I got a late start on this this afternoon. It seemed the phone wouldn't stop ringing, and I'm battling with a wiring job on a Sporty that needs to be finished. Plus, Kyle ( you've seen his green Sporty that I worked over and hardtailed here previously) is back from his tour in Afganistan, and he brought his buddy Lumpy and his CFL roller over for me to start Lumpy's build. And, Part-timer Steve had a photoshoot with a model for a feature article on his bike up in the mountains, and he wasn't around today, so I was pretty busy.
I skipped taking photos of bending the backbone, and making the slugs for the neck and seatpost, but they're done the same as I've shown on here before.
The shape of the backbone is similar to what H-D does on their Softail frames. The backbone doesn't follow the line of the rear head, because it needs to be a little higher, then dip down so I can mate the top legs of the hardtail with it later on, and still allow clearance under the top legs for the engine to slide in and out. The top legs will hit the backbone approx. where the white line is on the photo. Next, I marked the seatpost for the angle of the cope, so it will butt up to the backbone.........
.....then into the tubing notcher for a 10 degree cope with a 1 1/2" hole saw. I can't remember who made this notcher (I know it's USA made, but there's no name on it), but I've had it for 10 years, and it's still dead accurate, and it's been used a LOT.
Backbone and seatpost aligned and final fitted.
Closup of the coped top of the seatpost, and how it fits. Here's a bonus tip: If you ever do something similar to this, before you weld the post and the backbone together, trace the post on the backbone. Take the backbone, and drill a 1/2" hole centered inside your tracing, then weld the two together. That way, you can run your headlight wires, coil wires, etc. up your seatpost, and up through the backbone.
I cut the backbone to length, ending it in a "doefoot". I'll cap it to finish it off.Here's where I dropped off this evening. I still have to clean the neck area to weld the backbone there, trim the old neck gusset, and drill my plug weld holes for the backbone and seatpost slugs. Then jig it up, weld it together, and then fit up the lower tank brace tube. From here I'll have a good foundation when I do the hardtail. I'll post up the frame when it's completed.