A magnetic welding square can speed up fit-up, but the holding number on the package is not a substitute for clamps, joint preparation, or a safe fixture. The Strong Hand Tools MSA45 is useful when the job is temporary positioning: hold steel in place, confirm the angle, make the tack, then remove the magnet before completing the weld.
What the MSA45 actually is
Strong Hand Tools lists the MSA45 as an Adjust-O magnetic square with an on/off control and a mid-point position for easier placement. The manufacturer lists a 65 lb maximum pull force, a body around 4.4 × 3.8 × 1 in., and angle positions for 30°/60°, 45°, and 90° setup. That makes it a compact fit-up aid for square tubing, round tubing, angle and flat stock rather than a structural clamp or lifting device.
The 65 lb number also needs context. Strong Hand states that its magnetic force figures are based on the longest side of the magnet against 3/8-in.-thick steel. Thin wall tubing, scale, gaps, paint, curved contact or a smaller contact patch can reduce the holding force in real work. Do not use the catalog number as a guaranteed load rating for your joint.
The most important limitation: tack welding only
The manufacturer specifically says the MSA family must be used for tack welding only and removed before completing the weld. That matters for two reasons. First, heat can damage magnetic products. Strong Hand says to avoid prolonged exposure above 175°F / 80°C. Second, leaving a magnet near the arc can influence setup and collect hot grinding or metal debris.
- Use the magnet to establish position, not to replace a proper welding fixture.
- Make enough tacks to keep the joint stable after the magnet is removed.
- Remove the magnet before completing the weld, as the manufacturer instructs.
- Clean the contact faces so chips and scale do not create a false angle or gap.
Where the on/off switch helps
The practical value of an on/off magnet is setup control. With the magnet off or at its mid-point position, the parts can be placed and adjusted without fighting full magnetic force. Once the fit-up is where it belongs, the magnet can be switched on for the tack. After tacking, switching it off makes cleanup and removal easier than with a permanently energized welding magnet.
That feature is especially useful when fitting small frames, brackets and tubing assemblies where the fabricator needs to move the square repeatedly. It does not eliminate the need to measure diagonals, check squareness, confirm drawing dimensions or use a rigid fixture when distortion control matters.
Before buying: check model, size and holding requirement
| Check | Why it matters |
|---|---|
| Exact model | This article covers MSA45, not the larger MSA46-HD, MSA47, MSA48-HD or MSA53-HD versions. |
| Contact area | The published pull figure assumes substantial contact with 3/8-in steel; your workpiece may provide less. |
| Joint geometry | The MSA45 offers 30°/60°, 45° and 90° positioning; confirm those are the angles you actually need. |
| Heat exposure | The tool is for setup and tack welding, not for staying beside a long completed weld. |
| Magnetic material | A magnetic square only helps on ferromagnetic workpieces; it is not a universal fixture for every alloy. |
Amazon product check
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- 65 lb Max Pull Force: Strong rare earth magnets deliver up to 65 lb of pull force, rated on the longest side of the magnet with 3/8 in. thick steel, to hold workpieces firmly for tack welding.
- Holds 30°/60°, 45° and 90°: The fast and easy way to hold metal workpieces at 30°/60°, 45° and 90° angles. Ideal for round and square tubing, angle and flat stock in the shop.
- On/Off Switch with Mid-Point: Turn the magnet off or to the mid-point position while setting up for alignment and easy part placement, then turn it on when you are ready to work.
- Easy to Clean: The fully enclosed design makes cleaning easier; simply turn the magnet off and wipe it clean. The square measures 4.4 x 3.8 x 1 in. and weighs 1.0 lb.
- For Tack Welding Only: Use for tack welding only and remove before completing the weld. Avoid prolonged exposure to heat sources of 175°F (80°C) and above. Patented, U.S. Pat. 7009480.
Last update on 2026-10-03 / Affiliate links / Images from Amazon Product Advertising API
The Amazon placement above is intended for the exact Strong Hand MSA45 model. Confirm the model shown in the live Amazon box before ordering because similar Adjust-O magnets have different sizes and pull-force ratings.
Sources
Featured image is contextual metal fabrication photography and does not depict the named MSA45 product.
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