Wednesday, July 2, 2008

Chris's road frame, Ups and Downs...

Some builds go sooo very smooth, others feel like they are jinxed from the start, this one has been a roller coaster of both.

The SS couplers went in oh so cleanly, a result of nice preparation and some smiles from the heavens. I always pull a bit more silver into these to insure that they are well brazed in with a little feather at the joint that I create by quickly flashing around the edge and rotating the tube by hand.

Next up, I started on the actual mitering of the frame. I start with the seat tube, cutting the top at a 15 degree slant and then tacking in the binder bolt. I use the tig welder to quickly tack each side, this will hold the binder until I silver braze it in. with a nice smooth fillet.

Then it's off to the mitering fixture to cut in the bottom bracket miter. I shim out to the post and use the pinch clamp to indicate off of to insure my miters are in phase and aligned.

The seat tube is then held fast in the fixture by a clamp with a lot of surface area, insuring that it stays put in the center of the bottom bracket.

All was going smooth until the stuff of nightmares happened. Typically, I'll miter tubing down to .8mm without any ancillary adjuncts to facilitate the process. Thinner material will get a wooden plug to support the walls and keep the edges from catching the hole saw teeth and tearing the material.

Well, this one got me. I was on the last miter for the evening, the down tube at the bottom bracket, feeding it nice and slowly with the quill feed on the mill while I absent mindedly squirted cutting fluid in a happy little stream when "BANG"! My heart sunk, because I knew what that meant; a tooth had caught on the edge of the tubing and jacked the whole shebang. Now a lesser builder might have really been pissed, allowing anger to take charge. Not me, I just uttered a few choice curse words, curled up into a fetal position, and sank into a swirling pool of despair.

You see, normally it would not be too big of a deal...I'd re-miter the tube a bit farther or replace it all together, but this guy has a very expensive coupler attached to it...aww shucks!

The aftermath... The culprit...the missing tooth
I messed with what I was going to do for a bit and finally decided to use a few tricks I know to restore the shape and re cut the miter a skoosh shorter. If that would not work, I'd have to order another coupler and start all over, a move that would cost me financially but more importantly, in time.

Fortunately, I was able to work some magic and come out with a nice finished piece. The miter is a tad shorter than I'd like on the near edge by a few thousandths, but that will fill quite easily when I weld it. Set back overcome :)

The rest of the fit up...

I thought I'd share a quick series of pics on tacking up the frame. Here's the underside of the downtube/headtube junction prior to final clean and wipe;

Getting the tungsten length just right for the tack...

Getting busy with it...

The tack...
And the front triangle all welded up, a few shots of the same area for you...

So, the front triangle all done up, I'll start fitting the rear end next day in the shop. These are in between days at the FD so I'm a bit low on sleep and find myself just sitting staring at the frame for undetermined blocks of time...kinda coming out of it and moving on. Not the best for productivity, but still moving forward ;)

Thanks to Kalten for letting me borrow his Sum 41 CD today, the up tempo music kept me going. Good luck at the swim meet buddy.




Sabrosa Cycles said...

ouch. nice recovery.

steve garro said...

ditto what jruss said! at least you didn't scrap a whole painted frame like i did the other day. steve.

Vertigo Cycles said...

great recovery. I feel your pain. I once blew out a butted ti tube and one of Andy Newlands fancy cutters all in one go. I find that silent sobbing really calms the nerves afterwards.