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OldCelticMail

Question for Welding Mail

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Hello, I am new to this forum and only familiar with mail-weaving so I will be brief to not sound too dumb.

I am a welder by trade, familiar with every process of welding from stick to metalcore ( its punkrock mig!) and was wondering what method to use on mild steel rings. Tig seems like a safe bet but my machine is scratch start and I don't like grinding my electrodes that much. Mig is a little hot usually for 16 gauge wire... This is what goes through my head when I'm not at work. 

Here's what I'm considering:

Tig brazing (Lower heat, silicon bronze, looks very cool when polished and tensile strength 63,000psi when applied well, which is 300psi short of mild steel's ultimate yield point! Also can wick into joint and be smooth)

Tig spot welding (easy, though expensive on welding consumables, would leave small indentations?)

0.025 solid wire mig (A lot cooler than most mig might work but would leave a proud blemish)

Buying a shirt and giving up

 

I am a welder and not a mail weaver, so I want to know what the flip side of this is. What do mail-makers prefer for welded rings? Are brazed rings even a thing? Why am I bringing work into my hobbies?

Any help is appreciated!

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The most common method for ring welding is resistance welding; essentially with a purpose made spot welder. The RingLord used to sell resistance welders (I got one of the last three before they were discontinued), bu some people have built their own using coils from microwave ovens. It can be plenty strong if it's a weld right through the material, but this video shows little more than a tack weld.

 

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Resistance welding... the only welding I don't do...

I don't play with 2000w AC transformers often, but I do have a large welding machine with very finely controllable settings and exchangeable leads. Could I use my machine for resistance welding rings, likely by attaching the ground to a copper rod and the positive to another rod, oriented like seen in the video you linked? I have a foot pedal and the whole deal, and my machine can go as little as 20 amps to as much as 250. Besides, with the bronze tig brazing rods, I can braze the copper electrodes directly to a steel frame or ground etc which makes construction much easier.

What current does the resistance welder you have normally pump out?

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Couldn't tell you the output current, because it doesn't have a rating for it that I can find. I can tell you that it's rated at 2000W and two quick pulses will blow a 16 gauge mild steel ring like a fuse. It can be tuned with a digital setting over 30 steps from barely a tingle, to melt into slag.

This is my video of it in use.
 

 

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The soft hum of an AC weld, how I envy thee!

My welder is unfortunately DC only, and usually if a machine has AC only, there's a reason. AC welders are almost twice as expensive to manufacture as DC welders, and a machine with both is barely more expensive than AC only. Most AC welders are AC/DC welders, so seeing AC means there's a reason it's AC only. 

(The videos and the responses are very helpful thank you loads)

It looks like its running really high amps and fairly low voltage. Would you say an arc ever appears? Does the entire end flow together at the weld site or is it more of a spotweld between the faces of the joint?

Also you should wear polycarbonate or some other kind of ir/uv opaque glasses. The heat of glowing hot metal releases lots of infrared (heat vision!) which doesnt cause blindness instantly but instead causes cataracts to form sooner and worse in life. UV just kills the rods and cones in your eye, which is a sunburned retina. You shouldnt need a welding helmet unless it makes plasma or something crazy, so most standard polycarbonate safety glasses keep all the ir and uv out.

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I'd say your assumption of high current, low voltage is correct. I don't see any arcing. Thanks for the safety recommendations. I'm usually using darkened safety glasses, if not an actual mask.

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I'm in a similar situation to you @OldCelticMail, I'm currently weaving a hauberk and hoping to resistance weld the rings. I have a cheapo stick welder on its way from china and have gathered some supplies to build custom electrodes.

I'm hoping that I won't have to rewind the transformer but we'll have to see how it goes, if I'm reading the specs right this welder outputs up to 200A at 20-25V. I'd love to compare notes as we both progress as I'm *not* a welder. Perhaps between the two of us we'll have enough knowledge to come to a solution!

Edited by technophebe

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@technophebe I have a decent-ish welder I left at my parent's house (you cant weld in an apartment?!) that can do tig/stick and mig. The settings go down pretty low, I was thinking of trying to run it in tig mode (basically just stick but controlled by footpedal) and putting another ground in the torch power connection thing and clamping the positive and negative power leads to two (2 too) copper rails to use as the contact point for the rings. 

Basically I just want to run the power out of my welder into some resistance welding setup. What I'm thinking about is AC vs DC. AC tends to work very well on material that oxidizes easily and/or forms a very inert oxide coating (think aluminum) which the rapid switching of current (50hz!) pulls off of the surface of the metal. It's like welding electrode-negative. I'm concerned that if I don't have a shielding gas that the iron links will oxidize rapidly in atmosphere. I don't want to manage shielding gas in my apartment. 

The link welder that @Rob MacLennan posted seems to run at 60hz. That's about what a microwave-derived machine would work. I hope a low resistance weld will work, otherwise I'm going to silver-braze or silicon-bronze braze the links together with a small torch. 

