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Comment by HanClinto | Hacker News Reader

Excellent post! Excellent problem-solving, and very nice result!!

Taking a completely direction, my wife and I made our own wedding rings out of stainless steel (a low-nickel alloy suitable for contact with skin -- 316L, I think), and we milled them on a lathe in my employer's machine shop after hours. Nearly 20 years later, and they have held up remarkably well.

If you're going to lathe a ring, make sure you do as much shaping and polishing before you detach it from the rest of the rod, and then create a mandrel that is the correct size to hold the ring (using friction) from the other direction. Hammer it onto the mandrel, do your final burr-removal and polishing, then pop it off the hammer.

Important side note: Don't do a test-fit before taking the burr off, or else you'll slice the skin on your finger all the way 'round in a very nice ring-shaped pattern and it will be the absolute dickens to try and get it off. Maybe don't ask me how I know...

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I did a similar thing using some titanium out of the scrap bin. (Yes, I know that it will be nearly impossibly to cut off in an emergency, but we just take them off before we go climb or do other dangerous stuff.) It’s been 15 years and they still look great. I left the tool marks on them, I liked how it looked like it was machined.

FYI, only time I've known of a ring being cut off was due to a bee sting on the finger, causing it to swell.

Another anecdote for your collection: my father fell off a ladder last year - not far enough to sustain any injury, but far enough to catch his ring slightly in trying to regain his balance. Finger ended up swelling enough that the ring was a problem, ended up having to be cut off.

I wouldn’t have imagined that a fall off of the second step of a ladder could result in the destruction of a 40 year old wedding ring either, but here we are!

You can get it fixed https://youtu.be/aX866Kx4oU8

Thanks - they opted to melt both down and poured around a synthetic opals for a new set.

Plus a new "can't hurt myself with this if I tried" ring for any time spent outside.

Destruction? My wife crushed hers onto her finger in a cycle crash. It was across the park from our house. Her finger swelled terribly. I put her in the car and drove her to the fire station just down the road where they cut it off. I learned there was a special tool for this! I sent the cut ring to a jeweller friend of a friend... who melted it down and cast it into a slightly smaller ring! Edit: in another post there isa video where someone solders up a cut ring. My wife's ring was much more damaged by the crash than the rings in the video, hence the melt

can you precut it, then solder/polish it to hide the cut?

> titanium out of the scrap bin. (Yes, I know that it will be nearly impossibly to cut off in an emergency,

Most commercial grades of Titanium can be cut with common tools. The tools will dull faster, but it's not impossible.

I suspect a lot of the stories about Ti rings being impossible to cut are coming from people who confuse Titanium with Tungsten. People get exotic metals mixed up all the time.

On the other hand, if you pulled it from the scrap bin you may have gotten some extreme aerospace grade of Titanium that really is difficult to cut.

Even Tungsten isn't particularly hard to cut. Also truly Tungsten rings are a lot less common.

Most of the rings referred to as Tungsten rings are actually Tungsten Carbide. Tungsten Carbide rings, by comparison, is VERY hard to cut. You basically need a diamond blade/saw/grinding wheel to cut through TC.

Yet, you (gently) smash it with a hammer and it breaks to pieces. By adding a block that is a bit thicker than the finger bone, you prevent smashing your finger in the process

Locking pliers (aka vise grips) are a good tool for it, since you can set how wide the jaws will close

https://youtu.be/poM423pewRE?t=147

I had a titanium ring cut off my middle finger that swelled from high blood pressure and weight gain. It took a long time with a ring cutter at a jeweler's in Chico, CA, but it worked.

One big warning with this is that if you get into an accident and the doctors need to remove your ring, they're going to have a very hard time cutting stainless steel off your finger.

I saw a video of someone making a ring out of polycrystalline diamond and…if that gets stuck for some reason, it's never coming off.

Couldn't you just shatter the diamond with minimal risk to the actual finger?

Probably. That's how they get tungsten carbide rings off.

I was rotating the carbides on a wood planer and a couple of them were held in by machine screws that weren't budging. I called Byrd, and their recommendation once you've stripped the screws is to shatter the inserts. I put a crappy chisel underneath and whacked it with a hammer.

I can confirm that it works. I heartily recommend a face shield, and I wouldn't want to be the first guy the doctor had to break a ring off of.

Other than a few comments on Reddit, every jewelry site that I've looked up says that stainless steel can be cut off with regular ring cutting tools.

