Bottom bracket cluster mitering question
#1
Full Member
Thread Starter
Bottom bracket cluster mitering question
I have been using the TubeNotcher Pattern Creation Tool on dogfeatherdesign.com for my miter practice. This is my first fillet brazed frame. I hoped that the tool would provide some guidance on notching a multi-axis airframe cluster, but apparently not. I just wanted to check with the forum to see if there were pointers regarding this. The downtube and BB are both 38mm and the seat tube is 28.6mm. Proceeding cautiously
#2
Senior Member
Join Date: Feb 2012
Location: Rochester, NY
Posts: 18,092
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4208 Post(s)
Liked 3,874 Times
in
2,314 Posts
Are you asking about the two tubes having some overlap at the BB shell? Many just do this by hand and eye. Generally you decide which tube will have it's mitered end completely contact the shell (and for many builders this tube gets tacked or completely brazed/welded to the shell at this point) and then the other tube gets a small scallop/miter to both properly contact the shell and also nestle against the first tube. This gets easier after doing a few Andy
__________________
AndrewRStewart
AndrewRStewart
Likes For Andrew R Stewart:
#3
Senior Member
Join Date: Dec 2019
Posts: 956
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 321 Post(s)
Liked 263 Times
in
212 Posts
I generate two mitre templates, one for DT to BB and one for DT to ST. Then my CAD software tells me the offset between them on the DT inside centreline in this case 11.29mm. So then I can trace them both onto the tube at once. I cut the DT to BB completely first and then sneak up on the DT to ST one checking the fit carefully as I go. It is the trickiest mitre on the frame and when welding it you have to be careful not to burn back the corners.
Likes For guy153:
#4
Randomhead
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,398
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,698 Times
in
2,518 Posts
Is the tube notcher software still there on the Nova site? I thought it did the dt/st notch correctly
Okay, it was the same software and it looks like it's not there any more. The bike specific version was hosted there, so I think I would reach out to the author of the software and see if he can help you
Okay, it was the same software and it looks like it's not there any more. The bike specific version was hosted there, so I think I would reach out to the author of the software and see if he can help you
Likes For unterhausen:
#5
Team Beer
Join Date: Apr 2004
Location: Sacramento CA
Posts: 6,339
Bikes: Too Many
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 114 Post(s)
Liked 159 Times
in
104 Posts
The tube miter engine in RattleCad does this for you. I've been happy with it so far.
__________________
I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC
I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC
#6
Senior Member
Join Date: Aug 2012
Location: Seattle
Posts: 507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 103 Post(s)
Liked 144 Times
in
88 Posts
Using a 38mm downtube on a standard BB shell will be tricky. For anything that isn't lugged, I use a T47 shell. The larger shell decreases overlap between tubes and if you offset toward the bottom of the shell, you can avoid it completely. Also, what headtube are you using? a standard 1-1/8" is 36-37mm which is smaller than your DT so the ears are going to require some work and delicate brazing - or you'll want to ovalize it.
__________________
https://www.flickr.com/photos/54319503@N05/
https://www.draper-cycles.com
https://www.flickr.com/photos/54319503@N05/
https://www.draper-cycles.com
Likes For duanedr:
#7
Full Member
Thread Starter
Thanks for the very specific nature of your reply. That is helpful.
#8
Full Member
Thread Starter
It is a 48mm head tube. I was concerned about the large DT and the bottom bracket. My Rove has an ovalized DT to solve that problem. I don't have an idea how I would ovalize it. I might try to find a piece of scrap to see if I can do a neat job while keeping it round.
Thanks to all for your generous sharing of knowledge,
G. Gearloose
Thanks to all for your generous sharing of knowledge,
G. Gearloose
#9
Senior Member
Join Date: Feb 2012
Location: Rochester, NY
Posts: 18,092
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4208 Post(s)
Liked 3,874 Times
in
2,314 Posts
Every frame builder should have an ovalizing tool already. The bench vise. Andy
__________________
AndrewRStewart
AndrewRStewart
Likes For Andrew R Stewart:
#10
Senior Member
Join Date: Aug 2012
Location: Seattle
Posts: 507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 103 Post(s)
Liked 144 Times
in
88 Posts
It is a 48mm head tube. I was concerned about the large DT and the bottom bracket. My Rove has an ovalized DT to solve that problem. I don't have an idea how I would ovalize it. I might try to find a piece of scrap to see if I can do a neat job while keeping it round.
Thanks to all for your generous sharing of knowledge,
G. Gearloose
Thanks to all for your generous sharing of knowledge,
G. Gearloose
__________________
https://www.flickr.com/photos/54319503@N05/
https://www.draper-cycles.com
https://www.flickr.com/photos/54319503@N05/
https://www.draper-cycles.com