Go Back  Bike Forums > Bike Forums > Framebuilders
Reload this Page >

First Frame Build Questions

Notices
Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

First Frame Build Questions

Old 07-31-19, 01:38 PM
  #1  
imakecircles
Senior Member
Thread Starter
 
imakecircles's Avatar
 
Join Date: Mar 2019
Location: Seattle, WA, USA
Posts: 57

Bikes: 1982 Bianchi Nuovo Racing, 2012 Cervelo RS Rival, 20xx Redline Conquest (Commuter/Rain Bike)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Liked 8 Times in 7 Posts
First Frame Build Questions

I've always wanted to build myself a custom lugged steel bike frame. The idea is to build a classic steel road frame with lively 74 degree angles like the steel racers I rode as a kid.

I found a Columbus SL Tubeset and matching lugs from Nova, and once received, cut each tube to length (size 58.5 c-c) using a tube angle jig that worked with a 1/2" drill motor and a hole saw arbor that a buddy loaned me.

I built a frame jig primarily from 80/20 extrusion, with some machined and threaded cones to center the bottom bracket, head tube, and seat tube, as well as an extension using an old rear axle for centering and aligning the rear dropouts.

I'm getting close to being ready to assemble the frame with flux in the joints and clamp it into the jig to begin brazing, but I have a question about the joints at the seattube to toptube, toptube to headtube, and headtube to downtube. I have read that since the toptube is captured at both ends, failing to drill a hole in at least one of the tubes (head and seat) behind the lug will cause air to be trapped which will heat and try to expand without the hole to let the hot air escape.

My question (finally!) is would it be ok to drill out each of the three joints to lighten the frame, which I'd like to do as this is a dream build for me, or would this affect the structural integrity or stiffness of the build?

imakecircles is offline  
Old 07-31-19, 01:49 PM
  #2  
dsaul
Senior Member
 
Join Date: Jan 2013
Posts: 1,207
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 308 Post(s)
Liked 76 Times in 59 Posts
Vent holes.
Attached Images
File Type: jpg
IMG_20181102_104000.jpg (1.08 MB, 73 views)
dsaul is offline  
Old 07-31-19, 05:33 PM
  #3  
Nessism
Senior Member
 
Nessism's Avatar
 
Join Date: Jun 2004
Location: Torrance, CA
Posts: 2,780

Bikes: Homebuilt steel

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 164 Post(s)
Liked 25 Times in 21 Posts
I like to drill large vent holes partly because it allows water to flow inside to wash the flux. It's also nice to drain out excessive rust preventive spray applied after completion.
Nessism is offline  
Old 07-31-19, 05:48 PM
  #4  
TiHabanero
Senior Member
 
Join Date: Nov 2012
Posts: 2,688
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 870 Post(s)
Liked 132 Times in 89 Posts
This spring I brazed up the main tubes for a touring frame and decided not to vent the top tube joints. Not a problem. Did not experience any blow outs from heat. Of course I am unable to get in the top tube to flush it, but that will be another chapter in this story at some other time.

In a previous frame I used 3/4 hole at the head tube to vent with. The seat stays were not vented either. Does not seem to affect anything from were I sit. Long term corrosion may be an issue, but I doubt it.
TiHabanero is offline  
Old 07-31-19, 06:16 PM
  #5  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 18,725
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 94 Times in 80 Posts
I have heard people say they had breakage on frames with vent holes bigger than 3/8", but there are plenty of counterexamples. I have always drilled 1/4" vent holes, but went larger on this most recent frame.

I think you should go with 3/8" and not worry about a little weight. It's negligible. Hopefully your dreams will get bigger after this frame.
unterhausen is offline  
Old 07-31-19, 07:29 PM
  #6  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 12,195

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1940 Post(s)
Liked 132 Times in 100 Posts
I've made vent hole from tiny 1/8" ones to hugs 1/2". Can't say the diameter made any difference in how the frame turned out. It is nice to be able to drain/shake stuff out so I currently drill about 1/4" holes.

I learned to vent every tube, to not get cute with vent locations and follow my painter's preferences as to tube ID access questions. Andy
__________________
AndrewRStewart
Andrew R Stewart is online now  
Old 08-01-19, 02:59 PM
  #7  
imakecircles
Senior Member
Thread Starter
 
imakecircles's Avatar
 
Join Date: Mar 2019
Location: Seattle, WA, USA
Posts: 57

Bikes: 1982 Bianchi Nuovo Racing, 2012 Cervelo RS Rival, 20xx Redline Conquest (Commuter/Rain Bike)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Liked 8 Times in 7 Posts
Wow, thanks all for the informative responses! Sounds like the general consensus is that drilling larger holes won't affect the frame's riding character noticably and will aid in the ability to vent moisture and apply steel treatments to the inside of the frame.

Andy, you mentioned your painter's preferences. Are there implications for painting that I haven't considered?
imakecircles is offline  
Old 08-01-19, 07:41 PM
  #8  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 12,195

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1940 Post(s)
Liked 132 Times in 100 Posts
Maybe. Your cover will sell your book. People look at the paint job as the first (and often the last) aspect in determining the grade of your work. So if you want your work to be highly thpught of you need a nice paint job. For that you need a painter who wants to do a good job. For that you want a painter who isn't finding reasons to not work on your job.

I have had about 13 different painters over the years (including myself early on) and learned that making their job easier made my bikes look better. So when you have "hidden" vent hole locations, when sand or stripper chemicals are trapped in tubes and that perfect combo of time/heat/air pressure/position hasn't been found then the paint starts the hidden **** finds it's way out and onto the wet paint Don't assume that a list of the vent locations are going to be followed 2 months later when the painter is applying that last coat of clear. Or when a dip tank fluid can't drain and keeps dribbling out of a tube's single vent over time.

Either a tube should be completely sealed off or have two vent holes. Andy
__________________
AndrewRStewart
Andrew R Stewart is online now  
Old 08-02-19, 01:46 PM
  #9  
imakecircles
Senior Member
Thread Starter
 
imakecircles's Avatar
 
Join Date: Mar 2019
Location: Seattle, WA, USA
Posts: 57

Bikes: 1982 Bianchi Nuovo Racing, 2012 Cervelo RS Rival, 20xx Redline Conquest (Commuter/Rain Bike)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Liked 8 Times in 7 Posts
OK, thanks for the great advice! I had definitely not looked that far ahead.
imakecircles is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jayd2
Framebuilders
9
10-13-14 10:06 PM
dedhed
Framebuilders
6
09-15-13 05:44 PM
Contour
Framebuilders
8
06-25-12 06:16 PM
RoboMonkey
Framebuilders
13
10-31-11 03:46 PM
unterhausen
Framebuilders
13
08-07-10 07:47 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.