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Re: Carbon Arc Torch

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  • DENNIS SHELGREN
    Whoops the link went poof. Lets see if I can attach the diagram.
    Message 1 of 15 , Jul 22, 2011
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    Whoops the link went poof. Lets see if I can attach the diagram.
     
  • Shannon DeWolfe
    I have never touched a carbon arc torch. I never even thought about it, really. A quick Google search proves Dennis correct; dry cell batteries are a source of
    Message 2 of 15 , Jul 22, 2011
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      I have never touched a carbon arc torch. I never even thought about it,
      really. A quick Google search proves Dennis correct; dry cell batteries
      are a source of carbon for electrodes:

      http://donklipstein.com/carbarc.html

      Still digging to see if you can "make" carbon rods with a shop press.

      Regards,

      Mr. Shannon DeWolfe
      --I've taken to using Mr. because my name misleads folks on the WWW. I am a 55 year old fat man.


      On 7/22/2011 9:40 PM, zaphod wrote:
      > Does anybody know of a cheap source for arc torch carbons? Would a big pencil lead work? Could a screw press generate enough pressure to squeeze graphite powder into a solid mass?
    • Larry Ruebush
      Forney Welding Equip used to have carbon arc sticks, but I don t see them listed now. We have a Forney Welder that my dad bought back in the mid 50 s that had
      Message 3 of 15 , Jul 22, 2011
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        Forney Welding Equip used to have carbon arc sticks, but I don't see them listed now. We have a Forney Welder that my dad bought back in the mid 50's that had a carbon arc attachment to use to heat metal.
        You might try farm supply stores, if you have any in your area. Most of them include welding supplies. The carbon arc sticks used to be real popular.
        Larry Ruebush
        west central IL
        ----- Original Message -----
        Sent: Friday, July 22, 2011 10:16 PM
        Subject: Re: [multimachine] Carbon Arc Torch

         

        I have never touched a carbon arc torch. I never even thought about it,
        really. A quick Google search proves Dennis correct; dry cell batteries
        are a source of carbon for electrodes:

        http://donklipstein.com/carbarc.html

        Still digging to see if you can "make" carbon rods with a shop press.

        Regards,

        Mr. Shannon DeWolfe
        --I've taken to using Mr. because my name misleads folks on the WWW. I am a 55 year old fat man.

        On 7/22/2011 9:40 PM, zaphod wrote:
        > Does anybody know of a cheap source for arc torch carbons? Would a big pencil lead work? Could a screw press generate enough pressure to squeeze graphite powder into a solid mass?

      • Shannon DeWolfe
        It appears that carbon rods are made from a recipe of carbon black, graphite, and pitch: A carbon rod is used as a current collector for the positive
        Message 4 of 15 , Jul 22, 2011
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          It appears that carbon rods are made from a recipe of carbon black,
          graphite, and pitch:

          "A carbon rod is used as a current collector for the positive electrode
          in cells. The carbon rod is made by heating extruded mixture of carbon
          (petroleum coke, graphite) and pitch that serves as a binder. A
          heat-treatment temperature of about 1100ºC (2012ºF) is used to carbonize
          the pitch and to produce a solid structure with low resistance. For
          example, heat treatment reduced the specific resistance from 1 to 0.0036
          ohm cm and the density increased from 1.7 to 2.02 g/cm³."

          That is from this page:

          http://electrochem.cwru.edu/encycl/art-c01-carbon.htm

          I am still digging for the recipe. You could use your press to extrude a
          rod through a tube. The rod would then need to be "cooked" at the
          temperature given above.

          Regards,

          Mr. Shannon DeWolfe
          --I've taken to using Mr. because my name misleads folks on the WWW. I am a 55 year old fat man.


          On 7/22/2011 9:40 PM, zaphod wrote:
          > Does anybody know of a cheap source for arc torch carbons? Would a big pencil lead work? Could a screw press generate enough pressure to squeeze graphite powder into a solid mass?
          >
          >
          >
          > ------------------------------------
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          >
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        • Jack Coats
          I wonder if it is possible to get carbon arc rods from theater supply. I used them 30 years ago when working at movie theaters (yes, carbon arc before the
          Message 5 of 15 , Jul 22, 2011
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            I wonder if it is possible to get carbon arc rods from theater supply.
            I used them 30 years ago when working at movie theaters (yes, carbon
            arc before the halogens got popular). The Halogen bulbs are what I
            think I have seen exclusively in theaters in the last many years, but
            the carbon arc (antique now) projectors are still out there. So there
            could be a 'nostalgia manufacturer' that still makes them.
            It took a couple of roughly 1' long arc's to make it through one reel
            (about 20 minutes) of a film, before changing to the other projector.

