new lessons

[kakedog]

I found out why fiberglass products are so expensive, making fiberglass is difficult and frustrating. I am currently on my 3rd attempt at making a seat, and I am about to pull out what hair I have. Anybody know an easier way to do this than molding it around a form?

[burrpenick]

buy one already made, I bet it would be way cheaper than yur fiberglass costs so far.

[kakedog]

It's more than likely that you're right, but I've started to kind of get into it. At first I figured that it would be easiest for a beginner to make a basic form of the seat with wire, cardbard and a load of tape, then lay the fiberglass on top of that and finnish it with bondo to get the right shape. I miscalculated. the first couple of attempts weren't horrible, but they lacked a certain J'ne ce quoi. So I though about it for a while and decided that I would have to go through the same motions with making a plug for a mold. So I grabbed some styrofoam from the bakery and cut it to a basic shape with the hot wire and, as soon as I hae a little time to spend on it, I'll be going over it with a rasp to get my shape. this seems like a better and cheaper method, as I have a ton of styro, plaster and bondo are cheap, and if I fubar, it's not as permenant seeming as "fiberglass"

[spyug]

Way back in the archives ( maybe 2 years ago) I detailed the fiberglass over foam method which to me still seems the easiest way to produce a seat.

Get your foam to the shape you want. Using fine weave glass cloth and epoxy resin encapsulate the form. Finish with skim coats of bondo. Paint. Done.

This produces a very light but rigid form. With one coat of cloth and glass it is strong enough to hold 200lbs plus with no cracking.See my tracker seat:

The only real drawback is cost as epoxy resin can be two or three times more expensive than polyester resin but it must be used as it won't eat the foam.

To save money some folks advocate wrapping the foam in packing tape before applying cloth and polyester resin. having never tried it I can't say how well it would work.

I've done half a dozen projects this way and they work out quite well. Like most bodywork it comes down to preparation so make your form as true as possible, lay out your work surface with everything you need, precut and test fit your cloth and mix sufficient resin to cover the area you will work on. I start with the top. Lay on your cloth and pin in place with push pins. Apply resin and allow to cure. Do the underside and bond in any bolts or straps that you need to attach to the frame. Make sure you apply resin to bond the two sides.

If cost is no object, you can add a second layer but it really isn't necessary for strength. If you wanted, you could do a coat of polyester resin as a gelcoat but again not necessary. Use bondo to fare everything in.

As you are not farting around with bucks and molds, it is a lot faster and as mentioned, with the foam core, more rigid than plain glass.

Give it a try.

cheers,
Spyug.

[kakedog]

that sounds like a really cool technique, with the different resin, I would not have thought to look for something like that. The cost is not nessisarily the issue, (though the lady looks at me cross eyed when I get too happy with it) I was just wanting seat that is unique that wouldn't cost $500. I'm still only at $60 total, so if I can get a good usable seat for less that $100 more I am ahead! (she can't argue with that science!). I might have to give it a whirl seeing as it looks like a couple less steps than the molding process. Thanks

[volta3]

I was going to attempt to make a seat soon and I found a website that instructs you on how to make just the pan. It seemed helpful.
www.jeffreyphipps.com/seat_pans.htm.
Would it be easier to make the form you were speaking of? Would you then make a cushion to fit on top, or use as a hard seat?

[spyug]

I have seen that method before. The nutjobs on Orange County Choppers tried to do it and, predictably, screwed it up royally. I think that method works for those custom bobbers and choppers but doesn't really lend itself to cafes or trackers.

With the cafe or tracker you have more of a straight "plank" as your base, with a hump for a tail. This forms the integrated seat pan/ body work and is easiest achieved with the rigid foam.

The real nice thing about the foam is that it is super easy to work and you can form just about any shape you can conceive. As its cheap enough, you can try different styles to get what you want.
Once you have the pink formed the way you want, lay on the glass and resin as mentioned. the picture below is different from the original I posted above and I think it was likely the third or fourth model.

