An adjustable-angle magnetic fixture, available from Master Magnetics, Inc.

The arrow-shaped Radnor magnetic tool holder, available from Airgas, Inc., can support components in several different angles for welding.

Most production shops are set up with the jigs and fixtures necessary to hold workpieces in position for welding, permitting multiple repetitions of a set-up with reduced positioning errors. For limited production runs and maintenance repairs, welders tend to use vice grips, clamps, pliers or a vice for fixturing, when they're not supporting one part just long enough to set a few one-handed tack welds to the adjoining component.

Inevitably, there will be a job that defies most of the items in the toolbox, like welding a 2 in. pipe to a flat plate in a location where it's almost impossible to hold the pipe straight with one hand while tacking.

Magnets for shops
Magnet-based workholding devices can free both hands to weld while providing a temporary support to the items being welded. Over the last fifteen years, new types of magnets have been developed that are readily available at low-to-modest cost, with holding capacities (or "pull") of several hundred pounds. To ease the problem of disengaging such a magnet from a surface, the magnet may be equipped with a lever or switch that changes the orientation of the permanent magnets within the case, effectively turning the magnet "off."

Magnets offer consistent clamping pressure, so the grip won't be too tight or loose — a problem sometimes posed by mechanical clamps and vises. Magnetic holding devices also provide full support of the surface of a workpiece, which can be critical when welding thin materials. Additionally, setup and tear down speeds are faster with a reduced chance of marring surfaces, as opposed to using clamps or vises.

Even non-ferrous materials can be supported with magnets in situations where a ferrous plate is available back the part. Another trick would be to use magnets to hold other clamping or other support devices — especially handy when working in awkward situations away from a workbench.

Magnetic sources
Magnets off the kitchen refrigerator are probably not going to be of much use in a welding shop. However, many welding supply sources, such as Airgas (www.airgas.com) offer flat, arrow-shaped magnets that provide support at 45-degree, 90-degree and 135-degree angles, depending on which two edges are used for base and support. These workholders are manufactured in several sizes, and their low profile means that even a half-dozen won't take a lot of space to store near the work area — even on the legs of the worktable.

Larger magnets capable of supporting heavier structures are available in the form of blocks, and in fixed 90-degree or adjustable-angle structures. In some cases, the blocks can be drilled and even tapped for the creation of workholding jigs, or to accommodate other hardware for fastening the magnet to a crane hook or other support device.

Not all utility magnets are alike. Units sold for welding work can be resistant to heat up to 600°F, and welding that is done directly on a magnet can reduce the strength of its field severely, and can eliminate the magnetic field permanently. If possible, test an identical magnet before supporting a critical structure, or where sudden loss of support may cause an accident. Additionally, the magnetic pull will affect an arc when arc welding, and can cause the weld puddle to travel in an unexpected direction.

(www.mpimagnet.com/automag.php)

Master Magnetics, Inc.

(www.magnetsource.com)

and Northern Tool

(www.northerntool.com)