What Caused these spiral marks on a coin?

Windycity · January 10, 2016 4:41AM

1990-D Kennedy - Obverse shows light spiral marks through most of the coin but particularly noticeable in right field and across back hair of Kennedy. What causes such marks?

TopographicOceans · January 10, 2016 4:45AM

A sorting machine.

WoodenJefferson · January 10, 2016 5:06AM

Hasn't this been discussed here before?

I don't remember the most accepted theory but I'm certain someone does.

JCLIGHTBRIGADE · January 10, 2016 5:32AM

IIRC it was determined that this isn't the coin at all, but the slab...again IIRC.

ShadyDave · January 10, 2016 5:38AM

Originally posted by: JCLIGHTBRIGADE
IIRC it was determined that this isn't the coin at all, but the slab...again IIRC.

This coin isn't in a slab...

Looks like PMD from a coin counting machine

LanceNewmanOCC · January 10, 2016 5:54AM

Originally posted by: JCLIGHTBRIGADE

IIRC it was determined that this isn't the coin at all, but the slab...again IIRC.

there is an effect that is sorta similar.

lathe lines is what ive read as well.

seen them on several type.

Hasn't this been discussed here before?

yup.

would take some creative searching if one didnt know the useful terms to search.

.

TomB · January 10, 2016 6:06AM

I don't believe that is PMD. Rather, I think it was done during production at the Mint.

LanceNewmanOCC · January 10, 2016 6:13AM

Originally posted by: Hydrant

It does appear to be the slab, as the lines are also on the main devises, not just in the fields.

it is amazing what survives the strike of the die(s).

adjustment marks are key to this point.

.

Windycity · January 10, 2016 6:16AM

Definately not the slab as the coin is not slabbed. It's raw, uncirculated and line are on the fields and devices. I am certain it is a minting issue... not pmd.

davewesen · January 10, 2016 6:27AM

Here is another thread saying they are lathe lines that are on the die used to strike your coin.

https://forums.collectors.com/...yword1=die+lathe+lines

SoCalBigMark · January 10, 2016 6:32AM

D Carr was having that effect on some of his products.

dcarr · January 10, 2016 6:44AM

Those are "lathe marks" left over from machining a blank working hub or blank working die. When hubbed, the marks are not completely eradicated.

JCLIGHTBRIGADE · January 10, 2016 6:54AM

I meant through the flip...take it out and then report back...

LanceNewmanOCC · January 10, 2016 7:03AM

Originally posted by: davewesen

Here is another thread saying they are lathe lines that are on the die used to strike your coin.

fixed

.

ctf_error_coins · January 10, 2016 7:09AM

Lath lines error

Windycity · January 10, 2016 7:10AM

Here's another image without shooting thru the flip. Just the coin and camera. This image also shows the same effect below the ear.

MonsterCoinz · January 10, 2016 7:16AM

Weren't these called lathe lines? I think I remember Charmy doing a writeup about them if memory serves.

astrorat · January 10, 2016 7:18AM

Originally posted by: Hydrant
Dan, so I guess I was half right with my first answer. They were caused during the lathing. But why do the spiral lines show on the main devise. Wouldn't they be removed in that area during the engraving?

Modern dies are not engraved. The devices are impressed on the die during the hubbing process. So, it is possible for what is on the surface of a working hub or working die prior to the "squeeze" to be impressed into the recessed areas of the devices.

CaptHenway · January 10, 2016 7:52AM

Originally posted by: dcarr

Those are "lathe marks" left over from machining a blank working hub or blank working die. When hubbed, the marks are not completely eradicated.

Sounds right to me. Perhaps there are variances in the lathe lines on die blanks caused by the cutting tool getting dull or some similar cause. Stronger lathe lines would be more likely to survive the hubbing process.

Still in the realm of idle speculation, perhaps the die blanks are supposed to be polished smooth after they are lathed, and sometimes they forget to do so.

mannie gray · January 10, 2016 8:16AM

Agreed; they are lathe lines.

Zoins · January 10, 2016 8:18AM

It's great to see these lathe lines. Makes you think about how these coins are made.

kaz · January 10, 2016 8:22AM

Very interesting, I am surprised that those lines don't go away during hubbing. I learn something new every time I log on here.

Coppercolor · January 10, 2016 9:52AM

This is, for whatever reason, very common on 1935P lincolns, where it's seen on the face. Lathe marks

ricko · January 10, 2016 11:46PM

I have seen this topic here before... and yes, determined to be lathe lines.... However,

I have been searching for years for an example and yet to find one... so they seem to

be scarce. Cheers, RickO

asheland · January 11, 2016 1:49AM

Interesting thread

oih82w8 · January 11, 2016 3:37AM

Originally posted by: TomB

I don't believe that is PMD. Rather, I think it was done during production at the Mint.

I am with Tom, those look like lathe marks on the dies that were unfinished/hurried/etc... and were pit into production a little too early.

(Should have read the whole thread before making my comment.)

Icollecteverything · January 11, 2016 6:33AM

I was thinking maybe this was just a modern thing but then I remembered this CWT.

TwoSides2aCoin · January 11, 2016 7:54AM

Emory (sp)

cloth is a tool and die guy's friend.

BryceM · January 11, 2016 9:36AM

FYI, RWB copied the OP's photo and gave his explanation of what this likely represents in a thread ATS.

