I am taking my first dive into lugged fork construction. I bought a Nova Everest fork crown. This one is designed for a 28.6 steerer. The crown race diameter is 32mm with a ~1.8mm wall at the fork crown.
I expected the fork crown to be much closer to the 30mm for a 1 1/8 crown race.
Is it normal to need to machine off 2mm from the fork crown? I cannot imagine this is appropriate for a crown cutter. Are people making this cut on a lathe after the steer is brazed? I am guessing the extra thickness helps with heat control when brazing but I want to make sure I’m not missing anything.
I am also looking for some literature for lugged fork building. I cannot seem to find much on the topic. Any suggestions would be great. Thanks!
I’ve always turned the crown on the lathe. Having to remove 1mm of material (in radius) doesn’t shock me.
To learn: Do lots of practice. This is a harder than average joint to braze because the crown soaks up a lot of heat and you can’t see how the bronze is pulling through. I bought some cheap crowns and cut blades off of old forks to make the practice cheaper. You of course want to get enough brass in there to get an internal fillet, and want to cut up samples to see if you are getting good penetration (check for cold spots on the inside of the blade next to the crown).
Braze the steerer and blades at the same time if your process allows for it. I used to do this in two steps because I couldn’t turn the crown race in my lathe on an assembled fork. Once I figured out how to do that (and my newer lathe makes it easy) I would always braze that joint all at the same time.
I love building lugged forks, have fun!
Thanks! Given Novas current sale I picked up a few so I could do some destructive learning…
How often are people using Brass vs Silver? I have seen both in my research.
I use brass, it’s just more forgiving and there isn’t a real advantage to silver here (unless you do a stainless crown of course).
I use a lathe after the brazing and use 56% silver. Strong and you don’t need to invest so much heat into the whole mass to get it to flow.
What are you looking to know/find out by destructive testing? These things are as strong as tanks and put together correctly are not the weak point in the system.
I plan on learning nothing more than my build quality. I am totally self taught brazing and want better confidence in how well I can braze deep joints. These lugs are appear robust but I lack experience flowing brass that deep.
Ahh…cool. My first frame I cut up and cut the lugs in half for the same reason.