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Paul Rohrbacher

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Posts posted by Paul Rohrbacher

  1. Thank everyone for identifying the cause of my forge explosion, (I have been formally initiated into a large Forge Explosion Club). I ask very knowledgeable Blacksmiths about the explosion. (Interesting, that all experienced the same forge explosion under the same set of conditions.) The forge explosion is caused by adding green or wet coal over a hot fire and not running the blower.  I received a response from this forum,  Mark Aspery and from ABANA, Bob Valentine. All the responses are basically the same, keep the blower going when green/wet coal is added to the fire. The green coal over a hot fire will make a lot of smoke. The smoke is flammable and will burn the top of the fire. The flammable smoke coming off the top of the fire didn't cause the explosion, this smoke goes up the chimney or burns off.


    Explosion conditions: The input to the fire is the problem causing the explosion, adding green/wet coal with no air supply. Coal gases formed which  is heavier than air so it settles in the lowest part of the forge system, the tuyere, flex air tube and blower.  Turn the blower on and Boom! 


    From what I have read since my explosion, the Bellows were always placed high above the forge. If the bellows were placed at or below the forge fire, the coal gas would no only fill the air tube but the large volume of the Bellows.. A Bellows full of coal gas made a very spectacular, damaging and deadly explosion


    Conclusion: To prevent the Side Blast Forge from exploding after adding green/wet coal , keep the blower running for a positive air flow. 


     Using a plate over the fire hot spot increases the heat of the fire, ( something I have been doing this year with very positive results). The plate over the fire reflects some of the escaping heat back into the fire, making the fire hotter. I have been experimenting lately with using a Fire Brick over the fire which appearers to works a little better than the steel plate.  If any one reading about covering the fire with a plate or fire brick, tried this procedure and have either positive or negative results, please respond to report your findings. 

  2. FP1040807.JPG    P1040792.JPG


    This is the forge. The blower is connected to the tuyere by a long flex hose.                   This is the hood/chimney sucking the flames from my start up fire.




    This picture shows a little smoke being drawn into the hood. Today, the green coal was putting a significant volume of smoke!


    For the third time today, I fired up my just finished Side Blast forge. I had a good fire going and decided to add a couple shovel full of Bituminous Coal. I was getting a lot of smoke from the new coal that was placed around the edge of the fire to coke up. Since the Blower was off at the time I did a few tasks around the shop. The Supper Sucker Hood was doing a wonderful job of pulling the huge volume of smoke from the newly added coal .


    I turned the blower on and BOOM! My guess is the coal gas from the new coal had backed up back thru the Tuyere and into the Blower. The BOOM was as loud as a 22. pistol  shot. There wasn't any flying red hot coal luckily. I have heard of coal forges exploding but never thought about it as a problem. If the explosion had been bigger, the red hot coal could have sprayed all over the shop and Nr. 1, me.

    Has any of you had a similar experience? What do you suggest to prevent the coal gas explosion in the future?


  3. From what I have read, Brass wasn't available during the Viking times. Bronze was the metal that they had to use. If the Brass was exposed to Ammonia fumes  it would tarnish in a few hours to look like old Bronze. 


    I have a good supply of Copper Sheeting and old 1" copper pipe. I think that it could substitute for Bronze if aged with Ammonia fumes. 


    does anyone have any other comments or ideas for the metal work in the viking Sheaths?


  4. P1040807.JPG


    This is an overall view of the Forge and Hood




    This is smoke being drawn into the supper sucker Hood. The draw of the chimney system is much better than I anticipated.




    This is the Duck's Nest with the tuyere to the left and the hood to the right.




    This view shows the bosh that is connected to the tuyere with hoses. the blower is mounted on the table with the forge. The flex pipe can be removed to clear any blockage that mite occur in the Tuyere.


    The heated antifreeze flowed thru the tubing into the Bosh. the top tube gets warm and the bottom tube is cold. In the summer, the system will get much warmer and possibly boil.


    Are we having fun yet?


    PS: Thanks for the warning about IFI.



  5. P1040778.JPG


    Chimney -10" grain auger tube that was scraped, now repurposed. 





