The only adjustment needed on the first frame I built on my course was to adjust the chain stays for wheel twist before fitting the seat stays. This was achieved by clamping the bottom bracket in a vice and pulling on the chain stay until it moved. If it were to break then it wasn’t fixed properly in the first place!
I have since needed to develop some methods of adjusting frame twists and movements which are to some extent inevitable.
The ultimate seems to be a truing table which I have never seen and I am sure would be prohibitively expensive for most hobbyists. Some framebuilders use a surface plate to use as a reference but these are also expensive and take up a lot of room, but frequently are available on Ebay.
Novice framebuilders will probably have to get a frame alignment checker at some point though if you have an accurate jig you can adjust the frame to sit perfectly in the jig again, which is largely what I have done, though I also used the “string method” for a few frames. Given that mainstream manufacturers are alleged to accept a tolerance from front to back of the frame of 5mm I suspect most framebuilders can get better than that using their eye. A dropout alignment tool is probably a necessity also.

Cold Setting can be done largely with the frame clamped by the bottom bracket in a vice (Paterek recommends fitting bottom bracket cups into the threads first to prevent distorting the bottom bracket). I use a 4ft plus length of 3×3 (69 x 69mm) timber for leverage. Whilst this is unwieldy I am certain there is no flex in it and all the force is transmitted directly to the frame, so be gentle. By inserting the timber end on between the chain stays with the shaft abutting the dropouts I can lever the dropouts apart either side as required. This method does tend to have an effect on both dropouts rather the just the one you intend to move, you can correct this by pushing the overcorrected one back. The alternative method is to slide the timber between the dropout you intend to widen and the same side of the lower seat tube and lever outwards. I fancy this is more risky to the integrity of the seat tube but it’s only an opinion. You could insert half a tube block between lever and frame.

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Chamfering the end of the timber helps

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Insert firmly between dropouts

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Gently lever out the dropout, there will be slight movement of the opposite side also

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Or lever one side only

I prefer to close the dropouts if required by hand by pushing against the dropout which usually requires all my body weight. The idea is to check how far out the dropouts are from the centre first using the frame alignment checker or string with reference to the desired axle width which I always aim to be 2mm more than the wheel axle length to make wheel insertion easier.

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The dropout should touch the tip of the frame alignment checker, which is adjustable, on both sides, keeping the axle width required.

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Or adjust the position of the dropouts so the measurement to the string is the same either side

I have managed to adjust a small amount of front triangle twist by inserting the timber through the frame and levering. Care needs to be taken with thin tubes. Better to insert the timber close to the tube joints in this case. With jig built lugged frames I have experienced very little in the way of front triangle twist. However with fillet brazing outside of a jig this has become more noticeable. I had great success with Hot Setting in this instance. This involves heating the portion of tubing/joint at the perceived point of twist on the side to which the frame has pulled i.e. the contracted side. Use a softer flame than for brazing and waft the torch back and forth either side of the joint until the metal goes dark red, avoiding melting the brass, then stop and leave to cool. Hopefully the frame will be restored to its former position, mine was! The same method can be used on chain stays but I have stuck to cold setting here. Final dropout adjustment is done with a dropout alignment tool with which the dropouts can be bent back into alignment and checked.

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