Eng Coin Vise

[Craig Matsuoka]

Hope I'm posting this in the right section.

Has anyone here tried to make Harry Eng's Coin Vise? If so, is it working well for you?

I've been thinking of making a "quarter in Perrier bottle" as a conversation piece for my desk at work. I don't want to use a folding quarter for this, since I also want to make up a few bottles to give away as gifts to my friends.

[Adam Brooks]

Craig,

I haven't made the vice, but having made a number of impossible bottles, I can say that that there are objects that are easier to put in bottles that are more impressive than a coin. A Snapple bottle is the perfect size for a sealed deck of cards, for example.

From what I understand about the vice, the hardest thing about the design is how to apply the pressure to the coin in the proper way so as not to leave any stress marks when the coin is unbent inside the bottle. But however the vice was made, I'm guessing the exact design was taken by Harry to his grave.

Bummer too, I'd love to put a quarter in a bottle...

-Adam

[Pete McCabe]

Adam:

I've put a few decks of cards into bottles, and found the Snapple bottle's large mouth makes it less impressive than, say, a 200 ml Jack Daniels bottle (although much easier). Actually my biggest problem lately is it seems many brands are switching to plastic bottles in the 200 ml size.

However I've been thinking about branching out -- i.e. putting something other than a deck into a bottle. Any advice on a good next project?

BTW I figure a memory-metal washer could go into a bottle real easy.

[Craig Matsuoka]

Originally posted by Adam Brooks:
I'm guessing the exact design was taken by Harry to his grave.

Fortunately, he gave the precise construction details to one of his friends who recently published them complete with photos in the book "A Puzzlers Tribute" (a fantastic book by the way).

I like giving unusual gifts to my lay buddies, and this looked like such a cool idea and a wonderful way to do something novel for them.

[Lance Pierce]

Originally posted by Pete McCabe:
However I've been thinking about branching out -- i.e. putting something other than a deck into a bottle. Any advice on a good next project?

Pete,

I'd love to see some of your bottles. Harry was not only the master, but he apparently had no limits as to what he'd put inside bottles, from decks of cards to tennis shoes to ping-pong balls to locks to arrows to bibles. He told me once that he's even put a light-bulb into a bottle. Go figure THAT one out!

Cheers,

Lance

[Pete McCabe]

Lance:

Email me and I'll send you a photo.

I've seen some photos of Harry's bottles and to me the most incredible one is something (can't remember what right now) inside a light bulb. Since light bulbs are so incredibly thin, this is to me the most remarkable, although if he can put a light bulb inside a bottle that would take the cake.

At Bed Bath and Beyond they had a torus-shaped bottle filled with flavored cooking oil. I've been trying to think of something clever I could put inside that would go all the way around the ring.

The illustration on the cover of the Puzzler's tribute at Amazon shows a bottle of wine with a full wineglass sitting inside it. Not sure if this is just a clever Scott Kim idea or a real bottle, but it's a wonderful idea either way.

Pete

[Adam Brooks]

Fortunately, he gave the precise construction details to one of his friends who recently published them complete with photos in the book "A Puzzlers Tribute" (a fantastic book by the way).

I had no idea; I'll have to buy that.

A light bulb in a bottle? That really does take the cake...

Craig: I wholeheartedly agree about the novel gift idea. One really cool idea I found on the web is getting a framed picture inside a bottle. Perhaps suitable for a loved one, or a great friend.
I haven't gone much beyond what I've seen of Harry Eng's bottles: deck of cards, scissors, knots, ping-pong balls, tennis and raquet balls, golf balls. I am currently working on my first Rubik's cube in a jam jar.

Pete: I,too, have played around with the idea of getting something in a torus-shaped bottle. I thought that getting a hollow metal dowel, and gradually curl it and push it around the curb, and once it came around, cut it and sauter the ends together. For me, however, making this idea a reality was too tough. Perhaps you'd have more success.