    This is the rear of the tuyere. The Hot water pipe goes out the top and a similar pipe goes out the bottom. The Guillotine air Controller is used.





    This is the flames being sucked into the Supper Sucker Hood.




    The Bosh is connected to the Tuyere with Hot and cold piping. I am using antifreeze as a coolant. My Smithy is in an unheated building where the temperature can have a minus sign infant of the temperature.





    This is the Hearth. I usually place a steel plate over the hot spot in the fire. This forms an oven to make heating much more efficient. The heated item is a blank to make a Viking Broken Back Knife. 




    This is the Blower. The silver covered Flex Pipe can be easily removed for poking clinkers out of the air tube and reconnecting to a hand crank Blower. The Pulley on the motor can be adjusted to increase or decrease the diameter and thus change the air volume.



    I will take pictures of the entire forge assembly for the next post.


    The Mark Aspery Side Blast Forge design has the Tuyere welded in the Bosh. This is too heavy for me to move.  So, the Tuyere and Bosh are separated and connected by piping.  

  6. Gerald,

    I used your instructions to make an Axe Head. Your instructions were great!  

    It took me one try failure to get the process down. Then, I made two successful axe heads and have the third axe head ready for the Bit to be welded in.

    After hardening and tempering, the edge is ground and honed. The hammer marks are removed by grinding, draw-filing and finish with sanding to 600 gr..

  7. Please go to the "I Forge Iron" forum where I just posted pictures and a description of my Side Blast Forge, Mark Aspery design, and a Supper Sucker Hood.


    By using antifreeze, I hope to avoid rust out of the water system. I will collect more antifreeze to replace the evaporated antifreeze. More thinking, it may be possible to replace the Bosh with an auto radiator in a closed system. A fan can cool the radiator.


    When I was building the Bosh, I filled it with water to find then leaks, many leaks were found. the water started to rust the interior of the Bosh. When the Tuyere was water tested. it was filled with water for over a week. Rusty water came out after the test was over. 


    My big reason to use antifreeze is my forge is in an unheated building in Iowa. I expect to see temperatures with a (- F) many times over the winter. Draining 12 gal. of water at the days end and then lugging the fresh water from the well would be a real pain.


    I hadn't thought about the antifreeze being boiled off. I will keep a sharp look out for this problem. I believe that the boiling point of antifreeze is higher than water, how much higher???


    Thank you for your response,


  8. The forge rebuild, top topic,  is from gross rust out of the components that are part of the water cooling system. From what I have read, the water filled components will last about  7-10 years use before rust thru becomes a problem. 


    I decided to cool my forge with antifreeze because the forge is in an unheated out building. 

    1, Antifreeze won't freeze in my unheated out building blacksmith shop.

    2, Antifreeze has rust inhibiters so the life of the Side Blast forge should be greatly increased over using water.

    3, Antifreeze can be gotten FREE from your local car dealer.

    4, Antifreeze is amore effacing cooling agent over water.

    5, Disadvantages antifreeze is poisonous so it must be kept from animals.


    I went to our local Ford garage with two each 5 gal. containers. They were filled with used (free) antifreeze which is now filling my system.

    Time will tell if the advantages of using antifreeze make good sense.


    I will be taking pictures of my new Side Blast Forge with a Supper Sucker Hood when it becomes fully operational.

    The 10" chimney was installed with the top rising over 4" above the roof peak. The chimney is a reclaimed grain auger tube that had a kink in the middle.

    The forge can be moved to be closer to the hood. Initial tests indicate that at initial lighting of the forge, a temporary tube may be needed from the fire to the hood opening to keep the start up smoke going up the cold chimney. am alternative would be to role up newspaper, light it and place the flaming paper inside the hood to start the draw. I place the flame from by Brush Burning Torch into the hood and noted that the flame was drawn into the hood, a strong draw. 

    I will need to add a steel plate behind the Tuyere to keep the stored coal ready to be raked into the fire.

    The bed of the Hearth is filled with wood ashes with a small ducks nest dug in front of then air opening. I may cover the ashes that are filled up with wood ashes  to the top of the hearth's sides with a steel cover on both sides of the hearth, leaving the duck's nest open for the coal. 

