head tube weld distortion

L

Liam

New member
Many of the designs here, TimberWolf and LodeRunner for example, call for welding the head tube to the HSS frame. I'm not saying that's a bad idea, not at all. However, my experience in the welding trade tells me the head tube will distort due to weld metal shrinkage and heat effects. Has anybody else found the distortion to be a problem?

My main concern is that the top and bottom bearing cups will not be parallel after cooling. Is the distortion enough to worry about? Will I have to machine the cups to get the bearings to work smoothly?
 
I've done a few of these now, and have never had a problem. The bearings do not see significant load or speed, so any minor misalignment from welding is inconsequential.
 
I purchased 2' lengths of 1 1/4" head tube material which is slightly thicker than on most bikes plus it is cromo. never had issue with blowing holes etc. since I have been using this headtube material (purchased online from shop in Oregon that sells bike frame materials. use a search to locate. I can't find my old bookmarks on this computer.
 
I do my builds in stainless, and some extortion is expected after welding. Simply filing them brings them back close enough to call parallel. Same goes with the BB shell. I use a couple of half metre lengths of square tube on each end to check for parallel. I also put some old bearing shells in the tubes whilst welding, just to keep them sort of round. There's enough slop in the cheapo bearing sets I use to not need perfect parallel faces, but each to their own....:)
 
If you do see a small oval distortion, two things easily fix this; banging the bearing cups back into the tube, or a good swift whack on the front with a large hammer.

Brad
 
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