Other ideas:

-Get a computer mouse inside with the cord coming out the neck

-A dagger

While experimenting, I came up with a pair of impossible bottles. One used to hold Hawaiian Punch, the other, lemonade. Their contents have been switched. There are no cuts or breaks in the bottles, and both bottles still have an intact, tamper-proof seal. I'll be happy to share; E-mail me privately, and I'll send you the technique.

Loving this thread,

Adam

[Steve V]

I admit it, I've always wanted to learn to put things into bottles like Eng does. Very cool stuff.
Steve V

[Stefan Sprenger]

Hi there,

where can that book be found? Do you have an ISBN Number?

Greetings from Germany

Stefan

[Craig Matsuoka]

Originally posted by Stefan Sprenger:
where can that book be found? Do you have an ISBN Number?

ISBN: 1-56881-121-7

Click Here to buy from Amazon.com

Or click here to order direct from publisher A.K. Peters

The Eng Coin Vise looks like something you'd want Jim Riser or your friendly neighborhood machinist to make for you. The design uses bolts to connect some of the pieces. That's probably the most frustrating part. I suppose you could redesign the tool with some kind of "slot & key" type of configuration to eliminate the need for bolts. Perhaps some parts of the vise could also contain embedded magnets to help bring the various pieces together and make the intrabottle assembly easier. Manipulation could also be assisted by a strong magnet from the outside. Dunno. Just brainstorming here.

On a side note, the book also features a reprint of a short 1996 Genii article by Mark Setteducati
memorializing Eng.

The book also has one of the finest tributary articles I've ever read from Max Maven. Look up "Just For the Mel of it". It's laugh-out-loud funny and awe inspiring at the same time. Stover must have been a blast to hang out with!

You'll also find great articles by other writers like Gordon Bean, Meir Yedid, Larry White, Russell Barnhart, Allan Slaight, Jerry Andrus, and a fabulous scholarly essay on the early history of pasteboard legerdemain by Bill Kalush.

I also thoroughly enjoyed reading Epstein's "All You Need is Cards". There are some very nice card trick applications of the "Pigeon-Hole" principle buried in that article. William Fitch Cheney Jr. was a genius. Hopefully, no one will bother learning the stuff. My guess is that Max Maven is already working on a ton of variations.

Click here for contents

[Pete McCabe]

This was posted in another thread but it really belongs here:

Buchinger Impossible Bottle.

Thank you for pointing this out, Craig Matsuoka!

[Guest]

I've been fascinated by Harry Eng's Impossible Bottles. The vice that he made is very interesting, althought not easy to do. What I mean is even if you make one, assembling and dis-assembling it inside the bottle is more difficult than you'd think.

I'm hoping to have one made in January of February 2005. I've been making Impossible Bottles for about 2 years now. I've even duplicated about 4 of Harry's Bottles. By the way, I've never heard that Harry actually got a light bulb into a bottle. But, I do know he has put a deck of cards into a giant light bulb and has a monkey's fist know going through the middle of the deck.

If you'd like to see some of the bottle I've made you can by going to www.bottlemagic.com

[Jim Riser]

The coin vise sounds interesting. I'll have to scout around for a copy of the book to see what the vise looks like.
Jim

[Richard Hatch]

Puzzlers' Tribute: A Feast for the Mind, compiled by David Wolfe, which includes Eng's coin vise and other interesting information, is in stock and available from www.magicbookshop.com for $35 plus shipping. You can find it by searching on the title (or even just "tribute") or doing a search on "Wolfe".

[Brad Jeffers]

The Amazon link is interesting ... they list a new copy for $35 or a used copy for $94.06.
Hmmm, which one do I want?

I think I'll order from Richard.

[Bill Mullins]

If you go to the Amazon link for "Puzzler's Tribute", and use the "Search Inside the book" feature, you can see the pages with the pictures of the Eng coin vise. But buy the book anyway, it's well worth getting.