If none of that seems feasible (or fast enough!) I might try bringing it to work and using the machines there somehow. There's plasma torches, acetylene torches, and ridiculously powerful mig welders. I don't know what to do honestly!

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There's likely some form of adjustment hidden in its carcass. Perhaps both duration and strength of pulse. If so, then the 'conversion' would be easy.

*EDIT* In my searches I've turned up more than a few Chinese dental welders that have very similar cases to the old TRL welder.

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The hum of that TRL welder is very nice, sounds like the transformer has very very good eddy-current dampening. Most off-shore AC "welders" (broadly speaking) sound harsh and loud.

I'll try to find videos or images  of a tear down of the HF spot welder. Hopefully it's not just a single step-down transformer that's connected to the leads and powered by mains. Would I be surprised? No. Would I be disappointed? Yes.

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Hey guys, here's a link to the manual for the TRL resistance welders that I built. It has a handy circuit diagram and some pics you might find helpful. As you can probably tell it is essentially just a modified version of one of those harbor freight spot welders that Rob posted. They are more or less as you described them, just a step down transformer. The real trick is to find a beefy enough timed relay at an affordable price to get repeatable results.

For resistance welding you generally want to keep the output current below 5v. I have seen resistance welders using 12v or even 24v but they spit a lot of sparks and arcs and are hard to control.

I've built similar setups with TIG welders and they work well, anything that functions at 5A or less is pretty controllable for rings. I highly recommend a solid state HF arc starter though. Scratch start is a pain and you'll burn out an non-solid state HF start in no time. Same idea as the resistance welder, I just splice a timed relay into the pedal controls.

Once again the timer relay is the key here. The welds at this scale happen so fast that you can't really get consistent results without one. With a good relay you could probably use most welders to get okay results.

I've also used torch brazing to join rings in the past, it worked really well and looked great but it takes longer than welding.

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Thanks for your input Lorenzo!

My cheapo welder arrived and although I was able to achieve welds using my custom electrodes, they were brittle and came along with a lot of oxidation and discoloration. A good chunk of the ring is being heated for several seconds to achieve a weld so that's probably not surprising.

This little welder outputs 200A at 25V so I'm working on rewinding the transformer as per the various instructions for doing so with an old microwave.

I don't have a timing circuit yet, if I'm able to rewind successfully perhaps that'll be the next step.

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As close as I can get them, yes. I'd say points of contact are less than 90° apart on the ring.

I might be able to get them closer if I grind down the heads to a 'sharper' tip but I'm moving slowly, trying things one at a time. Do you think getting them really close (as close as I can without fear of them touching) would help?

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If they're already reasonably close, then you're minimizing the heavily heated area. I was afraid that you might have them quite far apart.

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There's no real benefit to having them closer than about 3 wire diameters apart.

From the sound of it you're burning up the rings, the weld should happen in a fraction of a second. I use 200A to weld 24g rings, you'll need a lot more than that for thicker wire.

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eMkwzYa.jpg

So I rewound the transformer and added a timer relay for consistency, and to my *great* surprise, it works!

I'm not sure exactly what sort of current I'm getting but I was aiming for the 1000A with the number of coils I used. The timer needs to be set to about 0.9-1.0s to get good welds consistently.

I'm using custom pliers with a groove ground into them to allow me to apply good pressure to the weld, I don't think I had enough pressure squeezing the weld together otherwise:

YPjoryR.jpg

I'm just working on getting into a rhythm and speeding things up now. Does anyone have any input as to how long hold time needs to be after the weld? I'm holding for 10s at the moment to be safe but I suspect I probably don't need anywhere near that much.

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You can use the color of the weld to judge the hold time, once it stops glowing it's definitely okay. 1000A @ 1 sec isn't great but it'll work. You should probably clean and degrease the joint on those rings before welding or use a bit of gas to reduce oxidation. Shortening those weld cables might also help.

The main problem I see with your setup is that those electrodes should be angled to better redirect the force applied by pushing the ring into the electrodes into a force pushing the ends of the joint together.

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Thanks for replying @Rob MacLennan @lorenzo.

Lorenzo are you saying that higher current / shorter burst would be better? I don't want to get involved with gases and my 'squeeze' pressure is coming from the pliers rather than the electrodes, but I could remove a winding from the secondary coil if even higher current / lower voltage would be better.

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Yes, as a rule you want the current as high as possible for as short as possible, this reduces oxidation in the weld.

Based on the pictures most of your welds are brittle as a result of oxide inclusions in the weld area. Those welds aren't even close to as strong as they should be.

The weld pressure needs to be applied by the electrodes, using the pliers is wrong. The whole point is that heating occurs where there is the most resistance and you need that to be between the ends of the rings, not between the ring and the electrodes. That means that the contact pressure between the ring and the electrodes needs to be higher than between the ring ends.

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Ah right, I thought we had a need for squeeze pressure to ensure that the ends had a nice thick contact rather than ending up with a thinned section at the weld. I'll modify the welder and how I'm holding the rings and see how that affects the welds.

Thanks again!

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