JP spot welder open source

[riba2233]

Hi, I have decided to open source everything related to my spot welder. It is a simple, reliable, and easy to repair battery powered spot welder.

You can use these files for all purposes, even commercial, at your own risk.

Here you can find all files needed to make this spot welder from scratch:

https://app.box.com/s/kg4blwtqwmwl68pgk58va8anifdw8jws

I will answer questions if I have time, but that is unlikely since I have started a new business, not related to EV's. If you like computer hardware, you might want to take a look:

https://smallformfactor.net/forum/threa ... ort.10919/



I wish you luck with building the welder!

[john61ct]

Wow!

Congratulations, and on behalf of the community, thanks so much.

FOSS and open hardware movements are a shining light of hope for a better future amidst all the doom & gloom of this timeline's current zeitgeist.

Are you taking donations?

[john61ct]

PS that SFFtime P-ATX looks like a cool case, best of luck with that.

[riba2233]

Thanks, I hope this will be helpful to someone.

I'm not taking donations.

Thanks, I am very happy with the design and I hope others will like it also. I have great plans for the future

[fechter]

Thanks for posting the code. Great to be able to make a replacement PIC if I blow mine up.

[amberwolf]

Thank you for posting this.

It took me some gyrations and time to get the linked page to work, so for anyone else that might have problems, I've attached the zip file that link leads to directly to this post.

[riba2233]

Thanks for reuploading, the more sources the better

[krlenjuska]

I ordered PCBs and all components - will try to make this

[riba2233]

I ordered PCBs and all components - will try to make this

Great to hear, please post your progress and pictures here

[krlenjuska]

I ordered PCBs and all components - will try to make this

Great to hear, please post your progress and pictures here

Most difficult thing to do for me is to program pic controller - never tried this

[riba2233]

I ordered PCBs and all components - will try to make this

Great to hear, please post your progress and pictures here

Most difficult thing to do for me is to program pic controller - never tried this

It's simple once you have a programmer like pickit 2 or 3 with their own software, just connect it to pc, load the hex file, and press program

[krlenjuska]

I ordered PCBs and all components - will try to make this

Great to hear, please post your progress and pictures here

Most difficult thing to do for me is to program pic controller - never tried this

It's simple once you have a programmer like pickit 2 or 3 with their own software, just connect it to pc, load the hex file, and press program

Thanks i ordered pickit 2.
1 question about resistors - can i use any resistor or wattage is important?

[riba2233]

You can use anything from 0.25 w above.

[krlenjuska]

You can use anything from 0.25 w above.

Can i use some other similar mosfets? Cant find 1324 at my local stores.

EDIT: never mind i managed to find it.

[riba2233]

You can use anything from 0.25 w above.

Can i use some other similar mosfets? Cant find 1324 at my local stores.

EDIT: never mind i managed to find it.

You can use those or better (watch for max voltage, IR, and gate charge).

[flywire]

Consolidating a few posts - please PM me the reference if I missed something.

[Note: ↑ after wrote links to original post]

Here you can find all files needed to make this spot welder from scratch: https://app.box.com/s/kg4blwtqwmwl68pgk58va8anifdw8jws

... I've attached the zip file

... Link to DIY version assembly manual, also includes pictures of welder rev2.0: https://app.box.com/s/vko7vtxh5ya5vyql72unfhfo4hgy70tr


standard kit [Right click and open in new tab to enlarge]

... Welders are based on mosfets that switch power from lead starter battery ... you need additional power source for logic, that can be small wall adapter or small 12 V battery.

Here are some videos that show what do you get in the kit and on how to use the welder:
https://www.youtube.com/watch?v=dqrIO_Bvsak
https://www.youtube.com/watch?v=G_JC4YGrvwA

I prefer a much smaller point at the end ... So I came up with this idea...why not use a steel pencil sharpener:

[riba2233]

Thanks man, this is really useful!

[flywire]

... Link to DIY version assembly manual, also includes pictures of welder rev2.0: https://app.box.com/s/vko7vtxh5ya5vyql72unfhfo4hgy70tr

Components need to be right and some are a little hard to identify - I'll try and update with sample links. Most of the board cost is in the IRF1324 Mosfets and your time. Hint: Copy paste table below into a spreadsheet as Tab delimited.

