'L' of a job

Brake 'L' Bracket and main support

One of the complicated bits of the design was working out how to make the L bracket for the load-cell. The L needs to be pivoted somehow. To achieve this I decided to use a rectangle 'tube' piece of aluminium with the pivot point going through the side and the L bracket bolted to the top. For this I will use M4 nuts and bolts.
I have cut a piece of rectangle to length and started drilling out some of the holes. The 'big' holes are 10 mm in diameter. I will be using an 8mm diameter stainless steel (SS) shaft as the axle which will fit inside 'flanged plain bearings' that are 10mm external diameter, 8mm internal. 

I had a lot of trouble finding the plain bearings – not because there isn't anywhere that sells them, but mainly because I had no idea what they were called before now. I spent a good few hours searching for 'plastic axle sleeves' and 'you know those things that...' until I found some. I'm still not sure 'flanged plain bearings' is a standardised term but I got mine from a website called motionco.

They seem quite expensive for what they are but they will do the job. I didn't want to go without these bearings because I'd be worried getting everything to fit and rotate smoothly would not be possible, also that over time, the soft aluminium would get worn down by the steel. I will use the same size shaft and bearings for the pedal arms but the pulley axle will just be metal against metal. I'm hoping this will be ok because the pulley itself should rotate and there is no need for the shaft to do so. Also the pulley axle will be slightly smaller diameter at 1/4” (about 6.35mm in proper money*), this is due to me struggling to find any 'idler pulleys' (as I learnt they are called) for sale. I eventually found some from the place I got the plain bearings from. They are 25mm diameter plastic pulleys to fit a 3mm cable. I am bit worried that the diameter might be too small as I will be using 'wire rope' (as I learnt it is called – not steel cable) that will go around the pulley and if the wire rope is not flexible enough to round it then it may cause problems.

*I try to work in metric for everything but had to make some concessions due to the availability of parts.

Rear Support Pieces with holes for Pulley axle

Anyway, I have made progress on the pulley bracket/rear support pieces. They are each 50mm long cut from the aluminium 1/4” thick channel section. I drilled 6mm holes and filed them out until the 1/4” steel shaft would fit. I will cut the steel shaft to the same width as these piece so that when this rear support is bolted between the two side pieces, the shaft will not be able to slide out. This method saves a bit on 'shaft collars' (as I learnt they are called) which I will be using to keep things in place on the peddle arm axle. 

I am finding marking out on the aluminium quite easy by scoring my lines with the point of an old compass. 

The pedal arms have also had some drilling done to them. As a rough guide the centre of the hole is 85 mm from (what will be) the bottom of the pedal arm – where the wire rope will be, and 250mm from where the pedal itself will be mounted to the pedal arm. Here is one with 'plain flanged bearing' fitted and one without.

"Pedal Arms"