Converting stick welder to tack welder.

[Tim Zimmerman]

I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks

 

[Clandestine]

Build your own resistance welder at home:

http://users.frii.com/katana/spotweld.html

Good Luck, please post results or casualties.

 

[Jamie]

Tim Zimmerman wrote:

I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks






find your self dead microwave oven ( high power line), use the

heater tap on the transformer.

 

[Si Ballenger]

On Tue, 22 Feb 2005 12:48:03 GMT, "Tim Zimmerman"
<Z@UCBerkeley.edu> wrote:

I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks

Check the rec.crafts.metalworking news group. Lot of info there
on things like this (and a lot of other DIY stuff).

 

[Eric R Snow]

On Tue, 22 Feb 2005 12:48:03 GMT, "Tim Zimmerman" <Z@UCBerkeley.edu>
wrote:

I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks





Tim,

The reason your stick welder is not good for spot (what you call tack)
welding is because the voltage is too high and the current too low. I
experimented with a microwave oven transformer and was able to get 400
amps at 3 volts. This is done by removing the high voltage secondary
windings and replacing them with a few windings of heavy wire or even
copper bars. See other replies for links etc. for building your own.
ERS

 

[Steve Taylor]

mike wrote:

How well did this work when YOU tried it? How did YOU keep from killing
yourself on the high voltage winding?

When I did it, I drilled the HT winding out. Brutal, but fast. To be
honest, the idea didn't work for me at all, and I built a miniature
capacitor discharge welder that DID do the job - a modest bank of old PC
power supplies yielded enough capacitors to hold "useful" amounts of
energy.

Steve

 

[Martin H. Eastburn]

Eric R Snow wrote:

On Tue, 22 Feb 2005 12:48:03 GMT, "Tim Zimmerman" <Z@UCBerkeley.edu
wrote:


I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks






Tim,
The reason your stick welder is not good for spot (what you call tack)
welding is because the voltage is too high and the current too low. I
experimented with a microwave oven transformer and was able to get 400
amps at 3 volts. This is done by removing the high voltage secondary
windings and replacing them with a few windings of heavy wire or even
copper bars. See other replies for links etc. for building your own.
ERS
With only 3 volts, the resistance of the metal and any 'dirt' best be doing zero ohms...

Not much punch through voltage.

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer oldtree@pacbell.net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

 

[Nick Huckaby]

"Martin H. Eastburn" <oldtree@pacbell.net> wrote

I experimented with a microwave oven transformer and
was able to get 400amps at 3 volts.

With only 3 volts, the resistance of the metal and any 'dirt' best be
doing zero ohms...Not much punch through voltage.
Martin

How about 12V? Would two car batteries work?

 

[mike]

Martin H. Eastburn wrote:

mike wrote:

Martin H. Eastburn wrote:

Eric R Snow wrote:

On Tue, 22 Feb 2005 12:48:03 GMT, "Tim Zimmerman" <Z@UCBerkeley.edu
wrote:


I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks






Tim,
The reason your stick welder is not good for spot (what you call tack)
welding is because the voltage is too high and the current too low. I
experimented with a microwave oven transformer and was able to get 400
amps at 3 volts. This is done by removing the high voltage secondary
windings and replacing them with a few windings of heavy wire or even
copper bars. See other replies for links etc. for building your own.
ERS



With only 3 volts, the resistance of the metal and any 'dirt' best be
doing zero ohms...
Not much punch through voltage.

Martin

FYI
Here's the voltage waveform for a Unitek 125 intoa .001 Ohm load .
http://nm7u.tripod.com/homepage/uniwvfm.jpg
mike

I'd be nervous calling it a 0.001 ohm load - but ok.

I think the connectors are exceeding that - two clamped down with bolts
and the two
on spring loaded clamps.

I'd measure the Tr fro 10 to 90% point

Thanks for the waveform and idea.

Martin

You're being too picky.
The manufacturer publishes a specified waveform for their device
under controlled conditions.
Gives you some idea of what you're up against welding battery tabs.
mike

--
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with links. Delete this sig when replying.
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[mike]

Steve Taylor wrote:

mike wrote:


Post some details on voltage, capacitance, how'd you switch it?
electrode construction?


Hi Mike,

We needed to weld some exotic metals, that required CD welding. Our
welder was built in a glove box, The electrode construction was similar
to your, we modified a toggle clamp to do the job with 1/16" diameter tips.

The cap- bank was around 2200uF (10 x 220uF 400V reservoir caps) Energy
supply was a large variable O/P PSU, large because thats what we have
around. Drive was 0-400V. Welding occured at around 40V.

Discharge was effected by a very large old automobile relay , with
contacts bigger than US pennies (around 1" - like the old UK pennies)

Thanks for the info. I was never successfull trying to switch the weld
current. Welded a lot of contacts, but no battery tabs ;-)
Typical CD system discharges more volts into a step-down transformer.
mike

Job was pinched in the jaws of the spotter, then the hands had to
operate two buttons simultaneously to activate the spot.

Yes, I'd have preferred to use a huge ignitron, or a hockey-puck
thyristor, but we didn't have time - this was a two day
oh-god-we-have-to-do-this-yesterday kind of thing.

