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 Replies: 10 / Views: 1,522 |
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New Member
United States
5 Posts |
I want to use a 5-hole US Mint State Quarter lens to display 4 bison quarters (ND, KS, MT, Yellowstone NP) and a 2005 bison nickel. I looked for something to use as a ring for the nickel, and found on ebay some rubber nitrile O rings which I think would work--the O ring has an I.D. of 21mm, an O.D. of 24mm, and a thickness of 1.5mm. But I have no idea if using a nitrile ring this way is a good idea or not. Not that it really matters that much with an inexpensive coin, I guess. Any info appreciated. |
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Moderator
 United States
56855 Posts |
Edited by John1
07/10/2019 10:13 am
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Bedrock of the Community
United States
20753 Posts |
A place called Harbor Fright sells large quantities of rubber type O rings in boxes. Some are all metric and some are all what ever they call non metric sizes. Really sort of cheap too. All are sorted by size and many, many sizes are available.
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Moderator
United States
56855 Posts |
Make sure whatever you use does not mess with the metal of the coin. John1  |
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Pillar of the Community
United States
1005 Posts |
Many rubbers offgas sulfur and will tone silver quite severely. Modern coins' cupronickel seems to be somewhat less reactive so less of a concern, but still I would lean towards a stable plastic or foam instead of rubber
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Moderator
United States
188213 Posts |
 to the Community! |
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Bedrock of the Community
Canada
24885 Posts |
To the Forum. |
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Rest in Peace
United States
17900 Posts |
We look forward to your participation. |
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New Member
 United States
5 Posts |
John1, attached is a photo of the O ring I ordered on ebay. I tried using scissors to trim one of those foam Air-Tite T-21mm rings down to 24mm O.D., and the result is functional but very uneven, to put it mildly. I'm not sure any custom work I would try on anything else would work out any better. I may just avoid using an O ring to be safe, even on a circulating nickel. Apparently nitrile is relatively inert compared to regular rubber. I found this online: "Nitrile rubber is used in a wide variety of applications, such as O-rings, gaskets, oil seals, automotive transmission belts, hoses, V belts, synthetic leather, disposable non-latex gloves, printer's form rollers and cable jacketing." But of course there's nothing in there about its potential interaction with copper and nickel. Thanks for everyone's comments.  |
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Pillar of the Community
United States
1667 Posts |
Airtite has standard sizes for their capusles and the sell rings for those sizes to downsize so a smaller coin fits snugly, problem is their capsules have a larger inner diameter on their standard sizing and as a result the nickel foam Oring (21mm) doesn't fit a quarter size holder. their nickle size holders are 30.6mm inner diameter, the nickel is 21mm and a quarter hole would be close to 24.26mm. Too wide of a O ring.I guess about 9mm width of O-ring.
I'm curious if someone makes foam O ring downsizers for direct fit capsules, because then the outer diameter would be right for a quarter sized hole, and I'd assume inner diameter would be right for cent, dime, and nickel sizes.
Perhaps buy a capital plastics holder for nickels and tape it off and use a step drill bit to size up the ones you want to quarter size? easier to make a hole bigger than it is to make a hole smaller. could probably do it with the insert of any nickel sized holder that has the number of holes you need but cardboard inserts have a tendency to shred when you drill it. maybe like a Nickel 5 Hole Mint or Proof Set Holder 2x6 by Whitman and drill 4 of them out to 24.26 or 61/64ths with a step drill or holesay so they can accept a quarter.
Other option I guess would be to size up one hole to an air-tite O-ring outer diameter, which would probably be easier than sizing up 4 nickel sized holes to quarter size.... yeah.
There's just doing 5 direct fit air-tites and getting a nice foam case to house them as a set or drilling out the insert of the lense to take all 5 airtites.
I dunno, sounds like no matter what you do it's going to become a total custom job.
Edited by Big-Kingdom
08/02/2019 12:03 pm
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New Member
United States
5 Posts |
Big-Kingdom, appreciate the suggestions.
I probably would require at least a few prototypes if I tried any of your drilling techniques, and am not up for that at present. You suggested "doing 5 direct fit air-tites and getting a nice foam case to house them as a set" and I am a little unclear on that. I know Air-Tite makes leatherette steel coin cases with a cardboard insert card in all kinds of configurations, but that is oriented to their A, T, I etc. foam ring holders. Any suggestions on where to find foam cases for direct fit holders (1 nickel and 4 quarter holders in this case)? Maybe I'm misunderstanding what you're saying.
Air-Tite does make a leatherette case to hold 5 T-ring holders, which would work here (one T-21 and four T-24's). I probably will go that route just to see how it works out.
On a final note--back to my original O-ring question--I got a nice reply from the customer rep of a company called Mykin. They apparently would make some custom foam rings to my specifications but the minimum charge for the set-up would be $800. So she suggested using silicone O-rings (rather than nitrile O-rings) in the case at hand. For what it's worth. The O-rings certainly work perfectly size-wise around a nickel in a quarter hole, at least in the 5-quarter lens from the US Mint.
Addendum: I just realized that the direct fit capsule size for nickels is the A-21 and for quarters is the A-24, both of which have an OD of 30.93 mm. My comments above about direct fit T-size capsules were nonsensical, so I am striking them through. A case with 5 A-size holes would work with direct fit caspules, and a case with 5 T-size holes would work with ring capsules. Period.
Sorry about that.
Edited by bordbord
08/02/2019 9:59 pm
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Replies: 10 / Views: 1,522 |
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Posted 07/10/2019 12:39 am
