View Full Version : Spot Welder Suitable For Brittish car Restoration?
12-14-2010, 08:07 AM
I am thinking of buying a spot welder for restoring British cars. Currently I use a MIG and plug weld the panels where they were spot welded by the factory.
The reason I want to switch from plug welding to spot welding is to replicate the look of visible factory spot welds; its a matter of "Authenticity". I also expect that it will save time grinding plug welds smooth. Not to mention quicker when doing a long run of welds like the rocker panels and wheel wells/quarter panels.
Problem is I have no experience with the hand held spot welders and what they are rated for. Much of the rocker work on these cars is three layers of 18 gauge tin. The factory spot welds the three layers in one go. Is it reasonable to expect the same capacity from a hand held? Not talking 120 harbour freight but rather a 220 volt name brand tool. (Open to suggestions since I don't see Lincoln as a supplier)
I would like to keep the budget under $2000 if that is reasonable.
12-14-2010, 08:43 AM
Many years ago I bought a SIP 220Volt pincer type spot welder in England and have used it on a variety of modern and old cars.
I found it was fine with two thicknesses of 19 gauge metal but it would not produce strong welds with three layers of metal
The welder was supplied with one pair of short arms /electrodes and very soon afterwards I needed more arms/electrodes to do real work.
These arm sets were expensive so I made up various arm/electrodes to suit the jobs I was working on.
Although the welder isfine and produces professional looking results, mine cannot do single sided welding which limits its use. A lot of the time I turn to my Mig welder and plug weld
12-14-2010, 08:55 AM
Having used an SIP MIG welder for a number of years, I am not ready to put them in the "Professional Tool" heading. I found that consumables were an issue with the welder also. The purchase of a Lincoln Mig welder was nothng less than a revelation in ease of use and results achieved.
The SIP spot welder is cheap enough that perhaps it would be worth buying just to do single layer stuff like wheel arches. Something to consider.
I am not aware of any way to do reliable single sided spot welds such as in the base of the A-post on MGBs.
12-14-2010, 09:05 AM
I have a number of the Miller type spot welders, they work better for thinner galvanized sheet. The other thing the ones that work the best/hotest are the shorter arms. Don't have a commercial water cooled tipped one, haven't used one in years, but that is what I think you will want. The Miller will work for many spots, but thru 3 sheets and the repetition slows the Miller also. Hope this helps! tt;)
12-14-2010, 09:39 AM
Yeah, duty cycle is not a big deal. Still quicker than making MIG pretty or invisible. Its the factory look that I am after.
Maybe I should head down to my welding supplier with a few pieces of tin and see how they feel about the application?
I went on line and found a few set-ups for body shops, but it was like 20k!
I have a Teckna 220v 16a hand held spotwelder, for most of the time it's coleckting dust :mad:
it wil handle 2x if good contackt but 3x ..........forget it !!
I think you have to dig deeper than 2000$ if you want to do 3x and singel side
12-14-2010, 10:34 AM
Pete, are looking for on the car welder/hand held or stand alone? a used one maybe your best bet for the money, just finding the right one.....tt
12-14-2010, 10:43 AM
Pete, a 220 volt hand held spot welder will do B sills just fine. Get short or shorten the arms, this will help it clamp tighter especially when they start to get warm. Take your time and don't try and do them all at once, let the spot welder arms cool down. The hotter they get the more resistance there is and therefore there will be less power at the spot weld itself. The outer sill, castle rail, and inner sill all must be absolutely clean and flat to work well. Keep the tips clean and don't let them get bigger than about 1/8" diameter. One trick that is a big help is to modify a set of vise grips with a round flat top button 3/16" diameter welded to each jaw. Before you do the spot weld, crimp the area you are going to spot as tight as you can. This gets the layers tight together without overstraining the copper arms. I've done dozens, the big thing for me too is so that the repairs would be indistinguishable from factory. I also have a Porta Spot 2001, it is much more powerful and has two 6 foot cables. I have a 12 square inch piece of 1/4" inch copper bolted to one of the cables. That end is clamped to a flat part of the body then you can use the single cable to do spot welds from one side. I don't think I have any pictures of actually doing it on my website but if you want I can send you a picture of the machine and setup. Jim
12-14-2010, 10:55 AM
There are diiferent spotwelders in power!
And as mentioned before don't by a hand held one like KFS as they are not up to the job!!!
Air cooled spotwelders(on trolleys) will work for mild steel and new High strenght steels! But will heat up fast.
You need at least 5000amps and enough power between the electrodes to squees them together.
Manual closing is about 8 kg force
Pneumatic closing starts at about 80 kg force.
New generation will generate forces up to 600 kg.
Check these settings on www.gys.fr (http://www.gys.fr)
Also if testing one of the machines(also secondhand)cut some different steel thicknesses(and quality's) overlap them , attach 2 vice grips to them and try to rip them appart ,if the spot weld stayes intact and it gets ripped around it then you got a good weld(or machine)
Also you can do mono point spotwelding but only on Mild steel, forget about it to do it on the new steels why?There's only 10 kg force single sided and not one car manufacterer agrees on using this technique.
