Spot Welder

[CCWKen]

Has anyone developed a weld schedule for the handheld 230v spot welders? Also, what's a cheap way of determining tip pressure? I was thinking of making up test dimples in lead using known weights (pressure) but my bathroom scale only goes up to 250lbs.
And, how in the heck do they expect you to fire that thing manually for 15 cycles? (1/4 second) Has anyone MADE a timer that will handle the 30A draw?

[Rotate]

Why are you interested in the tip pressure?

As for the timer, you can get 30A 240V relay and use a low voltage timer circuit to drive it. You can design one around 555 timers for couple of dollars.

Albert

[Forrest Addy]

Don't get too scientific. Those hand clamp spot welders reall haven't the oomph and contact force to make high quality spot welds.

I have one. I ran some test welds on strips and I found I can get a strong ductile weld if I zap it and hold the current on 'til I see a red glow. If you space the welds close enough you can make strong joints suitable for anything except aerospace applications.

Forget the timer as an unnecessary expense. Cultivate an eye for the process. Just be sure the electrodes are kept clean and the toggle clamp is free running and effective.

[Thrud]

I will side with Forrest on this one. Albert's idea is most useful for a floor standing unit that can do professional spot welds.

[CCWKen]

Well.... I can tell by your answers that machinist don't know squat about spot welding. Thanks anyway.

By the way Forest, weld time is measured in cycles...as in 60 cycle power. Most welds (autobody and metal up to 16ga.) are from 6-48 cycles. That's .1 to .8 seconds. If you're waiting to see a red glow, your cooking the metal (and your tips).
And Clamping pressure is a BIG part of weld quality. High pressure lowers resistance and thus lowers the heat generated. A lower tip pressure will actually raise the heat and shorten weld time. But, too low is not good either. That's probably why you have to wait for your "glow". The Tongs are NOT clamps, they are contacts.
Just playing with mine, I got excellent welds (class A) by flicking the switch. This had to be less than 1/2 second and closer to 1/4 or less. Since the weld current is fixed with this unit, you have to play with weld force and time.
I just thought one of you had already worked that out. (Weld Schedule)

[DR]

Having had a small portable unit without timer and now having one with a timer, I can say the timer is a very worthwhile accessory.

Without the timer it was always a guess, now a quick test to establish the correct cycles needed for the material and I get much cleaner, consistent welds.

Also, if given a choice, go for the 220V portable units. I weld 16ga to 1/8" all the time. Best the 120V unit would do is 2 pieces of 16ga if I was lucky.

[Forrest Addy]

Yup. Your right ken, As a spot welder, I'm a pretty good machinist.

When you speak of cycles of heat I assume you're referring to spotwelders controlled by mercury tubes or their solid state descendents where the circuit to the transformer is opened at zero crossing voltage of the AC line hence reference to the number of cycles as weld time.

I usually hand pulse my welder too. I should have said that but it's been over a year since I've used it so I'm rusty.

Another point is weld cleanliness. A trace of oil is transparent tarnish on otherwise clean metal poses no problem that I can see but paint residue, chips, rust, and dirt contaminate the deposit and in spotwelding interfere with contact causing arcing and spatter.

I've noticed that some high-priced welders have a welding cycle that when completed finish with extra clamping, presumably to upset the still red hot kernal of welded metal and make for a tighter weld.

Regardless I suggest anyone setting up a spotwelder on slim experience peel a couple of test welds before you move onto welding up the working parts.

[This message has been edited by Forrest Addy (edited 04-24-2003).]

[dvideo]

I have some U channel material to weld this summer for a steel frame garage - office building. Since I don't have the welder yet, are there any recommendations?

Usual outside gargage - U Channel frame building - 24' tall, concrete foundation, and I have not got the welder to do it... I take it you *do not* like Harbor Freight's small spot welder - :>.

It is 30' from power, and I want to do it safely, too... I am not the quickest or even best welder on the block....

- jr

[CCWKen]

DV- on the contrary, I do like the HF spot welder. I just don't like the service I got from the mail order end. USPS to be more specific. The one I ordered finally came in (took two months) but was damaged and inoperative. I got a response from HF just minutes ago and they said they would refund the price within 48 hours. I went to the HF store and they had one in stock, so I bought that one.
The HF unit is made in America. In fact, it's made by the same company that makes the Hobart/Miller versions. And, it's one-third the price. As DR says, go with the 230v version. I got mine on sale for the same price as the 115v version ($159). I think if you have power within 30', there should be no problem running a 10ga./30A circuit for it. If you go up arround 50', you should go with at least 8ga. wire. The lead cord is only 14/3 so I doubt that it pulls anywhere near 30A. If it does, it's for only a second or less. It has a 50% duty cycle so you won't even get set up for the next weld before it's ready to go again.
I've been spot welding for years using the mig but this unit is fast, easy and makes a better weld--When you get the force and time down close. Also, you'll want to dress the tips down (or get extras) depending on the gauge of metal you'll be welding. New tips come ready to weld .010 thickness. (Too small for me) If you need/want more info, email me at:
ccwken@wireweb.net
Ken

[Thrud]

<font face="Verdana, Arial" size="2">Originally posted by CCWKen:
Well.... I can tell by your answers that machinist don't know squat about spot welding. Thanks anyway.</font>

If you knew this all along, why did you ask? You trying to cause trouble, or what?

