Boss level custom spot welder

I just got a couple days ago a custom spot welder. It has tons of potential so i want to share this info with the community.
I live in a small house, we are swimming on electric and painting stuff so i can’t afford to have big machines. I looked for small custom spot welders on the net: microwave, car battery, supercapacitors… all of them too big or not what i was aiming for. Then i found this welder. It’s not a new device, was created time ago, since it is interesting many guys tried to buy it and the creator sold a few in his area but refused for a long time to ship overseas, i guess it’s looong time consuming for a low profit.
People insisted so recently he opened his hands to the world and i managed to get one for me. I’ll make a small review.

It’s made out of arduino custom shields. The creator is a korean genius named Aulakiria. He did many prototypes, ac powered…dremel size…this is the final item.
It’s powered by a 3s lipo, YES! lipo hates being shorted but he managed to limit the short to 16ms so no damage at all. The size is minimal 4x3x8 cm.

This is how i got it. The module, a pen, a momentary switch for manual use and a hakko solder iron (It solders as well) The shipping was incredibly fast 7 days from korea.

He sent me as a courtesy some nickel strips and the matching xt90 connector for the lipo.

everything fits inside this small box. PERFECT! my dream size.
All you need is a 3s lipo to use it. Just solder the xt90 and you are done. Aulakiria recommends top lipos, above 40c. It will work with whatever you have but the better the lipo the better the welds. He even did the demos with crappy b grade 25c to prove it.
UPDATE MARCH THE 25TH OF 2018 The new model has updated firmware and has become more resilient to 4s lipo use. Also many new users reported low performance on thick/wide tabs using unknown lipo brands or just crappy bricks around. Therefore i recommend ONLY top quality lipos. HOBBYKING Turnigy NanoTech and Graphene have been reported to be perfect. Use only high C lipos. They are often overrated or even exaggerated at C ratings so do not trust blindly the manufacturer claims.The thickness of the wire also matters.The continuous C is irrelevant. Look for the burst. Aim for 130C(burst) 5000 mah.
I use
You can use several bricks in parallel in case you do not reach the amps required. Avoid wired adaptors for parallel. The transport will lose lots of amps. Use only adaptors like this:[/color][/color]

It has top quality IFR1404 mosfet manufactured in Korea and Taiwan. He recommends to keep the mosfet under 50º celsius. The shield has a port for a 5v fan. The left side is negative and the right side is positive.

I installed a fan but totally failed. The temperature was always high, the welder stops automatically to avoid damage.
So annoying! My country is VERY HOT these days.

Well…maybe not that hot but very hot anyway so i installed some heat sinks on the plate.

and two 12 volt fans.The temperature never goes above 30º celsius now.

In normal conditions any 5v will do a perfect performance. If you have a soft weather there’s no need to mod.
mod video:

I did a small video to show the performance:

To use the hakko solder you need a power supply 12-35v. 19+ prefered .Any laptop power supply will do.

This is me testing the iron

This is Aulakiria himself using the iron:

Aulakiria translated the menu so we can read it. It’s easy to play.

using it:

in depth testing

How to make your own welding pen

Part two, welding pen with interchangeable tips

The welding times are usually:
For nickel strips
0.1 1.4ms
0.15 4ms
0.20 7ms
The machine is copper welding capable but requires 4s lipo. That is dangerous for the machine and yourself. The intense use of 4s lipo on high flux times may cause premature failure of the machine. Use it at your own risk.
copper times are:
0.1 5-6 ms x2
0.2 10-12 ms x4
Do not use copper unless you know what you are doing. The use of gloves and glasses are mandatory.

when the A is blinking is ready to weld in the waiting time you set. When manual set selected it will weld when you press the button. I plan to install a pedal.
My honest verdict:
if you are low on budget,have a small house and you just make small packs every now and then like me this is perfect.
If you have a huge garage plenty of room, you can afford semi-professional machines and/or you do intensive use of spot welder maybe you prefer something bigga hardda fastta strongga.

