So I needed a headstock for the bike, this was going to be one of the fiddly bits to make. (Bollocks,wait until ye see the chuffin’ wheel hub 😉 A quick glance at the M & P catalogue showed that the ZX-9R front end used 55 x 14mm bearings and they were the same size top an’ bottom waheey less measurin’ to do .
First thing I did was made a drawing, completely out of character but seeing as it was fiddly I thought it would save a lot of pissin’ aboot. This is what the finished article should look like, I didn’t know exactly how long the tube would need to be but the tube was too long anyway.
The tube is Seamless with a 5mm wall. I could have done the calculations for bending moments, forces but bugger than, just over engineer it, it’s not a race rep so I guess the titanium frame is a non starter. The reason not to use seamed tube is that there are huge forces applied to the top of the tube, like when the myopic git pulls out when yer doin’ 90 and have to undertake “Oh shit” braking, theoretically the seam could give/distort/explode/metamorphosize into a gerbil, well you get the picture.
Whilst on “Pub” theory, another (easier) way to make a headstock is to just use tube and sink some inserts into it, this makes the headstock more bulky and dosn’t have he same engineering satisfaction, me own worst enemy me. How It Was Built First ye need a bit of tube. Kindly donated by a mate, who works in a factoy and can get lots of bits, this was faced in the lathe to tidy it up. The same mate got me three of these cut, yes ye only need two but in case I made an arse of one it was handy to have one spare. These posed the first problem, they had been cut from the shaft of a big machine, I though it was just paint which I sanded off, but the first time I offered a tool up to the sides in the lathe there were sparks, Hmmm, methinks, that’s not right, of course, the shaft would have been case hardened.
Two mug’s of coffee, many beers and twenty fags (cigarettes that is) later I concoted a cunning plan, well I read it in a book, I welded up a bracket to hold the angle grinder onto the cross slide of the lathe Turning the lathe and grinder on I passed it over the sides to grind out the hrdened layer of metal.
Lo and behold, 10 minutes later I had a shiny mild steel (machinable) surface. I need to go and think of other uses or this technique. I faced off both ends of the bar before doin’ the sides, get the ends parallel first and the sides will follow.
I was left with a nice shiny smooth bit o’ bar. A centre drill was run in to start the drilling, try gettin’ a big ol’ wobbly drill bit to find a centre, it just does a merry dance in the vicinity of the centre and find about 20 of them. Time now for the big “fuck off” drill, this was a 32mm tailstock drill, I’ve got a 38mm but me poor old cheapo lathe of dubious Asian descent hasn’t got the guts to run it.
Having drilled as big a hole as I could get I set about boring the bearing seat out to the desired dimension, I don’t have internal micrometers so the old vernier “very near” gauge had to do, with lots of cutting a wee bit an’ tryin’ the fit. You need an interference fit for the bearing which is a bastard to get (lesson : must get some internal micrometers), this took up loads of time. Patience is the name o’ the game here.
Much cutting later I ended up with the inserts complete with chamfers (I doo like a good chamfer, but I was told it makes ye go blind). The plan was to get an interference fit into the tube, Dunno if I weld ’em in yet. Viola, the finished thing of beauty, I suppose if it doesn’t work I could use it as a dumbell.