I know this is a very DIY type bike you are making and the drop out tube method of bending it to shape is really approximating a curve through short cut and weld pieces. Quite short pieces if as you said when you can look at zoom level. Very very nice!
I have a problem that I need to fix. I think it really is not OK to leave as is on my bike build where the rear fork on one side needs to spread enough to allow the pulley drive attached to the spokes, to clear the rear fork tube on the left side.
I have used a spacer on the left side of the rear wheel hub threads to spread it over on just that side to make clearance. It is about ¼ inch but the tubes really have a lot of stress to widen it just that little bit.
I have heard of bending further that what you need and then the metal will not return back fully to the dimensions and there you have it. Hopefully just spread enough. I have not anything that can hold it and get that amount of leverage though.
I have also heard people have said to flame heat and make the bending easier on the metal and welds when you are bending. I have small propane or map gas torch that I have a wide tip to spread out heat, but I’m not sure that enough heating can be attained to a large enough area in a given time to be able to make the bending go easier.
I have also heard that the tube may collapse in the hollow area inside, and maybe that is why you chose the cut and weld many pieces. I could go for slightly longer pieces, more like a rise time of an oscilloscope waveform.
Cutting and welding as you do looks really good. I have a MIG 125 amp welder with ARCO2 or use flux core and should see if I can practice on some old steel bike tube parts to see if I can do as you have done. It has been mentioned that if I widen one side the rear fork can still be parallel, by use of an “S” shape bend.
Any tips on this,
Thanks Measure Twice