Converting stick welder to tack welder.

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Converting stick welder to tack welder.
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mike
Guest

Posted: Thu Feb 24, 2005 11:07 pm Post subject: Re: Converting stick welder to tack welder.

Nick Huckaby wrote:

Quote:

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

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

Quote:

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

Repeatability is a BIG issue with this. A CD system tries to deliver
fixed energy. That's less dependent in path resistance.

Quote:

Martin

How about 12V? Would two car batteries work?

Sure, if you had some way to turn them on/off quickly.
Be sure to use a heavy metal box to contain the battery explosion
if something goes wrong.

Quote:

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mike
Guest

Posted: Thu Feb 24, 2005 11:12 pm Post subject: Re: Converting stick welder to tack welder.

Martin H. Eastburn wrote:

Quote:

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

--
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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
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Steve Taylor
Guest

Posted: Fri Feb 25, 2005 2:45 am Post subject: Re: Converting stick welder to tack welder.

mike wrote:

Quote:

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)

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

Martin H. Eastburn
Guest

Posted: Fri Feb 25, 2005 6:10 am Post subject: Re: Converting stick welder to tack welder.

mike wrote:

Quote:

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

--
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
Guest

Posted: Fri Feb 25, 2005 4:58 pm Post subject: Re: Converting stick welder to tack welder.

Martin H. Eastburn wrote:

Quote:

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

--
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/

mike
Guest

Posted: Fri Feb 25, 2005 5:02 pm Post subject: Re: Converting stick welder to tack welder.

Steve Taylor wrote:

Quote:

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

Quote:

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

Steve Taylor
Guest

Posted: Sat Feb 26, 2005 12:24 am Post subject: Re: Converting stick welder to tack welder.

mike wrote:

Quote:

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
Guest

Posted: Sat Feb 26, 2005 6:10 am Post subject: Re: Converting stick welder to tack welder.

mike wrote:

Quote:

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
Guest

Posted: Sun Feb 27, 2005 2:48 am Post subject: Re: Converting stick welder to tack welder.

Martin H. Eastburn wrote:

Quote:

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/

billh
Guest

Posted: Mon Feb 28, 2005 3:20 am Post subject: Re: Converting stick welder to tack welder.

<snip>

Quote:

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/

While the risetime typically is not the 0 -100% rise the picture is what the
manufacturer indeed says this is what the waveform should look like. Not
surprising since the waveform is presented for setup or checking purposes
and it is much, much easier to verify with respect to the indicated points
rather than finding 10% and 90% points. Unless you have a storage scope or a
modern scope with memory it is a real PITA to locate intermediate points
with the one-shot nature of the device. Also, the rise-time in terms of the
edge of the waveform may not be the real issue but rather the the energy in
the pulse which is related to the area under the curve. The 100% point as
indicated does give an partial measurement of this and the voltage drop from
the peak is specified.

Billh

Nick Huckaby
Guest

Posted: Tue Mar 01, 2005 9:19 pm Post subject: Re: Converting stick welder to tack welder.

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

Quote:

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?

Quote:

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

Nick Huckaby
Guest

Posted: Tue Mar 01, 2005 9:20 pm Post subject: Re: Converting stick welder to tack welder.

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

Quote:

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?

Quote:

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?

Quote:

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

mike
Guest

Posted: Wed Mar 02, 2005 12:19 am Post subject: Re: Converting stick welder to tack welder.

Nick Huckaby wrote:

Quote:

"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

Energy proportional to the square of the voltage on the caps.

Wonder how they get 1000A through their output connector?
Wonder how they get 1000A through the small wires to their
welding tweezers?
My Unitek 125WS welder has half inch diameter output terminals
and runs #2 wire to the head.
Wonder what they use to switch the caps to the load?
Would be interesting to see a graph of weld voltage and current vs time.
mike

--
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/

mike
Guest

Posted: Wed Mar 02, 2005 12:33 am Post subject: Re: Converting stick welder to tack welder.

Nick Huckaby wrote:

Quote:

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?

"Automotive Relay" is a pretty broad term.
In general, a relay can turn on arbitrarily quickly, in terms of
risetime. Turning off can be a problem if the contacts weld together.
Even if they don't weld, there are mechanical and magnetic flux time
constants that limit the minimum pulse width.
The second pulse is problematic if the contacts are all "burnt" from the
first pulse.
I expect there are relays that could do the job, but not likely they'll
be found in an automobile.

Quote:

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?

Again, we'd have to be more precise about the definition of explode.
Take a new fully charged car batery. Shine up the connections.
Slam a 1" square copper bar across the contacts. Have somebody
videotape the experiment. Report back your results. It's likely that
the result can be used for my definition of explosion.
Do NOT try this at home.

Now pick a capacitor and voltage that gives you 100 Watt-Seconds.
Short it with the copper bar. Compare the results to the battery
experiment.
mike

Quote:

Thanks

Steve Taylor
Guest

Posted: Wed Mar 02, 2005 3:10 am Post subject: Re: Converting stick welder to tack welder.

Nick Huckaby wrote:

Quote:

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

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