    I designed the forge to be fully accessible from either side. So two blacksmith can work the forge from opposite sides. I have several 130+# anvils that can be placed on each side.              At the end of the forge, there is a huge Leg Vice that is accessible from either side. The vice is fastened to a 3' x 4' 1" thick steel plate welding table.


    More information and pictures  will follow when the forge is fully fired up for some heavy blacksmithing work . 

  9. I have just finished building a Side Blast Forge (Mark Aspery design) with a Super Sucker Hood and 10" chimney. Now for the testing of the forge. The Bosh is connected to the Tuyere with a bottom cold water tube and the top is connected to the hot water tube. I am using used antifreeze as a coolant for two reasons, 1, shouldn't rust the Bosh and Tuyere, 2, my shop is in a unheated outbuilding. Tonight it will approach 0 F. The Hearth is covered with firebrick and wood ashes are being used not sand to fill the Hearth. The 10" chimney was salvaged from a grain auger tube that had blown over and kinked in the middle. The chimney is 4' above the shed's roof peak. the Top Hat is a 15" sq. steel plate mounted 10" above the top of the chimney by two steel posts..

    The first test fire gave mixed results. I was using Anthracite Nut coal from Tractor Supply. I didn't have enough coal in the forge to make a large mound so the steel bar was inserted in the hot spot in-front of the Tuyere air outlet. the bar heated quickly. 


    The Super Sucker Hood started drawing out the smoke and flame. Then, I opened the big door to the shed and the chimney stopped drawing the smoke. Why??? Anyway, I decided to move the fire much closer to the hood opening which should solve the draft problem. The clinker was fished out of the fire with the three prong rake I made in the test firing. 


    The next test fire will be done with blacksmith coal and the coal will be piled much higher. Water will be used to control the fire size if it grows out of the hot zone.


    My criteria for the permanent size forge was to make no component over 50#. The steel tube frame comes apart in 3 pieces. The Hearth is 2' square by 9" deep with handles. The Tuyere is not part of the Bosh, but it is connected to the Bosh by cold and hot tubes/hoses. The Blower is an old motor driven Champion blower run by a 1/3hp motor running with a 1-1 ratio is connected to the blower with a belt. The air flow is controlled with a Guillotine that is lever operated. With the Guillotine closed. the air leakage will keep the fire from dying down . to meet the 50# criteria, the Bosh was cut down to hold a little over 10 gal. If this size is too small, the top water tube will be run to a screen mesh cooling system that will set on top of the Bosh. This system was used to cool gas engines around the early 1900's.


    At the next test firing I will take pictures to post.

  10. DSCF2426.JPG


    This is my Seax imitation sheath, first try. The copper trim is formed over the top.

    The question is the copper trim is formed over the top of the sheath traditionally correct.

    Or is the trim just on the sheath sides and riveted in place? The leather edge would now be seen between the copper sides.


    On Youtube one of the better videos has the trim in three pieces. The pieces are soldered together to make the "U" trim over the top and encompass the top and the entire end of the sheath..




    This is the copper trim removed from the sheath. The trim was made using a Bending jig                                .DSCF2439.JPG


    This is the Bending Jig. The top bar is the width of the leather being covered. The copper sheet is center  positioned and the top 3/8" bolts are fully tightened. The copper is soft enough to by finger pressure bend both sides up against the side of the bar. Then, using a piece of leather glued to a flat paint stirring stick the stick is hammered on the bend to make the bend as sharp as possible, both sides. 


    If both the "U" shape and side only trim are traditional then my approach would be valid. If the trim is only on the sides and riveted in place, then I am wrong with the "U" trim.

    The Gotland style shown above and Alan's comments indicated that the correct procedure uses the riveted side trim bent around the tip section and side trim on the remainder. The fill in trim is"U" formed over the top..

  11. I have been looking at Seax Knife sheaths. They usually have a Brass or Copper edge over the Stiching. My question is: The metal fooled over the sheet top to male a "U" shape the length of the stitching. Or, is the metal just riveted to the sides over the sticking. This will leave the edges of the leather exposed.


    Which method is correct? Or are both methods correct?

