One Handed Electrode Holder for Spot Welder or RSU

Batteries, Chargers, and Battery Management Systems.
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fechter
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One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Aug 09, 2017 11:13 am

I'm getting ready to build another 18650 pack and wanted to come up with an improved electrode for my Riba spot welder. I really like the one hand ability of the one Rojitor was using. (https://endless-sphere.com/forums/viewt ... 14&t=89076). This handle might also be useful for microwave oven transformer welders or resistance soldering units.

My Riba welder electrodes worked fine, but takes two hands and a foot to operate. This makes holding the nickel strip in place more difficult and I got cramps in my hands after long welding sessions. The wire was too stiff also.

I measured the existing wire and found it was closest to AWG 4, so ordered some super flexible welding cable that size. Temco has really nice stuff and it comes in a wide variety of AWG and color and they will sell by the foot. They also have battery jumper cables of assorted AWG and length that have ring terminals crimped on the ends.

I started with some sections of aluminum bar stock. The stuff I had lying around was 3/4" x 1/2", so that's what I used. Slightly thinner stuff might work just as well.
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I drilled holes to hold the copper electrodes and cross drilled and tapped holes for set screws. Did the same thing on the other end to hold the welding cables. Alternately you could cross drill the bars and use terminals on the ends of the welding cables.

After drilling and tapping the holes, I joined the two pieces using double stick foam tape. Tape adheres very well to aluminum and there is enough surface area that the pieces stay pretty rigid with respect to each other. VHB tape is the best, but for this application about anything similar should work.
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The actual electrodes are made from AWG 6 solid copper wire. This was the largest size solid conductor they stocked at my local hardware store. Sold by the foot, so you can make a lot of electrodes for a few dollars worth. Each electrode was cut and placed in my electric drill and spun against a flat file to form the tip.
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The electrodes are placed at an angle which allows the tips to get pretty close. Tip spacing can be changed by extending or retracting the electrodes. I made the holes in the bars a bit oversize for the electrodes so they don't get stuck when dented by the set screws. Right now it has a tip spacing of about 4mm.
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View of the welding cable entry. I used some pieces of copper tubing cut in half on the top side of the cable to keep it from getting shredded by the bolts.
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After assembly, I was going to use some big heat shrink tubing over the handle, but the stuff I had was a bit too small so I settled for electrical tape.

Picture of business end
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Not tested yet, but will report back when I get it set up. I may try placing a switch on the handle to replace the foot pedal. There will be some huge induced voltages in the switch wires during a welding pulse, so some kind of protection or isolation will be needed.
"One test is worth a thousand opinions"

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spinningmagnets
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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by spinningmagnets » Aug 09, 2017 11:39 am

Brilliant! I bought a copper rod to modify, but I now realize it would have been easier (by far) if I had purchased two flat bars.

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by kocetoMR » Aug 09, 2017 2:01 pm

TB28YmIcm4mpuFjSZFOXXaUqpXa_!!97084557.jpg
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TB2FE4QXae5V1BjSspkXXcoqpXa_!!2562038321.jpg
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fechter
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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Aug 09, 2017 6:50 pm

I like the one in the second picture. I might try to copy that. If each electrode was spring loaded you could get even pressure on both and it triggers the switch when you compress the springs enough.
"One test is worth a thousand opinions"

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by kocetoMR » Aug 10, 2017 4:51 am

fechter wrote:I like the one in the second picture. I might try to copy that. If each electrode was spring loaded you could get even pressure on both and it triggers the switch when you compress the springs enough.
https://item.taobao.com/item.htm?id=537 ... dmg8j26111
http://v.youku.com/v_show/id_XMTYwMjk2MTM2OA==.html
$40 without shipping

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fechter
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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Aug 10, 2017 1:56 pm

哎吔 !

My Chinese is not so good. $40 is not bad though.
"One test is worth a thousand opinions"

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by kocetoMR » Aug 31, 2017 12:00 pm


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fechter
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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Aug 31, 2017 12:40 pm

kocetoMR wrote:i buy this pen.It is very usefull
http://v.youku.com/v_show/id_XMjI4MjE3O ... ml#paction
That looks like a good design.
"One test is worth a thousand opinions"

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by shinyballs » Oct 28, 2017 7:56 am

I'm also looking to upgrade mine. What do you think of this one -

https://www.banggood.com/Spot-Welding-P ... rmmds=cart
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Sale section etiquette, pls be courteous to other members, if you know of a better deal or do not agree with the sale price, do not shove links to similar products being sold by someone else in another member's post.. it's just not nice. If you suspect a scam pls FLAG the thread for moderation and it will be checked out... i know this is a tough one to call but put yourself in the seller's shoes and imagine how you would like it.

https://endless-sphere.com/forums/viewto ... 31&t=25446

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fechter
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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Nov 20, 2017 10:50 pm

OK, so my first design is a
FAIL

It worked, but I found it extremely difficult to maintain even pressure on the two electrodes. Not wanting to scrap the work I did already, I decided to modify the design. I drilled a hole through the side and made a pin out of some 3/8" Delrin rod that was threaded internally for some screws. I separated the halves and individually heat shrinked them, then cut out around the holes. The Delrin pin holds the two halves together but they are hinged like a pair of scissors, so the electrodes can move independently but maintain a constant spacing.
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I'm looking at various spring arrangements but it seems to work quite well just by using two fingers, one on each side. More testing to come.
"One test is worth a thousand opinions"

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by progrock » Nov 20, 2017 11:36 pm

I'm a little confused at the whole point of the aluminum block.. I suppose it's not that heavy, and can handle the amps... but seems like it would jsut be a lot easier to just use the same wire you are using to attach to the aluminum blocks, 3d print a nice handle, use similar tips.. and end up with electrodes that have pretty much the same potential. Though maybe the ease of 3D printing to me, compared to building/machining the aluminum blocks... is the inverse for you.. Where building the blocks is much easier than 3D printing (I suppose having a few 3d printers helps, tho $200-300 will get you one that could easily do the job, among many others). Filament also costs next to nothing for something small like this, and it's an extremely easy design to make... plus considering how cheap and easy it is, it would be a lot easier to modify/improve your design over time (costing something like 5-10 cents each time + the copper tips/wire which could be reused).