update february 21th of 2019
Let me introduce the MinispotA

Lee has built a mini version of the Boss spot welder.
take a look here

I am not affiliated, associated, authorized, endorsed by, or in any way officially connected with Aulakiria. THIS IS NOT A SALES THREAD. And i have no profit nor gain with this, i just think it’s a nice thing and i am sharing it with you. If you are interested on buying one just mail him saying you want one here that’s his paypal account as well. If you mail him be brief and use only perfect academic understandable english. Something google translator can deal with.
The prices are :

basic set : usd $ 95

Hakko T12 soldering iron Handle & Tip : usd $15 (option)

full set : usd $110

Paypal fees 3.5%, Usd-krw Exchange fees 3%…It is double charged so please consider the option send money to family/friend

shipping method

Global RR (KOREA post registered airmail) : $15 (20~40 business days)

Global EMS fee : most $27 (10~15 business days)

U.K (Great British) : $33

Italy : $38

MAY THE 31TH OF 2019 i just did a copy and paste of this thread from used to be at our old forum.

The purpose of this thread is talking about the machines designed by @aulakiria and spot welding with them.



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  1. does anyone have these on hand in the US to save shipping time?

  2. If the ideal source is a 3s lipo, would it be better to solder an XT90 to some jumper clamps and use a 12V car battery? Far more amps and capacity, it’s basically a 3s15p battery


People reported 4 days shipping times to USA.
Car battery is not the best idea. Some succeeded on that but most people failed. Lipo is the best option.


What’s bad about car batteries? I’m asking because I don’t have any lipos or chargers, I’d rather not spend $50 on top of the $95 to get one

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Not good enough for this machine. Weak welds. This machine was intended to be as small as possible and work with a tiny lipo brick. Small, cheap and portable. That’s the purpose and has been achieved. Car battery is good for other machines but not for this one at least not any car battery.

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I’m a bit miffed by this, how can the welds be lower quality if lead acid can put out several times the amps at the same voltage? I’m not trying to arfue but I don’t quite understand

You’re definitely right about the size thing though


from my experience:
get yourself some nice caring case in which you could put everything needed for spot welding job.

also, get new welding tips as soon as possible. my tips are just 6mm wide copper rod shaped with drill and file. they are separated, which means I have to use both hands when welding. but every weld will be perfect, because you can make pressure with every tip as much as you need.


I’ll just put the tip in here

That’s the original pen made from circuit breadboard and two pieces of copper wire…it comes free

Thinking that I can just replace the tips as the copper is deforming which can cause one side to not press in as much as the other leading to blow holes, that’s why you see @Rojitor pressing down on the actual tips to maintain even pressure

They are Al Cu, let you know if they play nice


The continuous C is irrelevant for spot welding. You need high C burst. A common car battery can’t put out several times the burst of a lipo. This machine was designed to work with lipo. I had lipos and chargers around so it was a no brainer for me. If you need to use a car battery i do not recommend you this spot welder. Make a diy with an old microwave oven or buy a kit elsewhere. Look for the riva kit at endless-sphere for example. That works fine with car batteries.


copy and paste from the other forum for those who heard about the sandwich method to weld copper. Not needed with this machine.

ok here’s the test with the MiniA 0.05 copper

left scraps are from the sandwich test and right scraps are direct weld 3s

And this is the boss welder on 0.1:

left sandwich and at the right direct welds.
Direct are far superior with Lee’s machines.


Thanks for porting this content, in payment I would like to show you my tip


Just the tip…what a tease

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What if I was to tell you I’ll take it out in time?

3ms all night long, I though it was the battery and did this, now slowly dialling back settings and thinking it’s a combo. Here’s the change I made battery wise 4s2p

Turnigy 5Ah 60c-120c jerryrig pack, ugly as all sin but effective

Boss needs cooling need to check if I can give it a aluminium hedgehog effect

[quote=“ZachTetra, post:5, topic:1461, full:true”]
What’s bad about car batteries? I’m asking because I don’t have any lipos or chargers, I’d rather not spend $50 on top of the $95 to get one
[/quote] put more car batteries in parallel

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Nothing wrong with using a car battery with a bigass current delivery, or two if they are a bit old and weak. Some folk are doing exactly that

A couple months ago we got a new one and it think it’s 900 cold cranking amps…and it’s definitely not cold out here, so I think it can put out more power than a lipo


I did pens with those too. Not a bad option.

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They sacrifice very little current carrying ability but are stronger and less likely to stick to the nickel on high load, I was impressed with the good contact and pressure I could achieve = better welds

Is a burst of 40c way to low for welding? It does produce some good welds at around 10ms on 0.15, but the weld time seems a bit long…?