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A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

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Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#41

Post by linsomniac »

flipflipper wrote: post #16
ziml77 wrote: post #6

LTT has a video on a very simple battery powered battery spot welder https://www.youtube.com/watch?v=aHNmVV7THBs

Timing is inconsistent and the contacts will stick and weld together after a bit of regular use. Solid state is better if its designed well. Checkout the kWeld. https://www.keenlab.de/index.php/product/kweld-complete-kit/

I looked at the kweld, came very close to buying one, but ended up getting the Sequre version instead. About the same price, well reviewed, and looks to ship ready to go rather than you having to source pieces. It arrived earlier in the week, I haven't had time to open the box yet. kweld looks solid though. I thought about trying the DIY car battery and starter solenoid hacks, but wanted something a little more accurate.I have around $700 worth of battery packs to repair/rebuild (lawn mower and discontinued electric bike), so I hope to get my money's worth out of it.

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#42

Post by Cerium »

blamazon wrote: post #37
prpl wrote: post #36

Earlier quoted context omitted.

I used to get a kick in middle school disassembling disposable cameras (unlimited supply since dad worked in a grocery store with a photo lab), charging the circuit, and discharging on coins.

At my middle school we discharged them on our friends…

I remember very painfully learning that the flash trigger on a disposable camera is not low voltage.

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#43

Post by prpl »

blamazon wrote: post #37
prpl wrote: post #36

Earlier quoted context omitted.

I used to get a kick in middle school disassembling disposable cameras (unlimited supply since dad worked in a grocery store with a photo lab), charging the circuit, and discharging on coins.

At my middle school we discharged them on our friends…

I would try to do that but you could rarely get it to work reliably. I did get it myself a few times and that was always shocking

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#44

Post by minitoar »

bufbupa wrote: post #19
ricardobeat wrote: post #11

What are the dangers here? What happens if that thin insulation between the copper bars breaks? Can the current jump to you if you use this bare handed?

If the the insulation breaks the tool short circuits and the welding tips don't work. Electricity follows the path of least resistance, so given how close the welding tips are together I doubt it would ever choose to go through you; especially any of the sensitive parts of you. You'd have to be bizarrely well grounded for it to discharge current through your body.

I vaguely remember standing on a rubber mat being standard practice for this sort of tool.

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#46

Post by CapstanRoller »

motyar wrote: post #45

Check this too , Water Welding Machine https://www.youtube.com/watch?v=800BnMG8prA

Not pictured: everything is connected to mains voltage. The salt water bucket is just a huge current-limiting resistor to prevent tripping breakers or starting a house fire.

https://en.wikipedia.org/wiki/Liquid_rheostat

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#47

Post by kragen »

korethr wrote: post #25

In the end of the video he lists off the number of things he did that were fancier than necessary. One of them was the use of an Arduino for the pulse duration and switching. I found myself reflexively commenting, "It's called a 555 timer." I'm confident that the same function could be more minimally implemented with a 555 timer and maybe a couple other supporting chips. But he's probably getting more consistent cont…

He's probably getting a lot more error from using an AC solid-state relay (which probably uses a triac and so probably stays on until the next zero-crossing, thus a 10-millisecond error) than he'd get from using some metal-film resistors, a film capacitor, and a 555. But the Arduino has a much easier time displaying the pulse duration on the LEDs.

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#48

Post by kragen »

ricardobeat wrote: post #11

What are the dangers here? What happens if that thin insulation between the copper bars breaks? Can the current jump to you if you use this bare handed?

It's two volts. You can totally use this bare-handed, no problem. Just make sure you aren't wearing jewelry on your hands.

Re: A Battery Spot Welder Made from an Old Microwave and Excessive Mahogany [video]

#49

Post by kragen »

cronix wrote: post #8
blahblah23 wrote: post #7

Isn't it incredibly dangerous to disassemble microwaves?

Absolutely, for people who do not know what they are doing. Anything with high voltage capacitors is dangerous unless you know how to safely discharge them, and the magnetron in microwaves specifically.

Yeah, you're absolutely right. A bug in kernel programming might erase your filesystem and require you to restore from backups; a bug in handling high-voltage capacitors erases you.
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