Wednesday, May 18, 2011

KVA stainless - in progress!

I started work on Kris' KVA stainless cyclocross frame today, and shot a few pictures.
For those who aren't familiar, feel free to check out the KVA site. Long story short - it's stainless, it's butted and oriented to building road bikes (so please don't bug me about stainless mountain bikes - the tubing just isn't there yet), and it's more expensive than normal steel, but cheaper than ti (OX platinum tubeset = about $200 with dropouts, KVA tubeset = about $500 with dropouts, Ti tubeset = about $1000 with dropouts).

Initial thoughts on the build process:
-It's pretty hard and resists mitering/filing/cutting. A step beyond the air-hardening steels like 853 and OX platinum - I would NOT try to miter these tubes with anything but my milling machine/Anvil fixtures, or something equivalently solid. I ran 80 rpm and super-slow feed, and things were still complaining (read: making horrible noises while cutting) more than I'd like. The combination of noise and long cut times (due to the slow feed) meant an unpleasant 45 minutes or so of mitering time (of course, I'm using some of that time to write this!)
-The seat tube seems to be butted a bit thinner than .6mm at the top, hopefully it will distort a bit and snug down so that the post doesn't slip.

-Butts at the short ends are really short - 50mm. Great for road bikes, not so good if you need more flexibility with butting. But as I said, right now these are basically road tubes.
-Butting is similar to OX platinum or equivalent high-end road bike tubing (ie 7/4/7) so the frame won't end up much lighter than a standard steel frame. It won't need any paint, though.
-Speaking of paint, I have no idea how I'll do the finish work. It might look cool raw, it might need to be sandblasted or something, or it might end up looking best painted. We'll see.
-Welding with 309L rod is a gigantic pain. For some reason the puddle doesn't want to go where I want it to - so the welds are ok, but not as nice as I'd like them to be. More practice may help, of course, or it might be that this stuff is better joined with lugs.
-Head tube distorted like crazy (even with my usual heat sinks and backpurging with argon). Not enough to cause a problem with the headset, I think, but still disconcerting.


Anonymous said...

Scotchbrite and carnauba wax finish looks pretty good.

Walt said...

Yeah, fillet pro might be the way to go. The TIG did not go nearly as smoothly as I'd like.

Then again, regular non-stainless tubes might be the way to go...

Anonymous said...

Great post Walt. I have often wondered about the benefits of stainless. Have to say, after reading your post I'm not sure what they are. If the frame is about the same weight as a standard road frame is all of the extra work and cost worth it?