Understanding Internal Measurement Accuracy

While it is a bit more straight forward for taking external measurements with the T1 (the same kind most traditional taken), internal measurements have a series of physical items that stack up which lead to potential confusion when attempting to verify accuracy with the blade fully retracted.  The below article walks through the various components that are accounted for to ensure that internal measurements are properly accounted for and the correct value captured on the T1 Tomahawk.

1) Length of the T1 Body

The length of the T1 Tomahawk body (not including the tape hook) is about 165mm.  Manufacturing tolerance may change this value by around +/- 0.25mm.  This value is hardcoded into the T1 and cannot be changed by the user at this time. This is the value that will be added to any measurement when "MB/MF" mode is active to account for this length. The length of the T1 Tomahawk is compensated for digitally.

2) Tape Hook Thickness and Play (Movement)

You may notice that the T1 blade hook can move between two positions - one extended, one retracted.  This is intentional to account for the width of the tape measure blade (around 1mm) which correlates to the travel the blade can move (around 1mm).  This is a standard feature on almost every tape measure blade and is a mechanical way to compensate for the thickness of the The thickness of the tape hook is compensated for mechanically.

Tape Hook Extended (Exterior Measurements)

Tape Hook Pushed in (Interior Measurements)

3) Measuring the length of the T1 + Tape Hook

The total length of the Tape tip and the Tape Length should be around 166mm.  However, this is an awkward position to measure it in as the tape is not meant to be used without any portion of the blade extended.  You may notice the screen displaying 165mm in this position.  However, the tape measure hook needs to be in the pushed in position to show 166m on the screen.  This is primarily to highlight for demonstration purposes as why the T1 may appear to be showing an incorrect measurement when, in reality, it is because the blade hook is in the incorrect position.  

As seen in the above photo, the magnet is flush with the front of the blade hook and the calipers, along with the T1 screen, both show a length of 166mm (1mm hook + 165 tape length).

4) Other Factors

Ensure the T1 is held straight.  As the T1 hook extends slightly below the bottom plane of the T1 (to make it easier to grab materials) this may introduce a cosine error over shorter distances if not positioned correctly.