Filed In: Process
Father/Daughter Project - Part 12
Tuesday, January 21, 2020 | Chris Blandford
17. Make and braze on head tube reinforcement rings
18. Make and braze on seat tube collar/binder
19. Slot seat tube
I was planning on using a cast seat tube collar on this frame. When I went digging for the one I thought I had on hand, however, I discovered that it was the wrong size. So, I decided to make my own out of a Paragon binder and some .058” tubing (to slip fit the seat tube).
I began by mitering the binder to fit the tubing. Then I put a small slot on the opposing side of the binder. I need to figure out a better way to fixture these while brazing, but a slot and one of my usually-used-for-cable-stops Sputnik clamps works ok. Then I (bronze) brazed the binder to the tube.
Next, I soaked, cut, and cleaned up the binder, squaring off the top and bottom on my belt sander. I also drilled the binder and seat tube for a pin. The pin will help me keep the collar straight while brazing. This was just done by eye.
Once the collar was made, I set in on cutting a couple of head tube rings (also out of .058” tubing, to slip fit the head tube). I’m using a regular 1mm-walled head tube on this bike, meant for use with lugs (as I understand). As such, I need reinforcement rings on the ends so that reaming the head tube doesn’t leave the walls too thin and prone to cracking around the press-fit headset. To make these, I first squared up the end of the .058” tube on the belt sander. Then I hacksawed the ring to length, and repeated for the second one. When I go to braze these on, I’ll make sure the square sides of the rings face “in”. The less-than-square hacksawed edge will get squared up when I face the top and bottom of the head tube.
Next I cleaned up the rings, collar, seat tube, and head tube with 80-grit and isopropyl. Then I fluxed all the bits, clamped the frame in my Park stand, and silver (56%) brazed them to the frame. (More about the silver brazing once I get to the fork...) Once cool, I soaked off the flux and cleaned everything up. Small files and emery, once again. Finally, I machined the head tube with my Park head tube reamer/facer.
I should mention that I’d love to learn how to use a lathe, if only for little bits like this. I’d like to be able to make these types of things more unique… tapered, perhaps... or something. For now, however, simple, chunky little rings and collars are what I can do. Maybe down the road.
Lastly, I slotted the seat tube. I enjoy every part of making a bicycle frame, except for this part. Even in my short time of doing this, I’ve learned to despise this task! On my most recent (adult) bikes, I’ve drilled the little pucker hole as part of making the seat tube sub-assembly. Even still, I never manage to get it exactly centered. In this instance, the hole--again--ended up a touch off center. Cursing to myself, I cut the slot with my Dremel cutting wheel (I usually use a hacksaw but didn’t have access on this little frame, which was anticipated) and then set in on getting it cleaned up with progressively-larger slotting files. When I was done, it just looked… off. Per usual. So, I “fixed” it as I’ve done a couple times before: by brazing on a “reinforcement” washer around the hole, and making sure it was good-and-center. Call it a feature.
That’s it for braze-ons at the moment. I’m still undecided about brakes on this bike. So, after I finish the fork I’ll need to add either brake studs or a plate for a coaster hub. And of course there’s the headbadge. But that always happens last. No matter what.
Fork tomorrow. Here’s where we stand: