The Hobo Holder - Part II

[KurtB]

After the mammoth original coin collet thread, I decided to finally get off my rear and get a design done which will do the job I originally intended. Rather than hog all of Steve's bandwidth, I made a web page with all the gory details.

I've had a machinist hobby site for years, and I've always recorded my projects in this manner, so if you're not into machine work, it'll be rather dry. But it does show the detail and care that goes into such a simple device.

In a nutshell, it uses two pieces of tool steel, sandwiched together. A steel pin at the bottom forms a fulcrum. At the top, a recess is precision bored to hold only the rim of the nickel. Finally, a hole in the side near the top carries the clamping screw, which is a shoulder bolt. The very last operation is the removal of 0.010" of material from the faces of the blocks where they meet in the middle. This gives the holder clearance so that when the screw is tightened, the holder bears on the coin, rather than on itself.

Apart:



And together with a nickel installed:



Some initial tests showed that the holder grips a large range of nickels, which can vary almost 0.010" in dameter. I tried some real intense cuts with my Palmcontrol at full blast, and with each cut gouging out a huge strip of metal, and it appears that the holder is doing what it is designed to do.

I'm going to get one or two of these out to some Hobo people, and if all is well, I'll crank a few out. These are pretty labor intensive and will not be as cheap as I had hoped. Thank you for being patient with me... I know I really whipped up this whole concept and haven't done diddly with it.

[Danny C]

Very Nice Job - I can see the work involved, and why the cost.

For us money challenged people, how about one that has the a slightly larger coin diameter (Just at the maximum +.001) dimensions but with a band saw cut down to "the fulcrum bar" so that it can just be set into a vise and use the vise jaws to clamp it up tight. True, it will have to be undercut about 1/16" on both sides so that the jaws will apply clamping pressure farther up near the top (the attached jaws not the removable ones). It could also stick up about 1/8" above the top of the jaws. In essance just like the one on your site, just not as much machine work, with a heavy band saw cut allowing for the various diameters - if an overlarge coin has to be fitted, then a screwdriver tip in the slot would spring it out to accept it. This one is as simple as possible and still work (at least in my opinion, such as it is).

yes-no-maybe?

[Steve Ellsworth]

Money challenged? Does that mean you are having a hard time scraping together nickels?

IF you cut one decent coin and put it on EBay and sell it then you can buy yourself a decent vise from Kurt.

Then you could cut two or three andgeta nice scope.

The 20 or so and a nice 72 inch plasma TV

Perhaps it's time for someone to make a statement about coin cutting in general.

It's not at the low end of engraving costs, it is an expensive hobby. It's not as easy as some would think. It's a different animal and as such requires differnent tools and expenses more so than other types of enngraving.

you have to be nutz to do it
it causes cancer in rats

[robtsou]

Hey Kurt, nice work on that.

You know what they say, when your only tool is a hammer, every job looks like a nail? I don't have a mill (outside of the milling attachment on my lathe) so I saw a way you could make this on the lathe and save a little time if you're interested.

If you take your blocks, fixture them in the 4-jaw with a .020" spacer in the middle, you can turn the recess for the nickle. The only issue I see is the fulcrum hole, I imagine you could drill it and ream it the same way but with the spacer in place.

Thanks for sharing,

Rob

[KurtB]

Thanks Rob. I thought hard about using a lathe, because boring in a lathe is 10X easier than a mill. In the end, at least for these prototypes, I decided to use the mill to see how tough it would be. I'm going to look in the MSC catalogue for some 1" square or maybe 0.875" square 5C collets. If those are available, I'll be good to go. For production work, though, the thought of using a 4-jaw, considering how lengthy the setup would be, gives me some pause.

Even better, I'll stop being lazy and program a solid model of the darned thing, at least the coin recess. I've got a bench CNC mill that would make short work of that pocket, and produce a nice finish in the bottom of the cavity to boot. I just need to be sure it can be made with the necessary accuracy.

[Danny C]

Thanks Steve for the comments - appreciate the direction.

Went to eBay and found HOBO's from $10 to $25. 3 over $100 and 1 @ $1780 (rare original).

[Steve Ellsworth]

I have heard there is some speculation over the "rare" original.

A good one will bring a good price. Depends on the carvers reputation for hanging around, quality of coin, image, etc. 30 to 500 you never know.

Art follows the stock market.

Attention to detail is the main requirement.

It's like anything else in engraving. If it looks like a chicken it better be a chicken. An extra wing or leg is only good at KFC. So carve what you are best at and make it look right.

Never judge Ebay till the last minute. 30 bucks can go way high in a matter of seconds or you can get trashed by bid snipers
when in doubt throw a reserve on there.

I think it's better not to sell than to give it away. What doenst sell this month may be hot the next.

[monk]

i would be interested in one of these , if i don't have to refi my house. i'm currently living under a bridge and they wont refi that.

[Danny C]

Hey Kirt - what ever happend to the coin holders?

[monk]

i made one of these out of 30mm dia round nylon rod on my delta wood lathe. cut a recess half a hair less than the thickness of a nick. cut a couple cross slots with a jewelers saw. i use a ss band clamp for clamp pressure. seems to work ok. i stole the nylon , and when nobody was lookin, i borrowed the band clamp!