How do you magnetize a tape measure?

Magnetizing a tape measure is a simple process that allows the tape to adhere to metal surfaces. This can be useful for taking measurements in situations where holding the end of the tape is difficult. By inducing a magnetic field in the metal components of the tape measure, it will develop poles that create an attraction between the tape and ferromagnetic materials like iron and steel.

Why Would You Want to Magnetize a Tape Measure?

There are a few key reasons why you may want to magnetize a tape measure:

To make it easier to measure pipes, ductwork, steel beams, and other metal surfaces – the magnetic tape will stick to the surface rather than requiring you to hold the end

To get more accurate measurements since the tape will firmly adhere to the surface you’re measuring
To allow for solo measurements in situations where you don’t have an extra pair of hands
To prevent frustration caused by the end of the tape slipping while trying to take a measurement

Basically, magnetizing a tape measure adds convenience and improves precision when measuring metal objects. The magnetic attraction helps to prevent errors caused by the tape shifting or falling during measurement.

How Do You Magnetize a Regular Tape Measure?

There are a couple of simple methods you can use to magnetize a standard retractable tape measure made from a ferromagnetic alloy like steel or iron:

Method 1 – Use a Strong Magnet

You can temporarily magnetize a tape measure by simply running a strong neodymium rare earth magnet along the length of the metal tape a few times. This will effectively turn the tape measure into a temporary magnet. The magnetic field induced in the tape using this method may weaken over time.

Method 2 – Use Brief Electrical Current

Applying an electrical current to the metal in the tape measure creates a magnetic field which has a lasting effect. To magnetize using electricity:

Clamp both ends of the tape measure to either terminal of a 9-volt battery for 30 seconds.
Remove the battery and see if the tape adheres weakly to metal surfaces.

If a stronger magnetic field is desired, repeat the process again, clamping the tape to the battery terminals for 60 seconds.

The electrical current aligns the magnetic domains in the metal, inducing permanent magnetization. Be careful not to leave the current running too long as this can overheat and damage the tape measure.

What Kind of Tape Measure Can Be Magnetized?

The magnetization methods described above work on standard retractable tape measures made primarily from steel or iron alloys. Here are the characteristics that make a tape measure able to be magnetized:

Material – The tape must be made from a ferrous metal like steel or iron in order for magnetization to occur.
Retractable – The retracting mechanism contains coiled metal tape that can be magnetized. Fixed length metal tapes can also be magnetized.
Standard size – Wider tape measures of standard dimensions provide enough surface area for an adequate magnetic hold on metal surfaces.

Not coated – Any non-ferrous coatings on the tape may reduce the effects of magnetization on the underlying metal.

Here are some varieties of tape measure that are NOT suitable for magnetization:

Fiberglass tape measures

Tapes made from non-ferrous metals like copper or aluminum
Narrow metal tapes less than 1/4 inch wide
Metal tapes with heavy plastic coatings

Pro Tips for Magnetizing a Tape Measure

Follow these tips for getting optimal results when magnetizing a tape measure:

Demagnetize First

Use a strong magnet to remove any existing magnetic field from the tape before attempting to magnetize it. Pass the magnet over the length of the tape in the opposite polarity to eliminate residual magnetism.

Magnetize in Sections

Only magnetize the first 12-16 inches of the tape that you actually need to adhere to surfaces. Avoid magnetizing the entire length which can affect the recoiling mechanism.

Check the Polarity

Make sure you magnetize the side of the tape that will make contact with the surface you’re measuring. Usually this is the inward facing side of the tape once retracted.

Test on Metal

After magnetizing, check that the tape adheres firmly to a metal surface to confirm successful magnetization before relying on it for critical measurements.

Remagnetize as Needed

Realize that the magnetization will degrade over time, especially if banging the tape measure around. Remagnetize periodically to restore the magnetic hold strength.

Will Magnetizing Damage My Tape Measure?

Properly magnetizing a tape measure as described in this article will not cause any damage. However, there are a few things to avoid that can harm the tape measure:

Excessive electrical current for too long which can overheat the metal.
Remagnetizing without first demagnetizing which can lead to polarity issues.

Exposing to strong magnetic fields like MRI machines which can disrupt the mechanism.
Magnetizing the entire tape rather than just the necessary length.

As long as you magnetize in moderation just the portion of tape needed, there should be no risk of damaging the tape measure or impacting its accuracy.

Benefits of a Magnetized Tape Measure

Here are some of the top benefits you can enjoy from properly magnetizing a steel tape measure:

Easier one person measuring of metal objects
Prevents measurement errors from the tape shifting or falling

Faster measuring since the tape adheres firmly without support
Safer measuring on ladders or uneven surfaces
More versatility to measure tricky metal items

Minimizes frustration when working solo
Hands free operation once tape is stuck on a surface

While magnetizing requires a small upfront time investment, it can save significant hassle when working on later projects involving metal measurement.

Frequently Asked Questions

Is it possible to magnetize a fiberglass measuring tape?

No, fiberglass measuring tapes cannot be magnetized because fiberglass is a non-ferrous material. Only metal tapes made from ferromagnetic materials like steel or iron can be magnetized. The fiberglass material in a fiberglass measuring tape does not exhibit magnetic properties.

How long does a tape measure stay magnetized?

It depends on the magnetization method used. Tapes magnetized by brief contact with a magnet may only stay magnetized for a few days to a week. Magnetizing with electrical current produces a more permanent magnetic field lasting for several months. However, the magnetic strength will degrade over time and need to be refreshed by repeating the magnetization process.

Can you demagnetize a tape measure?

Yes, you can demagnetize a tape measure by passing a strong magnet over the length of the tape in the opposite direction of magnetization. This helps remove any residual magnetism. It’s recommended to demagnetize before attempting to apply a new field with a different polarity to prevent any issues.

Does magnetizing a tape measure affect its accuracy?

Magnetizing just the necessary portion of a steel tape measure should not affect the published accuracy rating for that tape. However, you should check measurements on non-magnetized surfaces to detect any changes after magnetizing. Extended magnetization of the entire tape length may impact recoil and could influence accuracy.

Can you magnetize a tape measure permanently?

There is no permanent magnetization method for tape measures. Electrical current provides the most lasting magnetism but it will still degrade over time. Maintaining the magnetic field requires periodically re-magnetizing the tape measure as needed for the application.

Conclusion

Magnetizing a steel tape measure is a simple process that provides valuable convenience for measuring ferrous metals in challenging situations. Using a strong magnet or electrical current, you can induce temporary magnetization sufficient for adherence during measurement. Periodic remagnetization will likely be needed over time. When done properly, this magnetic modification does not pose any risk of damage to retractable metal tape measures.

Magnetization Method	Pros	Cons
Strong Magnet	– Simple and fast – No equipment needed	– Effect diminishes over days/weeks
Electrical Current	– Produces longer lasting magnetism – Stronger magnetic field	– Requires electricity source – Risk of overheating tape

Magnetizing specific portions of your go-to tape measure can provide a safer and more frustration-free measuring experience when working alone on metal materials. Just be careful not to over-magnetize and test periodically to ensure accuracy has not been impacted.