Using a arc welder as a spot welder

[willy3486]

Is there a way to use a 220 Lincoln arc welder as a spot welder? My MIL gave this device for using with a welder. It has a handle and two heavy wires come out. It has two metal rods coming out of the plastic handle and then two copper looking rods are in each rod that comes out of the plastic handle. The copper rods are adjustable. My FIL had it and he also had a sears 110 welder I am wondering if the extra welder device.

What I was wanting to do is to weld some metal strips that are round and about the size of a 12 gauge wire. I figure I would just burn through the wire but a spot welder would be the perfect thing to bond them. If that isn't what it is could a person Put a piece of wood on top of the wire and bottom then clamp it together. Then clamp one of the pieces to the ground of the welder then touch the other rod with the hot side of the welder?

Anyway I am thinking out loud wondering if anyone has used a arc welder as a spot welder.

 

[cabranch47]

That sounds like a twin carbon arc torch. Old technology but still useful for some people without O/A to heat and bend metal.

 

[ian lewis]

i have one of these and it works well - i am sure thay must be availabe in the US

http://www.frost.co.uk/automotive-welding-tools/spot-welding-gun.html

 

[PAToyota]

Eastwood sells the one Ian mentions (or very similar): http://www.eastwood.com/eastwood-s-spot-weld-gun.html

 

[OccupantRJ]

A cheap transformer type arc welder can be used to make a spot welder for steels. A capacitive discharge spotwelder is needed for nonferrous metals. The basic requirements for a spot welder are (1) heat, (2) pressure, and (3) time. These three things are individually adjusted to produce the required weld relative to need, metal thickness, and metal type, whether stainless, or carbon steel. The steps of operation required are as follows: place metal parts to be welded between tips. Apply proper clamping pressure. Fire electrical through the tips for a prescribed time, then shut off. Release clamping pressure of tips. The proper transformer size or welder is used for electrical supply to flow through the welding tips, which can be made from Mallory 3 copper, available in stick form from a spot welding supply house. The tips can be solid for short-duty home shop use, or hollow water cooled for more rigorous welding duty. In basic form, the welder is the power supply. An electrical contactor of proper amperage rating is used to control electrical power to the SUPPLY, or PRIMARY side of the welding transformer, as a smaller contactor can be used, relative to trying to control the secondary side. A pair of welding tips must be arranged, and electrically isolated from each other, to apply weld pressure to the pieces being welded. An analogy would be to place your right and left hand index fingers together tip to tip, and pushing them towards each other with force. This can be accomplished by attaching tips to either a mechanical pincher device, or an air cylinder, in order to pinch the tips together. If the welder is to be mechanically operated, a compression spring can be provided to work as an overtravel device, so that after the weld tips are brought together, an electrical limit switch can fire the weld contactor after the proper pressure is applied. Once the contactor is fired, the engagement time is controlled by an adjustable timer, to control the weld time. Remember, heat, pressure, time? If an air cylinder is used to apply pressure to the tips, a pressure switch reading the pressure applied to the air cylinder can be used to fire the contactor after the proper clamping pressure is applied to the tips, and pressure rises in the cylinder. A timer is once again used to determine how long the contactor stays engaged. If one studies the individual steps involved in a basic spot weld as I have described here, it's easy to see that the mechanical application of pressure to the welding tips is the "hard" part of constructing your own spot welder, whether it is to be portable or bench mounted.

 

[OccupantRJ]

Though this post is a descriptive answer to Willy's question, I am also going to start another thread on spot welding basics in the Fab section.