!I want to make a seat base HELP!

General
1

I know alot of you guys have some experence in making custom parts. I have found that I do not really like nor want to spend the money on getting a carbon fiber Miyata style seat.

What I want to do is make a Carbon Fiber Viscount style seat. I personally like 2 key features about it.

  1. it has a wider back end alowing you to sit back more comfertably, I find that the miyata style seat although adiquite is still too narrow for my taste and I would prefer to make something a bit wider in the back of the seat.

  2. The viscount is great for seat in front due to its large overhang of material on the side for grip. The Viscount seat has a ~~ 1.5" lip on the side of the seat I find this great for when you have to do alot of stuff seat in front for trials.

The reasons I want to replase the stock Viscount seat are that is is 1) heavy, the Viscount uses a big heavy duty steel plate as a seat base. 2) the Viscount does not have a handle, I would like to add a Kingport style handle to the front of my ride. 3) some more padding would be the best thing since sliced bread.

So what is the best way to go about making a seat base from scratch. I’ve concidered using 2 materials Carbon Fiber, and Fiber Glass. I have no experience working with either, but Fiber glass seems to be cheaper and I have a friend that is going to be doing a project with it soon so I could probably pick up some scraps and do it for really cheap. The only question I have about it would be its strenght. Would it hold up to the viggors of a Trials rider Yanking on the seat and dropping it like crazy.

Carbon fiber seems to be the lightest and stronger of the 2 materials and I have no experience working with it either. My only reserve is that it appers that getting the stuff to play with carbon fiber would be arround $100 for just the material and resin.

The other question I have is what is the best way to mold something. I was planning on using this clay stuff, or plaster to make a mold of my existing viscount seat after I strip it down to bare metal.

Thanks for any info you guys have on this subject.
Mike

2

Anybody?

Can I make a fiberglass seat base?

Anybody?

3

Hey, Mike. there are a few ways to go about this, but I haven’t yet done it so I am speculating from my experience with composites processing. If you want to use carbon, you probably don’t want to go from dry fibers and resin. Resin tends to be quite expensive when bought this way. I would, if I were you get some prepreg. Yes prepreg is expensive, but it will make your life easier, and it is not as expensive as most people will tell you. Look on the web. Go with something woven probably. We aren’t talking aerospace quality here (You are going to rub your ass on it after all. Good, so now take a viscount seat. Here is where the speculation fires in, rip the foam and cover from it. What you are trying to do is get a mould that is viscount shaped to place the prepreg. Tightly affix a few layers of the prepreg onto your mould. This sounds dumb, but it has jacked up many people: Don’t forget to remove the release ply from the prepreg before you add another layer. Alright here it the sneaky part. To cure prepreg you used to need an autoclave. You can’t go buy one. in fact even companies usually can’t buy them so now a days we put the whole assembly into a plastic bag and suck a vacuum, and heat it. You should use a bag that will stand up to the heat. I am partial to bags from Airtech. You won’t need much, so you may be able to convince them to give you free samples. Of course, if you ask for free samples of vacuum sealant tape (To seal the bag)at the same time, they may catch on. Prepregs have a lot of extra resin because you would rather have to much then voids, therefore you need a peelply over the composite with a bleedter on top to soak that extra crap up as it runs from the heat. Alright so How do you pull vacuum? I use a vein style vacuum pump. If you don’t have access to one, then you will have to rig something. You will only need about 60-70% vacuum minimum. That should be good enough for what you are going to use it for. Alright, so you have your prepreg on a mould and under vacuum. You need to heat it while under vacuum. The prepreg manufacturer will tell you the cure temperature. It will probably be something in the ballpark of 120celsius for around an hour. Um, this is probably more effort and expense than is worth it for one off things. I mention it because if yo uhave an easy way to pull vacuum and can get the materials in small amounts, then this is a really good way to go.

An alternative is to use hand layup, which I’m guessing you meant up front. It is about like you would suspect. Mix some resin, put your fiber mat over your mould and paint away adding layers till you like it. Again go with many layers of something thing and woven. Do this because thin woven things are the most drape-able.

THE MOST IMPOSTANT PART! If you use the metal seat mould, Either coat it a couple times with release agent, or vacuum bag the seat before beginning, or use a peel ply, otherwise you will have a lovely heavy hybrid composite seat, because you will never separate the metal. Alright. If you have some specific questions I will answer them. Sorry, none of this is in much depth. But, then you kind of pitched a beach ball for me to swing at. Hope this helps some.

Also, if you bust your ass, don’t blame me. Composites are trick things. Producing a decent composite takes a lot of tries, or a lot of experience with these materials, or both. If they are done wrong, then they look fine but are so weak it is hard to imagine. Good luck!

-gauss

4

Thanks Gauss,

Your insite to using these materials helps alot.

And from my research I think I’ve concluded that Carbon Fiber is probably too expencive for me to work with at this moment. Maybe sometime down the road when I have some money.

I am still interested in using structural fiberglass though to do the same project. My only question would be is it strong enough? I have no idea how much stress a seat base actually takes up, but I assume its alot.

Mike

5

Hey, Mike

This is a project I had thought about, too. Fibreglass is plenty strong, but it’s heavier than Carbon. They make canoes and axe handles out of it, so done right it will take lots of abuse. It’s probably a little easier to work with, too. Kevlar (Aramid fiber) is another contender. Also, when you lay up multiple layers you can alternate and mix them to combine the properties of the different fibers - it’s a science unto itself, but if you over-build it your odds improve. gaus’ point is good, though - if you bust your ass, don’t blame me either! :smiley: Test everything you build before you ride it up high where a fall would hurt!

Here are some links for materials. Others may have better ones - Harper? these are just some I’d found trying to learn. I haven’t dealt with any of them.

ADVANCED COMPOSITE FABRICS
A&P Advanced Composites (Wound Up)
The Composites Store

Have fun, and post pictures!

Tim