Code: Select all

Step	Qty	Item
1-2	1	PCB - Order

4	6	82R 1/4w Resistor
5	5	4k7 1/4w Resistor
7	1	1N4001 Diode
8	1	3mm Green Led
8	1	3mm Red Led
9	1	100n Capacitor
10	3	1u Capacitor
11	1	78L05 Regulator
12	1	100u Electrolytic Capacitor
13	1	2 pin angled connector for 12V
14	1	1k-10k Potentiometer
15	1	DC Barrel Connector
opt	1	2.54mm Pitch 2 Row 8P IC Socket
16-19	1	PIC12F675 microcontroller
16-19	1	MCP1407 Mosfet driver
20	2	100mm x 20mm x 3mm Aluminium bar - Make Aluminum bus bar
20,23	14	M3 x 4mm long screws
23	6	M3 x 3mm long screws
23	6	R3 ~12.6 mm brass soldering lugs
21-28	6	IRF1324 Mosfet
33	1	M6 x 15mm bolt, nut and spring washer
33	1	Clear Vinyl Tube R60mm x L70mm

	2	110mm x 10mm solid brass rod - Make Electrode Holder
	4	M4 x 3mm Grub Screws		
	2	Shrink Wrap (Red/Black)		
	2	60mm x 5mm solid copper rod - Make Electrode Copper Tip

	2	Cables: 25mm2 1 x 450mm, 1 x 550mm
	2	Lugs for cables 25mm2, 6-8mm hole

	1	Footswitch and 2m cable with 2pin connector

		pic programmer like pickit 2 or 3
		Antistatic wristband
		Soldering iron
		Solder
		Pliers
		M3 and M4 thread taps
		Cable crimper

PCB order from jlcpcb is very cheap and easy - drag gerber to order and accept defaults and it should look like:

Code: Select all

PCB prototype:Y1-9999999A
Gerber file - PCB GERBERS_Y1
Build Time: 1-2 days
Layers:2
Dimension:67mm*73mm
PCB Qty:5
PCB Thickness:1.6
Impedance:no
PCB Color:Green
Surface Finish:HASL(with lead)
Copper Weight:1 oz
Gold Fingers:No
Material Details:FR4-Standard Tg 130-140C
Panel By JLCPCB: No
Weight:160g
Flying Probe Test:Fully Test
Castellated Holes:no

Thanks krlenjuska and riba2233 for helping with this.

[flywire]

One of the best things about open source is community contributions so I'll gather a few here:

I can't get the soldering lugs conveniently so I'll use M3 ring lugs ( https://www.aliexpress.com/item/32910958824.html ).

... make sure they are made out of brass and not steel, and look out for counterfeit mosfets, those won't work.

Right, see if there is voltage on the probes before the foot pedal is activated. If the FETs blow, they generally short so you'd see 12v on the probes all the time.

Old car jumper leads or the main wires to the car battery would probably be a good source of 4 AWG copper wire.

I always want to modify my electrodes, make new one with smaller, 2,5mm in diameter intake so I can just use regular copper wire for welding. When I was out of those 5mm electrodes I actually used 2,5mm wire inside the electrodes(above electrode in the pic) without any complications.

I got everything hooked up with the real long 6 foot 4AWG silicone wires. ...

Would it be possible to describe what diode and photo of how it’s installed?

The post above by Offroader shows it well. There are two diodes. One big schottky diode goes across the leads as close to the welder as possible. Another TVS diode goes across the FET legs to catch what the other diode misses. The leads, especially long ones, will act like an inductor and store energy during the pulse. When the pulse ends, that energy has to go somewhere. Without the diode, the voltage all goes to the FETs, which could possibly damage them.

Lots of people run these circuits without the diode and it doesn't blow up as long as the supply voltage, current and lead inductance stay within reason. I'm only using a diode across the leads and no TVS diode.

Keeping the two welding wires close together (zip ties or tape) will minimize the inductance. The idea is to minimize the loop area.

So which is better?

This:


Or this:


... both solutions give the same result ... Because I'm poor and prefer the cheaper MOSFET option.

... Are these the FETs you suggest? http://www.digikey.com/product-detail/e ... ND/3454578

Yes, those FETs should work fine. It's cheap insurance. With the diode, it should be pretty bullet-proof.

Here's the diode installed on my little battery:

[krlenjuska]

I recieved pcbs from JLCPCB. 13 days from order day. This is record for me when i order something from China.
Also i should take over other components tomorrow - arrived from mouser to my local electronics store.
After that i need to make busbars and cables with electrode holders/electrodes.
Also i dont have car battery right now...




I forgot - my Pickit 3 also arrived today.

