Terrapin_racing
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| posted on 16/2/04 at 10:52 AM |
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Alternative to welding - for those who want a choice
Bronze welding is extremely easy to do. Far easier than MIG/TIG etc. This is not an inferior alternative. Indeed in a lot of respects bronze welding
is far more superior in terms of strength and fatigue resistance. Used by Lotus, March, Williams etc. You must use a 9% nickel bronze rod (sifbronze
number 2). The method is then just like brazing - but you build up a fillet around the joint. Use a good flux- sifbronze again. If anyone wants
further details lease let me know.
The process is fully described in HSLC book.
cheers
Rob
http://7faq.com/owbase/ow.asp?NotesOnWelding
[Edited on 16/2/04 by Terrapin_racing]
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David Jenkins
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| posted on 16/2/04 at 12:26 PM |
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This was debated here quite a while ago - the MIG enthusiasts weren't convinced!
There is a 750 Club book that describes how that club formed. Part of that book discusses the use of brazing and the techniques used - quite
different from welding. Not hard, just different.
The most interesting part is the intro, where one author describes a crash that the other author suffered: 100mph to 0 in about 6ft! He wasn't
in very good condition, as you can imagine (he had a series of heart attacks from the impact against the harness) but he survived with few other
physical injuries. This was in a brazed chassis, very similar to the Terrapin in fact.
David
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Terrapin_racing
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| posted on 16/2/04 at 12:59 PM |
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As an engineer with direct contact to industrial certified welding inspectors I chose bronze welding for it's toughness & resistance to
cracking (MIG's form a very hard join!) - If you talk to the experts it is recognised that the parent metal will fail before the BW joint.
Incidentally, Allan Staniforth had a 80MPH crash at New Brighton Sprint (NW UK) and is still racing today. If anyone has seen the New Brighton sea
wall you'll understand !!
 
Rescued attachment NB.gif
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Alan B
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| posted on 17/2/04 at 01:57 PM |
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Terrapin, while I would agree that bronze welding is not too difficult, certainly easier than TIG or gas welding.......I would have to disagree it was
easier than MIG IMO
Neither would I ever claim bronze welding to be inferior (not that you are saying I'm saying that).....IMO, it is more difficult (somwhat) than
MIG, and many orders of magnitude slower....also it does demand better joint fit-up (OK, good joint fit-up is desirable.. )
Just my opinions to keep the thread alive...
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Terrapin_racing
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| posted on 17/2/04 at 03:30 PM |
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Well, i suppose the only answer is "if you can't do it yourself" employ someone who can!
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Alan B
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| posted on 17/2/04 at 03:37 PM |
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Not sure what you mean exactly, but I can bronze weld....just would not choose to build a a full car frame that way that's all...also, employing
someone to weld your frame is very impractical.......you may as well just buy one....
Although in our cases that is not option either as neither of us are doing a "book" build.
I have said this before, but I found High Speed low cost more inspirational than the "book"
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Terrapin_racing
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| posted on 17/2/04 at 03:42 PM |
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Alan, apologies. It's not directed at you. Just a general comment to all those who want an alternative to welding because they are having
difficulty mastering it.
Maybe I should say " If you can't do it yourself - then employ someone or buy it ready built"?
Or maybe - ask a mate
cheers
Rob
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Alan B
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| posted on 17/2/04 at 03:54 PM |
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No problem.
I like bronze welding and agree it is certainly no way inferior to other processes....bringing it back to everyone's attention is good for our
combined knowledge pool.....I just got used to the ease and speed of MIG I guess....
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Terrapin_racing
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| posted on 17/2/04 at 04:06 PM |
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I use my MIG all the time, but bronze welded the chassis because it will take the stresses imparted in a lightweight space frame (I lifted it up
single handed to put on the car roof to take to powdercoaters) chassis. Allan never experienced a joint failure - well if you read the book it says
some where that he spent many hours watching the joints during his early days, he is now very complacent and accepts that they're fine.
My other car is entirely MIG welded!
I think it's in the background of some of my photos - The 1st crossflow engine (trophy winning) Midge - anyone remember them (and the Locust - a
colleague built one at the same time)
I built it in the eighties and it's still concours! I remember ringing John Cowperthwaite (Moss cars, Monaco etc.)
about the errors on the Ford version plans and getting the response - "Oh - trial and error, your the first to build one"!
You guy's know the story!