[Guest]

A friend of mine made me one of these vises for Christmas. It's been great fun. After making a few key observations I was able to assemble the vise inside a flat brandy bottle (neck is wine bottle sized) very quickly. It took a little longer to get the coin manuevered into the vise but definitely doable. I then used it to perform an impossible coin-to-bottle effect that's great for magicians and the bottle can even be given away if you want. Maybe I should start selling these. :)

Anyway, the vises aren't that easy to make and my friend said that they might cost $200-300 if he were going to think about making more of them. If anyone is interested just let me know and I'll put you in touch.

Cheers,

Tracy (at) MyLovelyAssistant (dot) com

[Adam Brooks]

Tracy,

Consider yourself lucky you got one as a gift. I have a engineer friend in Australia to whom I sent the pages out of Puzzler's Tribute for Eng's vise. He's been hunting around, but can't find someone who can make one for a "reasonable" price.

Also, Jim, if you decide to make the vise, you can put me down to buy one. :D

[Todd Lassen]

I was wanting to make up a few of these a year or so ago, when looking through the book. Looks like a fun toy, and after reading Berglas' book I thought about it too. Maybe I can take a vacation from the coins for a weekend. I just bought a humdinger of a lathe from a gunsmith and have been itching to cut some threads with it, something that I used to be very proficient at but seldom do anymore in the coin business. The millwork is very basic. I'll pick up the stock and order some little knobs and stuff. Ha. Anyone that is interested, can shoot me an email.
Todd Lassen

[Jonathan Townsend]

Originally posted by Adam Brooks:
...who can make one for a "reasonable" price...

I wouldn't know what's reasonable. Can you get a half dollar or silver dollar into a bottle with that thing? I mean a soda bottle, oil or vinegar bottle... you know the stuff we have around the house. big grin.

Let's say you could... well worth 3,4,5 hundred dollars for the tool then don't you think?

[Jim Riser]

Todd;
Before you start making chips, email me. I think we can improve on the design a little :D
Jim

[Bill Mullins]

I've made an Eng coin vise, and could make another for less than several hundred dollars. The trick is to use off the shelf items instead of machining everything.

The one I did is size to put a half-dollar coin into a Snapple bottle. (A coin can go into a bottle whose neck is as small as half the diameter as the coin involved -- to use a smaller bottle, you have to fold/bend the coin multiple times, and it gets so stretched it will never look good and flat again. These dimensions also guide the size of the parts of the vise).

Some simplifications to the design in the Puzzler's Tribute book:

Use 1/8th inch pipe nipples for the tube. They come pre-threaded, in 6 inch lengths. You can get couplers to make a 12 inch tube if that works better for you (it did for me).

Of the three bars that make up the actual "vise" part, the top one must have three holes, the middle must have two, and the bottom one must have two.

Drill and tap the bottom one for 1/4-20 threads. It is MUCH easier to screw an allen head bolt into the bottom bar, than to put nuts onto the end of the bolt below the bar.

The middle bar must have holes in the same location as the bottom bar, but larger, so the bolts slip through it easily.

The top bar must have the same holes as the middle bar, plus a hole in the middle of it so the 1/8th" pipe nipple can be screwed into it. This must be drilled and tapped with a pipe thread (the tap should be available at a plumbing supply house).

The bar stock I use is 3/8th by 1" cold rolled steel stock, available at Tractor Supply locally (but available mail order at any good supply house as well), cut with a band saw to length. Home Depot and Loews don't seem to carry that particular size of stock, at least not in Huntsville.

When putting the bars into the bottle, line them up outside the bottle, and run some a long piece of string through the bolt holes. Then you can put the pieces into the bar individually, but can line them up by pulling the string, and they fall into place.

Use Allen head bolts and a long Allen wrench to assemble -- these work a little easier than a hex-head bolt and a long socket driver (for me, at least).

The design in the book shows a block of metal at the top (outside the bottle), where the screw is used to transmit force down through the tube, into the vise. It is drilled and tapped three times: for the screw, for the top of the tube, and for the long handle sticking out the side that lets you apply torque.