For a seat pad, I tried different combinations of foam and gel but ended up with some real spongy close cell foam as used in one of those kneeler pads designed for gardeners. Got some vinyl, wrapped the foam and attached it to the seat with velcro tape (glue one part to the seat pan and the other to the underside of the pad...or use some material like they cover speaker boxes in...kinda course like wool...sticks to velcro real well). I'll try and get some more pics for you but this may give more ideas:



One thing to point out. Don't try to ride just on the seat pan with out padding. It really is a plank and sitting on a plank for any length of time can seriously injure you. After building this tracker I came down with a Sciatic nerve injury in my left leg. The docs figured I had compressed my sciatic nerve in the leg by sitting on the plank( even with this blue pad...since changed to a thicker one).It is the most excrutiating pain like the worst Charleyhorse you ever had that lasts weeks if not months and recures from time to time (3 time now for me)As a consequence, I have only managed to get about 400Km on this bike in the last 2 years since I finished it. I really can't part with it however (too much of me in it) and I'm thinking of ditching the tracker seat and going back to the stocker. Keep it in mind.
Hope this helps.
Cheers,
Spyug

[volta3]

What type of foam do you use for the form? Possibly the type at a fabric store, the green kind or a more rigid type foam like styrofoam. What is the best temp to do the fiberglass? What is the avg. cure time? I really appreciate all of the info, Thanks for steering me away from a possibly botched attempt.
I am looking to go for a more bratstyle look, low profile, flat.

[spyug]

The foam you use would be the rigid pink or blue insulation foam for house construction available from Home Depot or Lowes or your local building supply store. You can use Gorilla Glue or foam in a can to glue up sections. It usually comes in 1", 2" or 4" thick planks in 2"x4', 4'x4', 4'x6 or 8' sheets. The white foam is not quite dense enough and while the green crafts foam can be used it is fiddly as it only comes in small bricks (at least around here) and you'd need to glue up a bunch to get the shape you need.

Take your first plank and cut the shape of the seat ( I used the 1" thick stuff). Make sure to extend it out far enough over the back wheel and about an inch outside of each side rail. Make two strips the length of the sides of the seat about 1.5" wide and glue to the bottom so they are flush with the edge of the seat. When the seats in place these side bits cover the frame rails.

Next build up you tail piece by gluing up a stack of planks. Once glue has dried shape your tail section using wood rasps, course then fine sandpaper. If you're building in a tail light hollow out a cavity for it and maybe drill out a channel for any wiring.

As mentioned before, use fine cloth if you can get it. Precut pieces to cover all surfaces but do upper and or lower one side at a time. Use push pins to hold things in place. For any cavities you make paint with the epoxy to seal the foam. Glass if you can but if its just a wire channel don't worry about it or perhaps use a big plastic straw or whatever tube you can find. Also figure out how you will fix the seat to the frame and epoxy in any straps, nuts or bolts that you may use.

Epoxy setup is an exothermic process (gives off heat as it cures) it will cure in cold but follow the manufacturers instructions. As I usually do these projects over winter I do them indoors. They will surface cure in less than an hour but I leave them overnight for a full cure before working the surface.

You may find some spots that you may not covered properly so if you find any dry patches or bare cloth whip up another small batch of epoxy and paint over. Epoxy can be made into a filler paste by adding "microballoons" which is fine silica powder. This stuff is usually available from the same reseller who sells the epoxy.

If there are any surfaces that have dips or ripples you can use Bondo or other plastic filler to fair out. Paint with primer and your preferred paint.

As mentioned, you can pretty much form anything with this method so if you want to do custom body work like side panels or cafe fairings, fenders or whatever give it a whirl.

Hope this helps but if not just ask.

Cheers all,
Spyug.

