[TheForge] Brazing (was: Chip Bed Forge)
Bruce Freeman
FREEMAB at pt.fdah.com
Tue Feb 21 08:41:32 EST 2006
Brazing is much less a mystery (to ME anyway) than welding.
But to understand how it's possible to fill a 3/8" gap (that sounds pretty big!) you have to understand the melt diagram of brazing material.
Now, there's NO WAY I can draw one of these in ASCII art, so here's a link to a pretty basic one:
http://www.doitpoms.ac.uk/tlplib/phase-diagrams/images/diagram1.gif
In this diagram, the composition of a mixture of metals is represented by the horizontal axis. For example, metal A might be lead and metal B tin, or metal A might be tin and metal B copper.
Here's how to read the chart:
1) The Greek letter alpha stands for a solid that is mostly metal A.
2) Likewise, beta is a solid that is mostly B.
3) L is any liquid phase - a mixture of molten A and B (except on the extreme left or right of the chart).
4) The melting point (= freezing point) of metal A is the point on the left vertical axis where the two blue lines converge.
5) The melting point of metal B is the point on the right vertical axis where the two blue lines converge.
6) The horizontal blue line in the middle of the graph represents a temperature below which the metal is ALL solid.
7) The region to the left with the alpha symbol is region consisting of a pure crystalline (solid) material that is mostly metal A.
8) The region to the right with the beta symbol is region consisting of a pure crystalline material that is mostly metal B.
9) The region below the horizontal blue line is region consisting of mixed crystals of alpha and beta.
10) The "triangular" region labeled "alpha and L" conisists of SOLID alpha crystals and a liquid consisting of metals A and B.
11) The "triangular" region labeled "beta and L" conisists of SOLID beta crystals and a liquid consisting of metals A and B.
12) Obviously, the top region of the chart represents a region where all the material is liquid.
13) The point on the horizontal blue line at which the two angled blue lines touch it is called the "eutectic point" and represents the melting point of the lowest-melting composition of A and B. (By melting point is meant when the whole gamish melts, not just some of it.)
The important points are these:
1) With a pure metal or a eutectic mixture, when you slowly heat the metal up it remains solid until it all melts at one temperature. (I don't mean it all melts at one TIME. It takes time to add enough heat to melt all the metal, but the temperature of the metal doesn't change during that time. If anyone's interested, I'll tell you how to prove that to yourself.)
2) With a non-eutectic mixture (center area, not including the alpha and beta regions at the sides), when you slowly heat the metal up, it remanis solid till the temperature reaches that represented by the horizontal blue line. At that point, SOME of the material begins to melt, and melting continues WITH INCREASING TEMPERATURE until the upper blue line is reached, by which point all the metal is melted.
>From a practical standpoint, this means that it is difficult to braze with a pure metal simply because it melts at a "high" temperature.
Likewise it is easy to braze with a eutectic mixture because it melts at a "low" temperature.
Either of the above will flow readily and fill tiny gaps by capillary action. However they will not easily form a strain-relieving fillet.
By using a non-eutectic brazing material, melting BEGINS at a low temperature, initiating the braze. But at this low temperature, there is solid present in the liquid. This solid is what allows the use of the brazing material to fill gaps.
Hope this helps.
Bruce
NJ
>>> michael.a.porter at comcast.net 2/20/2006 10:44:22 PM >>>
Rich,
I believe anyone can do that, given practice with the correct materials &
tooling. One of my favorite inappropriate expressions is "good hand/eye
coordination," which like "team player" is so frequently used to turn the
truth inside out, and sell a lie. Good hand/eye preparation is more likely
to be the heart of the matter, ninety-nine times out of a hundred. My bet
is, the filler rod--not the operator--was king that day. Not that practice
doesn't make perfect, but practice with the right technique brings
perfection much faster.
Mike P.
----- Original Message -----
From: "Rich Maynard" <rich at maynard.org.uk>
To: "'Sponsored by ABANA'" <theforge at mailman.qth.net>
Sent: Monday, February 20, 2006 4:42 PM
Subject: RE: [TheForge] Chip Bed Forge
> Reminds me of the time I visited Boxford's, who besides making educational
> CNC equipment also make wheelchairs. They had jigs set up and were brazing
> the frames together, so I asked why. They explained that it was
> thin-walled
> cold drawn steel, and it would lose a lot of its desirable properties if
> it
> were welded.
>
> I suggested that mig welding was better for bodging stuff together, being
> better at gap filling, so the brazer (who was really annoyingly young)
> took
> two pieces of 3/4" pipe, and simply brazed them together in a 'T' with no
> end prep, neatly filling a 3/8" gap with braze.
>
> Damned if I can do that...
>
> Rich.
>
>> -----Original Message-----
>> From: theforge-bounces at mailman.qth.net
>> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Mike Porter
>> Sent: 21 February 2006 00:17
>> To: Sponsored by ABANA
>> Subject: Re: [TheForge] Chip Bed Forge
>>
>>
>> Hope my assessment of European heating equipment was more
>> accurate. Feel
>> free to correct any mistakes with just as much ruthless
>> abandon. I try not
>> to be unfeeling about people, but equipment must stand on its
>> own. What's
>> that English expression..."let the weakest go to the wall"?