I found it easier to use a coupling nut that is used to connect threaded rod. That means you have to cut the end of the pipe nipple off with a hacksaw or band saw, and thread the end of it (the pipe nipple) for screw thread instead of pipe threads. Again, the threading die is commonly available at a good hardware store. Use a hex-head bolt of the same size to screw into the nut, to send pressure down through the tube via a rod of steel (available at Home Depot, cut to length on a band saw or hack saw) to the vise assembly.

Instead of using a long handle for torque, I simply hold the threading nut in a bench vise with the bottle, vise, coin etc. hanging out in space on the end of the tube, and use a box-end wrench to do the screwing. But you could use a wrench to hold the coupling nut, as well.

Once you've built the vise, the most complicated part is positioning the coin in the vise, and holding it there while squeezing it flat. I've come up with some tools to do that easier as well. It's easier to hold everything upside down while doing the initial positioning. I've got some ideas about putting springs, rubber bands, etc. that would allow stuff to be held in place during this part of the procedure, but haven't tried them yet. It may alse be useful to put double-sticky tape on both side of the coin, or on the jaws/faces of the vise.

I did use machine tools in the shop at work (band saw, drill press, end mill for making things a little prettier), but everything could have been done with hand tools and an electric drill.

Jim Riser, I'd be interested in knowing if these "improvements" are compatible with your thoughts.

And I'd be happy to swap emails/pictures with any one else working on one.

(note: I'm at my parent's house right now, away from home, else I'd be able to provide more precise sizes for some of the parts).

[Bill Mullins]

Originally posted by Todd Lassen:
Looks like a fun toy, and after reading Berglas' book I thought about it too.

I don't have the Berglas book -- what does it have to say on the subject???

[Jim Riser]

Hi Bill;
I put the "little gray cells" to work on this about a year ago and came up with how I will make my version of the Eng Coin Vise. A Snapple bottle! You can almost put your hand down into that. I want my coin vise to fit down through a 5/8" diameter bottle neck. This calls for a few design changes from the example I have illustrated before me right now.

I'll explain things based upon the assumption that you have a copy of "The Eng Coin Vise" article written by Gary Foshee. If not, things will be difficult to understand.

See fig. 1 & 2 of the article ... All three of the rectangular pieces shown on my model will be made from 5/8" diameter hardenable tool steel bar stock (that's round - not flat). The bottom piece will have a flat milled approximately 1/3 the way through the steel. This will give it a flat top and round bottom. The two holes in this part will each be threaded 1/4-20 to accept a socket head machine screw (grade 8).

The center piece will have a flat milled approximately 1/3 the way through the steel. The two holes are large enough to make a sliding fit over the 1/4-20 grade 8 socket machine screws. The flat goes down on this piece to mate up with the flat on the bottom piece. These two form the vise surfaces. This center piece also gets a round flat end milled in the center (only) of the top side (opposite the flat bottom). This is where the rod bears down on the vise to apply pressure.

The top piece has two slide fitting holes drilled in the ends. These allow the grade 8 machine screws to slip through easily for assembly and disassembly. The center of this length is dilled and tapped 3/8-24 to accept the long tube (Figure 3). The long tube is machined from medium wall stainless steel. A 1/4" diameter stainless steel rod or hardened tool steel will be the plunger. The top handle and rectangular piece with tightening bolt will be as shown in the article.

My idea is to use a flexible sheft with a magnetized cut off allen wrench in the end. This alows picking up the machine scews inside of the bottle and asssembling/disassembling the vise pieces. This is removed before the long tube is attached to the vise pieces.

Bill, do my modifications to the Eng coin vise make sense to you? By making the pieces from round stock, I can get maximum thicknesses of steel for the vise parts for the size of bottle hole.

Todd, buddy, what do you think?

Anyway, that's how I propose making my coin vise. :D
Jim

[Todd Lassen]

Hey Jim. Using roundstock is a great idea. I have a few other ideas for making assembly inside the bottle easier. I'm sure that I'd learn alot making and assembling the first one. Happy New Year.
Todd Lassen

[Guest]

Great ideas Jim!

