Subject: Re: Welder choice for auto welding

From: [email-masked] (Eric Perozziello)
Date: Tue, 1 Feb 94 00:07:42 GMT

[email-masked] (Harry Phinney) writes:
>Eric Perozziello ([email-masked]) wrote:
>: Why would race cars used brazed frames when there are stronger 
>: methods of attachment?
>
>For one thing, at-track repairs can be made more easily (it's easier to
>ensure the availability of a torch than a TIG).  Also, the strength of
>the joint doesn't matter as long as it's stronger than the base
>material.  A well designed and brazed joint will be significantly
>stronger than the material being brazed.  Also, cost is sometimes a
>concern in racing vehicles, as not all racers have infinite budgets.

Ok, I'll buy the at-track repair part, but there's still no
reason the car can't be fabricated with, say, and Arc welder,
and then still repaired at the track with oxy-acetyline.  

I would assume that the difference in cost between torch welded
and arc welded would be minor in ANy racer's budget, and if I,
as the welder, had a choice, I'd rather arc weld it.  If I were
the driver, I'd also rather have an arc welded frame under me  :^)

Just out of curiosity, do many people out there use their 
oxy-acetyline set for anything other than brazing thin steel
or cutting?  (besides materials other than steel, and assuming
you have an arc welder).  

-Eric

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From: [email-masked] (Harry Phinney)
Date: Tue, 1 Feb 1994 19:41:21 GMT

Eric Perozziello ([email-masked]) wrote:
: I would assume that the difference in cost between torch welded
: and arc welded would be minor in ANy racer's budget, and if I,
: as the welder, had a choice, I'd rather arc weld it.  If I were
: the driver, I'd also rather have an arc welded frame under me  :^)

This depends on the material being joined, and what you mean by "arc"
welding.  If you're fabricating a frame or part out of thin-walled 4130
tubing, you're not going to grab your stick welder and go for it.  In
this case, your practical choices are brazing, oxy-acetylene welding,
and TIG welding.  Brazing is easy, TIG welding is expensive (at least
the initial investment cost), oxy-acetylene welding works well, but
(IMO) requires more skill than does brazing.  Trying to join the thin
walled tubing to a thicker plate will make the TIG and brazing look even
better compared to oxy-acetylene welding.

: Just out of curiosity, do many people out there use their 
: oxy-acetyline set for anything other than brazing thin steel
: or cutting?  (besides materials other than steel, and assuming
: you have an arc welder).

Also hot-forming, annealing, hot-shrinking sheet metal, and freeing
seized fasteners.  I must admit that I don't do much oxy-acetylene
welding anymore, mainly because the MIG is so fast.  If I'd just break
down and spend the dollars for a Miller Econo-TIG, I'd probably not do
_any_ more oxy-acetylene welding :-).

Harry Phinney   [email-masked]

---

From: [email-masked] (Paul Compton -RESCU)
Date: Wed, 2 Feb 1994 12:41:35 GMT

In article <[email-masked]> [email-masked] (Eric Perozziello) writes:

   Newsgroups: rec.crafts.metalworking
   Path: math.fu-berlin.de!zrz.TU-Berlin.DE!netmbx.de!Germany.EU.net!EU.net!howland.reston.ans.net!vixen.cso.uiuc.edu!sdd.hp.com!hplabs!unix.sri.com!headwall.Stanford.EDU!cascade.stanford.edu!everest.Stanford.EDU!eap
   From: [email-masked] (Eric Perozziello)
   Sender: [email-masked] (USENET News System)
   Organization: Center for Integrated Systems, Stanford University, California
   Date: Tue, 1 Feb 94 00:07:42 GMT
   Lines: 29

   >the driver, I'd also rather have an arc welded frame under me!

	When you weld a metal this involves melting the parent metal.
At the edge of the molten pool, as it meets solid metal you WILL get 
a crack, this is inevitable. When dealing with race car frames you
can be involved with some very thin sections, so small welds are needed
to avoid stress raisers due to section change,ie no mig, your choice
then comes down to gas weld, bronze weld, braze, or silver solder.
	I have been building various tube frames for several years and
from experience can relate the following, on a road going sportscar
I would probably build the frame from mostly 1 inch square 16 swg tube
(16 swg is 1.6mm 1/16 inch, higher numbers are thinner, sorry, dont 
have the figures) and my preference would be to mig weld the frame.
When I have to cut a frame to modify or repair it I would expect the 
cut member to spring a considerable distance out of position due to 
the stresses set up when made. For a race chassis I would use 18-20
swg and braze the frame,brazing is effectivly a high temperature
soldering technique, a professional frame builder would bronze
weld, as the name implies bronze WELDING melts the parent metal but 
unlike a conventional weld fills its own cracks and provides a smooth
finnish reducing stress-raisers.
	Braze material is stronger than steel but will not stand 
bendin loads or 'peel'. A badly designed 'space' frame is best welded
out of relativly thick section tube in order to accept the bending
loads imposed, a correctly designed frame resolves all loads into 
tension and compression and is immensly strong. A 1960 Lotus formula
 One frame (bare) weighs approx 70 pounds and uses nothing heavier
than 18 swg.

