Mercury Dimes

Yes.

 

And interesting document and I thank you for posting it. However, this is rather pertinent to the discussion at hand and it comes from that document.

"October 1987
Final Report

This research was undertaken to determine the feasibility of automating the
polishing process of proof dies at the United States Mint, The dies polished
during this research endeavor were the obverse Kennedy half-dollar dies, While
most of the techniques used in this study are new, some of the techniques
developed by Sidney Weiser (Phase 1 December 16, 1985 and Phase 2 December 3,
1986) were incorporated into the polishing procedure. "

My point is this, those methods you describe of using polishing wheels that are 3/4" in diameter were not used until those dates you also see above. And the coins were talking about were minted before those methods of polishing dies were ever used. From the late 1800's on, and maybe even prior to that, dies were polished by machine using large polishing wheels that made it impossible for the wheel to touch the devices. Only the fields were ever polished.

I would also like to point out that while these more modern methods using tiny polishing wheels are sometimes used, great care is taken to not ever touch the devices on a die with those wheels. Only the fields of the die are polished. But yeah, I'll admit that a mistake could happen.

One last thing, the US Mint has provided videos of how modern business strike dies are polished, links to these videos have been posted here before. And the die polishing is still done by machine, fully automated, using large polishing wheels that make it impossible for the devices to be touched during polishing.

 

I wish there were some ! Then I'd be all too happy to post them. Many years ago I found the information describing the die polishing process in a copy of Numismatist published in 1917 I think it was. Other than that, I've never even seen or been able to find the information in a book or modern article and I used to own one of the most extensive numismatic libraries that just about any private collector ever had. Anyway, back then, as well as before and after, they used large zink plates impregnated with various grits of diamond dust paste (depending on which stage of the polishing they were doing at the time). And that's something else that a lot of folks don't realize, it's not all done in one operation. They'd start out using a course grit paste to accomplish the first stage of polishing. Then use a finer grit, and then a finer grit, and so on until the polishing was complete.

The zinc plate was installed in a machine much like a turntable on a record player which spun it at a high rate of speed. The dies were rigidly held by another machine which would lower the dies until they came into contact with the plate thus enabling the polishing to occur.

That basic method was used well back into the 1800's (never could find out exactly how far back) and it continued to be used until even today really.

Though in today's world they have changed things just a bit - now they use large brush pads and felt pads at various stages instead of zinc plates - but it's the same basic process, large pads small dies. Here's a screen shot, click on the image and it'll blow up for you. You'll find the pictures of that machine in one of the links I describe below.




Also in today's world, once a die has completed it's polishing process, it is inspected and if it needs any final touch up then that touch up is done with those small dremel tools the article you linked to mentioned. If no touch up is needed the die moves on to production. Oh, and they still use various grits of diamond dust paste to polish dies.

Now all of this regarding today's methods for making hubs, dies, and coins, can be found by using this link -

http://www.coinnews.net/2013/10/04/how-the-philadelphia-mint-polishes-dies-to-make-proof-coins/

BUT - it's not all on that one page. That single page only describes how they polish Proof dies in today's world. But that page does however also contain the links that are need to find out about everything else. What I'm trying to tell you is that you need to read, explore, and utilize all the other links you find on that page to find out about the entire process. And remember, what you find on these pages ONLY deals with the most modern processes. Similar, but different, methods were used in the - how else can I say it - the old days.

 

One last thing, I also think it important to at least mention this. Any time, on older coins or even modern coins, that you see die polish lines on a coin it's because somebody at the mint screwed up - made a mistake. You are never supposed to see die polish lines on a coin, not if they do their jobs right. When you do see them, it's because the final stages of polishing were not even done. If they had been - you wouldn't, couldn't see any die polish lines. And, about the only time you do see them is when a die has been re-polished after it has been used for a while. It can be re-polished to remove, or attempt to remove, clash marks or just because the die has too many or too severe wear lines from metal flow on it. Those are about the only times dies are re-polished.

But even the re-polishing follows the same process, they start out with a course grit and work their way up to a fine grit. The course grit is necessary to remove clash marks or wear lines. The course grit will leave visible die polish lines, the finest grit will remove all trace of them. So when you see die polish lines on a coin, it's because somebody skipped the final polishing sequences. They screwed up, got in a hurry or just plain skipped it because the dies were needed to continue production.

Also, if you follow the processes I have described in these posts, and think about it for a few minutes, it soon becomes quite evident that what I have been trying to tell people for many, many, years now about how die polish lines can only be in straight lines and never criss-cross each other. It simply cannot happen - because of the process.

Hopefully some will find all of this useful.