I like the idea of magnetizing the end of the push rod. I put a small, cylindrical neodymium magnet on the end of the push rod to use in placing the nuts on the machine screws. Having the end already magnetized, however, is much more elegant.

To make assembling the vice inside the bottle easier I threaded a long length of thin black thread through machine screw holes before inserting them into the bottle. Pulling on the ends nicely assembles the pieces and aligns them for easy placement of the machine screws.

Bill, to position the coin I don't recommend double-stick tape but you might try using a street cleaner bristle that's had the tip dipped in a tool handle rubberizing solution (available at your local hardware store). Please let me know if you come up with a better solution.

Cheers.

[Bill Mullins]

Originally posted by Jim Riser:
Hi Bill;
I put the "little gray cells" to work on this

Didn't realize you were a Poirot fan :)

A Snapple bottle! You can almost put your hand down into that. I want my coin vise to fit down through a 5/8" diameter bottle neck.

Yes, a Snapple bottle is pretty big. But for most readers of the forum, the mods to the original design that I mentioned will allow them to get a coin in a bottle after a trip to Lowe's or Home Depot, and an afternoon in the basement, if they are reasonably handy and have a reasonable set of home tools. After doing so, however, they can judge for theirself, based on their skills, tool collection, and desire, how far they want to go. With most projects like this, the first time you do it is a prototype anyway -- why not do it in such a way as to guarantee some level of success? Then start optimizing via better raw materials, better design, more complicated fabrications, etc. Tell most people that they've got to start hardening steel, and have access to a milling machine, and they'll go learn a new version of Triumph instead.

The largest diameter bottle neck that a half dollar will go into is about 1/2 the diameter of the coin (30 mm/2, or 15 mm) (assuming you only bend the coin one time). The biggest cross section of the parts I used is about 26 mm, and a couple of mm of the corners could be ground down on a bench grinder (again, commonly available tools. . . ) with no loss of strength or utility. A Snapple bottle neck has a minimum I.D. of about 29 mm. Obviously, "impossibility" is not maximized with my particular example. If a slightly smaller necked bottle is easily available, use it. If you have access to 3/4" wide steel bar stock rather than 1", use it, and you can do an even smaller bottle.

The long tube is machined from medium wall stainless steel.

I tried screwing SS tubing into the top piece of the vise. Worked fine, until I started squeezing the coin, and it stripped out. It turned out that when I threaded the tubing, it cut threads deeply into the tube, and significantly reduced the wall thickness. I suppose I could have rounded up some tubing with a thicker wall, but it was easier to get pipe nipples.

Bill, do my modifications to the Eng coin vise make sense to you? By making the pieces from round stock, I can get maximum thicknesses of steel for the vise parts for the size of bottle hole.

Absolutely. If I were trying to get the absolute largest coin into the absolute smallest necked bottle, these (or something very much like them) are the steps I'd take. But my original goal was to get a coin into a bottle soon, with minimal time spent making the tools. Next time, I'll start optimizing. (And one of my goals is to come up with a design that can be assembled in the bottle much quicker. That design will most likely not be simply an optimized Eng vise, but something altogether different.)

But from our email discussions, and from seeing your work, I know that "quick and dirty" isn't good enough for you. A Jim Riser product will certainly be better, in just about any respect, than a Bill Mullins product. And that's okay. We do what we do for different reasons. As my skills and my shop grow, I'll get to your level of sophistication, and I'll want to improve my vise.

My idea is to use a flexible sheft with a magnetized cut off allen wrench in the end.

I thought about magnetizing, adhesives, glue, rubber cement, post-it glue dots, double sticky tape, and other ideas. But in the spirit of KISS, it was easier to slightly deform the end of the allen wrench by banging on it with a hammer. Now the sockets in the bolts will "press fit" onto the wrench, and will stay on it well enough to start threading into the bottom of the vise, but will still pull off when I'm done. (I put the bolts onto the wrench outside the bottle, rather than inside). I don't usually advocate such rough treatment of tools, but the wrench in this case is dedicated to a particular task.

