Battery spot welder

[Michael West]

London hackspace is doing a pledge for a battery pack spot welder.

I have had use for this from time to time (last time I did a pack a while ago it was a ball ache with solder tags...)

Something like:
http://www.ebay.co.uk/itm/331657425476

I'd look to modify it to keep the electrodes still and having a foot pedal operation as that method becomes cumbersome once the pack gets larger.

Anyone interested in doing a pledge?

If not, I'm looking to do a personal purchase and put on long term loan to the makerspace.

I did look at making one, but I've decided:
a. I don't have the time
b. I can't be arsed.

c. The chinese thing can probably be modded to make it more user friendly.

Thoughts?

M.

[Andy Selby]

On Friday, 6 January 2017 01:01:14 UTC, Michael West wrote:
Anyone interested in doing a pledge?

I'd chip in for that

Andy

[James Morrison]

I'll chip in even though I have no idea what I would use one for :D

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[Adrian Godwin]

I suspect they're also quite useful for making jewellery.

On Fri, Jan 6, 2017 at 5:21 PM, James Morrison <morr...@gmail.com> wrote:

I'll chip in even though I have no idea what I would use one for :D

On 6 January 2017 at 10:28, Andy Selby <andyf...@gmail.com> wrote:
> On Friday, 6 January 2017 01:01:14 UTC, Michael West wrote:
> Anyone interested in doing a pledge?
>
> I'd chip in for that
>
> Andy
>
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[Andy Selby]

Should we say £20 each as a suggested donation?
That would put us only a fiver behind Londonhackspace cheapskates stalled pledge.
Hell! if it's only us three, £33.33p would buy us the thing but I'm sure there are some people who don't know about this pledge yet.

Andy

[Tomas Begley]

well i was going to make one as i dindnt have the capitol for a full one but will happily pledge like £ 10 - 15 another consideration is pure nickel strip as all the stuff under the 1KG reels always seems to be ni plated steel (much worse conductivity).

the last time i looked it was about £30 - £60 for 1KG

[Tomas Begley]

also if its going to stay at the shed then what about asking for a little bit of help from the improvements kitty?

[Andy Selby]

On Friday, 13 January 2017 14:45:57 UTC, Tomas Begley wrote:

also if its going to stay at the shed then what about asking for a little bit of help from the improvements kitty?

We haven't traditionally raided the kitty for equipment, the desoldering iron and lasercutter was us dipping into our own pockets
As for the battery connectors, how about aluminium from drink cans or cut strips from copper ground plane traces from PCBs both elements are in abundance in the makerspaces crust.

Andy 

[stewart dunn]

All

I have quite a few spare battery holders  - see below 

For  those who are not aware

I bought a set of clear modelling trays with lids  for the new modelling storage rack  (£40+) 

The boxes have now been labelled and are in use - feedback welcome if system can be improved.

The idea being for members to have a handy place to find  simple light modelling materials. 

Things of little value in the trays  can be taken and used,  such a card, rods. gears and new battery holders that I have put in there.

The tray with scissors, pens are for borrowing only.

PS

If you want more battery holders (AA and AAA type- 1.5V to 9V)  

 I may have the ones you want - email me if none in tray. 

Stewart 

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[Andy Selby]

You misunderstand Stewart, we are talking about welding tabs to 18650 batteries.
Five 18650's can make up a replacement 18 volt drill battery.
Thanks for doing that by the way, also we have individual 18650 battery holders if needed.

Andy

[Peter Fraser]

(Andy,

You should worry – when I first saw topic “Battery spot welder”, I assumed it was a spot welder powered by batteries – which knowing the power involved, I thought was quite ambitious.

I’m such an innocent…..)

--

[Michael West]

Pete, they do exist http://www.instructables.com/id/DIY-Arduino-Battery-Spot-Welder/

Just a pain having to have a lump of lead acid or something suitable to power it.

I did think about building it, but then decided no one would ever be arsed to keep the thing charged.

On 13 January 2017 at 23:12, Peter Fraser <pe...@aumod.co.uk> wrote:

(Andy,

You should worry – when I first saw topic “Battery spot welder”, I assumed it was a spot welder powered by batteries – which knowing the power involved, I thought was quite ambitious.

I’m such an innocent…..)

 

From: milton-keynes-makerspace@googlegroups.com [mailto:milton-keynes-maker...@googlegroups.com] On Behalf Of Andy Selby
Sent: 13 January 2017 22:49
To: Milton Keynes makerspace <milton-keynes-makerspace@googlegroups.com>
Subject: Re: [MK Make] Battery spot welder

 

You misunderstand Stewart, we are talking about welding tabs to 18650 batteries.
Five 18650's can make up a replacement 18 volt drill battery.
Thanks for doing that by the way, also we have individual 18650 battery holders if needed.

Andy

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[Andy Selby]

Who needs batteries when you can have ultra freakin' huge supercapacitors

https://thepihut.com/collections/components-parts/products/adafruit-super-capacitor-2-5v-630-farad

On Friday, 13 January 2017 23:51:06 UTC, Michael West wrote:

Pete, they do exist http://www.instructables.com/id/DIY-Arduino-Battery-Spot-Welder/

Just a pain having to have a lump of lead acid or something suitable to power it.

