Sunday, June 19, 2005

Fiddling Around

I sent another email off to Cecil at Renaissance (aka bananabrain on eBay) inquiring about my BB tapping set. It's been months, I think maybe 3, since I ordered it. Hopefully he's back from vacation and will get it in the mail. I need to clean up the BB. My other purchases from Cecil have always resulted in good experiences - but I'm having to put off buying anything else from him until I can get this problem resolved.

Speaking of vendors, I should put in a plug for Yellow Jersey up in Madison. I went to them looking for a build kit that was slightly idiosyncratic (Centaur w/ FSA compact crank, Brooks sprung saddle, threadless headset w/ quill stem, no brakes 'cuz I'm using NOS Mafacs - that sort of thing), needed competitive pricing, and wanted good hand-built wheels. While I haven't ridden the wheels yet, it looks like they delivered on all counts. There don't seem to be many places that can do all this. They did. And they were quick. Recommended.

Today was spent largely on non-bicycle activities, but after the kids went to bed I got about an hour in the garage. After doing some tidying up, I noticed how many hits my full scale drawing has taken. It won't be around for another frame. That said, it'll only be needed for one or two more checks on this frame.

In profile everything looks fine including the chainstays. When the frame is set upright, and the top tube is leveled, the headtube and seattube are within half a degree of their spec, which is the limit of precision of my measuring. Using a level, the stays don't twist over their length (yeah). But the Dropouts themselves needed a little work. A tap with the Ball Peen hammer on the left took the curve out of it. A tweak in the vice got the right properly plumb.

Getting the stays aligned horizontally is another matter. Next time I'm building a jig to build the stays aligned. Anyway, using the backbone of that future jig (made of 80:20), its possible to measure alignment to within a millimeter (or maybe less). Based on this, the ends of the stays were leaning way to the right.

Starting with the BB mounted in the vice between pieces of plywood, I took a pull on the left stay. It took a couple of tries, then scared me when it seems to shift a foot all at once. Checking on the jig indicated that it was just a couple of mm to far. So, back in the vice and a light adjustment. Then, it was right at 65mm from center - urg, I'd hoped to have a little extra room for removing/mounting wheels. Maybe this is where one of those screw based adjusters pays off.

Then it was on to the right stay. This one moved more easily, and went too far. It took several further attempts at adjustment to get it right. Then one last tweak of the left for space and I tried a wheel in it. It still seems like one stay is too long, although measuring with a tape to the BB says otherwise. Maybe its time to measure to the headtube? Eyeballing, with the axle adjusted to be square in the dropouts, the wheel is centered in between the front of the stays, and measures vertical on both the front and back surface of the rim. Maybe I'll have to mount the fork and another wheel to really know if this is correct. Hmmm.... I need to think about this some more before mounting the seatstays.

Then it was on to the fork. The tips are now parallel and plumb, so I mounted the wheel. Horrors!!! How did one leg get longer than the other? Pull the wheel, look at the tips, and see I didn't clean the flux very well. One tip still had a good bit in its slot - so this got cleaned.

Then the fork got mounted on its side in v-blocks. A square checked the crown for alignment while the fork got clamped tightly. Then the square went down the legs looking for twists. None noted. Using a surface gauge, I checked the height of the left leg from the table. Then turning the fork over, and repeating the process, found that the right leg was running wide - accounting for my 110+ mm width at the tips. Fork in vice, pull on leg, pull harder, pull harder - whoops something gives. It looked like the crown itself that bent. I could see that this one went too far, so pushed it back some. Tested again, pushed back again and tested again. Ended up with a pretty balanced setup. Put the wheel in and all looks good. Now I can file and sand the tip joints. Yeah.

Well, that's it for tonight. If I can sort out my chainstays and decide what (if anything) I want to do, it won't take me long to wrap up the remaining bits. There's still some cosmetic work to do, especially filing, but I found another new set of small files. As these should be sharp, they should speed up the process.

Good Night

1 comment:

Nick said...

So what do the parts that I exchanged in Madison do?