We just about managed to weld molybdenum foil ~0.2mm thick, with it.

Steve

--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[Steve Taylor]

mike wrote:

Thanks for the info. I was never successfull trying to switch the weld
current. Welded a lot of contacts, but no battery tabs ;-)
Typical CD system discharges more volts into a step-down transformer.
mike

It would need to be a very good transformer, to handle high speed, high
current transients like this - I doubt I could design one off the top of
my head.

Steve

 

[Martin H. Eastburn]

mike wrote:

Martin H. Eastburn wrote:

mike wrote:

Martin H. Eastburn wrote:

Eric R Snow wrote:

On Tue, 22 Feb 2005 12:48:03 GMT, "Tim Zimmerman" <Z@UCBerkeley.edu
wrote:


I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks






Tim,
The reason your stick welder is not good for spot (what you call tack)
welding is because the voltage is too high and the current too low. I
experimented with a microwave oven transformer and was able to get 400
amps at 3 volts. This is done by removing the high voltage secondary
windings and replacing them with a few windings of heavy wire or even
copper bars. See other replies for links etc. for building your
own. ERS




With only 3 volts, the resistance of the metal and any 'dirt' best
be doing zero ohms...
Not much punch through voltage.

Martin

FYI
Here's the voltage waveform for a Unitek 125 intoa .001 Ohm load .
http://nm7u.tripod.com/homepage/uniwvfm.jpg
mike

I'd be nervous calling it a 0.001 ohm load - but ok.

I think the connectors are exceeding that - two clamped down with
bolts and the two
on spring loaded clamps.

I'd measure the Tr fro 10 to 90% point

Thanks for the waveform and idea.

Martin


You're being too picky.
The manufacturer publishes a specified waveform for their device
under controlled conditions.
Gives you some idea of what you're up against welding battery tabs.
mike

When I was a Senior Scientist for Schlumberger ATE, to picky isn't it. It saved

the company and customers a number of times.

Tr is rise time of a waveform - 10-90 or 20-80. Some waveforms measured from 0 to 100
would never make the two levels - unless a static condition exists.

Math is based on the two levels.

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer oldtree@pacbell.net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

 

[mike]

Martin H. Eastburn wrote:

mike wrote:

Martin H. Eastburn wrote:

mike wrote:

Martin H. Eastburn wrote:

Eric R Snow wrote:

On Tue, 22 Feb 2005 12:48:03 GMT, "Tim Zimmerman" <Z@UCBerkeley.edu
wrote:


I need a tack welder for joining thin plates and electronic
components. Like the tack weld you see in your NiCad battery packs.
I have no practical use for my 120v, 80-Amp stick welder so now I'll
convert it into a tack welder.

I like to get some ideas on how to make a setup that will be safe
and
precise enough to do small electronic welds like the welds found on
some relays. Does this sound possible, if not can you point me to a
place to get a spot welding setup?

Thanks






Tim,
The reason your stick welder is not good for spot (what you call
tack)
welding is because the voltage is too high and the current too low. I
experimented with a microwave oven transformer and was able to get
400
amps at 3 volts. This is done by removing the high voltage secondary
windings and replacing them with a few windings of heavy wire or even
copper bars. See other replies for links etc. for building your
own. ERS





With only 3 volts, the resistance of the metal and any 'dirt' best
be doing zero ohms...
Not much punch through voltage.

Martin

FYI
Here's the voltage waveform for a Unitek 125 intoa .001 Ohm load .
http://nm7u.tripod.com/homepage/uniwvfm.jpg
mike

I'd be nervous calling it a 0.001 ohm load - but ok.

I think the connectors are exceeding that - two clamped down with
bolts and the two
on spring loaded clamps.

I'd measure the Tr fro 10 to 90% point

Thanks for the waveform and idea.

Martin


You're being too picky.
The manufacturer publishes a specified waveform for their device
under controlled conditions.
Gives you some idea of what you're up against welding battery tabs.
mike

When I was a Senior Scientist for Schlumberger ATE, to picky isn't it.
It saved
the company and customers a number of times.

Tr is rise time of a waveform - 10-90 or 20-80. Some waveforms
measured from 0 to 100
would never make the two levels - unless a static condition exists.

Math is based on the two levels.

Martin

I don't understand you at all...
The vendor published a picture of a waveform. On it, they clearly
defined a parameter Tr and quoted a number for a time associated with
that graphical representation.
I can't think of a more unambiguous way to define the parameter.

You have in your head a definition for a thing called Tr. That's where
the ambiguity resides. And it's unrelated to the picture and number
provided by the vendor. Unfortunate choice of parameter name?
Seems so in your case.
But it's still UNAMBIGUOUS!!
Picture >= 1,000 words. Math is not required.
Feel free to relabel the vendor data to suit your needs.

mike
Me do loves a good pissing contest...

--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
Wanted TEK SG504, don't need the head.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[Nick Huckaby]

mike <spamme0@netscape.net> wrote in message news:421E09C1.9040604@netscape.net...