[Edited on 17/2/04 by Terrapin_racing]
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Alan B
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| posted on 17/2/04 at 04:15 PM |
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I would certainly agree that BW scores higher the thinner you get.....burning through tubes is not an issue (within reason)
I'd say MIG starts to score when you hit 16g and thicker....
But we agree that both are perfectly acceptable processes for our tasks....
IIRC the Terrapin does use a lot of of lightweight 18g, 20g tubing?
Are you sticking with the mini power plant?...or using something more modern?
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Terrapin_racing
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| posted on 17/2/04 at 04:40 PM |
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Yes, the Terrapin uses a lot of 16g CDS round and 16g ERW tubing. I'm building to the original design using Mini powerplant (well Metro 1275MG
A+ series engine + box with twin pin differential - to replace the standard diff which is the g/box week point)
A lot of Terrapins subsequently used Alfa, Rover V8? and then bike engines in the rear.
Cheers
Rob
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Alan B
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| posted on 17/2/04 at 05:20 PM |
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Rob,
Many years ago I was a member of Longton and district MC.....Keith Gowers was a member as was John Aldred (I think) both early
"terrapinners".....do you know either?
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sgraber
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| posted on 17/2/04 at 07:24 PM |
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<cheerful banter mode>
Now don't chastise me for this question, but we are in Low Cost mode here. (I can imagine being told - "If you are building a car to the
safest standards then cost is not an object..." Well sorry it is and I am currently Mig'ing along quite blissfully. with a little cheapo
Mig welder.
</cheerful banter mode>
Excuse my ignorance (rookie builder mode). What is the expense of brazing vs mig welding? Averaged out over a typical frame say?
What would the average equipment cost and what are the material startup costs?
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Alan B
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| posted on 17/2/04 at 08:23 PM |
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Steve, a trip to Home depot and you could be bronze welding for 50 bucks..
A realistic decent setup maybe 300 dollars...
I believe there is certain stigma from both angles in this debate....
Traditionalists (Lotus, arch motors fans etc) say brazing/BW is the best and new- fangled MIG is cheap, corner cutting and inferior.....
MIG fans say that BW is outdated and new technology must be better...
Ok, I've exaggerated both viewpoints....but, IMO and sure Terrapin will agree is that both are good methods equally satisfactory when done
properly....
Just because BW is long established and used by Caterham doesn't make it superior any more than TVR using MIG makes it superior....
I think it has a lot more to do tube thickness and speed than anything.
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sgraber
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| posted on 17/2/04 at 08:34 PM |
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but it looks so purdy!
Actually, I AM very interested in Bronze Welding and would like to at least try it sometime.
Question, Bronze welding doesn't inherently make for a lighter structure right?
However, the decreased chassis weight comes simply from the ability to use a thinner gauge tube because you aren't heat stressing (making
brittle) the metal as much?
Sorry for the newbie style questions. :p You now realize that I have only ever MIG welded. (I am reading up on it now. Thanks for the link Rob.)
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Alan B
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| posted on 17/2/04 at 08:51 PM |
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Steve,
Yes decreased weight comes from the lighter tubing, but more because of better design taking bending loads out of tubes allowing thinner wall
thickness....which in turn make BW more desirable.....
So I wouldn't say BW was inherently lighter just a better process for really thin tubes...which make up lighter frames..
Another factor (which Rob will correct me on if things have changed) is that BW clean up is nasty....lots hard glassy flux deposits to
remove....sandblasting would be good I'd have thought...
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Terrapin_racing
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| posted on 18/2/04 at 09:56 AM |
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Well - Here I go....
To start bronze welding you need access to oxygen/acetylene gear. I have the middle range size bottle and rental is about £80 per annum in UK
(excluding refill costs). The Sifbronze number 2 rods are about £30 for a 1kg box (hell of a lot of joints!) and the flux is about £8 for a large
tub.
Bronze welding is a very similar practice to brazing but this type of rod allows you to build up a nice fillet around the joint. As Alan mentioned
this allows you to use far lighter guage tubing and sheet. My chassis is primarily 16g with areas of 20g & 22g sheet and tube also.
Flux clean up is an issue. You need lots of 'elbow grease' hot water and a wire brush - or if you are not in a rush (and you live in UK!)
you will find the glass like flux residue will turn to powder and fall away if left in a damp atmosphere for a few weeks. My chassis was then blast
cleaned and powder coated at a reasonable cost (£140). If cost in not an issue you can purchase a gas fluxer for about £300 - this is a device
installed in the acetylene line which used liquid flux (turns flame green) and leaves no residue.