            ... Memories ... possibly they are good for something!
          • Shannon DeWolfe
            Here is a recipe for homemade carbon rods:
            Message 6 of 15 , Jul 22, 2011
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              Here is a recipe for "homemade" carbon rods:

              http://books.google.com/books?id=ioNOAAAAMAAJ&dq=make%20carbon%20rods&pg=PA938#v=onepage&q=make%20carbon%20rods&f=false

              If you cannot see the page for whatever Google reason, let me know.

              Not easy and not inexpensive. Got coke? I don't and I cannot get it cheaply.

              Mexico, right? You should be able to find and buy relatively inexpensive
              carbon arc rods a few at a time from a shop. Failing that, from a
              welding supply house. Airgas Corp has them.

              Regards,

              Mr. Shannon DeWolfe
              --I've taken to using Mr. because my name misleads folks on the WWW. I am a 55 year old fat man.


              On 7/22/2011 9:40 PM, zaphod wrote:
              > Does anybody know of a cheap source for arc torch carbons?
            • Charles Patton
              The way I remember those rods (50 years ago) is that they were about 3/8 diameter, about a foot long and were heavily copper plated and came from National
              Message 7 of 15 , Jul 22, 2011
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                The way I remember those rods (50 years ago) is that they were about
                3/8" diameter, about a foot long and were heavily copper plated and came
                from National Carbon. Bigger diameter rods were used in the drive-in
                theatre projector (and searchlights, too) The arc lamp housing had a
                small metal cup below the arc point and the copper would drip off into
                the cup as the rod fed into the arc. Furthermore they were cored. I.e,
                the composition of the core was slightly different as it was loaded with
                rare earths (?) to balance the color temperature of the arc. If the arc
                was out of adjustment you would see the color change on the screen. The
                head projectionist would collect the copper and about once a year go to
                the scrap metal dealer to sell the multiple pounds of copper drippings
                he had collected. I understood that the copper was necessary to keep
                the resistance down on the rod as it was running quite a few amps for
                it's size, and also to improve the electrical contact of the moving
                drive wheel feeding it to the arc point. . In the past I have seen
                similar carbons at the welding store -- I think they're called cutting
                rods.

                I feel I missed my chance for a Nobel prize. The arc housings had a
                smokestack to vent the carbon fumes and this smokestack would "cobweb"
                with carbon smoke. I'm now positive that these were probably carbon
                nanotubes and buckyballs. If only I had followed up on my curiosity
                about the "cobwebs."

                Huge carbon rods (foot or more in diameter) are still in use for
                aluminum smelting and electric arc steel smelting. They may be a bit
                big for a carbon arc torch, though.

                Regards,
                Charles R. Patton



                and were On 7/22/2011 9:09 PM, Jack Coats wrote:
                >
                > I wonder if it is possible to get carbon arc rods from theater supply.
                > I used them 30 years ago when working at movie theaters (yes, carbon
                > arc before the halogens got popular). The Halogen bulbs are what I
                > think I have seen exclusively in theaters in the last many years, but
                > the carbon arc (antique now) projectors are still out there. So there
                > could be a 'nostalgia manufacturer' that still makes them.
                > It took a couple of roughly 1' long arc's to make it through one reel
                > (about 20 minutes) of a film, before changing to the other projector.
                >
                > ... Memories ... possibly they are good for something!
                >
                >
              • Brenden McNeil
                I have extenensively used air carbon arc cutting and gouging as a rail car mechanic. The size of the carbon depends on what kind of welds you are trying to
                Message 8 of 15 , Jul 23, 2011
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                  I have extenensively used air carbon arc cutting and gouging as a rail car mechanic.
                   
                  The size of the carbon depends on what kind of welds you are trying to remove.  Most of the stuff on a rail car is very heavy duty and has very large weld beads.  A 1/4" carbon was just about as big as you need for most work there.  Sometimes a 3/8" is nice but then you start needing much larger current requirments, need bigger welding leads, plus I find I do better work with a smaller carbon as I can make more accurate gouges, even it takes me a little extra time.
                   
                  Now that I no longer do that job, and bascially do stuff around my shop at home, I use 1/8" DC carbons exclusively.  On most of my projects, which use 1/4" thick steel or smaller, the 1/8" carbon is perfect, mostly because you can very precisely arc out the root of theh weld, grind it down and then have plenty of metal left over to re-weld it without having a funky fit up.
                   
                  The copper coated carbons are DC only.  I've never used an AC carbon becuase they are considereably more expensive then a DC carbon.  The problem is the AC carbons need chemicals added to them to help stabalize the arc that is constnatly changing it's voltage from alternating current.
                   
                  Problem, is most DC machines that run on single phase power still dont have a clean enough DC signal to run a DC carbon well.  Your best bet is to use a good engine driven welding machine that does DC, a machine running off of 3 phase power, or an Inverter type unit.
                   
