@Insider Have you ever seen a screw press dime?

I think I found a dime that was struck on a screw press from the Bombay Mint.
I didn't know if you saw the update I posted.
It's still in the US Mint packaging so you know I didn't tamper with it.

Anyone that wants to catch up can Google type of coin press at Bombay Mint

 

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I'm not sure if I understand this. You think a US coin in US Mint packaging was made at the Mumbai mint using a screw press?

 

No.... you would need to catch up on a prior thread on another forum. Google

It's kind of an insider joke.

 

Not that it is important, but it would have been Bombay, since the coin is dated 1981, if that is what happened.

But, that is not at all what he is referring to. (Hint: the piece has not been cleaned to produce the pretty swirling design).

 

@charley "the pretty swirling design"

What might have caused that pretty swirling design?

 

That's what I have to go on here. Maybe it's clear to you, I guess.

 

I think we both know the answer, and moving from a diamond 200 grit up the ladder to a 3,000 grit (wet) on terrazzo...cementitious or epoxy, will produce the same effects. The same effect can be produced in any machine shop, with varying intensity of depth...for instance S4S Stainless vs. 404 SS.

That would indicate the die was reworked and was stationary in the screw press. Swirling can not be controlled and certainly not when the die is slightly concave on the receiver side.

 

In machine shops, not uncommon to see machinists clean up tools/dies by placing them in a 3-jaw chuck and spinning the tool while applying Scotchbrite. But I think something like @charley is noting, where there may be a suspended diamond solution on a spinning plate where the solution is puddled and the die face brought down parallel and on center to clean up the face, leaving the swirls. A step like this would put the finishing touch to a die face after cleaning up some kind of witness mark on the face of the die (e.g., removal of a rougher cleanup, perhaps to remove a clash). Just speculation...

 

LOL, I forgot all about that thread discussing circular metal flow lines. I was shocked that folks never heard of it.
On occasion, circular die polish (on your coin) is seen on our vintage coins. Last week I imaged a WLH in the 1940's with a nice circular patch on the obverse.

 

...are you saying @Insider is a joke...you loser clown ref to another thread

 

@Kentucky "you loser clown"

I resemble that remark.

 

Diamond polishing paste has grit as small as 100,000 grit, shifted through sieve holes that passes 100,000 pieces of diamond per square inch. Aprox 0.25 microns size for extreme polishing of cut gems. I don't see the marks on the rim edge, are there such there? Jim

 

I am assuming you have never worked with terrazzo or used resin pads on terrazzo, concrete or on metal or plaster. Paste is not needed.

 

I've seen a rubber band

 

Thats a very nice picture.

 

Wow! I was the fool that plugged screw press at the Bombay mint in my Google hickey.that was some conversation!

 

No fool stays a fool when the fool learns something.

 

Since the dies are a reverse of the final struck coin , I don't believe the lines (seen on the bust and background in near equal pressure) are on the die. A polished planchet seems more likely, rubbed with machine oil and attracting dust? Wax on wax off, Daniel San.