  12. This is my approach to forging Copper Wire Rivets. You will need Number drills 45, 35, 32, and 20, steel blocks, 3/8" threaded rod, nuts and Wing Nuts, a spacer card (business card), 3/8" x 16 Tap and marking number punches. The drill size is marked on the block so when drilling the sheath, the correct Number Drill will be known.


    I am in the process of making a test sheath for my prototype Seax style knife. The Rivet Swage is now made.  The next jig will be a Bending Break to bend the Copper sheeting into the hardware around the top of the Sheath. 


    In the Viking period, I don't think Brass was possible to make. We have the Copper Age,  the Bronze Age  and then Iron Age, but no Brass Age. Bronze is a mixture of Copper and Tin which was harder and more brittle than Copper. Brass is a combination of Copper and Zinc. The Zinc melted long before the Copper melted so they were not able to blend the two metals to together.


    I think that using Copper Sheeting and Copper Wire as  Rivets would be period correct. #6 Copper Wire can make very solid Copper Rings. A lap joint can be soldered to complete the Ring.


    Since the aged Patina of Copper, Bronze and Brass look much alike, I viewed one sheath maker who places his Brass parts into an Ammonia atmosphere until the desired Patena has been achieved.


    I used scrap steel to make the Rivet Swage.  Copper Wire Rivets are forged using two blocks of steel that are bolted together. My steel blocks are 3/4" x 1-3/4" x 3". A bar stock Handle was added. Two stiff compression springs are located on the two bolt in a recess between the two blocks. The springs forces the blocks open when loosening the wing Nuts to removing the Rivet. The bolts keep the blocks aligned.


    The Swage was made by first match bolting the two blocks together. any block mismatch on the top surface was milled off .To drill the holes a business card was placed between the blocks to add a clamping space. #12 wire holes were drilled with a #45 drill, #10 wire, a #35 drill,  #9 wire, a #32 drill and  #6 wire a #20 drill. The #12 and #10 wire are for Copper Sheath Rivets. The #9 hole is for Annealed steel wire rivets and the #6 hole is for large Copper Rivets to be used on other projects.


    By spacing the blocks with a business card, the drilled holes are no longer round when the card is removed. The clamping force by tightening the Wing Nuts holds the wire quite firmly. The short hole is 9/16" deep and the long hole is 3/4" deep for the #10 & 12 wire. The inserted wire bottoms in the hole. 


    I have seen other approaches in videos where the end of the wire tip is melted into a ball and  just use a hand held vice to hold the wire. for hammering was used.  They all work to make a Rivet.


    When lightly  tapping the wire with the hammer, observe to make sure the Head doesn't wander off of center. If the head is swaging off center, tap the hammer in a sweeping or glancing motion to force the head back to center.


    Photos: #-47 swage with wire inserted, Hammer and Tin Snips--- -#-49 swage with wire ready to be  Headed.   #51 the Headed Rivet, #-53 completed Headed Rivet.  #-56 swage block open to see drilled holes.






    • Thanks 1
  13. Please view on Youtube "That Works" "How to forge Bevels on a Blade-The right Way". The video shows how to forge the blade bevel without making the blade curve and the correct way to use a hammer. My question is they dipped the hammer in water and wet the anvil face print to forging., While forging, the hammer tapped the anvil to get water on the hammer's face. There wasn't any POP or evidence that the water turned to instant steam. I am assuming that the water removed the scale from the forging peace. The water didn't appear to cool the blade either. 


    Can anyone comment to forging with water on the anvil face and hammer their experience using water as seen in the video.  

  14. Thanks for the mind blowing information. The best way for me to make a blade with carving would be to make a laminated blade. The 1018 outer layer could be carved and an inlay applied after hardening. With experience, the 1018 could be forge welded in the Damascus pattern where the inlay would be located. One of the patterns showed a laminated section where the edge steel is located. Thank you for the guidance information.Tthe blades were significantly more complicated than I ever would have imagined. 

  15. I have been searching information on the Seax knives and sheath design. My search has come up with you as an Expert on the correct design of the Seax knife. Could you point me in the correct direction to the dimensions for the "Honey Lane" blade?

