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# Converting stick welder to tack welder.

T

#### Tim Zimmerman

Jan 1, 1970
0
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

C

#### Clandestine

Jan 1, 1970
0
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 ½ 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

J

#### Josh Sponenberg

Jan 1, 1970
0
Clandestine said:
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 ½ 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.

J

#### Jamie

Jan 1, 1970
0
Tim said:
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.

S

#### Si Ballenger

Jan 1, 1970
0
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).

M

#### Martin H. Eastburn

Jan 1, 1970
0
Clandestine said:
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 ½ 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

B

#### Barry Lennox

Jan 1, 1970
0
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?

I believe you are following the wrong path here. You need little
voltage, but a LOT of current.

I made a very good spot welder for batteries and similar tasks from an
ex microwave oven transformer, the biggest I could find. Hack off the
HV secondary, thousands of turns of very fine wire, then I rewound it
with just 3 turns of wire, but I packed in as much 8g and 12g wire as
would fit, and paralleled all the turns.

The secondary is controlled by a SSR (Croydom CSD2410) pulsed by a
simple 555 timer circuit. It can vary from about 75-300 mSec I can
also switch in one of 3 wirewound resistors in the secondary to give
me fine control.

The electrodes must be made to suit your exact application, and some
trial and error can be expected. I first used copper and brass, but
now get much better results from a proper spot welding electrode
machined to suit my application. It was not cheap, about $11 for a 3/8" rod about 3 inches long, but it gives very good results. It had a trade name like "Elkalloy" IIRC. For optimum results, it is also important to control the electrode pressure, but I find I can achieve satisfactory results by hand. Barry Lennox E #### Eric R Snow Jan 1, 1970 0 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 M #### mike Jan 1, 1970 0 Jamie said: find your self dead microwave oven ( high power line), use the heater tap on the transformer. How well did this work when YOU tried it? How did YOU keep from killing yourself on the high voltage winding? mike http://nm7u.tripod.com/homepage/welder.html -- 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/ S #### Steve Taylor Jan 1, 1970 0 mike said: 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 M #### mike Jan 1, 1970 0 Steve said: 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 Post some details on voltage, capacitance, how'd you switch it? electrode construction? 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/ E #### [email protected] Jan 1, 1970 0 Hi. Oddly enough, you can do spot welding with an arc welder. I tried it, and all I got was the typical mess that you would guess. Burned up spots with no strength. But, just because I cannot do it does not mean that it can't be done. There are plans on Ebay: 385664469 This auction is for a set of completely illustrated plans to build a spot weldi ng/cutting gun that works with your arc welder for less than$50.00.

I have not tried this out, so please buy the plans and report back to
the group.

Or, you could try Eastwood's version, which is very similar, but uses
carbon electrodes. Also, please report back to the group after trying.

http://www.eastwoodco.com/jump.jsp?itemID=795&itemType=CATEGORY&iMainCat=688&iSubCat=795

Recently, I tried to do a blind spot weld with 1/8" steel. It worked
just great. So, the problem may be power, control, and excessive heat,
which the above solutions allude to. Note that this is arc welding,
not resistance welding with a low voltage rewound microwave oven
transformer.

M

#### Martin H. Eastburn

Jan 1, 1970
0
Eric said:
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

N

#### Nick Huckaby

Jan 1, 1970
0
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?

M

#### mike

Jan 1, 1970
0
Repeatability is a BIG issue with this. A CD system tries to deliver
fixed energy. That's less dependent in path resistance.

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.

--
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/

M

#### mike

Jan 1, 1970
0
Martin said:
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

--
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/

S

#### Steve Taylor

Jan 1, 1970
0
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)

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

M

#### Martin H. Eastburn

Jan 1, 1970
0
mike said:
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

M

#### mike

Jan 1, 1970
0
Martin said:
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/

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