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Seat Report

3200 Views 3 Replies 3 Participants Last post by  Bird76Mojo
OK, I've been working on the seat for my 450 project - what a nightmare.
The foam was completey shot, seat cover shot, seat pan cracked.

Stripped everything off and got my neighbor to braze up the cracks in the pan.
Soaked the pan in MSR and de-funkified it completely.
Primed the pan with self-etching primer, painted with semi-gloss engine enamel, then baked it. Looks better than new !!

Everything going normally to this point, I'm on familiar ground so far, and so very pleased with myself........

But, now for the foam - what a freakin' nightmare.
I've never re-foamed a seat before, though I've done seat covers with little problem.
I obtained a big chunk of 6" thick extra-firm seat foam - the idea was to "sculpt" a single piece of foam, into which the seat pan could be inserted and glued.
WRONG - the top of the seat pan is such a complex shape that it's just impossible to carve out the foam to the proper shape. This foam doesn't cut that easily in the first place.
I tried hacksaw blades and electric carving knives - pretty much useless for carving complex concave shapes like this.
Then I rigged up a hot-wire cutter using a big Weller soldering iron - no good.
Then I put a small wire wheel in my die grinder and started to remove the material. Within seconds me and everything in the shop was covered with a layer of foam dust, which seems to be electrostatically charged, and really hard to remove, even with the shop vac.
Wifey said I looked like a Teddy Bear that had been pulled inside out, covered head to foot in this stuff. Bad idea....

So I'm scrapping the idea of using a single piece of foam.
It may be easy enough to carve outside surfaces and corners of this stuff, but carving inside corners and concave shapes is nearly impossible. There may be some magic technique, but it hasn't occurred to me at this point.

Now I understand why the original foam seems to be built up from chunks and sheets.

So, a big sheet of 1" extra-firm foam has been ordered.
I'll start laying it up from the surface of the seat pan, using smaller chunks whittled from the 6", cover with layers of the 1", glueing everything together and finally reaching some oversized version of the final desired shape.
Then it should at least be possible to carve down the outside faces and curves using the electric carving knife.

This is unfortunate, as that chunk of 6" foam cost $50- money down the toilet, an oh-too-familiar story with these old bikes.
New high-quality seat cover remains in its package, waiting patiently.

More as it occurs............
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when I did my seat I had to "re-cut" the foam, and then built another seat and did the same because I did'nt like the first one. The one tool besides the electric filet knife, that worked very well, was one of those 90degree angle sanders, with fine grit discs. They spin so fast it removed foam REALLY quickly, and as long as you're good with your hands they should do any angle or shape you desire. If you use one, don't use the hook and loop sanding discs, use the screw in type. They're not so think as to get into your way with complex angles.

Here's the type of sander I used with good results: ... mber=99841 The 120 degree end makes getting into places a little easier than a 90 degree type.

These are the sanding discs I used. The orange/fine grit ones work the best with the foam, at least for me. ... nding-Disc I could probably mail you some of them to try??

P.S. Just a little discovery here, but there is no better or faster method that I've EVER EVER EVER found to remove gaskets without damaging/scratching/gouging anything than this wonderful little guy: ... 1500129806

GB :mrgreen:
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