I did think about building it, but then decided no one would ever be arsed to keep the thing charged.

On 13 January 2017 at 23:12, Peter Fraser <pe...@aumod.co.uk> wrote:

(Andy,

You should worry – when I first saw topic “Battery spot welder”, I assumed it was a spot welder powered by batteries – which knowing the power involved, I thought was quite ambitious.

I’m such an innocent…..)

 

From: milton-keyne...@googlegroups.com [mailto:milton-keynes-maker...@googlegroups.com] On Behalf Of Andy Selby
Sent: 13 January 2017 22:49
To: Milton Keynes makerspace <milton-keyne...@googlegroups.com>
Subject: Re: [MK Make] Battery spot welder

 

You misunderstand Stewart, we are talking about welding tabs to 18650 batteries.
Five 18650's can make up a replacement 18 volt drill battery.
Thanks for doing that by the way, also we have individual 18650 battery holders if needed.

Andy

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[James Newton]

https://gyazo.com/0bc785d2980d12ea528d062e0b058a36

willing to donate

http://www.instructables.com/id/DIY-Spot-Welder-From-Microwave/

[Peter Fraser]

[Mike, battery-powered welder]  Why am I not surprised!  Lead acid batteries have respectable energy storage & delivery, so would probably be OK, though I can’t resist chuckling over the prospect of it thus being ‘portable’; a phone which is mobile makes sense, but I can’t see a desire to “weld on the go” [image: think “Ghostbusters”, with backpack…]

Incidentally, only looked very briefly at his design, but not really sure what processor-control brings to the party that a NE555 timer wouldn’t do rather simpler….  And I worry about the durability of his (even 8 x parallel) 20V IRF3704 MOSFET’s in such a harsh environment, with inevitable stray inductance & sparks flying about.

(BTW, hilarious error on IR data sheet http://www.irf.com/product-info/datasheets/data/irf3704.pdf - “Ultra-Low Gate Impedance” – I think they mean channel impedance!)

 

[Andy, supercaps].  Interesting; these have been around for donkey’s years (my 1980’s Aiwa cassette deck has a small 3F supercap for tape-calibration-memory back-up), but they were originally heroically high ESR, so whilst they could provide low current for long time, could not provide high current for short time.  But the examples you cite http://pdf.datasheet.live/datasheets-1/nippon_chemi-con/DDLA2R5LGN631KA95S.pdf are actually quite respectable, with ESR in the <10mohm region – so can deliver quite respectable currents.  Progress…   However [0.5CV²], at such low voltages, ENERGY storage is still pretty low – about 2000 Joules, less than one AA cell, I think….

 

[James, oven TRF] re-purposing microwave oven TRF’s always good sport; I still occasionally come across short lengths of enamelled copper wire on my garage floor from a somewhat over-enthusiastic “chisel & peel” secondary removal about 20 years ago…..  It’s a shame the article “fluffs” dismally to define his new secondary; can see its about 3 turns, but crucially what CSA & length of wire, which I presume will define the secondary [welding] current.

 

General: I note the first article is for a DC welder, whereas the second is for 50Hz AC.  No idea which is best, and I don’t know what’s “inside the box” of Mike’s original commercial example http://www.ebay.co.uk/itm/331657425476 .  Have hunch that AC is better? – and allows control of lowish-current TRF primary, rather than [I presume] huge amps at DC – although we’re not doing MoT repairs here, so maybe reqd currents for e.g. ‘tabbing’ batteries is not that high?

For info, I have:

·         stock of 10A SSR’s (though warn that my experiences of using them to control high-inductance loads e.g. TRF’s is littered with blood-stained tee-shirts)

·         large stocks of chunky 50A stud-mount diodes

·         large stock of 12swg (2.65mm) enamelled copper wire

– happy to donate to anybody wishing to experiment.

Does anybody know of an article with more ‘considered’ sober analysis of welder technical requirements?

 

Pete.

 

From: milton-keyne...@googlegroups.com [mailto:milton-keyne...@googlegroups.com] On Behalf Of James Newton
Sent: 14 January 2017 23:13
To: Milton Keynes makerspace <milton-keyne...@googlegroups.com>
Subject: Re: [MK Make] Battery spot welder

 

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[Adrian Godwin]

This one

http://www.ebay.co.uk/itm/182409889697

claims that it's best to pulse twice : once to clear the oxides and make a deliberately high resistance joint, and a second time to make the proper weld. The version Michael linked also does a double pulse. The more important function of the arduino seems to be to control essential flashing lights.

I'm not sure I'd trust either a micro or a 555 to behave well near current pulses of 100A or so, but they might, with care.

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[Michael West]

Yeah, I did look at stripping the parts out of something and making one or the other, but I really just cannot be arsed as I need to make and source arms, welding tips, make/find/steal a suitable case to put it in etc.

Probably makes no difference with the AC/DC as is only a very short pulse.

I think the arduino control rather than the 555 was that he knows arduino so had to not spend time reading the data sheet - use what you have to hand and know I guess.

Easy to rig up a display to show your parameters for the pulses etc and make it self contained.

The double pulse is the way to go for it as well. Tried and tested by many people.

As I said, lead acid as a power source. Great if you keep it charged. And no one will and it'll die a noble death....

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