I was making a couple seat pans a few days ago, so I thought, what the hell, I'll share 'em with you. This is the first part, since there's some work left. I'll finish soon, so you won't have to wait too long.
There's lot's of people who make their own seat pans. A lot are made from metal and molded. Some builders are not master metal workers, and it takes serious time to achieve a good pan with metal, plus with all the curves in fenders and frames today. They create obstacles. I have found the use of fiberglass cloth and resin to be more “user friendly” and extremely “moldable”.
I warn you, this is not a bible on how to do it. It's merely a guideline. I have experience with surfboards and fiberglass (yeap, those damn dings!), but it's really simple.
I start by taping the whole area. I'm using wide masking tape. I let it drap a lot longer over the sides, so it protects and will be easier, at the end, to separate the pan from the tape. It also prevents dripping too much on the bike(photo 1).
I put several layers on to prevent the resin from seeping thru the tape. If you have a battery box or other elements under the seat pan, I create space with cardboard on top. I try to make the pan flat, and if I need any weird curves or points I tape it accordingly.
After that is done I take a permanent Sharpie and mark the lines of how the pan will look (a pattern). I do so loosely and mark any protruding pieces, that might take some special care or curves (photo 2).
I mark along frame tubes, inside the tubes and maybe any pointy ends or where I want the seat to end or match the frame. That's up to you and the style you're after. As you will see later the marker lines stay after the cloth while resin is applied.
After the pattern is complete, I take baby powder and spread it all over the tape base. Some people use wax or anything that comes to mind, to ease removing the pan from the tape and not pulling the whole fucking thing off stuck together. If you happen to be a very rich junkie, there's an alternate coca leaves by product that can be used. The only problem is that it's highly volatile and can cause problems if mixed with resin. (photo 3and 4)
I take the glass cloth and cut it into, more or less, the shape I'm looking for. Always leave room for error. In this case I'm using three cloths, then I proceed to mix a batch of resin and hardener. I tend to go a bit overboard on the hardener (you will know when it starts smoking). Read the instructions for the best mixture. Also a good set of latex gloves will save you from a lot of clean-up and the iratating itching produced by fiberglass threads.(photo5 and 8). Cut all three fiberglass cloths to size. Cut extra pieces for spots that need to be thicker or stronger.
Some spread the resin mixture right on the cloth before putting it on the bike. I'd rather save the mess and do it right where the pan is located. It also makes it easier to cut pieces of cloth for hard to reach corners and patterns. Once wet it should obey your domination… I start from the center and paint the resin outwards to avoid bubbles. Then I layer on another cloth pattern and paint again, until all three layers are completed. Also take special care of any part that has crevices or sharp angles. After this first step you should be able to see the marker lines thru the cloth. If not, I hope you have a vivid imagination, or rip it off quick and start all over.(photo 6and 7)
The second and third cloth are handled the same way. They should get to a point where they blend. Don't be bashful with the resin. It's not that expensive and it will make the pan harder and stronger with each layer. Don't overdo it or you will end up with a pan that won't cure (dry). As I said the template has been marked, don't be afraid to go a bit more, you will trim it anyway, so in this case, more is better. You can also trim the cloth as you go or cut sections for bitchy areas (photo 9)
Once you have all of the cloth tacky but not completely hardened, you can lift the tape and seat pan slowly. If the whole thing feels wobbly (soft) just let it be and wait some more. The right time is when the pan comes off without losing the shape (duh!). Rip the tape off and let the pan sit on a bucket or something similar to dry. If it sets up correctly, the tape should come right off. I tend to trim the edges right then (the ones with no resin), so I will not have a bunch of fibers floating around when I present the pan to the band saw. (photo 11) (photo 12)
Here's the first completed part of the seat pan. There's more work to do. Once it's totally hardened, I use the band saw to cut the shape. Remember the marker lines. Now will be a good time to refer to them. I start from the outside line first and the check the shape against the bike, then keep on going.
Just a reminder, to those who can't wait for the second part, things look bigger in the pan. If you think the backrest is too long, it won't be when it's upholstered. If you think the seat is too narrow, it will be wider when you add the foam and fabric. Again, the back rest always fools the eye…. And wear a face mask. Don't inhale that crap.
