[TheForge] Precision Forging

[Adam Whiteson]

The best way that I know is to take a ball of modelling clay - you know the 
stuff that doesnt dry out but remains plastic - work it into shape you are 
going to forge, trim off any excess and then roll it back up into ball or 
cube to estimate the volume.  Or, if you dont want to do any math at all, 
you can even work it into the shape of the stock you are going to start with.


*******Long, rambling anecdote follows**********************

I am a believer in simple, reliable methods.   Years ago, before digital 
scopes existed,   I needed to estimate the area under the curve of a scope 
trace.  Since my training is in mathematics, this was no 
problem.  Simply,    a. take a polaroid picture of the trace.  b .Sit down 
with a pair of dividers and measure as many points as needed for a good 
estimate - about 25 in this case - c.  type them into the computer - d. run 
a fitting program to find the spline coefficients -  f. feed the 
coefficients to another program that would do the integral and  g. 
wallah!  (voila).

About  10 mins into this exercise and still measuring points on the trace, 
Bob the lab tech  (not Bob Rackers :)  ),  poked his head in my office and 
said something like "it's  5.7 milliwatts".    My mouth fell open and he 
explained that , using a photocopy of the polaroid, he had   a.  taken a 
pair of scissors and cut out the area under the trace and weighed 
it.  b.  Then he cut out the silhouette of a single graticule  (the little 
squares on the scope grid) and weighed that too.  c.  he came up to my 
office to gloat.  (Bob had no college degree  and never missed a chance to 
show up a "dumb assed Phd")

In an effort to save some of my pride I went on with my scheme.  Took me a 
couple of hours and three tries to get the same answer.  If I hadn't had 
Bob's estimate in hand , I might have stopped at two tries feeling that I 
had the right answer.

Adam

At 04:17 PM 6/3/2002 -0400, you wrote:
>I'm curious to hear how everyone calculates the amount of material (i.e.
>length) required when the piece will have at least one bend.
>
>I figure there are four types of bends, and each requires a different
>calculation.
>
>Assuming a 90 degree bend, you could have
>  A. Radius inside the bend / Radius outside the bend
>  B. Radius inside the bend / Square corner outside the bend
>  C. Square corner outside the bend / Radius inside the bend
>  D. Square corner inside / Square corner outside
>  E. Long radius (many times the thickness of the material, e.g. a 10" radius
>made from 1/2" rod)
>
>Assume making something with the following shape and dimensions from 1/2"
>square.
>If the lengths of the horizontal portions (left to right) are respectively 3",
>6", and 3", and the two verticals are both 2", (in other words, the portion
>UNDER the middle horizontal line is 2")....
>  1. What is the total length of the item (horizontal distance S to E)?
>  2. For each of the above types of bends A - D (ignore E), how much material
>length is required?
>            ____________
>S______|                 |______E
>
>The straight portions are easy enough to add, but I'm curious how everyone
>calculates the required bending allowances for the different types of bends.
>
>Please show your work. :-)
>
>Bob
>
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