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Old 04-15-2007, 11:06 AM   #1
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Default Composite Chassis

After months of taking info from this forum I thought I would try and give some back when I can.

So I wanted a composite chassis for a 2.2 crawler.
To start I will need a side profile. Easy to make with poster board and a 2.2 chassis with all the shock and link points that work for me.

MikeP
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Old 04-15-2007, 11:15 AM   #2
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I need a width of 3". The paper side template is tacked to a block of Dow 3" pink insulation foam (scraps from a construction site, roofers use this stuff) 3" is hard to find.
I use a band saw to trim it close then sand it down to the template with a sanding block with 60 grit.
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Old 04-15-2007, 11:34 AM   #3
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Once the side profile is good i can shape it how I want with 60 grit then finish with 220.

The foam needs to be sealed with epoxy and a filler. I use West Systems products from West Marine. Epoxy with Silica mixed to a ketchup thickness and brushed on the foam, then sanded smooth using the 60 grit finished with 220. Make sure you don't sand through the epoxy. At first this may take a couple of coats. I got lucky on this one and got it in 1 coat of epoxy.

Now I have a plug of the part I want to make. I don't spend a lot of time on the the plug finish. I wet sand and polish the mold. (this is backwards from the way the pro's do it).


MikeP
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Old 04-15-2007, 11:41 AM   #4
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If I left the bottom of the plug flat I would not be able to get the finished part out. Now I need to make a bottom board to match. I used some pastic sheet on the bottom to keep the epoxy from sticking to it. All this is tacked together with 3M 77 spray glue.
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Old 04-15-2007, 11:45 AM   #5
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Here it is ready to make a mold, everything is waxed 6-10 times with Partall mold release wax.
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Old 04-16-2007, 03:48 PM   #6
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To start the mold I mix up epoxy with powdered graphite and silica to a mayonaise thickness to use as a tooling surface or Gelcoat and brush it on. Then wait for it to set up a little. Brush on more fresh epoxy then fiberglass cloth, work the epoxy into the cloth with a brush.
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Old 04-16-2007, 04:01 PM   #7
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Used about 2" wide strips of 10oz fiberglass, brush on epoxy then lay cloth and work it in. 2 layers of cloth with the overlaping seams should be about right to leave some flex in the mold so I will be able to get the finished part out of the mold.
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Old 04-17-2007, 02:00 PM   #8
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I really wanna see this finished, it has the ability to be a great body with its durability.
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Old 04-17-2007, 02:04 PM   #9
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Are you planning on competing with this rig?
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Old 04-17-2007, 03:24 PM   #10
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Quote:
Originally Posted by Unholy View Post
Are you planning on competing with this rig?

Yes
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Old 04-17-2007, 04:08 PM   #11
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Do you plan to run a chassis under this and this as the body?
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Old 04-17-2007, 08:25 PM   #12
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Quote:
Originally Posted by Rockpiledriver View Post
Do you plan to run a chassis under this and this as the body?
For it to be legal wouldnt it have to be a full tube chassis? I dont think it resembles any 1:1 rig
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Old 04-17-2007, 08:37 PM   #13
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subscribed!

Im gonna take a shot in the dark and say he will use a skidplate and crossmembers and use the skin as a monocoque type chassis. Its gonna take some skill to tie the shocks in!


Awesome idea, I have wanted to try this or see it done for so long. You build planes or boats too?
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Old 04-17-2007, 09:23 PM   #14
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You have a nice build going. I have also kicked around the idea of making somthing close to what you have. One of the things I am thinking of using is Aluminized Fiberglass for a body.

Steve

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Old 04-17-2007, 10:17 PM   #15
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Aw crap, I can here the rule committy's butt holes tightining as I type. Looks cool though.
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Old 04-17-2007, 10:24 PM   #16
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No tightening here...

Just trying to see where he is going with it.

It's a neat idea, and looks like he has the skills and resources to pull it off!

That said...

If he is building it as a standalone chassis, he'll have to run a legal body on it to compete.

If he is building a body, well he'll have to replace it to compete.
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Old 04-17-2007, 10:26 PM   #17
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Quote:
Originally Posted by Kamikaze View Post
Aw crap, I can here the rule committy's butt holes tightining as I type. Looks cool though.
X2 this isgoing to turn into pages of crap like our threads did.

Keep up the great work I'll be trying somthing similar soon too. I like the shape too nice and curvy.
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Old 04-17-2007, 10:39 PM   #18
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Rules and looks aside it's just something I needed to build, I get one of those ideas in my head that just wont go away. I figure throw it together see how it looks get some input and go from there.

John,
I learned how to make composite parts from the airplane forums so I could build R/C boats (outriggers).

Aluminized Fiberglass, now that sounds cool, I getting kind of tired of the CF look.




Yahooo..... after digging out the foam plug no flaws to fix. I polished it with 220, 400, 600 wet.
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Old 04-17-2007, 11:01 PM   #19
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I made paper templates to cut the pieces needed to fit the mold, I had enough left overs for 3 layers of 3k plain weave. The roof will be done in 2" strips and the sides will be one piece. The strips in the roof will overlap giving extra layers in the areas where the windows will be cut out. Should be good.


After a lot of waxing and then PVA I Brushed on a coat of epoxy with a little silica. The silica will keep it from running to the bottom. Let this coat get tacky, this will help hold down the cloth in the sharp corners. Brush on a fresh coat of epoxy first and start laying in the CF work the epoxy into the cloth, more epoxy then cloth. Working the epoxy from the back side out insures good saturation.
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Old 04-18-2007, 05:07 AM   #20
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That is without a doubt one of the coolest things I have seen. I may have to take a wack at carving out a body. Not sure of my skills though, my truck attempt might end up looking like a Pinto wagon

Looking forward to seeing the completed chassis.

Matt

Last edited by maddog2099; 04-18-2007 at 05:28 AM.
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