Framebuilding Class, Part I

I have a new found respect for bike framebuilders, especially TIG welders since that's how I'm attempting to build my new frame. Being a closet OCD perfectionist that hates to do things poorly, I am finding TIG welding little skinny steel tubes quite difficult! I like to think I have a steady hand, good hand-eye coordination, and good eyesight, but all of these traits have come into question these last few days. Granted, this is not something you learn in a week-long class, but OMG, I suck.

Here's a photo essay of the week since Monday when the class in Denver started. The framebuilding class I'm taking is from a local builder. For this class, I chose to build a singlespeed cross frame with Paul's dropouts.

Monday, Day 1. Measuring, Cutting, and Mitering.
Using BikeCAD Pro, we took my measurements and put them into the program. We futzed around a lot with these numbers - for at least an hour - and compared the resultant/recommended geometry to my Independent Fabrications Planet Cross that I love so much. The BikeCAD program, I learned quickly, gives you a good starting point. You really do have to know what you like and make the appropriate changes to such things like head and seat tube angles, top tube length, and more. The standover and seat tube lengths are less flexible I'm told. The program spits out a CAD drawing with tube lengths to cut and miter angles. The tubing we used is US made True Temper - not the lightest tubing but good for the first frame since they're so thin enough. They are not straight gauge but .9/.6/.9 double butted tubes.

Milling the downtube. Doing the mitering by hand would be insanely time-consuming but I hear there are many framebuilders that don't have Bridgeport milling machines and use only a hacksaw and files. That is indeed impressive but would take much longer to miter the tubes and fit and weld the frame. It's likely what I will do for awhile as the above machine costs around $3k used. I still think this is just a over-hyped drill press and one could do the same thing with the hole saws and a big drill press...but what do i know.

Here's the BB, Seat tube, and downtube being fitted using an Anvil fixture (frame jig). The Anvil is one sweet jig but I think I would like to get the Henry James fixture as you can more easily weld within the jig and it is a better jig for brazed and lugged frames which I would eventually love to learn how to build. The mitering process is one of trial and error, at least for beginners. You look, file, replace the tube, find where it's hitting the other tubes right and where there are gaps, and then file some more. Repeat over and over. I spent an hour getting the downtube to fit with the headtube and bottom bracket. This is apparently where people lose the love - where the romantic notion of being a framebuilder suddenly disappears - because the mitering process is truly a laborious process that I can see takes years of experience to master. You need the tubes to be touching all the way around because any gaps make the weld weaker and simply harder to weld together.

Day 2. More mitering and tack-welding the front triangle.
By the end of day 2, I had relatively successfully tack-welded the front triangle of the frame. I say 'relatively' because I blew a couple of good holes in the tubes in a couple of places. Nothing that can't be fixed, but even tack-welding these thin tubes was more difficult than I thought. There's a bit of yoga that goes into welding a frame since welding flat surfaces is WAY easier than round tubes. Getting the frame positioned in a way you can see the joint clearly is key. You tack weld around each tube around 6 times so that it holds the tubes in place. Some builders then weld the frame in the fixture itself while others put it on a welding table or bike stand that is connected to the table and weld it there. Theoretically, the tack welds should hold it in line if done correctly.

Day 3. Weld the front triangle, start mitering the rear tubes.
Here Chris shows me how to cut the chainstays lengthwise to fit into the Paul's dropouts. Instead of using a hacksaw for this, he brought out the secret weapon -- the air-compressor-powered cutting wheel...pretty sweet tool, i want one. This cutting wheel can cut through tubing in seconds compared to the hacksaw.

By the start of Day 3, I had the front triangle tack-welded. I started that morning, after a late night out at a metal show in town, tired. So to practice, I used some scrap tubing and practiced on them instead of my frame, just to be safe. I am REALLY happy I did because the hour I spent on the practice tubes got me past my frustration and feelings of inadequacy (wait, what are we talking about...?) and I gained enough confidence to weld the actual tubes. It's a pretty sure bet beginner TIG-welders blow thru tubing, a few times. I did exactly that but after watching how those holes get filled I was able to fix my errors myself which was probably the best feeling of the day second to actually making stretches of bead that looked relatively OK.

Here's the bottom bracket after we finished welding it. We did these joints first, and Chris did the most 'sensitive' tubes first (where the down and seat-tubes touch) to show me how it's done. So these welds should look better than below which is all me.


Chris has a Miller 200 amp welder, water cooled, argon gas, etc, etc. It has a 'pulser' which increases the amps from a low to high value (5 - 38 in this case) approximately every 1 second. This makes the uniform round bead that is so characteristic of TIG-welded frames. It helps even the novice make ok looking welds (I'll take myself out of that since the above doesn't look so great). Some don't use a pulser and go it alone. In those cases, i think the bead is smaller and may not be as uniform but is no less strong.


By the end of day 3, I welded the rest of the joints myself and fixed my own mistakes for the most part. We also mitered, fit, and tack-welded the chainstays to the BB.

Throughout the day I needed a bunch of coaching and hands-on guidance. It was extremely helpful to have someone standing over you for awhile telling you what to do what to STOP doing since it's very hard to see through the dark welding mask what you're actually doing sometimes. The key for me was to get comfortable and get a good sight on the joint you are trying to weld - don't get too twisted trying to weld the joint, move the frame around in the fixture to be in a good position. Relax and be patient. Wait for the puddle to form...don't rush it. Put in the filler rod only after the puddle has formed and you have started moving the puddle forward along the joint. Patience...relax....be steady....be comfortable...and don't try and do too much too fast.
Hah, I guess I could use this way of being and knowledge in other aspects of my life such as work and bike racing.

Friday and Saturday I finish the frame, more later.