[flywire]

I notice in comparison to the JP spot welder the kWeld uses a much lighter electrode system. Is this system an option for the JP spot welder? Can someone explain the theory, especially in relation to inductance and heat? (I'm looking to use .15mm nickel strip.)

... I have changed the electrode design like this now. ...

... The new system only requires crimping the cable to a brass tube, thread-tapping tube and copper electrode, and heat shrinking an isolation. This also makes electrode replacement easier than ever before.

Right click to open in new tab

... the upgraded electrode system

Right click to open in new tab

Frank and I came up with two slightly different designs for electrodes, but they both follow the same design principles. You must use thick copper, and any connection must have a solid copper-to-copper connection. I'm not saying that my electrodes are best, or that Franks are, but lets take a look at those electrodes from China.
...
If you are thinking about using thicker copper conductors to reduce the heat from welding, be aware that any brass parts will be 3 times hotter. When copper is out in the weather, corrosion is a serious issue, but indoors it is not a problem. Copper may turn a little brown instead of bright reddish, but the conductivity of a solid connection is still MUCH better than brass.

The electrode tip holders that frank and I have used is C14500 "Tellurium" copper. It has 93% of the conductivity of pure copper (so they run cooler) but they have a tiny amount of alloy that makes them easy to machine/drill. I approve of cylindrical electrode tips (the replaceable part) because we can find those in copper, tungsten, and carbon.

Just wanted to share a piece of work with you that I am doing for a customer. These teflon handles will provide additional heat insulation and should allow significantly faster welding speed. The assembly also uses 6AWG leads, which should help keeping them cooler as well.


Right click to open in new tab

If a copper pipe electrode holder was viable it would probably be easy to make, even if it had plastic covers.

[riba2233]

Sure, it will work.

[spinningmagnets]

I'm sure anyone here can order the welder electrodes from kWeld and try them on a JP welder. I am certain they would work fine.

[riba2233]

I'm sure anyone here can order the welder electrodes from kWeld and try them on a JP welder. I am certain they would work fine.

Yep, that's correct

[flywire]

I'm sure anyone here can order the welder electrodes from kWeld and try them on a JP welder. I am certain they would work fine.

Nice to see mod is a reasonable suggestion but in reality for many locations open source parts either need to be sourced locally or from China:

kWeldElectrodeSystemLooseParts.png (15.11 KiB) Viewed 4299 times

I think something more like below (maybe solder cable instead of crimp and/or a pin instead of thread) is more the go for home hackers (assuming focused on good entry-level performance):

... The new system only requires crimping the cable to a brass tube, thread-tapping tube and copper electrode, and heat shrinking an isolation. This also makes electrode replacement easier than ever before.

Right click to open in new tab

* 1m x AWG8 (8.4sqmm, 3.3mm) silicon high flex wire
* 2 x M6 (10sqmm) ring cable shoe
* ??mm x ??mm copper tube for electrode holders
* ??mm x ??mm copper rod for electrode tips (AWG8 suggesting 3mm and rounded tips noted)
* ??mm x ??mm plastic tube as electrode holder handles for thermal resistance (maybe pvc or polyethylene pipe)
(electrode tips and holders could be same piece using 5mm or 6mm solid copper rod)

I wonder if some of the heat issues could be reduced with AWG6 cable which might suit a 4mm electrode rod and 6mm OD copper tube with 4.5mm ID.

Maybe I'm over-thinking the cable-tip joiner:

TerminalStrip-Specs.jpg (14.61 KiB) Viewed 4299 times

Hey - just putting it out there for those with tried and tested experience. No idea if it will over heat or blow mosfets etc.

Edit: I'm going to try this basic Electrode System Hack with non-replaceable tips

- 2 x 500mm AWG8 wire, maybe silicon, with M6 tinned copper lugs on one end
- 2 x 70 mm of 5mm copper rod, maybe C14500 (tellurium copper) if available as it seems more workable

* Turn rod in drill and form tip with (file, grinder, pencil sharpener) tools leaving a 1mm blunt rounded end
* Swap rod end in drill and turn holding a felt tip pen to end to roughly mark centre, remove and hit with centre punch, drill (1/8" ??) 7mm deep hole to match wire
* Strip 7mm of AWG8 wire (8mm if soldering), feed into probe and crimp or heat probe with torch and feed solder into join
* Cover probe and part of cable with some sort of plastic handle (approx 2mm thick) then heat to shrink supporting wire join and as thermal barrier

Comments welcome!