I know this will seem odd in a world of smart phones, but this little gadget has come in very handy many times and I’m not yet ready to retire it.
If you remember the old Casio Databank watches, it’s like that, but much, much better. Timex made one that hooked up to your computer via USB and stored contacts, notes, a calendar, etc, etc. Here’s a pic.
The problem is the small black links you see in the photo. The band is stainless steel, but the links that hold it together are a hard rubber of some kind that is now deteriorating. Timex still stocks the watch band and I have a couple of extras. Plus the links are removable so that you can repair it when one breaks. Even so, they break with some regularity and forcing the tiny pins out can be tricky (although to be honest, I do have it down to a science at this point so don’t feel too bad for me).
So my idea was to cast a set of link in sterling silver to replace the rubber ones. There are only about 20 all together (I have dainty wrists), so it’s not completely crazy. And they’re basically just rubber blocks, so there’s nothing intricate about the casting. Any really rough parts I can fix afterwards anyway.
The only caveat is that I would have to get the holes for the lynch pins more or less dead on for this to work.
However even here, there might be options. The most obvious is to just drill it out after casting. It’s a very small diameter hole so that’s probably the best option, but maybe not.
Also, it doesn’t have to be silver. It’s just one of the few things I can use that won’t tarnish that I can melt with a propane and oxygen torch. I’m willing to consider other materials though. I’ll even consider another type of polymer if it will do the job and hold up to wear.
Are they all identical?
If you could get a mechanical drawing of the part a tooling shop could make them for you out of whatever material you want. If you can’t make a drawing the tooling place could probably make one but they’ll charge you extra.
But this doesn’t require that kind of refinement I don’t think. They’re just little blocks.
What I was thinking about was a plaster mold. I’d make some plaster, do the impressions (maybe mount 4 or 5 on a piece of balsa wood so I would get the mold hold just right) and then melt and pour the silver.
From what I could gather, clay is normally used but I saw plaster a few times, so that was one of the things I wanted to know.
Lost wax is way far beyond what my terminal clumsiness would permit. My sphincter starts puckering up just thinking about something like that.
Hampshire, as far as I can tell and from the replacements I’ve done, I would say that they are in fact identical.
But like I said, it really doesn’t have to be a fancy operation. If they just come out vaguely block like and mostly the right size, I can file/abrade them into the right shape after casting - no problem. I don’t even care about tool marks. Those would be badges of honor as far as I’m concerned.
Lost wax allows you to make multiple copies.
You create your master in Fimo (or some such), use it to create a plaster mold, cast multiple wax copies, then us the lost wax process to cast them all in silver at the same time.
OK, sorry if I’m being thick, but how would that be different from having a plaster mold with 20 impressions for the 20 blocks that I need? I would also pour those at the same time - although it would probably get a little messy.
You see, that was you’re problem - you gave me far too much credit. Yes, of course I’m only going to cast one side. Nobody’s going to see the other side anyway. I mean it’s as silly as vacuuming under the furniture or brushing the backsides of your teeth - right?
Anyway, I have a full set of tools of every variety including a pretty nifty cordless Dremel. So if I really want to get fancy and make them look “nice”, I should be able to do that afterward with a soft metal like silver.
I know that sterling isn’t THAT soft, but still, it should be doable - do you think? Or am I misguided on this point?
There is also such a thing as silver clay. You make your thing out of the clay, bake it in a kiln, and there you have the silver part. Accounting for a small shrinking factor.
I’ve been wanting to do that but don’t have a kiln.
My hardware store mentality says you can buy a brass strip (or buy a sheet of stainless steel or brass you cut into strips), cut it to size and bend it around to hold the pieces together. Probably look alright from the show side.
Reminds me there was a thread here about jewelry dopers made that had me a bit envious.
I assume ‘jewelry practice’ is a technique of some kind?
Can you tell me more about hi-temp silicon? I’m guessing it takes a very fine impression easily and that you use it directly as the mold. That sounds very promising. What else would I need to know for casting sterling? Are there different types for example. Any hints on working with it, etc?
Actually, you just gave me an idea. What about the brute force approach? These things are only about 3mm think. Couldn’t I get a slab of some soft metal and a hollow punch about the right size and just go to town on the slab punching out little chucks and then finishing them off with a grinder?
It seems Amazon also sells transparent and opaque dyes to color the casting epoxy.
I don’t have much experience in disciplined epoxy casting. When strength is important the JB Weld people make some very tough products and give detailed specs on their website. The JB Weld original is much more durable than most other hardware store epoxies.
When a very thin product is called for, I’ve used canned, liquid marine epoxy.
I’m probably misunderstanding, but your idea is to make the links out of epoxy? I’m not sure it would have the tensile strength though.
Although my wrists are dainty, I used to bench well over 300lbs and the problem now is that links are too brittle to flex with me. So I’ll be doing something and the next thing I know, the watch is gone.
That 3960psi is for compression i think - yes? If it’s tensile strength, then that would be great. Oh, also there is torsion to consider as well since the links have to flex in more than just one direction. That’s why I was going to use a metal. It just won’t give at all.
I have used that Precious Metal Clay (PMC) stuff, and it wouldn’t be at all good for this application. The metal particles are bound together with some sort of mineral oil, and when it burns out in the kiln, it leaves the finished product kind of porous throughout. This makes it weaker than normal, not good for any load-bearing pieces. It is fine for pendants and earrings and stuff, but not for links that are going to be stressed
Well when you cast rings etc one makes a wax, resin or metal original than takes mold off that with with high temperature silicone and the metal can be cast in that. It makes very fine castings that needs little “fetteling” One draw back is cost. A its usually sold in quantities of a pound or so. Googling Casting silicone" brings up kits and prices for your region. Nowadays bronze and silver can be cast using it. Its two pack and easy to use you can take the original object and add “runners and risers” out of wax or clay then pour,let it set, cut the mold.
What would you say is the difference between silicon and plaster for casting sterling? Because I have some modeling plaster I could use and if I can get away with that, it would be cheaper at least.
However I’ll get the silicon stuff if it’s clearly going to be better in this application - as long as you know I’m not very demanding.
edit: also - can anyone give me pointers on the melting process.
you could hand machine the parts out of whatever material you like with a good set of files and a Dremel with the various hobby grinding heads. The same goes for casting. If all you need is a rough cast then sand molds work just fine but they’re so small that I’d just start with a rough block of the material. Setting up a sand mold would be a little time consuming versus the small amount of material that needs to be hacked off to start fine tuning it.
There may also be shops with LASER scanners that can rapidly create a cad drawing and machine what you need.
