1971-D Ike "Peg Leg"?

These Peg Legs were created by the polishing (or abrading) done to the area between Ike's head and the "R" on the working or master dies.
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robEzerman
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Re: 1971-D Ike "Peg Leg"?

Post by robEzerman » Wed Jan 27, 2010 9:31 am

To expand just a bit on that theory, proper annealing requires precisely slow heating to an exact end point and then precise slow cooling back down, uniformly throughout the die (one reason it takes days to anneal a die).

The "elevated highway" configuration on the die between the foot of the R and Ikes head gives this little area a greater surface area to volume ratio than elsewhere on the surface of the die.

Thus, during annealing, the die steel in this elevated narrow strip would tend to heat faster and cool faster than the surrounding die, setting up a greater likelihood of heat-check die cracks.

In other words, the design problem here is the proximity of the two incuse cavities on the die, the foot of the R and the top of Ike's head.

And all of this, IMHO, is the main reason Gasparro was fiddling with peg leg designs early on (Lee's Prototype, for example, and the initial batch of 71-S Ike Proofs (design peg legs), and why when serifs were put back on the foot of the R ("Funny Foot" 71-S Ike Proof and 73-on Ikes) there was greater separation from Ike's head.


Rob
Now is the time to cherry Ikes. Lots of fruit still on the trees but don't wait too long. Rob Ezerman

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AndyO
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Re: 1971-D Ike "Peg Leg"?

Post by AndyO » Wed Jan 27, 2010 7:10 pm

By and large, Rob has it correct. The whole metallurgical "failure" of the die steel in that area is due to the cross section of that area being dramatically thinner than the other areas of the die. Its just tough to keep that little isolated "island" of die steel cooling at the same rate as the other areas. This area had to fatigue much more rapidly once in service. I am totally comfortable out on this limb saying that is the root cause as to why you see much more space between the R and hair area on newer year Ikes.

Andy
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