With that said, they do look nice, and hope they work well (I imagine they do). I'm just wondering if making them so large was necessary, seems like that would be more of a PITA to handle, and you still got the wire between the welder and the blocks, so I'm assuming the amps aren't anywhere close to the max those things could handle. Of course, also make sure you're being careful.. without sufficient insulation. and all that metal, a short across your hand is not going to feel good at all.

Anyway, not really trying to critique, more trying to understand the reasoning behind some of the design (I seem to be missing a lot of obvious things lately... so it's much easier to ask questions than to just think my initial assumptions are correct... too often they are not). I'm also planning to design my own handles very soon, tho planning to make the majority of it with 3d printing... but need to look at all the current electrode designs that people have done, to attempt to steel all their good parts. And, of course, I'll be releasing the designs (unless they are total shit.. in which case you wouldn't want them in the first place).

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Nov 20, 2017 11:59 pm

The aluminum bars were scrap stock sitting in the garage. It's what was lying around. If I had to buy stuff, the design would be different.
I agree the cables could go closer to the tips and you could do a nice 3D printed housing that looks like some of the other designs posted above. I'm just cheap.
"One test is worth a thousand opinions"

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by progrock » Nov 21, 2017 8:29 am

Haha, great explanation, that now makes total sense. I've been debating on how exactly I wanna build my next set of electrodes. So far considering something extremely simple, along the lines of a decent gauge highly flexible silicon stranded copper cable with tips made from a smaller gauge solid copper wire... with a simple 3d printed housing. So far nothing special at all there of course. Tho hoping to progress through different experimental ideas, as well as just simple improvements. I'm not half bad at "utilitarian" 3d design... it's surprisingly easy to figure out something you need, and construct a 3d printable model of it. But planning on trying an ergonomic design... but I think the only way I'll ever succeed at that is by making lots of iterations until I'm happy (or even better, finding other people with 3d printers that also spot weld to test out the designs, and provide feedback). It's incredible what a second set of eyes (and hands for this matter) can make... when designing/building something, it's very interesting how significantly different you view what you are making compared to someone who is just testing it. Seems like you almost inevitably produce some form of tunnel vision when designing something.

Aside from those straight forward, uninventive plans I'm trying to search around for different ideas. Initially, I just need a set of electrodes that are separate to work with, I only have ones that are combined into a single handle right now. But I'm hoping to figure out a good way to consistently be able to weld thin copper, instead of just nickel, to batteries. I think a major part of this is likely gonna involve building a bank of super capacitors capable of providing enough power in a short period of time.... as well as either finding, or building a welder that can handle this power. BUT, I've also seen people claiming to accomplish copper welding by utilizing unique designs in their electrodes. One guy used some copper pipe, and jammed a chunk of graphite into the ends of two pipes, shaping them into tips, to use for welding copper. He demonstrated by welding copper sheets to themselves,,, which is significantly different than welding copper to batteries.... and I am very skeptical... but it at least is a unique idea to give a try. I believe his theory was that the graphite would have a higher resistance than your stereotypical electrode tips (copper or tungsten), which would cause the tip to heat up more, and this heat + the high current would make welding copper possible. But this not only involved copper to copper, but involved having the tips on opposite sides facing each other (very similar to those "cheap" spot welders, like the one you can get from harbor freight... which I believe are basically useless for battery spot welding). Sadly if these do produce a lot of heat, even if they did work, would go against one of the main reasons for spot welding batteries (vs soldering that is). None the less, I feel obligated to at least try his idea... doesn't cost much, and not gonna try it on good batteries in the first place, so aside from wasting some time and a couple of dollars, there's no harm in trying.

Hopefully I find something in all this research I'm currently doing to help improve my odds with copper. Though I do have backup plans... currently developing a method to utilize copper, but not require spot welding it... probably in combination with spot welded nickel. To be fair, my current "design" is just ripping off a design I saw that an aliexpress seller was marketing, with some improvements (not to mention cheaper, considering how inexpensive 3d printing is, as well as raw material... nickel/copper). But I'm still not giving up on spot welding copper just yet.

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Nov 21, 2017 9:15 am

Check out my last posts here:
https://endless-sphere.com/forums/viewt ... 6#p1335096

If you want some really high weld currents, consider using some little Graphene Lipo batteries. The little 2.2Ahr packs can produce some impressively high outputs. If you put a bunch of them in parallel, I'm sure having enough current won't be an issue. These will probably be less expensive than capacitors, but not last forever.

Welding copper to batteries seems to be extremely difficult. The amount of heat you need will be on par with soldering to the cells, which works pretty well with copper strips. Some combination of copper and nickel may be the easiest. Use a short section of nickel from the cell to a copper strip. If the nickel path is short, the losses won't be much. Similar to how a Tesla pack uses bond wires.
"One test is worth a thousand opinions"

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Re: One Handed Electrode Holder for Spot Welder or RSU

Post by fechter » Nov 26, 2017 8:10 pm

A little more testing today.

I took a random piece of PVC pipe I had lying around and sawed out a half circle that had the right spacing to fit between the bars. This acts like a linkage that keeps the pressure even between the two electrodes, as long as it's reasonably straight. It seems to work well. I was getting very good results with .15 and .20mm nickel.
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"One test is worth a thousand opinions"

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