Sunday, January 17, 2010

Metal work.

Been busy doing some more metalwork. That is an 11-34 shimano xt block. I have limited metal working tools, so i didnt do the cleanest job. It ain't bad though.

Initially i clamped the block lightly in my small vice, on the plate for my pillar drill. I'm not sure if it is just the quality of the tool, but it seemed to be very sensitive to where the end mill hit the alloy carrier as to how easily and cleanly it took off material. It slipped a couple of times, as can be seen from the scarring on the alloy carrier, until i hit upon the idea (d'oh!) of wrapping a section of chain around the teeth of the ring to allow me to hold the block more solidly. I then proceeded more easily.

Once i got close to level, i transferred the block to a bigger vice (thanks dad!) and used a dremel with a grinding head to take the carrier down to a constant level as best i could. I used the bevelled sections of the teeth that engage on the freehub as my guide. Its not perfectly flat, like you might get if you used a lathe, but it is pretty neat, and with a 2mm washer behind, and after some work with the file to reduce the height of the chain catching sections on the back of the 34 tooth cog, i have a pretty good 6 speed block.

Next time, i would need to pay more attention to how the end mill hits the alloy. I think it needs to touch it close to the edge, rather than centre onto it. Need to do some reading!

Fun. If you likethat sort of thing....


Alex said...

Nice job. Perfection is rarely worth the effort when "good enough" will do :)

I just got an old (LX possibly?) 8sp cassette and punched the 3 rivets out of it and used the middle 6 cogs :)

I have to say that for off-roading 6 is a good number, I have 2 easier gears and 3 higher than I normally run and it seems spot on...we'll see how I manage in Nepal though!

Vertigo Cycles said...

Were you holding an end mill in a Jacobs chuck? When it slipped, did you have to re-seat the chuck? Jacobs chucks can't take much of a side load at all. It dislodges the tapered quill.

Al likes to be milled with a very high cutter speed, probably higher than your drill press can go. At low speeds it feels a little grabby and you don't get a great finish on the part.

Nice job though. Way to use what you have!

dRjON said...

thanks for wise words! yes it is a jacobs chucj and thats exactly what was happening....

lathe lust continues...!

Anonymous said...

...and lathes tremble (fear or yearning?)