But if you do it put the ground cable behind the rear of the support steel,this way current flows between the two steels.
In my opinion if you use one and use it properly it shouldn't be visible that you repaired it,also if the steel gets damadged again after repair,you can again easely remove the spotwelds and start all over(replace).
If you do everything by mig then the steel behind when replacing get damaged also!
12-14-2010, 10:59 AM
No reason you couldn't take a pincher type hand held and substitute cables for the arms. If I remember correctly they are only held in with some allen head bolts. Use some 2/0 welding cables but as short as convenient, make an insulated handle for one of the copper arms and attach it to the end of one of the cables. Bolt a copper plate to the other cable and clamp it to the car. Duty cycle would depend on size of cable, length, and thickness of weld. Jim.
12-14-2010, 12:57 PM
Bolt a copper plate to the other cable and clamp it to the car.
Why not just use a heavy duty bolt on type earth clamp for a MIG/stick welder?
12-14-2010, 01:19 PM
The large area of the copper limits heating of that area so you don't get any warpage issues as the high current is not concentrated on one small spot. My plate is about 2 by 6 inches. An average hand held spot welder with short arms puts out about 5500 amps. Putting that kind of amps through a MIG clamp would probably burn it through the surface. I think I remember learning the hard way on this one. Jim
12-14-2010, 02:06 PM
You seemed pretty clued in to what I want to do. I am going to have a quick look to see what I can learn about the Porta Spot 2001. It does not sound like the pincer type of hand held units that I was envisioning; more of a cart with a remote head?
I cant find where Lincoln does any spot welders. More like Hobart and the cheap Harbourfright stuff.
12-14-2010, 04:40 PM
Why not just use the tig? It can make very nice spot welds and all from one side. no holes to drill either.
here is an example on a new seat box I made. They look just about like the original welds.
12-14-2010, 05:04 PM
I also have a comercial tig spot welder. it is water cooled. the gun kind of looks like a paint gun. you push the copper cup down on upper sheet forcing it down and holding it against the back sheet. then pull the trigger. the timers control the arc time and current. when you first pull the trigger, the tungston automaticly moves down the right amount from work to start the arc. It works ok but i have decided around ten years ago i could do just as good or better with the regular tig torch.
Mine is a 220V Portable (hand held) Miller with timer, I used it most extensively on a roof and gutter repair/replacement job. But sometimes you'll need to make your own tips.......
During the replacement process, I noticed the standard tip would not work:
Looks like we'll have to make our own, so lets start out with some flat tips, and start on the bottom. This one has to be trimmed down pretty short to fit in there because of the outward crease just below the drip edge:
Then to shape up the top one, it will need the extra length to reach past the drip edge:
Then a test fit, this just may work!
Let's see the spot welder in action:
This looks darn near a factory finish!
We got the rest of the spot welds done, and the welder performed beautifully:
12-14-2010, 10:33 PM
Pete, here is my Port-a-Spot. Forgot that this one is a model 2000, I used to have the 2001 but no longer have it, long story. The 2001 has adjustments for weld power as well as time but this one works just fine. It's made by Controlled Systems in Windsor, Ontario. Bought this one used for $50 a couple of years ago. Deal of the century. Bought the first one I had new, the 2001, in 1978 for $1200. Jim.
12-15-2010, 07:45 AM
I actually cribbed your TIG spot method a couple of years ago. It does work reasonable well as long as I add a dab of filler rod as the upper sheet melts.
I never did get it to work to the point where it was better than a MIG puddle weld, and of course the need to control the pedal makes it awkward in a lot of situations.
By the way, how is the Bugeye project coming along? It was a couple of years ago I last saw some pics, should be done by now right?
Jim: Not sure how the porta spot works? Do you not need to firmly clamp the two (or three) sheets firmly between the two electrodes? The system you show has two hand held electrodes and while it seems great for reaching around, how do you maintain the strong clamping action? Keep in mind that until now, the only spot welders I am aware of have been the Pincer type like the Hobart. Must say the education so far has been worth the asking!
12-15-2010, 10:57 AM
Pete, this setup is just for doing spot welds where you cannot reach the other side, like the four that hold the A post to the top front of the outer sill in the door jamb. Like you when I've done MGB's in the past the welds must be absolutely indistinguishable from factory, so TIG or MIG just won't quite do. Also the best way to do an MGB is to spot weld in the vertical middle panel to the castle and inner first, then spot weld the outer sill to that. Does a better job than trying to do the three layers at once. The setup shown also works well for shrinking. Normally there is another handle and electrode on the wire that the copper plate is attached to. It is out of view on top of the machine. The control switch is on the rectangular black box on the floor. Normally it is bolted to one of the handles but I find it easier to have it on the floor so I can operate it with my foot. You can also use this machine as intended, holding the two electrodes about an inch apart, on the same side of the panel, push the button, and do two spots at once. This works best where you can really push hard against what you are welding as that is the only clamping action you get. It works fine this way on MGB sills if you do them one on top of the other. Use the vise grip trick I described earlier to ensure good contact before making the welds this way. Jim
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