Sunday, 27 June 2010
I did say I'd try and get something finished didn't I? Well there you have it, one finished set of headlight mountings, and bolt on ones to boot. Though, I did bolt them on, decide that the headlight stuck out too far and that the actual bit the headlight bolted to had all the elegance of a duck in a ballgown, and set out to make some more.
So, despite getting something done, I still didn't manage to make it much of a "bolt-on" operation. To be honest, while I'm claiming that its done, I may visit the new brackets with a selection of drill bits and add a few lightening holes, because the new brackets, while made out of aluminium, are a little on the portly side at a quarter of an inch thick.
The quarter inch ally was the thinnest suitably sized piece I had floating around the place and I'd already been assaulting it with my trusty Bosch jig saw to make the rear sets to the motorcycle.
I machined the footpegs from some 1 3/8" aluminium bar off cuts that I have (courtesy of my younger brother), and I hole sawed out an inner "washer" out of some 3/8" thick aluminium that came out of the scrap bin at Wasp Motorcycles ten or twelve years ago. The footpeg and the washer sandwich a piece of 20mm steel bar which has a 10mm hole drilled through it, and forms the pivot. I made the levers from the afore mentioned quarter inch ally plate, jigsawing them out roughly to shape and then finishing them with a selection of files. The levers are composed of two parts, the obviously lever shaped bit, and a teardrop shaped piece that lives behind it and will connect to the operating rod eventually. The lever has a selection of holes drilled in it and the "teardrop" has two threaded holes in it, which makes the whole set up widely adjustable.
I used the original gear lever to get the dimensions for the ones I made, which ought to mean the gear change feels very much like the standard one to use, as the lever ratios will be identical. The brake pedal is a bit more of a problem as my new lever has a 3:1 ratio and the factory brake pedal has something more like 6:1. That means that if I just hooked the new lever to the back brake, it would take twice the pedal effort to achieve the same amount of braking as the standard set up. It would also mean that the swing arm pivot and the brake rod pivot were nowhere near each other and introduce some interesting conflicting arcs.
To get round that, I'll make an "idler" lever that mounts in the same place as the factory brake lever, and has a 2:1 ratio, which will reduce the pedal effort and put the rod that actually operates the brake back in its original position, reducing the conflicting arc troubles to a minimum. I need, or at least want, to get some stainless Rose joints (Heim joints in the USA) to make the linkages. My dilemma there is whether to spend some extra money and buy a left hand tap and/or die so I can adjust the linkages without removing them.
The Tap and Die Co. in London has left hand 6mm x 1.0mm taps for £10 each, and the dies for £20 each, which is tempting, and once I'd bought them, I'll doubtless use them again.
Making the rear sets did consume most of the week, but in fairness to me, everyone who's looked at the polished items in the flesh has assumed that I bought them.
The other thing I made a start on was a front mudguard. In a spirit of scientific enquiry, I cut out a flat blank and fold the edge over while it was flat to see if I could make a mudguard by just stretching the middle without shrinking the edges.
"Yes I can" was the result of the experiment, but getting it to fit the BMW's 18" front wheel wasn't happening, although it was an admirable fit on my 21" Harley Davidson wheel.
Having found that particular orphan child a home, I went back to making one the usual way and shrinking the edges as well as stretching the middle. You can see the edge of the blank starting to ruffle up as I make the second pass along it with the arbor press. I made the nylon tooling and I have four different ones with varying amounts of "crown" on them, and I use them in the press to either force the metal into a hole in a piece of MDF to make a dent and stretch the material, or I use them on a flat piece of 1/4" steel plate to shrink the ruffles around the edge, or planish out the dents.
What I'm trying to end up with is a mudguard that has a cross section to match the "hoops" of the fork brace and a radius that closely matches that of the tyre once it's been fitted to the fork brace.
I find myself unexpectedly busy next week, so I may not have time to make a lot of progress. Though, the carburettors still need some cleaning, and soda blasting is something that needs looking into I think...