I hope I can jump on the second part soon, as soon as I fix the damn band saw. The trimming of the pan is the itchy part, so I'm not looking forward to it at all, and last but not least, don't be afraid to try it out. It's the least expensive and quickest way to build your seat pan. You'll will be proud that you did it (not bought from a catalog), and it will fit, only your bike, perfectly.
— Jose De Miguel
— mailto:jose@chopperfreak.com
— Visit our Web Site http://www.chopperfreak.com
Caribbean Seat Pan Tech Addendum
I use any cloth or resin available, I rather use the same cloth that is used in boards since it comes by ounces. I guess experience and thickness of whatever you get let's you know how many layers of cloth. I hate the one that has all the fibers all over……but that's the one I used for that seat, since it's the one I had. If it's thick enough, I use three or you can use as many as you want.
You can't let the cloth layers harden since you have to blend the coats, the only way to do that is as fast as possible. If you really need a very hard place you can add strips of cloth or even a thin piece of sheet metal to sandwich in between. I add more cloth to the points were I will attach the seat to the frame. That will be covered in the next part… I hope I can fix my band saw tomorrow so I can do the rest.
— Jose De Miguel
This is part 1 1/2 of the seat tech. Why the half? Well, I'm taking off for Daytona and time did not allow me to finish the whole tamale, plus funny as it might sound, me doing the How To, fucked-up the seat pan. I guess I was multi-tasking, but then again, everything is fixable, and the error won't be visible once done. It just takes a bit more time.
I guess you are wondering what I screwed up. My marker lines mysteriously erased from one day to the next. I have no clue why since they were there when I laid on the glass.
Anyway, here we go:
The pan spent a couple days drying. I took it to the band saw (now fixed with a brand new blade), and cut the rough shape around the markings (that I could see). Remember to leave room for error. It's better to cut less than to start over. I cut the shape loosely.
I sliced once more, cutting closer to my felt pen marks. As I trimmed excess, it became easier to work around the band saw(seat pan-1.5, photo 1).
On the third try I cut the outer side of the line marked. This is closer to the actual shape of the seat. Then I went back to the frame to check fit, then cut some more. Next, I cut the turns and back rest. If you notice the photos, it's not even close to being the same from side to side.
I started seeing things. That was my mistake for screwing up the lines, but do not fear it can be fixed (seat pan-1.5, photo 2).
As I went back to the frame, I noticed some edges that were too straight or completely off the mark. I drew the lines with the felt pen once more from the underside. They will guide me later to reach the perfect shape (seat pan-1.5, photo 3).
Now you'll be forced to imagine some of this, since I forgot the photos (that dust again). I took the pan to the belt sander and sanded around the edges. I handle this by eye and then refit it to the frame to check progress. Once all the marks are gone, it's up to the eye and frame to achieve the correct shape. I repeated this procedure many times. If you shave off too much it can't be replaced, but take your time. Don't be like me and try to finish it in one pass.
I use both the belt sander and the round whatchamacallit on the sides. The round disc is great to get reach the curvy waves and the belt to shave the general curves. It takes some figuring out, but it's still a no-brainer.
As you might see in this photo, the pan is a lot closer to the necessary shape. It still needs work, but I'll jump the task when I return from Daytona. It's little details for getting a better all around shape, which takes time (seat pan-1.5, photo 4).
I still have to deal with the back rest. Keep in mind that it doesn't require perfection, since once upholstered the edge of the pan won't be visible.
I'll keep talking, just for those who can't wait for the final installment. The next step, after the seat pan is sanded to the shape wanted (the final sanding is handled by eye and frame fitting), includes drilling the pan for mounting the frame bracket or stud. I inserted a small screw with the flattest head possible on the inside, then add a couple more resin soaked cloths to sandwich it in. I just do this in the front since the back will be Velcroed and the pan's fit really snug. But you can do the same as a rear anchor point (backrest).
Then it's off to the upholsterer. I use PDQ in Melbourne, Florida. They do a kick-ass job. When the long awaited seat is back, check the anchor screw against the mark on the frame, if it's still the same one you marked, drill and install. One more hint, sometimes the seat sets a bit higher, due to the upholstery thickness, piping and bottom covers.
Now go and beat the crap out of that bike…….
–There's more to come.
