Building the arse end

Friday, 8 March 2013, 3pm

Another long break since the last blog. Putting the back end together involved a lot of machining and a lot of waiting for epoxy to harden around threaded inserts.

First off the rank was making the frame to hold the rear cross-shaft/swing arm pivot from a few bits of M-board –

I riveted the outer bearing brackets in place, clamping them back-to-back with a bit of tube through the bearings to make sure they would line up. Fancy bit of clamping –

After fitting the frame tube mounts similar to the front ones, these members were clamped in place on the floor panel and bolt mounting holes drilled in the ends of the tubes. The rear cross-shaft has been fitted to check the alignment of the bearings –

Next up I machined the threaded inserts to connect the supports to the floor –

The lugs are to ensure positive location of all the brackets. Gluing the outer mounts in place –

The large alloy plates are to spread the load -

Threaded inserts are fitted to the inner mounts -

Note I have started drilling 2mm holes either side of the inserts, the epoxy being introduced on one side until it starts to exude from the breather hole on the opposite side. And here are the brackets that they mount into riveted to the M-board -

I’ve been using large ¼” rivets, drilled out to 3/16” and then riveted from the other end with 3/16” rivets, thereby making double-walled and double-headed rivets. These are the inner mounts fitted in place and bolted to the floor –

Note I’ve also added a couple of small brackets to the inside of the outer bearing mounts to stiffen them up.

These are the forward floor brackets, made from one big chunk of high tensile aluminium -

The thicker band at the top of the circular holes will later have slots filed in them to house the carbon fibre seat mounts. This is where they fit –

The right hand tube extends inward beyond the mount to support the derailleur dropout. And this is what it all looks like bolted together –

So that’s most of the chassis finished and most of what’s left to do is fiddly stuff. I’ll probably be finishing off the drive train next.