A lot of the racing car manufacturers use these. Other points of really value - I have had bushes made from high tensile heat treatable steels EN24
etc (suspension lower ball joint tapers etc.) - you should not weld to these unless you have the facility to heat treat afterwards - the joints will
be very brittle. Using Bronze welding for this is ideal as the effects are negligible if the joints are allowed to cool naturally (don't
quench!).
On the issue of cost - someone said my car looks like it was all new bits so how could it be "High speed,low cost" - and how much did I
spend?
Well, I gave a lengthy answer - but really - it is a case of how much do you want to spend? - I think you will all agree - you get what you pay for. A
very acceptable car can be built on a budget but might not win any concours prizes. I did mention that you should never skimp on brakes, steering etc.
Safety first guys - I once read an article where someone used second hand brake shoes from a breaker and cleaned them off with paint spirit prior to
fitting - then wanted to know why the linings had broken away from the shoes (bonded, not riveted) - crazy!!! - fortunately he was lucky, the linings
fouled up inside the drums and locked the wheels when they failed and nobody was hurt.
cheers
Rob
[Edited on 18/2/04 by Terrapin_racing]
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dmottaway
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| posted on 19/2/04 at 05:22 AM |
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Sifbronze?
anybody have an American equivalent to Sifbronze?
dave
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Terrapin_racing
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| posted on 19/2/04 at 09:22 AM |
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Here's the spec to ask for -
SIFBRONZE No. 2 (9% Ni)
BS: 1845 CZ8, 1453 C5
Nearest Equivalent Standards: DIN L-Ns, AWS RBCuZn-D
A high quality, free flowing rod containing 9% nickel which produces an exceptionally strong joint on cast iron, copper alloys, stainless and alloy
steels. It has excellent wearing properties and is recommended for building worn components like gear teeth, bearings and valve seats, since it work
hardens. The high strength characteristics make Sifbronze No.2 ideal for tubular structures, brazing cutting tips and as a general maintenance alloy.
Use Sibronze or special purpose flux.
Melting point - 920-980 C
Tensile stength (N/mm2) 540
Hardness (BHN) 200
Typical composition:
48 Cu
10 Ni
0.3 Si
Balance Zn
 
Rescued attachment sif.jpg
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David Jenkins
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| posted on 19/2/04 at 09:55 AM |
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I tried this with my basic TIG - it's bl**dy difficult!
Mind you, I was trying to braze a couple of bits of copper, and it was taking all the heat away from the joint area. I probably should have
pre-heated the metal with propane before I started. Model steam engine boilers are often TIG'd, but they take the whole thing up to near
red-hot before starting to braze (I'm talking about 30 - 50 lbs of copper here!)
David
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Terrapin_racing
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| posted on 19/2/04 at 10:04 AM |
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Yes, seen TIG used for this but.... Dave hit the nail on the head!
Problem is bringing the surrounding material up to temp so heat isn't drawn away. OK on small stuff.
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David Jenkins
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| posted on 19/2/04 at 10:50 AM |
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Also much easier on mild steel, which is a poor conductor of heat when compared to copper or brass - the heat stays near the joint long enough to
allow the braze to flow.
David
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stutz
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| posted on 19/2/04 at 09:49 PM |
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Stainless Steel
Probably a silly question, but does anyone know if you can bronze weld stainless steel?
[Edited on 19/2/04 by stutz]
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britishtrident
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| posted on 13/3/04 at 07:59 AM |
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The arguments are finely balanced -- bronze welding has much in its favour -- the only major downside is the jig arangments need to be better to
avoid building a twisted chassis.
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Terrapin_racing
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| posted on 15/3/04 at 09:44 AM |
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Stainless Steel - Yes!
SIFBRONZE No. 2 (9% Ni)
BS: 1845 CZ8, 1453 C5
Nearest Equivalent Standards: DIN L-Ns, AWS RBCuZn-D
A high quality, free flowing rod containing 9% nickel which produces an exceptionally strong joint on cast iron, copper alloys, stainless and alloy
steels. It has excellent wearing properties and is recommended for building worn components like gear teeth, bearings and valve seats, since it work
hardens. The high strength characteristics make Sifbronze No.2 ideal for tubular structures, brazing cutting tips and as a general maintenance alloy.
Use Sibronze or special purpose flux.
To prevent any distortion the practice is to tack the chassis together and then bronze weld diametrically opposite joints
.The process is well decribed in Allan's book - HSLC
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