    The Honey Lane blade as shown in the British museum pictures doesn't give dimensions other than the overall length, including the Tang as "266mm".  


    The Honey Lane knife has twisted silver/copper wire embellishment inlay. I would assume that the original blade was Iron  or unhardened steel of the day. Is there any way to make a hardened/tempered blade and soften the spine area enough to make the inlay work? The silver/copper inlay would melt at heat treatment temperatures.


    From my limited search of the forum, others have make the seax knife Ie: Robert Suter in 2011.


    The sheath is equally important to correctly complement the knife. Can you point me in the direction of the correct Sheath design? It appears that the sheath may not be sewed but secured with a rivet every 4-5 cm. rivet iron or copper? Bronze would be too brittle to reliably forge the Head and upset.


    Copper and bronze plus iron/steel were the metals of the day. I would assume that most  Seax knives were very basic, with no embellishments. The embellished knives probably would have been owned by the wealthy and leaders of the day. From my google searches, the knives and sheaths shown fall into the "seax-inspired"  category.

  16. DSC00917.JPGDSC00916.JPG


    Viking knife progress report. :

    Blade: 15N20/1080, 15 layers, Twisted, forged flat, flat sides forged blade to a  "V" shape, back 1/4" thick, length 6", sanded with 1000 Gr.

    Handle:Curly Maple, 5" long

    Etch: 10 Min in FC/water, 50/50 solution (Too Strong)


    There is very little contrast between the layers. I tried Cold Gun Blue thinking the 15N20 would not blue-Wrong. The entire blade was a very dark blue. I used the 1,000 gr. wet sandpaper to start removing the blue from the 15N20 and hopefully leave the 1080 alone-wrong. Finally, the blade was buffed with White rouge. I did wind up with a little better pattern definition in the line around the 15N20. Both steels remained about the same sheen. The scratches seen in the blade photo are from wet 1,000 gr. sandpaper. 


    The handle was shaped using a belt sander, the Brass ends were shaped and CA glued on. The handle was then finished as one piece, sanding to 400 gr.. The cavity in the handle was partly filled with epoxy and the blade was then inserted. After the epoxy was hard, the handle end of the knife was soaked in Walnut stained Walco Oil for 30 min. and wiped dry.  When the oil has curbed in several days, the handle will be buffed. The blade will be buffed to eliminate the sandpaper scratches.


    The leather sheath will be next. I have never worked leather so any suggestions will be appreciated. I bought half a Tandy store for leather tools.  


     I use the Black 3M wet/dry sandpaper, wet and wrapped around a flat steel bar. This maintains a flat surface. But, it doesn't' prevent sanding a dip in the blade.  When the blade was annealed after grinding, it was draw filed , then flat sanded.


    Are we having fun yet?


  17. I again thank everyone for their  "How to do it" processes. The responses are very similar which leads me to conclude 15N20/1080 or 1084 is the way to go.  


    Thinking, since the 15N20 stands proud of the 1084 and the 15N20 has nickel in the composition, could the hardened/tempered blade be polished and then  hot blued? The 15N20 shouldn't take the blue while the tool steel should blue nicely. Has anyone tried the hot bluing idea on their blades? If so, what were the results?

  18. Thank you for the information,     


    I will be using my almost finished being built Side Draft Forge.  My home built propane forge won't reliably reach welding heat. However, I have a aspirated two burner Mankel forge with three open sides. With 2" thick brick stuffed into the open spaces on 3 sides and the open side choked with another firebrick, it just might be able to hit welding temperature. I will need to get clay type kitty litter to fill the bottom depression that is about 1"deep x 3" wide and 12" long. It uses a blower that has a regulated air flow flap. I got the forge almost 20 years ago, didn't like it and pushed it off into a corner. I use coal for all my craft type forging. Making knives and especially Damascus blades is new to me.                                                                                                                                                                                                                                                                                    


    I just checked with the Jersey Steel Barren and they have 15N20 and 1084 in 0,070" thicknesses. I had dbbe checking the knife supply houses like Jantz to be treated with a "Out of stock" note next to the steel.


