These two lathe company links...
RobertLahti
Posts: 328 ✭✭✭
...have both written how one of the centers of the lathe has a socket holding it and can be turned. That is why coins have taken on a square center. They have a lathe saying "good enough" when the center comes at the conclusion.
This is in regard to Jason Cuvelier's 1982 cent reverse squared concentric lathe lines concern. Also this same sighting of 15.
https://www.lprtoolmakers.com.au/blog/lathe-alignment-guide-for-beginners/
We'll see...WHAT? What brought your attention...?
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Which means it's rather reduction hub related, which supports how it can remain after a subsequent hubbing.
We'll see...WHAT? What brought your attention...?
One of these days we'll find a way to tell which 1982's came from the west point mint.
We'll see...WHAT? What brought your attention...?
4 excerpts from numismatic periodicals dealing in reduction lathe master hubs.
We'll see...WHAT? What brought your attention...?
This coinworld link houses the Jason Cuvelier 1982 cent reverse lines. (Its the last picture at the top of the page, touch the red arrow to scroll) It also shows the squared middle, which the lathe companies links in the first topic in this post have confirmed is a sprocket hold the lathe in the middle allowing it to spin.
https://www.coinworld.com/news/us-coins/die-ring-error-coins-lincoln-cent-jefferson-nickel.html
We'll see...WHAT? What brought your attention...?
That last photo in the Coin World article does closely resemble the photos you posted in the other thread. Color me surprised.
Nothing is as expensive as free money.
@RobertLahti
i looked over the info and am still wondering what you are aiming at.
it has been known for a long time that the concentric circles so often seen on coins are from the reduction lathe and probably with other man-made methods as we also know the mint(s) did a LOT of different things to the dies, re-engraving, using acid, re-hubbing, re-punching, grinding etc etc.
now, if you are just sharing and studying up, more power to ya!
OR is this all to track down an explanation(s) for the "square" marks you referred to?
A reducing lath and a conventional lathe are very different creatures.
What you are describing in your first post is called a live center, basically a pointed part that can spin that supports the end of a workpiece and is used on a conventional lathe. This is attached to the non-powered end of the lathe called the tail stock which can slide to accommodate the length of the part being produced. A center is only used if the workpiece is long enough that it needs end support. Additionally if you are using a live center the workpiece needs a center hole on the end to accept the point, and while the live center is being used no work can be done to the end of the shaft.
All this is irrelevant though since a reducing lathe is not a conventional lathe and does not use live centers.
I'm sure there is a machinist or two around here who can probably explain it more in depth than I can.
As far as the "hexagonal" (they look more octagonal to me) lines in the link above, my only guess would be a worn or flat spotted bearing, or some other source of imprecision caused that.
What question are you trying to answer with our research?
Collector, occasional seller