[TheForge] TheForge Digest, Vol 87, Issue 7

Mon Apr 4 13:35:09 EDT 2011

...Excellent post.
  ----- Original Message ----- 
  From: doveknives at aol.com 
  To: theforge at mailman.qth.net 
  Sent: Monday, April 04, 2011 1:08 PM
  Subject: Re: [TheForge] TheForge Digest, Vol 87, Issue 7

  Gents,
    I will try to answer the questions if I can.  Change in font size to make easier reading, not yelling.  :  )

  By "dry welding" do you mean without flux?

    As mentioned by another post, Yes this means no flux.  By eliminating the flux I eliminate the attack of the flux
   on the forge lining, the flux splash around  the shop and on me.  As well as the concern raised by the fine layer 
   of flux found by those who have done electron microscope exams of many different makers whose welds 
   appeared to completely clean. 

    What thickness material do  you use in your billets?

      .05 for both types of steel, 1095 & 15N20, both new bought in coil.  Average  billet size depends on intended pattern, 
    Can double up layers of the same material for pattern definition.  Start my students on a stack of 30 layers cut 2" x 4".  
    I buy the coils slit to 4" to begin with.  Now anyone who has tried to stack thin stock and forge weld it will tell you that 
    it will expand unevenly and open up allowing scale to form between layers.
      The way to stick a dry weld is to do the job of flux for yourself.  That means keeping O2 out of between your layers.
  Many have done the forge welding in a box with some kerosene in it to consume O2, This is called "hydrocarbon welding".
  I am basically lazy and did not like building the boxes.  So to eliminate the afore  Mentioned uneven expansion of layers 
  under control  I used Mr. Binnions (spelling might be wrong, sorry James) trick for setting the fusion of Mokume.  In my first 
  stack I place a fusion barrier, in this case some oxided SS foil on top and on the bottom of the billet, this keeps the billet 
  from sticking to the pressure plates .  The pressure plates are 1/2x 2x4 mild steel and placed on the top and bottom of the 
  billet.  I run a cold MIG bead down each corner of the billet to hold it all together.  I then weld a handle onto one end of the 
  billet.

     Using the pressure plates keeps the billet from expanding and allowing O2 in.  The billet heats very evenly using this 
  technique.  Just be certain to allow the heat enough time to completely penetrate the billet.  I view the billet in the fire using
   foundry glasses that clip onto my ball cap brim.  I usually set my weld at just below 2000 degrees F  in a 30 ton forging
  press only reducing the height of the billet by 1/2".  I then go to the welding table, using a side grinder I cut the two welds
  on the end of the billet at the pressure plate and peel the plates off the billet. The all that is left is to draw the billet out to 
  .75 thick, 1.125 wide and however long it wants to go.  I use a combination of my power hammer and a rolling mill.

    To gain pattern density I generally cut this bar into four or five equal pieces and surface grind both sides to 400 gt.  Now
   I can hear someone say "I don't have a surface grinder".  Don't let this stop you, use a belt or disc grinder, start with 50 grit
  and go to progressively finer grits, I use 220 then 400.  It is during the traditional cut and fold technique where many problems
  occur.  This is one step I was glad to eliminate, and one that benefited me perhaps the most.  By investing the time in 
  polishing the mating surfaces I increased the surface area that is in contact and eliminated the air gaps that can allow scale 
  to form between layers.

    I next lay up the stack and button weld (read as round puddle tack weld) the stack together placing the button welds only on
   the ends of the billet.  Anytime you are arc welding on your billet, only weld on the ends, these are cut off along with about 
  1/2 inch of stock between the first weld and re-stack as well at the end of the finished billet to eliminate any chance of the arc
  weld showing in the finished billet.

   Do you use an induced-draft forge or a blown-air forge?  Do you do anything special
  to adjust your flame conditions?

    I have used both with great success.  When designing your forge remember that propane needs 18 inches of extension for
  optimum performance, this is what works for me, I know there are those that will disagree, but this is what works for me.
    Currently I am using a forced air gas forge that is a slightly modified Don Fogg design.  The forge body is a12" tall 12" dia.
  .1 wall thickness black iron pipe that we split down the length and welded in 6" of .1 thick strap that makes the fire chamber 
  an oval shape.  Burner is injected at a tangent at the bottom rear.  We lined the forge w/2" of Fiberfax in 1" layers doubled 
  to allow us to wrap the wool out the door to cover the pipe at the door edges to protect from burning the steel away over time.
  The doors are side sliding fire brick slit on the edge to allow for guiding on an angle iron frame.  We are using about half the 
  fuel as with the aspirated forge and welding muck larger billets, largest is averaging 4x5x4 inches.  

  I've heard arguments on both sides of the debate, and am curious.

    I don't pay attention to the arguments, try both theory's and use what works.

  Gas forges are notorious for producing scale.  

   The point made by another post is true, the mix is critical.  I used a .035 mig contact tip in the aspirated forge burners.  On the 
  current forge we are using a blower but we have the gate valve almost shut and we are using a flow meter, the type with a little ball in it to regulate
  the propane.  Used to run at about 60 on the meter, have tuned all the way down to 24 and still making welds perfectly.  

    My shop is at 5000 feet elev. The greatest difference in my production made by switching to dry welding is hard to say.  I will name the most 
  notable ones being, my forge lining is lasting for 2-3 years between relines, My weld failure rate has dropped to 2  in 7 years, yes, that is only
  2 in 7 years, one of which happened last year at the RMS conference in front of about 50 blacksmiths, over worked it in an unfamiliar press.
  Boy was my face red!!!   Weld was able to be cleaned w/ acid and reset w/o problem.  The other was not letting the billet soak long enough to get 
  to welding temp all the way through.  None of this is said as a means of bragging.  It is to say that using clean stock, proper heat, cleaning well
  between welds, yields predictable, controllable results that even a bumbling fool as myself can achieve good forge welded Damascus.

  Trusting HIM,
  Steve Rollert
  keenedgeknives.com
  doveknives.com

  -
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