how much heat will my chosen system produce because i wanted to use it in a plastic plug, ant they said it wont be a problem (it is 30mins until the system gels up). So thats not a problem thankfully.

I also just came back from a hardware store. I bought a lot of wateroproof sandpaper and PU glue
Apr 02, 2020, 11:38 AM
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All 4 parts are now together. Glued using pu adhesive. Tomorrow when they will be hardened, i will do lots and lots of sanding. Thats all for now!
Apr 03, 2020, 03:30 AM
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What epoxy are you using , in my experience you will be surprised how hot it gets when curing , my fear is your going to see some distortion of the plug so if i were you id start with one thin layer of glass to start so as not to create too much heat and let it fully cure before adding any more layers . Ive built a few plugs and moulds over the years .
Apr 03, 2020, 03:47 AM
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I dont think it will tell you much, but the resin is LH287 with 30min hardener from Havel composites. I will use gelcoat, too. I was thinking that if it creates too much heat (i will conduct a small test with a few layers first), i can do it in 2 takes, but im afraid that uneven hardening might warp the mold

Left to right: LH 287 resin, H 146 hardener, EG 100-T gelcoat, H 100 gelcoat hardener.

All epoxies
Last edited by Jansvast; Apr 03, 2020 at 03:55 AM.
Apr 03, 2020, 04:25 AM
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It should tell you in the tech sheet for the specific resin and hardener your using , id read it fully . Id do it in a cool place to allow it to gel slowly and move it somewhere warmer once its gelled to allow it to fully cure .
Apr 03, 2020, 04:46 AM
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The technical sheet doesnt mention any information about the exotherm, it only says that when it is worked with in 50C+ it might increase the exotherm up to 200C when large batches are mixed (not my case). It also states that the pot life is up to 2h at 25C.

"The exotherm od the system shloud not exceed 50C in 3 layers of 160g cloth. When using hardeners with more than 30min pot life, the temparature increase will be even smaller"

Cited from an email from the company's technical help. The hardener i bought says 1-2h pot life, so i think im entirely safe

Anyway, do you like the hull design?

Jan
Last edited by Jansvast; Apr 03, 2020 at 06:41 AM.
Apr 04, 2020, 03:29 AM
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The sanding is going very well so far. The first layers sanding is almost done, i just have to finish the nose. Then, more filler!
Apr 04, 2020, 05:46 AM
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Usually i coat the whole plug with durabuild filler primer or similar product like duratec sands to a smooth shiny finish ready for waxing .You can apply by brush roller or spray equipment sands easy and shines up perfect for moulding from.

1041 Duratec Gray Surfacing Primer (1 min 50 sec)
Apr 04, 2020, 12:08 PM
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Only if i had a spray gun Being polyester, how well does it sand?
Apr 04, 2020, 05:35 PM
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Originally Posted by Jansvast
Only if i had a spray gun Being polyester, how well does it sand?
I use a brush to put it on and it sands beautifully .
Apr 05, 2020, 01:49 AM
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Thanks for the tip. That should make the application a lot easier compared to a classic paste filler. I can get similiar stuff here, too
Apr 05, 2020, 07:52 AM
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Originally Posted by Jansvast
Thanks for the tip. That should make the application a lot easier compared to a classic paste filler. I can get similiar stuff here, too
Yea its cool stuff , obviously theres more sanding to do if using a brush but it really does sand easy and gives a lovely shiny surface once compound polished and buffed to a nice shine .


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