heres the glassed up test piece, presumably this would be stronger done in epoxy and carbon . my inclination would be to glass the outside of the rim , then lay up the wheel , and do the inside glassing as part of the wheel construction.
my plan now is to cut a ally rinforced section and a un-ally reinforced section and hang some weight off it to see the results. the join surface is 6mm(1/4") so theoretically 100mm length would represent 1"sq so the weight hanging could be expressed as a strain of x psi, ?
any thoughts on that?

results are IN!!!!!!!
Excuse the change to inches and pounds, its so i can relate all the measurement to PSI and the tyre pressure.
I cut a 4" piece ,with 2 ally strips and loaded it up with 80, then 200lbs of weight and nothing happened!

I then cut a 2" piece with NO strips and nothing happened. my maths says we now have a strain of 400lbs per square inch!!!!!!!!!!

next step is to reduce it to 1" of strip and add the 80lbs. this resulted in a distortion of the rim section of almost 1/8", but no breakage or cracking of the joint

finally I did the 200lbs test, resulting in a further 1/16" deflection, but the thing held up
if my maths is correct thats 800lbs per square inch!!!
I would appreciate if lachlan , in his capacity as an actual engineer, could check my maths.
of course this now begs the question , why bother with the tig weld?
perhaps you could simply wire the 2 rims with some twist wire to hold the shape then just glue/glass/tape after roughing up with a wire wheel

I tried just bonding/glassing the rims together a couple of years ago(they where repairable but a pain in the a#$ to do). They blew apart with heat . So I decider to weld them together and that solved the problem. I think the strips and rivets will work fine.

Just a thought here
How about if the two rims were cut down so the spoke holes were left on each half and then a strip of aluminium flat was rolled around and pop riveted through the spoke holes joining the two parts together ?
A bit of epoxy glue could be used as well under the strip

Sound good Hiko, give it a try.
Cheers
Vic

Thanks Landyacht. That looks good enough for me!

IPKSA said...

Impressive testing ....

Im blown away by the cotton flock as a mechanical adhesive, its supposed to be even stronger with epoxy. when I read up on it and cabosil ,you start to realize that some of the important names and numbers attached to some products is really just posh names for wood dust or ground cotton fibre or very,very fine sand

The 1/2" test piece hasnt the slightest crack or strain indication after 18hrs of hanging

Hiko said...

Where do you get cotton flock Paul ?
Some times asking for things around here all I get is raised eyebrows even somewhat mundane things

i just rang my fibreglass supplier.
they supply to industry as well as people like me who only use small quantities.
if you struggle in NZ let me know and i will send a bag to you as it is rather cheap.
the postage will be as much as the cost of the material

mailto:info@nzfibreglass.co.nz -----try this one
I googled fibreglass suppliers, dont google cotton flock, unless your into flannelete lingerie!!!!!

I finished the wheel, it came out a bit heavier than my welded rims ,but still lighter than my original domed wheels.
when it came time to balance the took rather a lot of lead bu came up well balanced.
Im looking forward to getting them rolling in september