Gordy
Well-Known Member
Hopefully soon
Custom Board Track Racer
- Thread starter a.tab56
- Start date
robe
Well-Known Member
Paul Brodie's claim to fame is his ability to filet braze his frames together. Look at some of his you tube vids, he is a master of this skill. Welding just doesn't cut it at his level. Welded frames came be fine but no where near the level of fillet brazing.
If you pay a shop to tig weld the frame for you it better look pretty
If tig welds look like sh^t then they'e no good
Don't worry Fabricators who tig weld do beautiful work
NeedSpeed
Active Member
Do not flux core chromoly. Try to make bends instead of welded joints where you can and put gussets where you can. Support is key.
a.tab56
New Member
I don't have whole drive train modeled yet but the idea is to have two sprockets on the jack shaft similar to how to old btr's used to have. The two sprockets would be connected to each other to transfer power and ride on their own bearings. The jack shaft is 5/8 keyed shaft inside flange bearings with set screw collars. I was thinking of welding a mounting flange to the bottom bracket shell for the flange bearings. The only reason I'm using bearings and not just using static foot rests is because I'd like to be able to pedal the bike. So on the starboard side there will be a conventional single speed pedal drive train
Also thinking about using mild steel for the bike frame instead of chromoly but haven't made a final decision on that. I'm still learning how to use Ansys which will probably take me a while. I know a shop could tig weld a chromoly frame very well but honestly I think I would enjoy it a lot to try and do it myself with mild steel if it ends up being strong enough in my simulations. I guess if I really wanted to stick with chromoly I could just braze that with map gas as well?
Another thought about map gas is that I wonder if it would get hot enough to bend mild steel? I would make some sort of fixture for the tube, fill it with sand so it doesn't deform, and then bend it around a makeshift die. This would be nice for the large down tube piece and the top tank tube. I would reduce the stress concentrations and be less welding. I wonder if the mild steel ends up not being strong enough if I could add gussets in the corners.
Not 100% sure about the forks. I've see some springer forks online that are tempting because their already put together, but the ones that look sturdy enough cost an arm and a leg. I'm not so sure about the other ones. I'm thinking I could build one myself that safe and strong enough for cheaper.
Lots to think about! Looking forward to all your input.
cloakedvillain
Well-Known Member
I have bent 1/8th inch flat stock easily with map gas. Sheet steel ought be just as easy, only taking longer to heat.
If you're going to braze get a proper oxyfuel kit. Don't need the 6 ft tanks, just the little ones will do. While map gas only can do it, oxygen and map is much easier
If you're going to braze get a proper oxyfuel kit. Don't need the 6 ft tanks, just the little ones will do. While map gas only can do it, oxygen and map is much easier
a.tab56
New Member
Good to know. Could you tell me why having added oxygen is better? Is it a more efficient burn?
Gordy
Well-Known Member
It's a lot quicker. Map gas and some flux covered bronze braze rod should do just fine for 18 gauge
a.tab56
New Member
I assume its quicker because its hotter? I'll probably go without the added oxygen just curious. Do you think bronze braze would be enough for a frame in this application? Or should it be a flame welding specific rod?
Gordy
Well-Known Member
Yeah Oxy-Acetylene just gets hotter faster. I managed to do with MAP gas, it just takes a long time to get hot enough. I'm not sure if MAP gas and a bronze braze rod would be good for a full frame, I've never looked into it.
