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Spot weld gun... experience?


Jedi Knight
Country flag
Hello all,

I'm a lucky guy: my wife's grandmother found a spot weld gun at the Ft. Myers flea market, which she gave me for Christmas. (I knew my wife was a good catch, but who knew her grandmother would be too!!)

It does not come with directions, however I found the same at Eastwood:

Does anyone have any experience with these? Tips to give? Do thise welders provide quality spot welds? The one concern I have is the welder pushes from one side, to use it properly there needs to be some sort of support from the back.

Baiscally, I would need an arc welder to use it. I have a Hobart 140 MIG welder, so I would buy a cheapie stick welder off Craig's list. Before I do that, is the tool worthy?

66 TR4A


Jedi Warrior
Mike, you're better off just using the MIG and making plug welds. That type of spot welder is at best a compromise to get an old stick welder machine to make spot welds of a sort. Your MIG welder will do much better. Say thanks and very kindly and put it aside, not worth buying another welder power supply for that.


Great Pumpkin - R.I.P
Why can't you use the Hobart power supply?

You should be able to disconnect the wire feed gun and connect the spot gun in it's place; and the lowest heat setting is surely low enough for the spot welder. This setup wouldn't be all that different than using a spool gun with it, which is a Hobart recommended configuration. And surely the spot welds wouldn't be any worse with DC power instead of AC ?


Jedi Knight
The problem using the 140 M.I.G. power supply would be the contractor {controlled by the trigger on the M.I.G. gun} that turns the welding current on and off.
The spot welder he has requires a constant supply of welding current such as supplied by an A.C. or D.C. S.M.A.W. machine.
The spot welder is a cost effective way to produce spot welds. That is IF you are going to be doing a bunch of them!
For our purposes I have a tendency to agree with Bill. Where we are not doing weld after weld after weld on our cars.
On the other hand there could be applications where a spot welder might just be the ticket.
The question then being
1.Do you have uses for a S.M.A.W. machine other than to power the spot welder.
2.Can you afford a S.M.A.W. machine to sit and collect dust If not.
3.Do you have the space to accommodate a S.M.A.W. Machine.
4. Is your work facility wired to accommodate a S.M.A.W. machine {normally 220 V @ 50 A.}
Yes ... you could buy a 110 V S.M.A.W. machine The question being would it produce enough current to provide the size and type of spot welds required.
{usually these 110 v S.M.A.W. machines arn`t up to much! Most won`t even run 3/32 electrodes.}
The pros:
you CAN spot weld non ferrous metals!
You can spot weld in very tight places and awkward positions.
You are not consuming costly argon/co2 mix gas. {yes you could use cored wire with the M.I.G.instead}

A little information { Not much} I hope it helps you decide what you need/want to do


Jedi Warrior
The basic problem with that type of spot welder is shown in the diagram I made versus the standard resistance type spot welder. Plug welding using a MIG you would drill or punch the top layer and then weld to the lower panel filling the hole for a "plug weld".


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Jedi Knight
They actually work on the same principal. The only difference being that a "regular" spot welder has a mechanical {usually pneumatic or mechanical clamping force} where as the spot welder he has only has what force you can apply to the weld bodily. EG. What weight you can apply with your body weight and hands and arms.
Keep in mind that amperage settings and where you place the negative terminal {ground} and how much clamping force you can bodily apply will have a great effect on how much penetration to the base material is achieved. The ground should be on the work piece opposite of the carbon rod placement Eg. NOT on the work piece that the carbon rod will actually touch.
AND as Bill says this type of spot welder is NOT ideal. And WILL take a lot of trial and error to make it make the kind of welds you want and need. But it IS achievable!
If you are going to try and use it on actual projects my suggestion is Practice, lots of practice, and then ....... practice making welds on similar material of which you intend to spot weld. Be familiar with the spot welder and it`s characteristics and how to make it preform to your satisfaction before attempting welding something do not want to mess up.

As with any spot welder BOTH pieces where the spot weld is to be applied MUST be free of ANY impurity's in order to get a reliable weld.
Clean both pieces of material until they are bright and shiny!
NO rust, paint, grease, or dirt of ANY kind!
And I might add the surfaces MUST be as flat as possible {minimize ANY air gap {preferably NONE} between the two materials}


Great Pumpkin - R.I.P
AweMan said:
The problem using the 140 M.I.G. power supply would be the contractor {controlled by the trigger on the M.I.G. gun}
Ah, my mistake. I thought the Hobart 140 was one of the units without a contactor. Still seems a lot easier to add a suitable switch than to buy another power source.


Jedi Knight
Country flag
Many thanks for the insight - much appreciated. You guys are great!

I think I'll stick with the plug MIG welding technique that I have been practicing for about a year now... with some success, but FAR from perfect!! :smile: (I finally did my first welds ON the car this past weekend... woo-hoo!!)

I do have 220 V, 40 A in the garage; however as I would have more need for a spot welder than a stick welder (already having the GMAW / MIG, I don't think there would be that much need for a SMAW)... for the $ I'd be better off with a proper spot welder to do cool things like weld aluminum and copper.

GMAW = Gas Metal Arc Welding ~ MIG = Metal Inert Gas welding
GTAW = Gas Tungsten Arc Welding ~ TIG = Tungsten Inert Gas welding
SMAW = Shielded Metal Arc Welding ~ MMA = Manual Metal Arc welding ~ "Stick welding"

... I need to learn those terms!!

66 TR4A


Great Pumpkin
Country flag
This is probably the cheapest unit you can get. But, it does a very good job if used sparingly. It is not for continuous commercial use, but works very well for short term work like we do. Different longer and deep reach tongs can be had at a welding equipment supplier. It can be had in 240 or 120 volt models. Commercial units start around $600.00 and up beyond a $1,000.00 https://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=45690
Harbor Freight Tools - Quality Tools at the Lowest Prices
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