                  With a good power source, the 1/8" carbon should do most work people on this list will need... some 3/16" may come in handy now and then but I doubt it.  I have some 3/16" carbons in the shop but I've never used them.
                   
                  1/4" carbons unless you are doing heavy duty structal steel are usually a waste, as they are more expensive.  Also you need about 350 amps+ to run a 1/4" DC carbon, and unless you got three phase power, finding a machine that can do that with a half descent duty cycle is very hard and expensive.
                   
                  Trying to use an underpowered machine for the size carbon you are using makes for an arc that is hard to start, and maintain, which creates a very frustating situation.
                   
                  At home, I use a Lincoln Weldanpower engine driven welder, 1/8" Arcair DC carbons, and a Arcair K2000 torch.  Does everything I need.
                   
                  I've never attempted to make my own carbons.  To be honest, I don't do enough gouging these days to make it worth while.  The box of 1/8" carbons I bought 4 years ago is still more then 3/4 full!!!
                   
                   
                  On Sat, Jul 23, 2011 at 1:22 AM, Charles Patton <charles.r.patton@...> wrote:
                   

                  The way I remember those rods (50 years ago) is that they were about
                  3/8" diameter, about a foot long and were heavily copper plated and came
                  from National Carbon. Bigger diameter rods were used in the drive-in
                  theatre projector (and searchlights, too) The arc lamp housing had a
                  small metal cup below the arc point and the copper would drip off into
                  the cup as the rod fed into the arc. Furthermore they were cored. I.e,
                  the composition of the core was slightly different as it was loaded with
                  rare earths (?) to balance the color temperature of the arc. If the arc
                  was out of adjustment you would see the color change on the screen. The
                  head projectionist would collect the copper and about once a year go to
                  the scrap metal dealer to sell the multiple pounds of copper drippings
                  he had collected. I understood that the copper was necessary to keep
                  the resistance down on the rod as it was running quite a few amps for
                  it's size, and also to improve the electrical contact of the moving
                  drive wheel feeding it to the arc point. . In the past I have seen
                  similar carbons at the welding store -- I think they're called cutting
                  rods.

                  I feel I missed my chance for a Nobel prize. The arc housings had a
                  smokestack to vent the carbon fumes and this smokestack would "cobweb"
                  with carbon smoke. I'm now positive that these were probably carbon
                  nanotubes and buckyballs. If only I had followed up on my curiosity
                  about the "cobwebs."

                  Huge carbon rods (foot or more in diameter) are still in use for
                  aluminum smelting and electric arc steel smelting. They may be a bit
                  big for a carbon arc torch, though.

                  Regards,
                  Charles R. Patton



                  and were On 7/22/2011 9:09 PM, Jack Coats wrote:
                  >
                  > I wonder if it is possible to get carbon arc rods from theater supply.
                  > I used them 30 years ago when working at movie theaters (yes, carbon
                  > arc before the halogens got popular). The Halogen bulbs are what I
                  > think I have seen exclusively in theaters in the last many years, but
                  > the carbon arc (antique now) projectors are still out there. So there
                  > could be a 'nostalgia manufacturer' that still makes them.
                  > It took a couple of roughly 1' long arc's to make it through one reel
                  > (about 20 minutes) of a film, before changing to the other projector.
                  >
                  > ... Memories ... possibly they are good for something!
                  >
                  >




                  --
                  Brenden McNeil
                  moya034@...
                • GGB
                  ... That s a very full account. Do you mind explaining please how you would use one of these? Paul
                  Message 9 of 15 , Jul 23, 2011
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                    Brenden McNeil wrote:
                    >
                    > I have extensively used air carbon arc cutting and gouging as a rail car mechanic.

                    That's a very full account. Do you mind explaining please how you would use one of these?

                    Paul
                  • Brenden McNeil
                    Last year I made a post about air-carbon-arc gouging at BYMC: http://www.backyardmetalcasting.com/forums/viewtopic.php?t=4431 That may answer more questions.
                    Message 10 of 15 , Jul 23, 2011
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                      Last year I made a post about air-carbon-arc gouging at BYMC: http://www.backyardmetalcasting.com/forums/viewtopic.php?t=4431
                       
                      That may answer more questions.  It's a tough process to actually describe how to do.  Starting and maintaining the arc is different then stick welding.  The arc really wants to start itself, assuming you have a good power supply, so once started it requires a very light touch.  You want to run the carbon at about a 45 degree angle.
                       
                      The hardest part really is you have to imagine how the weld was done, and what rod angles the welder used.  The idea is to remove as little metal as possible, and go straight to the "root" of the weld.  If you look carefully while gouging, once you go deep enough, you will see a seam of two pieces of metal.  Once you see that seam, that means you've removed the root, and the weld will come apart.  The challenge is "finding" that seam!
                       