Keep it up and I will be forced to feed you my sister's infamous meatloaf as punishment! http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//eek.gif

[CCWKen]

No Thrud, just looking to improve. How many methods for a job have you tried in machining that were made easier once you found out how it was supposed to be done? Or with what tool? Welding has come down to "rocket science" these days. There's over 25 variables in spot welding alone. Sure, it can be done without a timer and a good guess but having a chart (schedule) of where to start and a timer can sure make the job easier (and look better).
By the way, I happen to like meatloaf...and I'm single. What's your sister's name?

[Mark Hubler]

Spot weld timer circuits

http://www.5bears.com/welder.htm

http://metalworking.com/DropBox/_2001_retired_files/Miller_Time.txt

By the way, the spot welders that HF carries are made by a division of Armenmotors (Armenia, not USA). I inquired about one of their European ads selling spot welders, asking who thier US distributor was...Harbor Freight. By the way, HF pays $85 per spotwelder, FOB Armenia.



[This message has been edited by Mark Hubler (edited 04-26-2003).]

[Thrud]

CCWKen:
I know, but I could not resist - you walked into that one!

The basis for good welds starts with a timer, then a method of consistant pressure of the welding tips, water cooling the tips, material prep (in production nubs are sometimes embossed on the metal to ensure a solid weld - the tips crsh and melt the projections to the mating half). if you are serious about the welding you could order some enginerring books from ASM international. http://www.asminternational.org/ The books out of the metals handbook (30+ in total) cover complete metal work under different sections id est welding, casting, forging, etc.

The books are not cheap, but you have to start somewhere. A technical college or university would also be good sources, and you can always order a "book on loan" from other Libraries at your local Library.

One thing I can tell you, it is faster to just do experiments when you are in production that to refer to books. Test spots tell reams! We used scrap material left over from the shearing of the sheets for test bends and welds when needed.

[Bill Neufeld]

CCWKen;
RWMA hand books also have schedules for various metals and thicknesses. Use the schedules as departure points in making up schedules. (RWMA=Resistance Welders Manufacturing Assn.) They also have a lot of information on what parameters are required for a good weld. The easiest way without being able to cut the test weld and polish it for a microscope test is to see if the test material will fail befor the weld. Use a cold chisel to try to separate the test pieces.

[CCWKen]

Mark H.:
If what you say is correct, then I think the FTC would like to know more about HF badging there units with "Made in America". I wonder if this is a similar tactic that was used years ago by companies in Usa, Japan? Products made there were labeled "Made in USA".
In any case, the manual doesn't seem to be "translated" to English and appears to be nearly identical (parts pics, etc.) as the Miller/Hobart unit.
"HF pays $85 per spotwelder, FOB Armenia" ... Hey, I got a pretty good deal then. I didn't pay shipping and didn't have to buy 50,000 of 'em!

[docsteve66]

I've no idea how the welder is marked made in USA if it is not. But I was at HF and a customer was excited about the little electric grinder, spins 11,000 RPM, cost &lt; $20.00 and made in USA and UL approved!!!!

More careful examination revealed the power cord was UL approved and made in USA. The tool body was made in Asia. He did not buy the tool, but I have had one that looks exactly same, bought somewhere else, that has been used, abused, droppped etc and I am pleased with it for grinding welds etc. I considered it a one time use , throw away tool (at time of purchase).

[wierdscience]

To anyone interested you can pick up commercial floor type spot welders for next to nothing and many are single phase.As for tip pressure I was thaught to keep the tips clean and no bigger than.187"dia.at the contact surfaces.If you really want something neat rig up an argon tube on the top and bottom tips,you will be suprised at the quality improvement especially on thin stainless.

[ronk]

I am a newbie to welding, but eager to learn.
I am looking for a spot welder to weld stainless steel wire. Basically there are 3 types of welds to be made.
1. 1/8 inch dia wires to be welded to each other one crossed over the other
2. Same as above with 3/16" dia
3. 1/8" welded to 3/16"

The wires are SS304 or 18-8 stainless and nickel plated. Most of the 120V spot welders I looked at specify a combined sheet thickness of 1/8". How does one translate that for crossed wires?