>> Of course, we
>> are only doing so well on this side of the pond because
>> someone decided to
>> push propane instead of butane.
>>
>> You and I should get a chance to compare notes more closely
>> on brazing
>> hearths in the coming months, as joining is the thrust of
>> book two. But, you
>> would have guessed that already, if you've been following the
>> thread on
>> vision enhancement.
>>
>> It is my contention that the steady retreat of brazing and
>> soldering before
>> the onslaught of welding technology (which started during
>> world war two) is
>> over. Joining is a process that is far better suited to
>> today's Hi-tech
>> world, and to the demanding sort hobbyist that world is
>> creating; very much
>> like revisiting the late nineteenth century.
>> Mike P.
>>
>> ----- Original Message -----
>> From: "Rich Maynard" <rich at maynard.org.uk>
>> To: "'Sponsored by ABANA'" <theforge at mailman.qth.net>
>> Sent: Monday, February 20, 2006 1:49 PM
>> Subject: RE: [TheForge] Chip Bed Forge
>>
>>
>> > Hi Mike!
>> >
>> > It's 'Design and Visual Arts' by the way, not 'technical
>> department'!
>> >
>> > Rich.
>> >
>> >> -----Original Message-----
>> >> From: theforge-bounces at mailman.qth.net
>> >> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Mike Porter
>> >> Sent: 16 February 2006 17:02
>> >> To: Sponsored by ABANA
>> >> Subject: Re: [TheForge] Chip Bed Forge
>> >>
>> >>
>> >> Michael,
>> >> Try Flame Engineering if you want to find "state of the
>> British art"
>> >> crafts heating equipment. Unfortunately, every bit of
>> their stuff is
>> >> also quite out
>> >> of date. England and the rest of Europe designed all their
>> >> forging/brazing
>> >> equipment to run off of butane--not propane. Butane had been
>> >> thought to have
>> >> several advantages over propane. One of them is that butane
>> >> receives a big
>> >> flame temperature boost (356 degrees more than propane) from
>> >> a lot less
>> >> added oxygen (a ratio of 1.8 to 1 instead of propane's 4.7 to
>> >> 1). But, the
>> >> main advantage was supposed to be safety. Propane cylinder
>> >> pressure is 109
>> >> PSI at room temperature, to butane's 17 PSI. Sounds almost to
>> >> good to be
>> >> true, right? Well, it is. Lower pressure turned out to be a
>> >> mixed blessing
>> >> at best. You see, all their heating equipment needs large expensive
>> >> motor/compressors, and the attendant safety equipment that
>> >> goes with such a
>> >> system...and we find it all down hill from a design
>> >> standpoint from there.
>> >> Oh sure, 17 PSI is plenty of pressure to establish a flame
>> >> with, but the
>> >> fuel cylinder rapidly super-cools, with a resulting drop in
>> >> pressure that is
>> >> pretty close to zero. Europe is now starting to mix butane
>> >> with propane,
>> >> playing catch up, but not doing very well at it. Catching up
>> >> always requires
>> >> 'fessing up to your mistakes as a first step.
>> >>
>> >> The only real innovator I have found in English heating
>> equipment is
>> >> Bullfinch, who not only has come up with some pretty clever single
>> >> gas torch designs (I love their ignition system), but even
>> appears to
>> >> have its own
>> >> foundry. However, I tested Bullfinch's biggest brazing torch
>> >> against a 3/8"
>> >> tube burner last year, and the burner won (just). When tested
>> >> against a 1/4"
>> >> burner with a much narrower target pattern, the 3/8" burner
>> >> was completely
>> >> blown away, but by then I'd got rid of the torch, so they
>> >> couldn't go head
>> >> to head. For about fifty-seven bucks you can buy a High-heat
>> >> Torch (Model
>> >> "D" blowpipe): Made by Grobet USA, which will keep up with
>> >> the 1/4" burner.
>> >> The Model "D" blowpipe uses compressed air, to collapse a
>> >> brush flame into a
>> >> super fast (and therefore super-hot) needle flame. All this to say:
>> >> "European heating equipment isn't worth the shipping charges,
>> >> let alone the
>> >> prices they ask."
>> >>
>> >> Apparently, Europeans agree with this view, since you can
>> find used
>> >> brazing/forging equipment for sale on UK sites at about
>> 1/10th of its
>> >> original price. As near as I can tell, sales to the school
>> system is
>> >> all that keeps these guys in business. However, the head of a
>> >> London school's
>> >> technical department corresponded with me for a while last
>> >> year, while he
>> >> was building a tube burner and pipe forge for home use.
>> >> Apparently 1/10th
>> >> the price still didn't make local gas forge designs appealing
>> >> to him. You
>> >> can draw your own conclusions :-)
>> >> Mike P.
