A Special Builder's Notes


The Special Builder's Breakfast Club

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16 August 2012

The Lesson Today....

... is about following the instructions - especially when it comes to copper and nickel plating. I did read the manual, I just thought that I might get away with a quick brush up and a lucky rub.... No. Everything has to be surgically clean (like the man in the manual says) and particularly old bits of oil soaked steel. The latter presents a bit of a problem when it comes to bits and pieces that have been lubricated from time to time. Steel is absorbent and old steel is fit to bursting with impurities absorbed over time. I'm going to have to look for a stronger de-greasing agent and soak overnight before proceeding with the acid pickling process.

And this is all before the copper plate which I'm putting on to give the nickel a sporting chance. Learned Counsel came up with the idea of hot copper spraying.... worth a look for some stuff. Anyway, here below is the first trinket out of the plating bath:

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It's all a bit of a palaver to get set up and running and it can be tiresome when things don't go as well as expected and you're not quite sure of the reason why. But it's worth it if you have the patience to take the trouble with the preparation. Well, if you don't, as I quickly learnt, you may as well not start.

I've also made the time to draw up the brake cylinder plates and whizz them off to the laser people. I included a schematic because if the dimensions need tidying up, they know what the whole thing should look like.

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And that's just the beginning of the adventure that will be the brake system. Further reading has thrown up all sorts of stuff to try to get to grips with. For instance, the wheel size to drum ratio (which I've increased) will have a bearing on the amount of pressure required at the pedal to make the brakes effective which in turn is determined by the (very important) relationship of the bore sizes of the wheel and master cylinders . The pedal ratio (which I understand is the distance travelled by the foot contact part of the pedal in relation to the distance travelled by the master cylinder piston) is a function of the pushrod attachment position on the pedal lever and I might do well to make that mounting adjustable.

And, as I'm seeking only pedal assistance, I might be misleading myself in thinking that what in effect will be an almost full hydraulic system on the front brakes (the only difference being that the cylinders are not acting directly on the shoes) will be much the same as a servo system. Obviously the 2 animals are fundamentally different in design and operation and, although they have much the same effect on brake application, there might be some 'gotcha' in my proposal that's yet to reveal itself.

I could read some more but getting everything up and running (like the nickel plating) is really the only way to learn.

previous post The Brakes' Progress.
next post The Olympics: My Part in Their Success....


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