Note: I wasn't able to buy a long enough allen wrench at the local hardware store, or Home Depot. They are available mail order, but I found some at a local electronics supply house. And I didn't use one with a flexible shaft -- wasn't necessary.

I'm thinking the next "impossible bottle" will have a padlock in it. It's looking like the limiting factor will be the width of the shackle -- I can't dissasemble (surreptitiously or not) to a size smaller than that. Although once I get the lock into the bottle, and reassembled and locked, it'll be too big to come out.

[Bill Mullins]

To make assembling the vice inside the bottle easier I threaded a long length of thin black thread through machine screw holes before inserting them into the bottle. Pulling on the ends nicely assembles the pieces and aligns them for easy placement of the machine screws.

I liked and used the string idea, as well (see above). It also helps to slightly countersink the holes, so the bolt slips through easier. I didn't have a countersink bit, so I just used an oversized drill bit. Worked just as well for my purposes.

Bill, to position the coin I don't recommend double-stick tape but you might try using a street cleaner bristle that's had the tip dipped in a tool handle rubberizing solution (available at your local hardware store). Please let me know if you come up with a better solution.

The rubberizing solution is a good idea. I'll also try heat shrink tubing.

Street cleaner bristles are also often mentioned for fabricating your own lock picks. I've never been able to find them -- streets stay dirty in Huntsville :) . Much more easily available are the steel reinforcements that go in windshield wiper blades. Go to your local Autozone, O'Reilly's Autoparts, or even outside the auto service bays at Walmart, and their are almost certainly some laying around on the ground, or in the trash barrels near the entrance. People often change the blades as soon as they buy them, and discard the old ones while still at the store.

[Jim Riser]

Bill;
I like your adaptation of the Eng Coin Vise. It is perfect for those without the scrap pile I have and available tools/machines. I was merely expressing my thoughts on how I propose making the coin vise. Anything that works is good :)

I just like nice looking and well finished tools (my problem). To illustrate how bad I am about this - I'd probably polish all parts on the coin vise too! I know, sick :eek:

Rather than concentrating on half dollars in the bottles, I'm interested in more readily available coins (nickles, dimes, pennies, quarters) in much smaller bottles than a Snapple. These are perfect for a coin in bottle routine where the vessel is given to a spectator. The Snapple bottle is a good size for beginning attempts due to the amount of mouth space for the coin vise, tweezers, windshield whiper stiffeners, flexible grippers, etc. BTW - steel strapping material (1/2" wide) can prove useful. Again, anything that works is good. Shrinking fluid (in combination with re-expanding fluid) would be a nice tool too.

Bill, thanks for sharing your practical version. Anyone else have design ideas?
Jim

[Robert Allen]

Bill, if you want lock picks, buy them cheap online. They are basically spring steel flat ground material, tempered for toughness rather than hardness. Jim Riser will tell you that "sprint steel" is not enough to describe a particular steel. Picks are rustable, so they are typically carbon steel, blued for resistance. Carbon steels will often temper tougher, rather than stainless steels which will temper harder but more brittle.

Sigh. Years ago I had a complete set of handcuff act picks. It was vintage stuff, but probably worth a mint now. Including a threaded cork-puller gaff for some british cuffs, and an extended double ratchet shim gaff made of a brass handle w/ spring steel (carbon) shim picks soldered on.

I love steels. My knowlege is most based in the knife world though, not general metals.

[Craig Matsuoka]

Thanks for reviving this thread guys.

I'm still interested in building one of these things. In fact, I was talking to James Riser about this over a year ago but I got busy with other projects and neglected to follow through. My apologies to Jim for being out of touch for so long (I haven't forgotten about our discussion :) ).

Since everyone has been so generous in sharing their experiences here, it's only fair that I return the favor and share some of my ideas.

I started a blog describing the proposed design here:

Coin Vise Blog

As coin putterinners go, it isn't nearly as accessible as Bill's device, but if things work out, it could potentially make the task a no-brainer.