>> >>
>> >> ----- Original Message -----
>> >> From: "Michael Horgan" <lughaid at earthlink.net>
>> >> To: <theforge at mailman.qth.net>
>> >> Sent: Wednesday, February 15, 2006 9:35 PM
>> >> Subject: [TheForge] Chip Bed Forge
>> >>
>> >>
>> >> > Some years ago I made a gas forge for use at the Renaissance
>> >> > Faire, hiding the hot box under some black lava rock. It worked
>> >> pretty well , at
>> >> > least as a nail forge, but you could only heat one end of
>> >> the bar, with no
>> >> > pass through. Last year we used a Whisper Mama, tucked away in a
>> >> > faux-brick forge. Still pretty obviously a gas hotbox. I
>> >> wanted a coal
>> >> > or charcoal fire, but the Faire site, regulated by the Army
>> >> Corps of
>> >> > Engineers and the local county Fire Inspectors wouldn't
>> >> allow the "Open
>> >> > Fire"
>> >> >
>> >> > This year we are putting together a ceramic chip forge,
>> basically a
>> >> > gas burner feeding the bottom of a pile of heat resistant
>> >> "rocks." I've been
>> >> > looking at the past postings on the forge, and talking off
>> >> list with Paul
>> >> > Boulay , Rex Price, Frosty and Mike Porter, about the
>> ins and outs,
>> >> > advantages and disadvantages of this type of forge. Whether
>> >> it can be made
>> >> > to work with a venturi burner or if a blower is needed,
>> >> what type of media
>> >> > to use for best heat transfer to your steel, and so on.
>> >> I've also been
>> >> > looking at the "expensive" commercial versions available in
>> >> England as
>> >> > used in the school systems,as shown in the graphics page
>> >> here, and some
>> >> > slightly different types available in Germany,
>> >> >
>> >> http://www.angele-shop.com/catalog/index.php?cName=gas-forges-
>> >> gasforges .
>> >> >
>> >> > There have been some great ideas pop up, not to mention
>> the usual
>> >> > kludges I'm apt to come up with. <GRIN>
>> >> >
>> >> > Mikie in particular has a great idea for a recuperative
>> forge that
>> >> > looks great for a commercial forging station, if perhaps a bit
>> >> more than I was
>> >> > looking to do as a portable forge at the Faire
>> >> >
>> >> > Seems like there's some interest in this, so I'll be
>> summarizing in
>> >> > later messages some of the stuff we've been talking
>> about, as well
>> >> > as the results from some experimentation I'm doing.
>> I've got some
>> >> refractory
>> >> > media due in this weekend so I can try to produce some
>> >> results to share.
>> >> >
>> >> >
>> >> > Michael D. Horgan , lughaid at earthlink.net
>> >> > http://members.aol.com/lughaid/ posting from A BRAZEN FORGERY
>> >> > Blacksmithing and Metalwork
>> >> > Claremont, Ca.
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > Manage membership or unsubscribe at:
>> >> > http://mailman.qth.net/mailman/listinfo/theforge
>> >> > theforge mail list group photo site is http://www.photoaccess.com
>> >> > Login: blacksmithblacksmith at hotmail.com
>> >> > password: anvil
>> >> > ___________
>> >> >
>> >> >
>> >> >
>> >>
>> >>
>> >> _______________________________________________
>> >> Manage membership or unsubscribe at:
>> >> http://mailman.qth.net/mailman/listinfo/theforge
>> >> theforge mail list group photo site is http://www.photoaccess.com
>> >> Login: blacksmithblacksmith at hotmail.com
>> >> password: anvil
>> >> ___________
>> >>
>> >>
>> >>
>> >>
>> >> --
>> >> No virus found in this incoming message.
>> >> Checked by AVG Free Edition.
>> >> Version: 7.1.375 / Virus Database: 267.15.11/264 - Release
>> >> Date: 17/02/2006
>> >>
>> >>
>> >
>> > _______________________________________________
>> > Manage membership or unsubscribe at:
>> > http://mailman.qth.net/mailman/listinfo/theforge
>> > theforge mail list group photo site is http://www.photoaccess.com
>> > Login: blacksmithblacksmith at hotmail.com
>> > password: anvil
>> > ___________
>> >
>> >
>> >
>>
>>
>> _______________________________________________
>> Manage membership or unsubscribe at:
>> http://mailman.qth.net/mailman/listinfo/theforge
>> theforge mail list group photo site is http://www.photoaccess.com
>> Login: blacksmithblacksmith at hotmail.com
>> password: anvil
>> ___________
>>
>>
>>
>>
>> --
>> No virus found in this incoming message.
>> Checked by AVG Free Edition.
>> Version: 7.1.375 / Virus Database: 267.15.12/265 - Release
>> Date: 20/02/2006
>>
>>
>
> _______________________________________________
> Manage membership or unsubscribe at:
> http://mailman.qth.net/mailman/listinfo/theforge
> theforge mail list group photo site is
> http://www.photoaccess.com
> Login: blacksmithblacksmith at hotmail.com
> password: anvil
> ___________
>
>
>
_______________________________________________
Manage membership or unsubscribe at:
http://mailman.qth.net/mailman/listinfo/theforge
theforge mail list group photo site is
http://www.photoaccess.com
Login: blacksmithblacksmith at hotmail.com
password: anvil
___________
More information about the TheForge
mailing list