Showing the parts & components required to set up to C.D. Weld apply Weld Stud.

  • Capacitor Discharge Stud Welding: Definition, Process, Equipment & Accessories
  • How to SET UP the C.D. Welder for Weld Studs
  • Accessory options for Weld Studs
  • Weld Gun Adjustments
  • Proper Stud Welding Technique, Design, & Testing


At Midwest Fasteners, we know that portable stud welding can be used to install many types of fasteners quickly and with strength for practical use in everyday applications. Setting up for stud-welding is a simple process.

Weld Studs, sometimes called “Stud Welded Fasteners”, can be welded using Capacitor Discharge stud welding or “C.D.” for short. This is a portable welding process which uses readily-available electric power from an everyday, one-hundred-and-ten-volt power outlet.

In addition to being portable, CD Welding Systems have:

  • simple components,
  • work quickly,
  • and can be used on sheet metal thickness material to apply Studs and a variety of Welded Fasteners using the capacitor discharge process

Using Capacitor Discharge for Stud Welding offers a high strength weld, both quickly and reliably.

It can be used with Stainless & Mild Steel — even coated and Galvanized materials— plus Aluminum; with no burn-through of the metal, AND no special weld set-ups required.

The process of Capacitor Discharge welding occurs in a series of 4 fast steps:

  • Contact
  • Ignition
  • Placement of the Stud
  • and “Completion” of the Pin Weld

The standard, portable CD system consists of:

  • The Controller [ or Power Unit] which is plugged into the one-hundred-and-ten-volt power outlet.
  • The CD Gun with Cables which is used to command the power unit and deliver weld current with the Gun also serving as the Stud holder to properly place the fastener during welding.
  • Then, on the other side of “the circuit”, a ground cable and clamp is attached to the work-surface to complete our weld connections.
  • Finally, special Accessories are used to hold the Stud in the Gun.

These parts make up the CD weld system.

It is critical to set the gun up properly, to allow these steps and components to go into action and to allow CD Studs to weld reliably. There are several ways to set up for stud welding with the MIDWEST CD portable.

First, a simple assembly called,”B” Collet and “B” Stop.

To install these accessories as an assembly, prepare the C.D. Gun, by loosening the screws at the end of the gun-shaft to accept the parts. At the same time, loosen the set screw on each gun leg.

Before installing the Collet, make sure the Collet is the proper size for the stud diameter to be welded. Next, insert a proper length “Stop” into the back of the Collet.

Proper sizing means the Stud will protrude past the end of the Collet, but still be held tight and rigidly during welding.

NEVER allow the head of the stud, or what is call the “Flange” to come in contact with the Collet during welding action.

Insert the Collet and Stop Assembly into the Gun until it “seats” and stops fully.

Next, tighten the set screws, in this case 2 of them, and check to see that the Gun is free and clear to operate smoothly during the weld.

With the Collet installed, insert a Stud fully into the Collet until it stops. Slide the Leg and Foot Assembly until you have only an eighth-of-an-inch of Stud sticking out past the foot. This is called “proper protrusion” and is critical to allow the Welder, Stud and Capacitor Discharge Welding Process to perform properly.

Once the eighth-inch is set, tighten both set screws to keep the foot steady.

If your job requires different length Studs to be used from time-to-time, make this adjustment to each Stud length to be welded, always ending with the critical eighth-inch of protrusion.

That completes set up of The Collet with Stop and you are ready to weld. Just:

  • load
  • contact
  • and weld

And finally where Stud placement requires C.D. welding to place long fasteners, the MIDWEST C.D. gun and it’s special design, can accept another set of accessories to accommodate these jobs with what is called an “Internal Stop”.

Removing the rear cap from the MIDWEST C.D. gun exposes the back side of the gun shaft.

Made with internal threading, this type shaft will accept a “stop-holder” and a “stop”.

Size the stop to accommodate the longer Studs to be used. (For extra assistance with stop sizing and length consult the MIDWEST Equipment manuals, accessory parts lists, or your MIDWEST Distributor.)

With the stop mounted in the “Holder”, install this assembly into the shaft and replace the Gun’s Main Spring & Rear Cap.

Now install a “B” Collet just like before, with NO stop this time; allowing the stud to pass down-into the gun. The fastener will be held in place at a set stopping-point by the internal-stop and set-up can proceed with adjustment of the foot and legs, which is one-eighth inch protrusion and welding as previously shown.

With any of the MIDWEST Gun accessories shown you can get fast welded results with the C.D. stud welding process.

Midwest Fasteners’ Capacitor Discharge stud welders can cycle for 15-20 welds per minute, and material can be installed quickly and cleanly, using only one-hundred-and-ten-volt power, with reliably welded fasteners, one-after-another, and all with good holding-power to support materials of all types.

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