Hofi

IForgeIron Blueprints Copyright 2002 - 2008 IFORGEIRON, All rights reserved. BP1052 Big Spirals by Uri Hofi I had an order for 25 each 16 inch OD spirals made out of 20 mm (800thou). And 86 small spirals 22 inch OD from flat steel 3-1/4 inches x 5/16 inches. To forge those i had to fabricate a spiral template made from 1/2 inch round plate and constructed that the spiral is made of segments.To be able to bend the steel on in flat dimension. Its having handles around to be able to rotate while heating the steel. The plat is having a shaft in the bottom center and the tool is seating in the swage block. After calculating the length 9 feet we forged the starting point to 3/8 inches to the length of 13 inches. Bending the start point to mach the template on the point of the round bick. Because of the length it is supported with a leg on the other side. Re adjusting and holding the start with the vice grip to the template. With a rosebud heat and turn the template. The segments. Adding the next segment. On with the heat and turn. Adding the last segment. Coming with the bending to the 16'' od whit mark. One can see the supporting leg in the rear. Taking the spiral out with a crowbar. In with the last segment for storing. Shay Vaknin my student helper with the tools. The customer wanted a counter bend so we made a template for this too. The finished element

IForgeIron Blueprints Copyright 2002 - 2008 IFORGEIRON, All rights reserved. BP1051 Punch Calculations Calculations for holes, punching, tools, and measurements marking by Uri Hofi There is a basic debate on the calculation and tooling (chisel+drift proportion). For round hole punching. Lots of tradition and legends are involved. What I will try to show and demo is a very modern approach out of the tradition. The basic idea is how to punch a line of holes, in a bar, in a way that the length of the bar and the distance between the hole centers will not change. The calculation in the inch system. The formula for ''shrink and expansion'' for steel is 0.00000635 xtempin degrees fxod of the hole in thousandths of an inch. The average temp of the process is 1500 degrees F, if we will calculate on any given dimension we will get 1%. For example for a 3/4 inch hole 750 thou 0.00000635 x 1500 degrees F x 750thou = 7.08 thou 7.08 thou :- 750 thou x 100 = 0.945% We take as 1% to make the calculation easy Always when we make the tooling calculation we start with the drift For 3/4 inch or 750 thou hole we add 1% which is 7.5 thou = 757.5 thou Now we have a problem if we will follow this calculation of 1%. After we'll finish the drifting the hole will shrink the 1% back and we will get exactly 750 thou hole and it will be too accurate to put the cross bar in. So practically we add not 1% but 3% then the drift will be 750 thou + 22.5 thou = 772.5 then after cooling the cross bar will have 15 thou clarence which is very good result for assembly of a complex lattice work. We do not have in the market steel in 772.5 thou od dimension !! So we have two options 1) To take a bigger od steel forge to the rite od and leave a little more for final grinding. 2) Cut a piece of 3/4 inch steel (I use H-13) from which you are going to forge the drift. Heat 3/4 of the height with a rosebud, upset a bit more then the 3%, and forge the drift and grind to the final od of 772.5 thou. Next is the chisel According to the system you saw in the demo the width of the chisel is exactly the same like the drift 772.5 thou. We will forge and grind the chisel according to this calculation. Even if we forge 10 holes in the line on a bar, the length of the bar, and the distance between the holes will be maintained as planed and marked originally. Left is the drift, Right is the chisel. Law If the bar will be longer after the operation that means that the chisel was too narrow. If it become shorter the chisel is too wide Always when I have a project with lots of holes, I take a certain length for sampling and check if there is a change. If there is a change, I adjust the chisel accordingly. Only then do I start the job.

IForgeIron Blueprints Copyright 2002 - 2008 IFORGEIRON, All rights reserved. BP1050 Punch /Drift Round Hole in Round Steel by Uri Hofi In this case the hole is 20 mm od in the 20 mm steel. 20 mm is a bit more then 3/4 inch (800 thou). Cut 600 mm (24 inch) long steel, mark a line along the steel, mark the center of the bar, and mark 150 mm (6 inch) to both sides. This marks will be the center of the 3 holes. The punched bar will be a part of a window railing in an entrance door. Center punch with squared point. When hot one can see the mark better. ''The third hand tool''. Will be demo and explained later. 3.3 hammer, two chisels, two drifts, two aligning bars. The can with the ''moly-graphite'' lube. All the tools are smeared and dipped in the lube before every operation. The steel is hold and supported by the tension of the rubber. And chiseled from one side. Chiseled from the other side. You could not see in the photos but Shlomo took the other chisel and returned the first one to cool in the lube. By this we save a lot of time and finish the chiseling in one heat. When punching many holes we work in a team and a striking hammer, then we finish the slitting and the drifting in one heat. Final touch with the chisel. Reheating in the gas forge. Hammer the drift into the slot half way. Push out. Turn around and go all the way to get the hole finished. The drift is falling into the water under the anvil prichel hole. With a round shallow fuller we brake the sharp corners of the hole. And center the hole in the bar line. The drift out of the water to be lubed again for the next operation. Second hole first side. Second side and finished slot. Now we heat a local heat it is going faster and you do not over heat. The drift from the first side and pushed out. Finished two holes. Again the brake of the sharp corners. Straightening the bar on the anvil corner. One of the advantages of this type anvil. Reheat the steel for the aligning operation. When punching holes in a round steel the holes never come out aligned and parallel we must align them. Stick the two bares in the finished holes and ''twist'' from side to side. When the interval is the same you know you are ok. Preparing for the third hole. The third hole to the finished three holes. The tools and finished bar. Shlomo Erel that forged the demo very professionally. The third hand. We cut the steel 600 mm and after the forging the 600mm remain. The distance 150 mm between the two holes and the 300 mm between the three holes is as planed exact. The shelf with all the drawers with the different od chisel-drift. OD ready for any operation. As sample the 20 mm drawer we used. How we maintain the length and the distance between the holes and what is the proportion between the chisel and the drift is Blueprint BP1051.