Retrobike Forum Index

It is currently Sun Dec 11, 2016 3:44 am

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 28 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject:
PostPosted: Fri Mar 09, 2012 12:17 pm 
Dirt Disciple

Joined: Mon Apr 05, 2010 5:24 pm
Posts: 39
what kind of scale of operation is silver brazing with say one of those OxyTurbo kits?

i.e. could i do it in a reasonably large flat kitchen with a vice on the table, or does it require more of a workshop environment?


Top
 Profile  
 
 Post subject:
PostPosted: Fri Mar 09, 2012 6:41 pm 
rBoTM Winner
rBoTM Winner

Joined: Sat Aug 28, 2010 3:44 pm
Posts: 422
Location: at my computer
jeffcapeshop wrote:
what kind of scale of operation is silver brazing with say one of those OxyTurbo kits?

i.e. could i do it in a reasonably large flat kitchen with a vice on the table, or does it require more of a workshop environment?


To heat up the tubes sufficiently to get the silver to flow, while not as hot as is needed for brass, you do need quite a high temperature and I most certainly wouldn't want to do it in my kitchen. The vise must also be firmly affixed which is another thing that I wouldn't want to subject my kitchen table to.

For the rest, you could indeed get by with what you are describing. Let me only say that the simple fact that you are asking such a question makes me think that you need to think teh matter over a bit more before you go ahead...


Top
 Profile  
 
 Post subject:
PostPosted: Fri Mar 09, 2012 6:53 pm 
Dirt Disciple

Joined: Mon Apr 05, 2010 5:24 pm
Posts: 39
Quote:
Let me only say that the simple fact that you are asking such a question makes me think that you need to think teh matter over a bit more before you go ahead...


haha - quite! let me assure you that this is very much an exploratory query. Just surprised to see the videos above of someone seemingly doing it in his garden with very little equipment (or measurements..)
Thinking about it further i might have access to somewhere slightly more appropriate/better equipped but again, i'm not going to jump into waving torches and molten metal around lightly.


Top
 Profile  
 
 Post subject:
PostPosted: Fri Mar 09, 2012 8:15 pm 
Retro Guru
User avatar

Joined: Tue Aug 24, 2010 8:39 pm
Posts: 258
Location: Brighton, UK
I'm always thinking about this at work. If you look at the week long courses Dave Yates does, the total cost is only a little more than getting him to build the frame for you! If I was after a custom frame, that's definitely what I'd do.

It's kind of my dream retirement plan to build frames in my own little workshop, but I think I might have a little competition locally. Mercian are about 10 minutes up the road. :?


Top
 Profile  
 
 Post subject:
PostPosted: Fri Mar 09, 2012 9:26 pm 
Gold Trader
Gold Trader
User avatar

Joined: Fri Aug 20, 2010 11:28 am
Posts: 5652
Location: Gorleston-on-sea (If there is a bright center to the universe this is place furthest from it
I remember years ago watching a programme on the T.V. They had Jack Taylor ( I think :oops: ) on there and his frame jig was a sheet of plywood with nails hammered in, between which he placed the tubes and then brazed them looked totally archaic but worked beautifully (for him).


Top
 Profile  
 
PostPosted: Sat Mar 10, 2012 12:52 pm 
Dirt Disciple

Joined: Sat Mar 10, 2012 12:43 am
Posts: 13
Location: Settle N.Yorks
For my sins I have to admit that I have built quite a lot of frames, having started way back in about 1953...but it wasn't until about 1958 that I was allowed to wield the torch as well as a file and hacksaw.

In those days the principle source of heat was a torch burning coal-gas ( the same stuff you cooked your meals on) enhanced by compressed air. The flame was a very large soft quite hot one that had the advantage of wrapping around the lugged joints, thereby providing a thorough heat that emcouraged the brazing spelter to flow through all the joint.

However the heating up process took longer but there was hardly any danger of overheating the tubes. Cast lugs were often used in those days and these were thicker and heavier - meaning that they took longer to heat up than the tubes..and the later pressed steel ones. This is one of the reasons that the lugs on older frames were often filed and thinned down..both to provide a better cosmetic look but also to reduce heating times.

Then along came oxy-acetylene, and oxy-propane..but that's a different story. If you know how to gas=weld and braze with oxy-acetylene that's fine..it's quicker, very effective and essential for anyone thinking of bronze-welded ie lugless frames.

However misuse of this heating soource can ruin a frame in seconds...My advice to anyone thinking of starting to build a frame is to take some lessons in brazing..It is simply esential to know how to use the torch. Once you are proficient then you have a reasonable chance of building a decent frame. Remember that even with the best jigs, the brazing/heating process can create stresses and distortion that you would not expect..the town-gas-compressed air method minimised this problem.

Use a brazing rod such as SIF-Bronze that flows around 850degrees. as for silver soldering..OK excellent stuff, flows about 200 degrees lower temperature....but is SO expensive..and needs great care not to be overheated. Too much heat and you burn the joint, and waste a lot of money spent on the solder..and possibly the steel tubes. Silver-solder is not gap-filling ie the gaps between the tubes and the lugs have to be very close..closer than with SIF-Bronze..and they have to be exceptionally clean..and you have to have the correct flux, a slightly higher temperature one than you would use on non-ferrous metals such as brass, copper, silver..

Oxy-propane is a good choice for the job..not quite as hot..and the gases are cheaper and more readily available..but it takes more time to heat the joints..and its quite clean. Most builders use oxy-acetylene because they know what they are doing..it's quick..and because Once Upon a Time when they bought the welding kit, the gases were cheap as was the rental for the cylinders...But these days..well you've heard what inflation can do!

As has been noted by others..you do not necessarily need a jig..but you do need to know how to test for alignment at various stages in the build process. If you get the first joint wrong - which is usually the seat-tube into the bracket shell..then everything else that follws will be wrong too..and out of alignment.

Otherwise it's great way of passing your time down in the garden shed. Do NOT braze or weld in your house as there are certain gases that are given off that can be dangerous. Always weld/braze in a well-ventilated room..but avoid draughts...


Top
 Profile  
 
 Post subject:
PostPosted: Sat Mar 10, 2012 1:40 pm 
rBoTM Winner
rBoTM Winner

Joined: Sat Aug 28, 2010 3:44 pm
Posts: 422
Location: at my computer
Perhaps a request put out to Norris (Bespoke) could convince him to teach you how to build a frame. With his patience and experience, I couldn't imagine a better teacher.


Top
 Profile  
 
 Post subject:
PostPosted: Sat Mar 10, 2012 6:25 pm 
rider | rBoTM Winner
rider | rBoTM Winner
User avatar

Joined: Fri Jan 25, 2008 1:42 pm
Posts: 5133
Location: Wakefield, Yorkshire
Welcome to the forum Norris!

I thought it must have been you with a name like that. :wink:


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 28 posts ]  Go to page Previous  1, 2, 3

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group