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Will W.

Formula for drawing out?

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Good day. I just finished the initial welding on a damascus billet I'm working on. The welding went suprisingly well! The piece is currently 1" thick by 3/4" wide by 6-1/2" long. I want to draw it out to about 1/2" thick by 1 inch wide by ??? long before cutting, folding, and welding again. I'm wondering, is there any sort of mathematical formula that I can use to figure out roughly how long the piece will be given the current and desired dimensions? I realize this is very dependant on several variables, but I'm looking for more of an approximation than anything. I also realize that I could just do it, and what I have is what I'm left with, but this would be useful information for many situations.

I did search for this question, and the little I found was more about "I know what finished dimensions I want, how much metal do I need?" Rather than how much I will end up with given what I have.

Thanks in advance. 

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I think you can just do a volume calculation and be pretty close.  

You currently have 1 x .75 x 6.5 = 4.875 cubic inches.  So your target is .5 x 1 x ? = 4.875, so your answer is 4.875 / .5 = 9.75 inches long.

Just doing this in your head you could see that the current cross section is .75 sq inches, and you're going for .5 sq inches, so based on the cross section being 2/3 as much, the length will be 3/2 or 1.5 as much. 

-- Dave

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In my opinion, the best way to determine this is "conservation of volume" (as long as we dismiss the metal you lose to scaling).

Before drawing out, and after, you have the same amount of metal. The same volume.

You start with  1" x 3/4" x 6-1/2" = 4  7/8  cubic inches, which is the same volume you have at the end.

So: 4 7/8 cu.in. =  1/2" x 1'' x ??? => Dividing, you get ??? = 4 7/8 divided by (1/2 x 1), which in this case equals 9 3/4''

 

EDIT: Well, WMG jsut beat me to it by a few seconds.

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3 minutes ago, Andres Bello said:

EDIT: Well, WMG jsut beat me to it by a few seconds.

Two great minds!  I'm glad we came up with the same answer!  -- Dave

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Thanks for the quick replies guys. That's actually what I was hoping to get to, about 10 inches. I appreciate the help, and I will definitely be recording these formulas for future note. 

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For more obscure things, a lump of clay sometimes is happy to do some really complicated stuff.

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I've heard of that, C-1. Never tried it myself though. I think it would be hard to do precisely though, clay is a little too maleable, it would seem. Like I said though, never tried it. 

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When you reduce the diameter of stock by half it grows at a 4 to 1 ratio in length. One inch of one inch square reduced to one half inch square will be four inches long. Take your dimensions and do the maths! Happy forging!

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Good Morning,

C-1 is correct. You should have a container of Play-Doh, Plasticene, Modeling Clay or Cookie Doh in your Tool Bag. The answer to your question would be in your hands. K.I.S.S.

Neil

 

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Surprisingly, Neil, I have none of that around. Looks like I may have to make a trip to the local craft store to pick up some clay (or head down to the river bank with a shovel and a bucket lol)

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Go for the plasticine from the hobby store: it's reusable and doesn't dry out like river clay.

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