The biggest difficulty that I know of with it is that the material is not very workable, and so if you need to get the ring resized, you may be out of luck.

A Dremel with a regular cut off wheel would cut right through titanium.

>I saw a video of someone making a ring out of polycrystalline diamond and…if that gets stuck for some reason, it's never coming off.

Diamond is easy to remove: it'll melt with a blowtorch.

(You didn't say the finger had to be preserved intact...)

> a low-nickel alloy suitable for contact with skin -- 316L, I think

Now I’m curious: why use any nickel at all? Plenty of stainless steels (including, AIUI, basically all the tool steels) don’t use nickel, and many of them have excellent corrosion resistance. Is austentitic steel enough easier to machine to make it worthwhile?

Shorter answer: We don't know -- those are good questions!

Longer answer: It was 20 years ago, and we aren't exactly metallurgists. IIRC, at the time it was something to do with a variety of "surgical stainless" to focus on the best corrosion resistance combined with something that was somewhat machinable. At the time, I think we were comparing 304 (easier to machine, much worse corrosion resistance) vs. 316 (harder to machine, but much better corrosion resistance). I think looking at metals that we were able to source in partial lengths might have been a factor as well.

In hindsight, one might be able to find something with better properties in a more specialized alloy, but if I had to do it over again, I would 100% be willing to choose the 316L again. I have zero complaints with it, and the corrosion resistance it offers is superb. In 20 years, I've never polished my ring once, and it still has that mirror-finish quality (especially on the inside where it has never brushed concrete).

I rarely take the ring off (sometimes when juggling) -- I don't worry about it and leave it on even when using tools or scrambling up a rock ledge or carrying cinder blocks or whatever. Very occasionally it will get scratches (concrete is one of the few things that has left a mark from time to time), but they're never very severe scratches, and they buff out nice and naturally over time. I imagine that I would be much more concerned about a softer precious metal, and I'm glad I have a more durable ring instead.

> I imagine that I would be much more concerned about a softer precious metal, and I'm glad I have a more durable ring instead.

Well, you could also just live with the scratches in your ring (if you had one made of eg silver) and declare them part of how it matures with the passage of time. Just like copper gets a patina, too.

(I'm glad you are happy with your ring! I'm just saying that if people decide to be happy, they'll find a justification to be happy with what they have. And if they decide to be unhappy, they'll find a reason, too.)

Great point -- well said! :)

For what it's worth 316 is more corrosion resistant than 304 in saltwater environments and I've been trying to find various fasteners made of it for my boat.

If you’re in the US, try McMaster-Carr.

Or fastenal, they have saved me a few times with odd requirements. Between McMaster, Fastenal, or even Grainger you should be able to find plenty of whatever you need.

Here’s a study on this very issue:

https://www.sciencedirect.com/science/article/abs/pii/001093...

Conclusion: 304 and 316 are probably fine, as is 430 (which should be entirely unsurprising due to its near lack of nickel), but 303 would be a poor choice.

Being stainless does that mean you could blue them by heating to ... what was it, 550F?

Ooooh, that's a really fun idea!

This instructable seems like a decent intro for a home gamer with a kitchen oven if you wanted to experiment:

https://www.instructables.com/Home-Oven-Steel-TemperingColor...

Excellent example! That's a really excellent instructable.

Reading that page, it's interesting that the stainless steel rivets and fastener hardware are the only bits that didn't color. Quoting from the article:

> It is possible that the stainless steel might start to color if left in the oven for longer but my cursory research lead me to believe that stainless needs to get to about 800F to color. My oven certainly can't do that.

I've heard that welding stainless steel gets it too hot and removes something (the carbon?) essentially de-stainlessing it (?). I wonder how much of that would be happening at these temperatures.

Definitely not going to experiment with this on our 20-year old wedding rings, but it seems like this is very much worth keeping in mind for any potential future projects! Maybe if I ever help one of my kids make their rings for their wedding? :)

Thanks for the idea, and for the link!

> I've heard that welding stainless steel gets it too hot and removes something (the carbon?) essentially de-stainlessing it (?).

I don't know if it's possible, but even if it is, it's not the carbon that makes the steel stainless. It's the additional chromium, nickel, or molybdenum.

Maybe when the steel melts during the welding process, those other metals get separated from the iron.

Are you thinking of this?

https://www.materialwelding.com/what-is-sensitization-in-aus...

Yes, that sounds like it -- thank you!

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