--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Paul Compton                                    Rothamsted Experimental Station
                                                  Harpenden, Herts. AL5 2JQ. UK
e                         Harpenden, Herts. AL5 2JQ. UK
e-mail: [email-masked]                         +44 (0)582 763133 x2413
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

---

From: [email-masked] (Harry Phinney)
Date: Wed, 2 Feb 1994 19:09:53 GMT

Paul Compton -RESCU ([email-masked]) wrote:

: 	When you weld a metal this involves melting the parent metal.

This is true.

: At the edge of the molten pool, as it meets solid metal you WILL get 
: a crack, this is inevitable.

I strongly disagree.  Countless welds are made each day with no edge
cracks.  Cracks are not allowed in any sort of certified welding process
which I am aware of.

: When dealing with race car frames you
: can be involved with some very thin sections, so small welds are needed
: to avoid stress raisers due to section change,ie no mig, your choice
: then comes down to gas weld, bronze weld, braze, or silver solder.

Or TIG welding.

: ...,brazing is effectivly a high temperature
: soldering technique,

Agreed.

: a professional frame builder would bronze
: weld, as the name implies bronze WELDING melts the parent metal but 
: unlike a conventional weld fills its own cracks and provides a smooth
: finnish reducing stress-raisers.

I have only heard, read, and used the phrase "braze welding" to describe
the filling of "V" joints or creating substantial fillets at joints
using normal brazing temperatures.  I have never seen or heard it to
imply melting of the base metal.  If the base steel is overheated to the
point of allowing significant brass inclusion into the grain structure
of the steel (let alone melting of the steel), the material properties
of the steel at the joint will suffer.

---

From: [email-masked] (f.w.kerfoot..iii)
Date: Wed, 2 Feb 1994 22:53:51 GMT

>From article <[email-masked]>, by [email-masked] (Harry Phinney):

I owned a tube-frame Lotus 23 in the early 1970's, and did significant
repair and redesign on the frame. I spent a fair time assuring that I
understood and could duplicate the joining technology used in the
original manufacture. The process was called "nickel-bronze welding",
or sometimes simply "bronze welding" or "braze welding". The process,
as the mname implies, uses a special high nickel content filler rod,
and uses relatively large fillets, created at temperatures relatively
low compared to traditional brazing temperatures, let alone welding
temperatures. The wisdom at the time from experts using the same
technique in manufacturing formula ford chassis in the US, was that
exceeding a relatively low brazing temp. creates a low strength weld.

Frank Kerfoot
[email-masked]

---

From: [email-masked] (RICHARD ALLAN JOHNSON)
Date: Thu, 3 Feb 1994 18:04:29 GMT

In article <[email-masked]> [email-masked] (Harry Phinney) writes:
>From: [email-masked] (Harry Phinney)
>Subject: Re: Welder choice for auto welding
>Date: 2 Feb 94 19:09:53 GMT
	The mandid not say how big the cracks will be, but he is correct in 
saying that there will be cracks.  Go to your local college and take a class 
in materials.  You will learn that ANY working be it forming, casting, 
forging, or welding will cause cracks.  They may be very small but they are 
there.

	Rick

---

From: [email-masked] (Ole-Hjalmar Kristensen TF.DT/DELAB)
Date: Fri, 4 Feb 94 07:32:53 GMT

