Saturday, 30 October 2010
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.
Sunday, 17 October 2010
Once again, another week has slipped by without me getting anything done on the Beemer. Frankly this would be a disgrace if it weren't for the other projects I've got on the go. It has to be borne in mind that I'm also building a tricycle with an Alfa Romeo engine, a GS 550 chopper, and usually something else as well, of late, making a Mustang fuel tank from some sheet metal and a tree trunk.
Next week isn't looking too great either as I need to tidy up behind myself.
I'll endeavour to squeeze some Beemer Werken in between the tidying up.
Sunday, 10 October 2010
I could have made a simple tag from 1" x 1/8" and a knurled thumb wheel, and just used those to locate the seat base on the motorcycle, but I'd decided I wanted something a little more "factory". It's taken me a while to get around to it, and you might be wondering what the big deal is, after all, how hard can it be to mount a seat? Well, if you've decided you want a concealed, cable operated, spring loaded catch and can't find a suitable ready made one, then quite hard enough would seem to be the answer.
The first problem was finding a spring, but since this is a perennial problem (in the past, I've ended up winding my own...) I bought a box of assorted compression springs from Screw-Fix for a shade under £9. These ones in fact. While rummaging around would undoubtedly turn up a suitable spring in the workshop, one piece of revealed wisdom that I am privy too is that in the course of this sort of exercise, the spring will inevitably go flying off. The question is whether you manage to find it exactly the same number of times it does this, or one less. Since most of the other components will tend to be sized to suit the spring, losing it, is a bit of a disaster. Unless you have a box full of them.
In the first picture you may notice that the "tongue" of the catch has a rather pleasing chamfer to it. Sadly, I managed to snap a drill off in that one, so the tongue in this picture is another one that I decided to drill for the cable nipple and thread for the stop before I got Trevor to file another pleasing chamfer. The components are (from the top left, going clockwise) the easy bit of the catch body, the bit of the catch body I made the press tool for after it had been drilled for the BA bolts that hold the catch together and the slot for the travel limiting slot filed out, the spring, the new tongue drilled for a cable nipple and the M4 stop screw, the stop screw itself with the silly little spacer that keeps it from tightening up onto the catch body, and the four BA screws and nuts that hold the whole thing together. The spacer under the stop screw was cut from a piece of 6mm OD 1mm wall aluminium tube that I bought from B&Q (think Home Depot if you're American) to make some grilles for the side panels on my GS550 chopper, which look a lot better than they sound. Cutting 2mm off of the end of a piece of flimsy aluminium tube was quite an interesting experience...
With all of the fiddly bits made and working properly, I marked and drilled the seat hump to accept the catch. I used pop rivets to locate it because I didn't want the fasteners to protrude any further from the mounting face than they absolutely had too, and frankly, I was getting a bit pissed off with all the fiddling around and wasn't really in the mood to make some dies to press countersink dimples into everything. Once I'd filed a square hole in the seat hump and the catch was riveted in place and working correctly, I marked the seat base and drilled some 1/8" holes in that which were definitely in the vicinity of the tongue of the catch. Once I had a hole and could see where the tongue of the catch was than it was simple a matter of finessing the hole in the right direction until it was both square and aligned with the tongue of the catch.
That still leaves me needing to make a cable, a handle to operate the cable, some sort of locating arrangement for the front of the seat base, and file (or get Trevor to file) a chamfer on the tongue of the catch, but since it all works after as fashion already, I don't see that as a huge problem.
Though, I may need an extension spring for the release handle.....
Monday, 4 October 2010
Well, Wales was nice, my Dad seemed quite pleased with his present, and I borrowed a few books off of my Mum relating to my house building aspirations. Didn't actually do any BMW though.
I did poke a few pieces of steel in a desultory fashion, and wander around looking for the springs that I'm sure I've seen in the last couple of weeks, and even got as far as sawing off a length of 10mm square bar with the idea of making the tongue for the seat catch, only to discover that the compression spring I had was 12mm in diameter. It wasn't an insoluble problem, but it would have meant a lot more work for a less efficient finished product. The idea of expending extra effort to make something that works less well because I haven't tracked down either a spring to match the metal, or some metal to match the spring, seems fundamentally stupid to me. As I had some other things that needed working on to meet a real world deadline (as opposed to a self impoosed, blog related one) I didn't manage to find the time to run around, source and acquire what I needed. I suppose I could have made a start on the frame braces, but I find that having a motorcycle project with too many unfinished jobs on it is depressing. You reach a point where you feel there's not much left to do, and remember that there are in fact lots of little things left to do, so not only is it a long list but it's all the jobs that you couldn't muster the enthusiasm to do at the time.
On the other hand, if you stick to getting the irritating, fiddly little jobs done instead of rushing ahead and doing something you're looking forward to doing, then you (or at least I) are more highly motivated to get the job at hand finished.
With that in mind, I'll leave you there and hope to have the seat base sorted out in time for next week.