[George Olson]

Really interesting! Guys like you, Todd, Jim, Tabby, Joe make our life wonderful.

I just wish my Dad was around, he'd really like to do this sort of thing.

Thanks

GO

[Jim Riser]

Craig!
Long time :)

Cute idea on your proposed coin vise modifications. The final pin would be my concern too. Remember the hinge pins are also critical. In addition, there needs to be enough "swing room" within the bottle to fold your version into shape.

Actually, this afternoon I cut some tool steel for making three of the coin vises I described above. I think it is necessary to actually build a few "prototypes" to see how well the things work. I'll see if I can find any time to finish them up. I'm making the vise portion large enough to accept a half dollar. Some shape fine tuning can make in-bottle assembly easier by using the inside curve of the bottle for support.

Bill, for the guys who like to "do it on the cheap" - I'll use a polished stainless steel push rod salvaged from an old dot matrix printer. These are great rods useful for lots of things (around 12" long). Cost = zip!

Thanks for joining in, Craig.
Jim

[Bill Mullins]

Originally posted by Jim Riser:
Bill, for the guys who like to "do it on the cheap" - I'll use a polished stainless steel push rod salvaged from an old dot matrix printer. These are great rods useful for lots of things (around 12" long). Cost = zip!

It's amazing the kind of useful, precision machined parts you can find for dirt cheap. If you ever get a chance, disassemble an old computer hard drive. Once they've gone bad, they're worthless -- unless you want ball bearings, stepper motors, rare earth magnets, etc.

[Todd Lassen]

Interesting design Craig. Looks like a ton of work though. Your CAD certainly looks good. If you ran a production of them, it may be practical. ie...you could stack 10 pieces in a vice and cut all the slots, etc. at the same time. And you could cut a few corners, like instead of reaming press fit and slip fit pin holes, you could simply make them all slip fit and loctite the pins in place. I am sure that would be good enough for this device. Instead of inserting a pin to lock the top piece, you could just have a litle pall attached and rotate it 180 degrees to lock. While it is an ingenius design, and no doubt easier to assemble inside the bottle, I feel the overall integrity of this design would be less than the original. Since I am not an engineer, there would only be ONE way for me to be sure. Haha. The old trial and error method works best for me. Haha. I just had a vision of the whole thing pulling apart at the pins when applying enough pressure to squeeze the half dollar. :eek: And I don't know about the center piece just floating the way it is. Not meaning to burst your bubble, just a few things to consider.

[Craig Matsuoka]

Originally posted by Todd Lassen:
I just had a vision of the whole thing pulling apart at the pins

Hey, you had the same nightmare I had! Youre right about the questionable physical integrity of only four pins. Im hoping theres a mechanical engineer reading this who can give me a better idea of whether those pins will hold or not. This project is hinging on the answer to that question.

How soft is a U.S. quarter anyway? It would be great if a compression test could be performed on a bent quarter to find its yield strength as the coin straightens out. That would conclusively tell us what kind of load these pins are bearing. Is there a practical way of performing such a test short of hiring a material-testing lab?

I don't know about the center piece just floating the way it is.

The center piece could be held in place by embedded magnets if it doesnt behave as expected otherwise.

Clearly, there are plenty of questions to answer before attempting a full build. Whatever happens, I figure if this ends up being too weak for coins, at least itll be strong enough to use for extracting confessions or punishing naughty genies.

[JR Russell]

I just bought "A Puzzlers Tribute" and the book has paid for itself in beer thanks to Ron Wohls Stack of Quarters Bar betand it works great with EURO coins as well.

"JR"
Fly Navy

[james graham]

i liked the idea of the 1/8 inch pipe nipples to connect into the vise. i have a "flaring tool" for use with small diameter copper pipe that spreads it open for flare fittings. it has a two part piece with several size holes and wingnut tighteners that grab the pipe (a torque handle)and a compression tool much like a gear puller that fits around it. the tool has about 2 inches of travel. about $26 in the plumbing section and it hold up to a 5/8" od pipe. i'll try to get a photo link for you.