Nick Huckaby wrote:
"Martin H. Eastburn" <oldtree@pacbell.net> wrote

http://nm7u.tripod.com/homepage/uniwvfm.jpg
Sure, if you had some way to turn them on/off quickly.

Could an automotive relay switch them on/off quickly to acheive
the wave form you posted?

Be sure to use a heavy metal box to contain the battery explosion
if something goes wrong.

So you're saying that capacitors are less likely to explode?

Thanks

 

[Steve Taylor]

Nick Huckaby wrote:

This CD welders (below) require 680,000 mirco F.
What's the different about yours?

http://www.powerstream.com/spot-welder.htm

....it cost about zero to build for a start !

Steve

 

[Nick Huckaby]

"mike" <spamme0@netscape.net> wrote in message news:4224B217.6070909@netscape.net...

The cap- bank was around 2200uF (10 x 220uF 400V reservoir caps) Energy
supply was a large variable O/P PSU, large because thats what we have
around. Drive was 0-400V. Welding occured at around 40V. - Steve

This CD welder (below) requires 680,000 mirco F.
http://www.powerstream.com/spot-welder.htm

snip
Would be interesting to see a graph of weld voltage and current vs time.
mike

I found a graph for a dual pulse CD welder here.
http://religion.p5.org.uk/cdwelder.htm

I assume that most CD welders require about 680,000 mirco F.
How's it possible that Steve can weld with only 2200uF? How does
the power supply provide the necessary current to the capacitors?

 

[Nick Huckaby]

"Steve Taylor" <steve@ravenfield.com> wrote in message news:421f6d52$0$8745$db0fefd9@news.zen.co.uk...

Discharge was effected by a very large old automobile relay , with
contacts bigger than US pennies (around 1" - like the old UK pennies)

You mean a starter solenoid?

Job was pinched in the jaws of the spotter, then the hands had to
operate two buttons simultaneously to activate the spot.

Are these just safety buttons to prevent electrocution?

The cap- bank was around 2200uF (10 x 220uF 400V reservoir caps) Energy
supply was a large variable O/P PSU, large because thats what we have
around. Drive was 0-400V. Welding occured at around 40V.

This CD welders (below) require 680,000 mirco F.
What's the different about yours?

http://www.powerstream.com/spot-welder.htm

 

[Clandestine]

Those "tack welds" are created by resistance heating between the
parts. There is no arc involved. It takes considerably more power
(watts) to weld by resistance than by arc. They are also done faster
than most arc welds. To put this in perspective those electrical
components required about 1,000 Amps in ˝ second. Usually the current
is turned on/off by an SCR (or similar switch). I have never heard of
converting an arc welding power supply into a resistance welding power
supply. Keep in mind these critical factors during this type of
welding

FORCE - you must "pinch" pieces together (approximately 500 lbs)
POWER - you need a high, controlled amount of electricity
TIME - You need to regulate the power flow within 1 cycle (1/60
second).

Unitek-Miyachi makes small resistance welders. www.unitekmiyachi.com

 

[Josh Sponenberg]

Clandestine wrote:

Those "tack welds" are created by resistance heating between the
parts. There is no arc involved. It takes considerably more power
(watts) to weld by resistance than by arc. They are also done faster
than most arc welds. To put this in perspective those electrical
components required about 1,000 Amps in ˝ second. Usually the current
is turned on/off by an SCR (or similar switch). I have never heard of
converting an arc welding power supply into a resistance welding power
supply. Keep in mind these critical factors during this type of
welding

FORCE - you must "pinch" pieces together (approximately 500 lbs)
POWER - you need a high, controlled amount of electricity
TIME - You need to regulate the power flow within 1 cycle (1/60
second).

Unitek-Miyachi makes small resistance welders. www.unitekmiyachi.com

I can vouch for the Unitek-Miyachi system, they work well and the price

is usually decent. They're step-pulsed, capacitive-discharge systems,
and are as far removed from arc welding as swimming is from bob-sledding...

I worked for 4 years at a battery "wholesaler" my main job was to crack
dead packs open and "re-cell" them, and then glue them back together.
generally cheaper for the customer than buying a new pack, and 9 times
out of 10 they had more capacity. If you're looking into this kind of
stuff, let me know and I'll give you my former boss's contact info and
he'll be able to point you to our connection on the west coast where we
got our welder from.

 

[Martin H. Eastburn]

Clandestine wrote:

Those "tack welds" are created by resistance heating between the
parts. There is no arc involved. It takes considerably more power
(watts) to weld by resistance than by arc. They are also done faster
than most arc welds. To put this in perspective those electrical
components required about 1,000 Amps in ˝ second. Usually the current
is turned on/off by an SCR (or similar switch). I have never heard of
converting an arc welding power supply into a resistance welding power
supply. Keep in mind these critical factors during this type of
welding

FORCE - you must "pinch" pieces together (approximately 500 lbs)
POWER - you need a high, controlled amount of electricity
TIME - You need to regulate the power flow within 1 cycle (1/60
second).

Unitek-Miyachi makes small resistance welders. www.unitekmiyachi.com

Likely a capacitive discharge to deliver the high current.

Or like said a RC that drives an SCR as a switch of a storage Cap.

Martin
--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer oldtree@pacbell.net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder