Hofi

IForgeIron Blueprints Copyright 2002 - 2007 IFORGEIRON, All rights reserved. BP1003 Hofi Hammer Eye by Uri Hofi 75-80 metric ton hydraulic press "denison" made in England. THE TOOL The side and front adjusting screws are 14 mm OD every full turn is 2 mm with this i can adjust very easy the steel in the center and exactly to adjust the place of the chisel from the head of the hammer. We can see the stripper plate in "open" position. The chisel is made out of pure tungsten (out of an armour piercing shell ). The tungsten is not steel it is a different element in nature specific gravity is almost 3 times more then the steel, and it can withstand much more heat. There is almost no friction between the steel and the chisel!! When the tungsten is red hot (we can see it later in on of the photos) the H R C is still 38 and it will go through 1200 degrees steel easy. The bottom plate is 1.5" mild steel. Chiseling adjustable supporting tool. The stripper plate in "close" position. The steel out of the forge. I use two gas forges one for primary low temp and the other for the higher one 1800 degrees max. I call it "progressive entry". From the moment you start you do not stop and the sequence is 1.5 minutes a hammer in the punching. Try to keep the heat of the metal of the hammer at not more than 1800F degrees or 1050C degrees. And if the whole process is kept at this temperature to the end, you do not have to normalize the hammer. If you go over 1800F degrees or 1050C degrees, you create grain in the metal. It takes only some 10 tons of pressure to form the eye in the hammer. The steel in place, stripper plate "open ". Stripperplate "close". The chisel is pushed into the steel. The chisel moves up and the steel is striped off the chisel down. "The chisel is pushed in 3/4 of the depth and then turn around and repeat the same operation from the other side all in the same one heat " The eye is chiseled punched. Cooling the chisel with anti seize coolant. The chisel is out red hot. Another photo of cooling. The coolant is 50% graphite, and 50% MSO2 (Moly-disolfide). Mix with liquid soap until blended, then add water until it is a thin solution. The 30 eyes are finished. the whole process takes 40 minutes. THE GERMAN STEEL IS MATERIAL NO 10503, GERMAN NO. C-45 COMPOSITION : C 0.42--0.50 Si 0.4 Mn O.50--O.80 P 0.O45 S O.O45 Cr O.40 Mo 0.1 Ni 0.40 FORGING TEMP 1500--1900 F NORMALIZING1500--1690 F QUENCHING 1480--1550 F WATER OIL HARDNESSRC OIL 54 - 56 HARDNESS RC WATER 58 - 62 TEMPERING 550--900 F Hope every thing is clear. Additional material: I really do not know the composition of the tungsten ,what i know is that they are getting better and harder and tougher every year,when i started to use the tungsten 17 years ago they were 37 hrc to day they are 43 hrc .i get them from my student that are coming back from the training fields after the shooting they collect it on the ground,you can form the tungsten by grinding with flap or belt grinder, milling machine with carbide bits or on the lath also with the same cutting bits.

IForgeIron Blueprints Copyright 2002 - 2007 IFORGEIRON, All rights reserved. BP1002 Hofi Hammer Technique - The Swing by Uri Hofi Photos by Johannes Angele Many blacksmith think that to forge down or to hit the steel is the moment u need the power which is NOT !!! right.The moment u need the power is when u raise the hammer.The style and length of the handle, the place and the way u hold it in the Hofi system solve that problem and keeps the hand undameged. The hammer is an constructed as an balanced ergonomic hammer. Why balanced? The construction is designed that when you tilt the hammer and we all ways tilt the hammer( to moove more mass and faster) it will stay the way you want it without having a rotational move and by then you do not loose forging power and there is no effect what so ever on the wrist and again you protect it. Shows it and I will explain: When you hold the hammer loose first of all u do not waste power on holding the hammer,with the limited power we have every bit is importent.SO HOW WE RAISE THE HAMMER? When we swing the hammer down to forge with full speed the moment it is all most hitting the steel we loose the grip on the handle, the hammer is aimed, the speed is there, the hammer do not need us any more we LET IT GO them we do not disturb it to bounce up from the reaction! There is always reaction to the action we use it to help us raise the hammer first with the wrist by that we shorten the distance between the hammer and the shoulder shortening the liverage to half and then using half of the power to raise the hammer. Now the hammer is up and we start the forging down.To get maximum work we need to exelerate to maximum speed (we all know the second law of motion of newton, Work is equal to the mass times the volocity squared, divided by 2. YOU CAN SEE IT ON THE PHOTOS). How do we exelerat? We use the 4 joints the shoulder-power, the elbow--power + more speed the wrist--speed and the last is the loose grip on the handle. (Remmember that when we raised the hammer it came first now it comes last) the heavier hammer we can swing in the higher speed the v is in square we get much more forging power and we move more mass.. Holding the hammer another view. Tilting the hammer while forging. Using the edge of the anvil and hammer to move the mass faster. Hope every thing is clear. Uri Hofi