Link

leothelyon · January 12, 2016 2:24AM

Here's a video. Well, I see the link is broke. Just Bing US Mint How coins are made to see the lathe in action.

leothelyon · January 12, 2016 2:51AM

Click here to see a couple more examples.

jcping · January 12, 2016 7:32AM

Originally posted by: CaptHenway

Originally posted by: dcarr
Those are "lathe marks" left over from machining a blank working hub or blank working die. When hubbed, the marks are not completely eradicated.

Sounds right to me. Perhaps there are variances in the lathe lines on die blanks caused by the cutting tool getting dull or some similar cause. Stronger lathe lines would be more likely to survive the hubbing process.

Still in the realm of idle speculation, perhaps the die blanks are supposed to be polished smooth after they are lathed, and sometimes they forget to do so.

+1, very common on Calfracs. Usually, when these lathe marks shows, coins were well struck and many are top grade coins.

kaz · January 12, 2016 8:44AM

The discussion between DCarr and RWB on the NGC forum is very informative. Thanks for the link BryceM

Unknown · January 12, 2016 8:46AM

This content has been removed.

Coppercolor · January 14, 2016 6:34AM

Here's as 1935 Lincoln I now own that has them on the forehead, cheek, neck and jacket. Hard to see in this image due to the toning and die polish but it's real obvious in person.

Broadstruck · January 14, 2016 7:42AM

I happen to find the lathe marks attractive as they add character

Coinstudy · January 14, 2016 9:47AM

I was about to say lathe line from dies being turned

dcarr · January 15, 2016 4:44AM

Originally posted by: kaz
The discussion between DCarr and RWB on the NGC forum is very informative. Thanks for the link BryceM

Interesting but also typical of a RWB/dcarr exchange (unfortunately).

Note that I did just add conclusive pictures of a hubbing test that I recently performed.

BryceM · January 15, 2016 5:38PM

Dan,

Nicely done experiment you presented ATS, and in line with my own expectations....... (used to teach a strength of materials lab while finishing my engineering degree).

nk1nk · January 15, 2016 6:45PM

I find it unfortunate that RWB allows his disdain for Dan's overstrikes to prevent a very informative discussion. I see threads over AT coins produce over 20 pages of back and forth drivel and a few pages into a very good topic and he stomps his feet and takes his ball and goes home. Not what I would expect from such an esteemed researcher.

Nick

kaz · January 15, 2016 9:22PM

I think Dcarr's experiment pretty much settles the issue, as far as I am concerned.

BryceM · January 16, 2016 8:46AM

Dan,

Have access to any conical die stock you can try this with? I'd be willing to put money on a wager that you'll still see plenty of artifact on the surface of the die making it into the final product.

grip · January 16, 2016 10:53AM

I have two 69-d from a obw that show the spiral marks. and was told by Alan Herbert? it was lath marks

dcarr · January 16, 2016 11:50AM

Originally posted by: BryceM
Dan,

Have access to any conical die stock you can try this with? I'd be willing to put money on a wager that you'll still see plenty of artifact on the surface of the die making it into the final product.

I do not have any conical die blanks. I could always machine such thing. But I don't think it would be necessary to go to that trouble since I already know what the result would be.

BryceM · January 16, 2016 11:51AM

19Lyds · January 16, 2016 3:41PM

Originally posted by: dcarr

Originally posted by: BryceM

Dan,

Have access to any conical die stock you can try this with? I'd be willing to put money on a wager that you'll still see plenty of artifact on the surface of the die making it into the final product.

I do not have any conical die blanks. I could always machine such thing. But I don't think it would be necessary to go to that trouble since I already know what the result would be.

True, but there will always be someone that thinks a conical die blank makes the big difference.

3keepSECRETif2rDEAD · January 16, 2016 4:19PM

...so why did dude run away? It hasn't been too long so maybe after the weekend he will respond. I don't know anything about what you guys are doing but I have read all the text and learned all I could learn without having any true passion involved...however, I did get my passion tapped into when Dan offered a simple wager. Put your money where your mouth is, even if you lose, no one can say that you are "hiding in a cacoon," for losing a fair wager...regardless of the price

dcarr · January 16, 2016 4:41PM

Originally posted by: 3keepSECRETif2rDEAD
...so why did dude run away? It hasn't been too long so maybe after the weekend he will respond. ...

I doubt it.

He has made over 20 posts on that forum (in different threads) since I made my wager offer.

But not a peep in that thread.

nk1nk · January 16, 2016 7:46PM

Yeah he won't be back to reply. He's to busy commenting on possible camera toting pigeons as a security option at major coin shows and training them to poop on any thieves as a way to mark them until security can come and......I believe he said execute them. You know important numismatic topics.

TopographicOceans · January 16, 2016 8:01PM

Originally posted by: dcarr

Originally posted by: 3keepSECRETif2rDEAD
...so why did dude run away? It hasn't been too long so maybe after the weekend he will respond. ...

I doubt it.

He has made over 20 posts on that forum (in different threads) since I made my wager offer.

But not a peep in that thread.

Can I get $20 on dcarr

BryceM · January 16, 2016 8:50PM

There's no reason to be mean spirited. One of the reasons to spend time on a forum is to share information and bounce ideas off of each other. It's OK to be wrong once in a while, and RWB has forgotten more about coins than I'll ever learn. This has been an informative thread and there still might be more to the story behind lathe lines than we've seen. I do think Mr. Carr is on the right track though.

What Caused these spiral marks on a coin?

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The more qualities observed in a coin, the more desirable that coin becomes!

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