I saw that HF sells one for $149, but the Millers and Hobarts with similar capability are in the $400 range. Also am I better off
with water cooled tongs?

I would prefer a floor model so that I can manipulate the work piece, but then it has to have sufficient throat depth. The wire baskets that I am planning to weld are 18" x 14" x 6"

Do I need a timer?

Thanks in advance.

[jfsmith]

I am think about buying the HF one that is one sale. I do a lot of mock up work for things that will end up being covered with thicker materials.

Jerry

[gglines]

CCWKen:

Miller has a spot welding handbook online. Here's the link:

http://www.millerwelds.com/education/bookspamphlets.html

Hope this helps.

George

[J Tiers]

The "5bears" timer is along the right idea, but turns on and off randomly with respect to the line cycles.

Using a triac or a multi-scr circuit could give zero current switching, and full half cycles at any current level you wanted to control.

A counter could be set up to count zero crossings and give any number of half cycles wanted.

If I didn't already have 25 projects to do I would sketch out something as a start for that.

[CCWKen]

Wow, this is an old thread.

I put together the 5-bears style timer. As JT says, it's not accurate down to the cycle but it's close enough. With the HF 240v unit, most of your welds will be in the .4 to .8 second range. I did some 20ga. to 1/8" flat pieces a while back and got good results at 1.2 seconds. The duty cycle is 50% so I wouldn't worry about water cooling. It takes longer than that (1.2sec.) to get to the next weld.

The HF unit will fit the brand-name stands. The timer setup will require you to make a few mods to the internal switch wiring. Not a big deal. You can either use the switch to trigger the timer or bypass it and use a pedal activated switch to trigger the timer.

By the way, those water cooled production units START in the $5,000.00+ range. Also, I can't imagine making wire baskets with a "single point" spot welder. I'd get bored. You may want to concider a Roll or Press type welder. If you're going into production, the $30-50k investment would look better.

[sandman2234]

Ronk,
Have you considered a butt welder for those wires? Basically welding them under pressure with heat, end to end, then grinding the interrupted metal out of the way. That is the way we did it in the prestressed business, and it would hold as much as the virgin wire, if you did it right.
David from jax

[ibewgypsie]

WE used to put "Stitch" timers into the Mig units. You could flip s switch, pull the trigger and a second later it would time out and stop.

They were a cube type relay that was adjustable from .1 second to 5...

It kept from burning up the metal.

Spot welding Ain't rocket science. It does work with proven principles. I worked on the spot welders at SGW last year too. I had a book at one time that was 1 inch thick bespeaking of working principles. Main information was that it was mostly always something simple. Coolant not flowing, pressure wrong, tip dressed up wrong..

David

[This message has been edited by ibewgypsie (edited 07-16-2004).]

[CCWKen]

"Spot welding Ain't rocket science."

It was never meant to be; However, there's over 30 variables in determining the correct weld. Just like any machining problem, anyone can ram a tool into metal. Results are determined by a plan and skill. ...And a whole bunch of variables.

It can be done right or not--The results speak for themselves.

[ibewgypsie]

CCW:

Most home shops are not repetitive spot welds. You can make a book there with varibles of eash setup. BUT, you will find out it is like making bisquits a small difference each time. (even with same thickness metal) BUt with experience the biscuits will turn out edible.

A spot welder contact patch is constantly changing by the nature of use. This affects both the current needed and the time to transfer heat.

We used to break the welds, check the pattern of the molten metal. Embrittlement and non-weld are microseconds apart. I think inspecting the contact patch or spot is the most important item to diagnosing welds.

I have saw some home-wound transformers in spot welders. NOW that impressed me. The way the welders worked at SGW, the contacts came together, pressure built, made a switch then applied current to the contacts. Arcing is not your friend in Spot welding.

I'd like to buy one of the HF welders too.
Kinda tied up this minute thou.

David

[ibewgypsie]

On second thought, I don't want the HF model. It looks like trouble. The tips are a little too complicated shaped and probably hard to order and replace. A simple limited use type design. This unit is "air" cooled" making the duty cycle and desired results harder to hit.

A tip should be able to be made/dressed on a lathe in twenty minutes or less.

I'll build mine when I need one. Probably water cooled and on a stand. Water cooling can be simple as a valve and drain.

David

[RobDee]

I have a Hobart (Miller) 110 spot welder. The first thing I did when I got it was design a timer with a solid state relay circuit and a cable with a remote switch.
I know it's tempting to buy the 'cheapo' stuff but I've found out in the long run that you get what you pay for.
I wouldn't trade my little portable Lincoln 110 MIG for one twice the size from HF. When you start to look at the fine print you'll find the duty cycles are way down or a week after you get it the wire feed stops working. I fixed one for a man I know and I couldn't wait for him to take it home.
My advise, save up the extra money and buy a better tool.