[trickster]

I have done several hundred custom parts with foam and glass.

use Blue foam high density (not the White low or pink medium density stuff)

build up your layers with spray contact adhesive 3m spray 77 is best make sure it dries fully before laminating. (go light here)

surf form rasps, and a hot ire bow, work best for shaping.

if you cut two profiles and put on your block one on either side, you just run the hot wire along the two templates and you have a perfect profile.

use FINISHING resin, not just epoxy resin it is thinner and produces a lighter part.

use 6ounce cloth

when the part is done pour a little acetone in a hole drilled into the core and the foam will just run out as a syrup.

then carefully refill the part with urethane expandable foam leave some holes so it doesn't pop.

if you need an odd gas tank this process is the berries, just do not refill the part with foam, for gas tanks FOUR layers of 6ounce woven fabric, then red coat te inside it wont leak ever, epoxy in the filler neck in with slow set steel or aluminum filled devcon. and add petcocks you can glass in mounting plates as you go and t nuts for later mounting.

make the foam smooth and perfect it will pay off later

soak the fabric in the resin lay over the foam and use a small foam roller to work it down, do not try to lay the fabric on the form and brush resin over it.

cross the weave at every layer for max strength.

wear gloves, and a mask for organic solvents!

Have a SHOP VAC for the foam

coarse open grit (like 36-60grit) paper on a palm sander does well for shaping.

after you make friends with this process a amazing world opens up, you can add carbon fiber, and kevlar, metal inserts, there is no limit.

also vacuum bagging is super, take the foam lay the soaked cloth over it insert into a vac bag pull the vacuum and all the laminating happens at once, and you get the lightest strongest parts as the resin to glass ratio is closer to ideal.

a good site model airplane related but excellent basics:

www.charlesriverrc.org/articles_foam_vac.htm

[xs650bobber]

Same for me, i made a hoodscoop for my friend out of foam,gorilla glue and wax paper, worked like a charm!! id sugguest the soft foam route!

[wtmtdfl]

Check out the Do The Ton web forum. A bunch of cafe racers from Canada and else where, they have a giant thread on building your own seat from fiberglass and other "found" materials.

Terry
J'ville, Fl.

[volta3]

After my failed attempt at using the blue construction foam and the fiberglassing over top, I decided to use the method I first became aware of. I did not remove the stock seat mounts.
I used painters tape directly on the bike to mask off the area I would be using fiberglass, filling any holes or oddities with cardboard.
Then I used Aluminium duct work tape on top of the painters tape ( painters tape releases with less residue), and coated with some automotive wax as a releasing agent.
Taping a plastic drop cloth to all surrounding surfaces to catch drips finishes the prep work.
I built up the fiberglass about 6 layers thick, and let it cure on the bike for about 4 hours. Upon removing it I trimmed the shape with a Dremmel.
After test fitting a few times and trimming a bit more, then came the padding.
I used a new yoga mat cut up, and glued it to the pan with a DAP counter top veneer glue.
Once the padding was complete I recruited my mom to sew some leather 1 3/4 in tuck n' roll the length of the seat.
I stretched the leather and used grommets and a shoe string to fasted the bulk of the cover to the seat, some more of the glue for a few spots.
The seat fits over the stock mounts, but does not use them, instead I have a bolt bondoed through the pan and fastened with a lock nut to the rear fender. The front uses 3M dual lock velcro.
Check the link for the finished product!!!
img33.imageshack.us/gal.php?g=wave7005p.jpg

[swinewerx]

What I always do is, make a template that is molded to the frame where you want the seat to be, then after you decide which side of the template you like then fold in half and cut according to one side only. This is made from paper board. Then, take that template and trace it's flattened shape onto steel, either 14 to 16 gauge. Then start molding to the bike and continue till it is how it should be then foam then of course you should take up tooling leather and go extreme. Whenever I do a seat for me or the wife I go extreme. Never hold yourself back really try until you got it down

[dpmulvan]

Best article I have found for making seats works very well Go to www.dotheton.com and you should be able to locate it under seats great tutorial lots of pics