Saturday, 30 October 2010

Not the end, but a place from where you can see the end.

I'd like to announce that the whole on-going seat catch scenario has reached a resolution. Rather amazingly, the resolution it has reached is one of completion as opposed to one of the far more sensible file under "B" for "binned" variety. As you may know, the actual catch part of the equation was made some time ago and seemed to function admirably, and the metal base for the seat has been knocking around for a while too. What was lacking was a means of operating the catch to effect the release of the seat base.

The major part of that problem, at least as far as I was concerned, was the bracket. A few  moments thought should make it clear why. Essentially, the bracket has to attach the number plate to the seat hump, which in itself is a simple enough thing to achieve. The Construction and Use regulations (and the M.O.T) also require that the number plate be illuminated by a white light, and that that light shall not be visible from the rear of the vehicle. So, the bracket has to carry the number plate, and the number plate light, right? Well, yes, but....

The idea, as you may recall was to have a concealed seat release mechanism, with the operating lever concealed behind the number plate. That tends to imply that the bracket would also have to support the operating lever.

It doesn't end there though, as not only does the bracket have to support the lever, it has to provide a cable stop so that the lever has something to operate against, and while it's at it, it has to provide for routing the cable in a fashion that's discrete and doesn't force the cable through any overly tight bends which would impair its operation. On top of which, it would be nice if this masterpiece of design was as near to completely innocuous as possible. Oh, and it has to position all of the a fore mentioned items in a region of space that the rear wheel isn't going to occupy at any point in the proceedings.

If you stop and take stock of all that, it's actually quite a complex design brief, but for a moment let's just consider the operating lever. Clearly it has to operate the seat catch, and it's going to have to do it through the medium of a Bowden cable as do many other things on a motorcycle, what's not stated in the "design brief" is that it's really quite important that the lever doesn't rattle. At the same time, it would be nice if the effort required to operate the lever was such that you knew you were operating a lever without it being a struggle to operate.
  
This is where the elusive concept of "build quality" slips in. It needs to be pointed out that build quality is not a conspicuous feature of many thoroughly enjoyable, exotic, and (it has to said) Italian cars. So, by the same token, it ought to be perfectly possible to build a motorcycle which was complete rubbish, but, at the same time, fun. Since, almost by definition, that wouldn't involve spending four weeks of your life making a seat release mechanism, it certainly has a lot to recommend it. On the other hand, there is something to be said for the satisfaction of a job well done, or even a ludicrous target set and met. The target I set myself for this particular motorcycle was that it ought to have an air of "factory" about it, more suggestive of low volume production than of a one off built in a shed.
Literally on the other hand though, the more observant will have noticed that the release mechanism is "left handed". This is because, I am.

When I've been prototyping things in the past, I've made left handed prototypes so that I could assess how easy they were to use, and then mirror imaged them for the production version. Strictly speaking, I suppose that means that there never was an actual pre-production prototype, but it seems to have worked out quite well on the whole.

While it's easy enough to sit here and pontificate on the merits of design philosophy and assert that one's seat release mechanism was a success, I suppose we live in an age which is a little more "show me" than that. So in keeping with the spirit of the times, here's a rather gloomy video of it all in action...


video

Hopefully that should mean that some far more interesting frame related things are next on the agenda.

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