Sunday, 1 August 2010

Last time, I mentioned making a rear light to suit the seat hump I'd started building and that I didn't really want to do that. With a little more thought devoted to the issue, it turned out that not doing it was a good idea, because the shape of the hump, while quite interesting as a shape, missed looking like it belonged there by a margin of indeterminate, but definite, size. Since it took me most of the week to come to this conclusion, I didn't actually manage to get around to making another one.

In an effort to feel that I'd actually achieved something, I did manage to order a pair of rubber tank mountings for the R80 tank from James Sherlock. That was a bit of a shot in the dark, as I had no idea how the rear of the tank was supposed to be mounted, so the vague hope was that buying the mounting rubbers would make it all clear.

With the rubbers attached to the tank, it seemed fairly obvious that the much longer threaded studs were supposed to go through the frame so I took some 10mm bar and drilled a 6mm hole up the middle of it in the lathe to make some crush tubes. With that done, I put masking tape on the frame, and used a felt tipped pen to mark the positions of the studs prior to drilling some 10mm holes through the frame. With the crush tubes located in the holes in the frame, and the mounting rubbers attached to the tank, it all lined up marvellously.

In the corner of my workshop, there's a UCB, or Ubiquitous Chinese Bandsaw. Mine managed to get buried in a corner sometime ago, and we recently unearthed it. The UCB comes in quite a few guises, and some are better than others, but they all seem to work after a fashion right out of the box. To some degree how happy people tend to be with their UCB depends on what they use it for, if your hobby is making gates and you just want something to cut bar to length while you do something else, it'll probably make you happy. If you're a model engineer and you want to cut bar stock to length before you machine it, I suspect it would start to annoy you very soon. If you're thinking about buying one, or indeed already own one that you're less than pleased with, probably the best thing to do is to type "bandsaw mods" into Google when you've an hour or two to spare.

I used mine to make some risers for the seat base, I took some 2"x 1" 16 gauge (about 1/16" thick) box section and cut it to length, then I used the bandsaw to scallop out the lower edge to form a bridge to go between the seat rails. Aside from looking a little more like someone had thought about it, the scallops allow for missing the rear wheel, and removing the battery. I took the piece I'd cut out of the box section and cut some rectangles out of it to cap the end of the box section with and prevent the supports from lozenging under the weight of the rider.

This is where the seat supports are going to fit. I haven't welded them on yet as I thinking about how the seat hump and the seat proper will attach. Some of the electrical items should ideally be easily accessible, such as the fuses, but with a decent quality gel battery, and provision for charging it in situ, how often do you actually need to take the battery out? With that in mind I'll probably attach the seat base/hump by bolting it on, and have the upholstery separate, and located by a couple of pins and either a thumb wheel, or some poppers around the hump. As long as removing the upholstery lets you get at the fuses and some storage space for a few tools, then that ought to do the job.

On reflection, I should have attended to the tank mountings and the seat base supports before I started messing about with making the seat hump. Trying to make a seat that follows the lines of the tank when the tank isn't in the right place and the seat is balanced on a block of wood, isn't making the task any easier.

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