I’m done with mitering and slotting the seatstays. It took me way longer than I thought it should because I had some pre-bent S-bend seat stays from Nova…and I totally crunched them too tight in the fixture. I know now how very carefully to tighten the tubing blocks down on the stays. They’re only o.6mm at most in the middle after all! Duh…but now they will make perfect TIG practice tubing before going on to the real thing. BTW, found a Anvil SS fixture online for sale, never used! a couple hundred cheaper than a new one so i pulled the trigger. Very nice, but I can see why they’re improving on it since compared to the Sputnik it could use a few upgrades IMO.
Anyways, after I dented my pre-bend SS’s, I luckily had some extra straight (not pre-bent) 16mm/14mm tubing to use instead. This turned out to be a blessing in disguise. I used the oak mandrel in the vise and only messed up one tube before getting it right. The bend is a bit more than it should be (it’s a 7″ radius mandrel, should probably make a 8 or even 10″ mandrel for stays) but you don’t have to bend the tube against the mandrel all the way. Makes it harder to replicate with any accuracy, but with a lot of stopping and checking against the first one I bent, it was ok. I think they look pretty good in there! I can see why most builders bend their own seatstays. It’s really pretty easy!
The biggest pain is the coping/filing of the stays where they meet the seat tube. I’m using an externally butted ST so it’s a bigger diameter on the outside than a normally butted seat tube (29.8 instead of 28.6mm), and I haven’t found a hole saw that is the right size…so there was some detailed filing involved. Being good at mitering seat stays seems like it’s gonna take me several tries. Keeping them in phase (not rotated the wrong way up or down), and the right length to the frame specs as well as to eachother…!…is hard. I know why some builders prefer wishbone stays. I believe they’re easier to build, and you don’t need to put in a brake bridge/boss between the stays either. I do have to admit though…once you get it right, it feels pretty good.
Moving along on this frame nicely! I’m done with the mitering and heading next to brazing the bosses BEFORE I weld the frame together. I read that Engin does it this way because it is easier to clean up the tubes after brazing than when the full frame is all built. Makes sense to me since with a complete frame you can’t get flux out of the inside of the tubes, and you can also dry out the inside of the tubes than you can the inside of a frame (if it’s vented and you soak it in the bathtub) . Maybe this is commonplace, but since it’s not the way I learned it’s new to me! This bike is a mountain touring bike so it’s going to have 4 water bottles – two on the inside of the downtube, one on the underside of the downtube, and one on the seat tube. I hate riding with water on my back while touring so this is the main attempt to remedy that and help my back out a bit. Fitting the two cages and bottles on the inside of the downtube was pretty tight, but with small or medium size bottles it should be just right.