In article <[email-masked]>, [email-masked] (Paul Compton -RESCU) writes:
|> 
|> In article <[email-masked]> [email-masked] (Eric Perozziello) writes:
|> 
|>    Newsgroups: rec.crafts.metalworking
|>    Path: math.fu-berlin.de!zrz.TU-Berlin.DE!netmbx.de!Germany.EU.net!EU.net!howland.reston.ans.net!vixen.cso.uiuc.edu!sdd.hp.com!hplabs!unix.sri.com!headwall.Stanford.EDU!cascade.stanford.edu!everest.Stanford.EDU!eap
|>    From: [email-masked] (Eric Perozziello)
|>    Sender: [email-masked] (USENET News System)
|>    Organization: Center for Integrated Systems, Stanford University, California
|>    Date: Tue, 1 Feb 94 00:07:42 GMT
|>    Lines: 29
|> 
|>     [email-masked] (Harry Phinney) writes:
|>   >Eric Perozziello ([email-masked]) wrote:
|>   >: Why would race cars used brazed frames when there are stronger 
|>   >: methods of attachment?
|>   
|>    >For one thing, at-track repairs can be made more easily (it's easier to
|>    >ensure the availability of a torch than a TIG).  Also, the strength of
|>    >the joint doesn't matter as long as it's stronger than the base
|>    >material.  A well designed and brazed joint will be significantly
|>    >stronger than the material being brazed.  Also, cost is sometimes a
|>    >concern in racing vehicles, as not all racers have infinite budgets.
|> 
|>    >Ok, I'll buy the at-track repair part, but there's still no
|>    >reason the car can't be fabricated with, say, and Arc welder,
|>    >and then still repaired at the track with oxy-acetyline.  
|> 
|>    >I would assume that the difference in cost between torch welded
|>    >and arc welded would be minor in ANy racer's budget, and if I,
|>    >as the welder, had a choice, I'd rather arc weld it.  If I were
|>    >the driver, I'd also rather have an arc welded frame under me!
|> 
|> 	When you weld a metal this involves melting the parent metal.
|> At the edge of the molten pool, as it meets solid metal you WILL get 
|> a crack, this is inevitable. When dealing with race car frames you

You will change the properties of the material for sure, but there is no reason
you should get a crack. If you get cracks, you are either using the wrong
equipment, technique or both.

|> can be involved with some very thin sections, so small welds are needed
|> to avoid stress raisers due to section change,ie no mig, your choice
|> then comes down to gas weld, bronze weld, braze, or silver solder.
|> 	I have been building various tube frames for several years and
|> from experience can relate the following, on a road going sportscar
|> I would probably build the frame from mostly 1 inch square 16 swg tube
|> (16 swg is 1.6mm 1/16 inch, higher numbers are thinner, sorry, dont 
|> have the figures) and my preference would be to mig weld the frame.
|> When I have to cut a frame to modify or repair it I would expect the 
|> cut member to spring a considerable distance out of position due to 
|> the stresses set up when made. For a race chassis I would use 18-20
|> swg and braze the frame,brazing is effectivly a high temperature
|> soldering technique, a professional frame builder would bronze
|> weld, as the name implies bronze WELDING melts the parent metal but 
|> unlike a conventional weld fills its own cracks and provides a smooth
|> finnish reducing stress-raisers.

This is also wrong. Bronze welding is also a form of brazing, and you are NOT
melting the parent metal, at least not when working with steel. But as you say,
bronze weldings does allow you to fill cracks better than brazing.

|> 	Braze material is stronger than steel but will not stand 
|> bendin loads or 'peel'. A badly designed 'space' frame is best welded
|> out of relativly thick section tube in order to accept the bending
|> loads imposed, a correctly designed frame resolves all loads into 
|> tension and compression and is immensly strong. A 1960 Lotus formula
|>  One frame (bare) weighs approx 70 pounds and uses nothing heavier
|> than 18 swg.
|> 
|> 
|> 
|> 
|> --
|> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
|> Paul Compton                                    Rothamsted Experimental Station
|>                                                   Harpenden, Herts. AL5 2JQ. UK
|> e                         Harpenden, Herts. AL5 2JQ. UK
|> e-mail: [email-masked]                         +44 (0)582 763133 x2413
|> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

---

From: [email-masked] (Harry Phinney)
Date: Fri, 4 Feb 1994 23:58:43 GMT

RICHARD ALLAN JOHNSON ([email-masked]) wrote:
: In article <[email-masked]> [email-masked] (Harry Phinney) writes:
: >I strongly disagree.  Countless welds are made each day with no edge
: >cracks.  Cracks are not allowed in any sort of certified welding process
: >which I am aware of.
: >
: 	The mandid not say how big the cracks will be, but he is correct in 
: saying that there will be cracks.  Go to your local college and take a class 
: in materials.

Thanks for the advice, but I happen to have been there already.  I hold
a BS in mechanical engineering and my study emphasis was in materials
science and physical metallurgy.  I worked through a senior sequence in
general materials science, plus another in physical metallurgy, and in
the process earned a student award from the ASTM.

: You will learn that ANY working be it forming, casting, 
: forging, or welding will cause cracks.  They may be very small but they are 
: there.

This is simply not true unless you try to count dislocations and/or
grain boundaries as "cracks", which would lead to you declaring cracks
in any and all polycrystalline metallic materials, regardless of the
working history.  This would be a fairly useless definition of the work
"crack".