    I will order the steel in 1-1/2" width 0.070" thick. I will find out what the postage difference is between 24" and 48" stock. I will check out "L6" also.


    At the Thrashers Reunion I found a vender selling O1 flat stock from 1/16" up to 1/4" thick and 2" to 4" W ,18" l..  The thicker O1 will be used to make laminated blades in axes.


    I will send an order in for the steel blade stock tonight.


    great information!!!

  19. I am new to making Damascus blades. 15N20 seams to be the desired steel for the silver appearance in the Damascus pattern. Other carbon steels such as 1080/1084, O1, W1, 1095 are all listed as good steal to partner with 15N20. Looking thru the knife blade material suppliers shows various thicknesses of each of these steels. The thinner the steels, the more layers can be forged in the initial billet.


    Can you recommend what your favorite steel type numbers are for the billet? What is the best thickness for each steel?  What is a good pattern sequence of these steels as stacked into the billet? How many times do you recommend  folding the billet? How many layers  of steel give the best Bling? 


    I assume that each time the billet is to be folded, the billet is ground to a flat, scale free surface before the next weld. How much extra thickness of the initial steel layers  (or added layers of steel) do you add to the initial billet to account for the steel removed from grinding so the final billet can be forged into the desired knife blade? 


    After the Damascus blade is ground to shape, is then etched. What is your recommended etching solution concentration, solution temperature  and time to etch? The 15N20 steel stays bright and the other carbon steels will be eaten away making the 15N20 layers stand proud. After the black carbon deposit is removed from the fresh etched knife blank the carbon steel won't be significantly darker in the pattern. What is the best way to darken carbon steels to better pop the Damascus pattern?  


    If possible, what are your favorite suppliers for the steel grades that you use to make Damascus blades?


    I will be using the Mark Aspery design Side Blast Forge with the Super Sucker Hood , burning coked coal with green coal around the outside of the fire.. 





  20. I greatly appreciate the great information concerning pattern welding. 

    From the information I have received, using coal throws a huge snag in the welding process. Namely, there  is a huge risk of overheating the blade.on the outside of the stack and having the interior too cool to take a weld. 

    Just thinking, the size of the stack may be a major contributing factor in coal forge welding problems. If the stack is kept thinner, then the interior would have a much better chance to reach welding temperature at the same time as the exterior. Of course, thinner stack mean more cut and weld heats.

    My propane forges won't reach Welding heat, so the coal forge is to my rescue.

    I have been reading about dipping the stack in Kerosine

    I have a lot of diesel fuel to run tests on instead of kerosine. Anyone tried diesel when welding in a coal forge?

  21. Being new to knife making and forge welding Damascus knife blades, I see references to Welding with no flux, welding with Borax, welding with WD40, and Kerosene. Could some of the experts members detail how they prepare the blade material stack for a, Dry welding (no flux) , b, borax and other commercial welding compounds, c, WD-40 and, d, Kerosene. 


    I use a coal forge for most forge work including welding. To determine if the metal is hot enough for the weld, should I look for the first spark and then weld or match the color of the wet looking billet to the coals under and around the billet? In the past when the first spark welding, when the metal was removed from the fire it burst into sparks. Matching the metal color to the background coke worked best.

    • Like 1
  22. charcoal making using 30 gal. barrels and dirt. Cut the top and bottom out of one barrel. second barrel remove the top by cutting it off about 2" down on the side and for the bottom cut small holes all around the bottom,. Fill the bottom barrel with small pieces of wood. Light a fire on top of the wood in the bottom barrel.. Place the first barrel with the end removed on top of the bottom barrel. throw more wood on top of the bottom barrel as the charcoal volume will shrink when the wood becomes charcoal. When the fire is seen in the holes cut in the bottom sides of the bottom barrel, knock the top barrel off and place the cut off barrel top on the bottom barrel. shovel dirt to cover the vent holes cut in the bottom barrel. When the bottom barrel is cold, it will be full of charcoal.


    second method. build a large pile of wood chunks, tree limbs etc. set the wood pile on fire, When the wood pile has burned and the flames are mostly out. shovel wet dirt on the pile to keep the air out. After several days, the fire should be out and the wood turned to charcoal.

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