                      When you start out, you will find you remove more metal then necessary, and as you gain practice you'll be abel to very accurate gouges.
                      The main use for air-carbon arc cutting is indeed weld removal, be it to dismantel something, or more commonly, remove a bad weld in order to redo it.  (Like when that wind gust comes thru, obliterating the sheilding gas of your MIG gun, and you have to remove the porosity.)  However, I've used air-cabron arc alot for fitting up weldments.... It's faster then a grinder, can be mroe precise then torch cutting in some cases, and this is most important... it puts very little heat into the weld.  The compressed air from the nozeel does a great job at keeping the heat confined to the metal being removed, instead of the workpiece.  This in the end, causes less warpage.
                       
                      On Sat, Jul 23, 2011 at 12:14 PM, GGB <self.adhesive@...> wrote:
                       

                      Brenden McNeil wrote:
                      >
                      > I have extensively used air carbon arc cutting and gouging as a rail car mechanic.

                      That's a very full account. Do you mind explaining please how you would use one of these?

                      Paul




                      --
                      Brenden McNeil
                      moya034@...
                    • David G. LeVine
                      ... Please define cheap and the area where they will be used. In the USA, a carbon arc electrode might be cheap, while in Rwanda it might be cost prohibitive.
                      Message 11 of 15 , Jul 23, 2011
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                        On 07/22/2011 10:40 PM, zaphod wrote:
                        > Does anybody know of a cheap source for arc torch carbons? Would a big pencil lead work? Could a screw press generate enough pressure to squeeze graphite powder into a solid mass?

                        Please define cheap and the area where they will be used. In the USA, a
                        carbon arc electrode might be cheap, while in Rwanda it might be cost
                        prohibitive. On the web, 1/4" x 12" are about $1-$2 each. See
                        http://www.csnstores.com/Arcair-21-043-003-1-4-X-12-DC-Plain-Air-Carbon-Arc-Gouging-Electrode-50-Per-Box-21-043-003-OBB1104.html?refid=FR49-OBB1104
                        for one example. From
                        http://www.welding-technology-machines.info/arc-welding-processes-and-equipments/single-carbon-arc-welding.htm
                        "For welding with 3, 6 and 10 mm diameter carbon electrodes the
                        approximate arc currents are 25, 70 and 125 Amps respectively."

                        Carbon arc electrodes are often encased in copper both for support and
                        conductivity. Smaller ones appear to be electroplated, larger appear to
                        be thin tubes which are swaged to compress the carbon/graphite mixture.
                        The coating improves conductivity, hence lowers I^2R losses and enhanced
                        performance and life.

                        For what power input? For a few watts, a pencil might work, for 40 KW,
                        it wouldn't. I measured a 2" length of 0.5mm Pentel HB (roughly #2
                        pencil) lead and got a few ohms (I distrust DMMs at such low levels.)
                        Put an ampere through it, it will get hot, it will likely work at around
                        10-100 ma but it won't work at 10 Amperes.

                        Again, you are asking a poor question. A big screw press can generate
                        hundreds of tons of force, but it may be too expensive to build and
                        operate. A carbon/graphite/clay/powdered metal mix might work at more
                        modest pressures.

                        So to answer your second question, yes, but the devil is in the details.

                        Dave 8{)
                      • Darwin Wandler
                        Just use AIR ARC rods for blowing apart old welds. Any welding shop has them. They are copper coated but it peals off easily. Darwin
                        Message 12 of 15 , Jul 23, 2011
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                          Just use AIR ARC rods for blowing apart old welds. Any welding shop has them. They are copper coated but it peals off easily.
                          Darwin

                          On 7/22/2011 11:09 PM, Jack Coats wrote:  

                          I wonder if it is possible to get carbon arc rods from theater supply.
                          I used them 30 years ago when working at movie theaters (yes, carbon
                          arc before the halogens got popular). The Halogen bulbs are what I
                          think I have seen exclusively in theaters in the last many years, but
                          the carbon arc (antique now) projectors are still out there. So there
                          could be a 'nostalgia manufacturer' that still makes them.
                          It took a couple of roughly 1' long arc's to make it through one reel
                          (about 20 minutes) of a film, before changing to the other projector.

                          ... Memories ... possibly they are good for something!

                        • Bruce Bellows
                          Helwig Carbon Products do make a .025 dia. carbon brush for a motor and they also mention doing custom sizes. Maybe worth a try. http://www.helwigcarbon.com/
                          Message 13 of 15 , Aug 1, 2011
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                            Helwig Carbon Products do make a .025 dia. carbon brush for a motor and they also mention doing custom sizes. Maybe worth a try.

                            http://www.helwigcarbon.com/

                            Bruce

                            On 7/22/2011 10:40 PM, zaphod wrote:
                             

                            Does anybody know of a cheap source for arc torch carbons? Would a big pencil lead work? Could a screw press generate enough pressure to squeeze graphite powder into a solid mass?

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