IForgeIron Blueprints Copyright 2002 - 2008 IFORGEIRON, All rights reserved. BP1000b The REAL story about the Hofi Hammer by Uri Hofi I want to clarify some subject in this discussion and tell a story. There is ''no'' ''Czech hammer'' a ''Czech hammer'' is not existing in the Czech republic. The Molnar the Biehal the Josef Muck the Habermann every one of this long time blacksmith families that all of them I know and visited and with all of them with very good relationship are forging with d i f f e r e n t hammer .the hammer that people here and in the us are referring to as the ''Czech hammer'' is the Hofi hammer. It is not a modification of the Habermann hammer (that was invented and forged first by his grandfather). The ''Hofi hammer ''is completely different hammer" and if one looks at the hammer one can see that the design is completely different the balance the handle the longer pien the radiuses and the grinding. The story of the ''Czech'' hammer started when George Dixon in his book on Francis Whitaker the late in the paragraph of hammers. He put a drawing of the Hofi hammer and called it Czech. In three places in the states the ''Hofi'' hammer is forged 1 At the Ozark School by Mr. Tom Clark that I was teaching at the school for 5 years and Mr. Clark visited my shop in Israel 4 times and I taught him how to forge the Hofi hammer. Tsur Sadan that is now teaching at the Ozark was my student for 4 years at my smithy. 2 The BigBlu by Mr. Dean Curfman that also paid twice a visit to my smithy in Israel twice special to learn how to forge the Hofi hammer and to grind it and also to learn about the quick change system for the air hammer die and about forging other tools that he sells now. The air hammer school is also my idea and I was teaching there the '' free form air hammer system''. Mr. Dean Curfmann also took three classes with me at the Ozark and in NY. 3 Doug Merkel that took also three classes with me two at the Ozark and one at the air hammer BigBlu school. Now Thomas Dean the story of kissing the hammer. 10 years ago I was invited by BABA to participate in forging elements for the ''niddle'' a huge sculpture the is now located in Newcastle on the side walk along the river. The meeting was in France in doarnane on the brest bay a beautiful fishermen harbor on the channel in brest bay the other side of England. 54 blacksmith from Europe and England took part in the forging meeting. A young man by the name of clod was following me like a shadow all the time where ever I moved he was there. After three days he dared to ask me: Mr. Hofi how come you are forging with one hammer only and do it easier and faster then all the others? I with my sense of humor answered him very earnest, clod when you enter the smithy in the morning first thing I do is standing opposite to the anvil take the hammer and kiss it then go around the anvil and kiss again when you do it 7 times the hammer will forge alone. Next morning he came to me and said Mr. Hofi I tried it and it did not help. A month later clod came to me to my smithy in Israel and stayed 1-1/2 years. Now he is married, has two kids, an he is teaching the Hofi system in France. This story I am telling every where I teach and also kiss the hammer daily. Sorry for the long story but I think it is nice Hofi The Hofi Hammer Cast Hammer vs Forged Hammer To my opinion the cast is better then the forged. The deference is small. An amateur will not fill the difference. The 6150 steel of the cast is a better steel then the c45. The cast is more balanced because casting on a mold I could arrange the steel in a better and more balanced form and there for more ergonomic. I myself forge today mainly with the cast hammer. There is a belief that the forged because the grain re-organizing is better then the cast. Not any more !! To day with the lost wax system that the air is leaving the mold from all around the mold and not only from the air outlet the grain dispersion in the cast is better. Even in the industry many parts that were forge are cast today. And it is very interesting also that more and more I sell more cast hammers then forged. The people loves them. Hofi