Anatomy of a build

The customer for thos scandium 'cross frame requested a pictorial of the assembly process. I'll share it with all of you who check out this blog on occasion. Granted , this isn't every last step but given the time I had, it shows most of the process. Below is my drawing table with the plan for the frame well under way. I do a full-scale drawing for every bike-no autocad here , just your basic drafting equipment and a bevel protractor to accurately find the angles.
Here you can see that the drawing is finished. I made a correction to it-that's why there are some extra lines where the top tube is pictured. Having a full scale drawing makes it easy to chek the work as I go along. If the something dosen't line up with the drawing, Iv'e got a problem to solve.

Here's a photo of the boring operation on the lathe. I remove a little material from the head tube to make it a little easier to weld and later machine for the headset. I only have 50 amps in the shop so if the material is too thick , I can't get good weld penetration.

Here's the first weld-seat tube to BB shell. I always start here. I don't have to but it seems the logical place to start as it is pretty much the center of the frame.....all tubes project outward from this point, more or less.

I lay out the complete tubeset on the drawing table to make sure the tubes are the correct length to be used in this frame-too long and I'll cut off the butting and not have as strong of a bike in the end.
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This is the final turning operation on the head tube. I take a small amount of material off the outside and leave a 'collar' at either end of the head tube. I like the way it looks and it puts more material where it is needed in the higher stress zones.

I weld the finished head tube to the top tube early in the process. If I make an error in the head angle , it will be easy to check at this point ans start over if it is too far out of spec.

This is the mitering process being done on the front end of the down tube that will meet the head tube at approximately 60 degrees. All the main tubes and stays are cut this way if they are to be welded to another tube.

This is my home-made main triangle jig with the seat tube, BB shell and downtube held in place for welding. I'll tack the down tube in three places, then remove the assembly from the jig and do all the weld passes. When this is done the main triangle will be in two pieces, this one and the head/top tube sub-assembly.

Here's the front triangle all welded up sitting on the jig.

When the fron triangle is aligned, I check it against the drawing to make sure it's correct. At this point I can use the drawing to orient my rear-triangle jig which bolts to the seat tube.

Here's the rear triangle jig being used to hold the dropouts and chainstays for welding. I leave this jig on the frame until all the stays are fully welded on.

Once the rear triangle is welded up I go through an alignment stage, doing the final check with an appropriate rear wheel and a Park frame alignment stick. It's pretty basic but it tells you all you need to know about inaccuracies in your craftsmanship tht need to be addressed.

Here's the final product laying on the drawing and hooray ! It all lines up as it should. There are a lot of little steps that I didn't get a chance to photograph but this is my first attempt at showing how a frame goes together in my shop. Some day I'll produce a DVD if I have the time.