[CCWKen]

The HF welder uses the same tips as the Hobart/Miller welders. I got some off ebay last year. You can even use the same arms. (Longer reach etc.) If you make the tips yourself, DO NOT use brass or pure copper. The tips and arms are made from Chromium Copper, C18400 or C18200.

[CCWKen]

Rob;
I've got two HF 220v spot welders. One on a stand and one portable. Both get heavy use and I've never had a problem with them. 50% duty cycle is plenty for shop use. The Hobart/Miller units are no better and three times the price. (I did steal their stand and timer design though. http://bbs.homeshopmachinist.net//biggrin.gif )

I've also got a Centry 130 mig. I wouldn't trade it for two Lincoln 110's. Before getting the spot welders, I did all my "spot" welding with the mig. Took hours to do what the spot can do in 10 minutes. (No punching holes or grinding)

When I need more than that, I bring out the 275A buzz box or A/O tanks.

[RobDee]

CCW,
The Lincoln I'm talking about isn't the cheap one they make for hobbyists. Mine can weld 1/4" plate with fluxless wire but most of my work is MIG on thinner stock. A lot of pros I know use the 110 all day long and metal fence builders use it also. After almost 20 years I can still get parts and even the welding teacher up at the college uses the Lincoln for his kids who beat everything to death. My welding supplier said the 110 is the best small welder he’s ever seen but advises the Miller’s for bigger work. He sells them both. I don’t know one pro that uses an HF welder.

I don't personally know the Century machine and the few things I bought from HF years ago were really bad and I was always getting these ‘cheesy’ salesmen calling me with bogus deals from there, so I don't buy from them anymore. Welding transformers are an art and some of the copper coatings can get costly no matter where the transformers are wound. To each his own, no offense, if it works for you use it.
Rob

[DR]

Back to spot welders for a second......

I've got two Miller 220V units with timers. One's old and uses vacuum tubes in the timer which is mounted on the end of the welder. The other has a separate box with the timer in it. Both seem to work equally well. Time intervals are in cycles, I believe.

My question involves changing to water cooling. Is there anything other than the arms/tips that needs cooling? If that's all, I'm thinking of a way to run a water jacket around the arms, or maybe get some hollow (?) arms off a junker big welder.

In case you're wondering why I have two spot welders. First one was sold as "broken" at a school auction, it was mounted on a Di-Acro bender stand which I wanted. Turned out the switch was the only thing broken, so for $50 I got a welder and the stand I needed. Second one was in a friend's storage shed and he wasn't sure whether it worked or not, $25 later it was mine. It works fine.

Two spot welders are overkill, but hey, a bargain is a bargain and you have to take advantage when the opportunity knocks.

[CCWKen]

DR - An easy way to convert to a cooled welder would be to install capilary tubing around the ends of the tongs. Coil it near the tips then run it back along the tongs.

As far as cooling the transformer, I've used mine for about 10 minutes one weld after the other. (Over 200 welds - Building seat risers) After that length of time, the transformer was only warm to the touch--not hot. The tips and tongs were HOT!

I also do hoods and doors in one run. My portable gets more use than my stationary spot welder. Adding cooling lines would make it harder to work with. Cooling a stationary would work but how many welds can you do on bulky items. I use the stand unit for small pieces which means fewer welds--short use.

If you're going into production, get a production unit. They're made to take the heat.

[ronk]

<font face="Verdana, Arial" size="2">Originally posted by ronk:
I am a newbie to welding, but eager to learn.
I am looking for a spot welder to weld stainless steel wire. Basically there are 3 types of welds to be made.
1. 1/8 inch dia wires to be welded to each other one crossed over the other
2. Same as above with 3/16" dia
3. 1/8" welded to 3/16"

The wires are SS304 or 18-8 stainless and nickel plated. Most of the 120V spot welders I looked at specify a combined sheet thickness of 1/8". How does one translate that for crossed wires?

I saw that HF sells one for $149, but the Millers and Hobarts with similar capability are in the $400 range. Also am I better off
with water cooled tongs?

I would prefer a floor model so that I can manipulate the work piece, but then it has to have sufficient throat depth. The wire baskets that I am planning to weld are 18" x 14" x 6"

Do I need a timer?

Thanks in advance.</font>

Just renewing my question.
sandman2234, I cannot do a butt weld, the wires have to be crossed.

I think I will call up Miller and ask them the question. Also does anyone know who makes commercial/industrial quality spot welders?

[RobDee]

While we're at it what's the process to spot weld 316 stainless.
It seems the heat build up changes the cycle time. Because I'm not doing it in an industrial application I let the metal cool before the next weld. How are you spot welding pros doing it?

[Ted Coffey]

I just experiment with some pieces until I get what I want and then practice a few and go at it.