Measuring Wheel / Measuring Disc

How to Use:

This measuring wheel has a circumference of 20cm and will click on each revolution. This product is good for measuring along curves but works well for straight lines too. Start with 0 at bottom and  the beginning of your measurement, roll along the object you are measuring and keep track of the clicks. If the object you are measuring clicks 7 times and the end of the object is at the 17 mark the measurement would be (7x20)+17=157cm. 

Tips for Success:

• Start with 0 straing down on your beginning mark
• Press down with moderate pressure (especially if not using an O-ring option)
• Keep perpindicular to you object you are measuring

Optional Bill of Materials:

• 608 bearing - common bearing used for fidget spinners and skateboards 
• O-Ring - You can use the largest O ring in the SAE (Part 327) or Metric (Part P-48) Storehouse O-Ring assortment. Below are the harbor freight links but they are also available at on Amazon and other hardware stores. 
  • Harbor Freight SAE: https://www.harborfreight.com/382-piece-o-ring-assortment-67554.html ($11)
  • Harbor Freight Metric: https://www.harborfreight.com/397-piece-metric-o-ring-assortment-67580.html ($11)

Print Options: 

0 Bearing / 0 O-Ring - Print Plate 1 if you do not have 608 bearings or an O-Ring (P48 or 327)

0 Bearing / 1 O-Ring - Print Plate 2 if you have the O-Ring but not the bearing

1 Bearing / 0 O-Ring - Print Plate 3 if you have a 608 bearing but not an O-Ring

1 Bearing / 1 O-Ring - Print Plate 4 if you have both a 608 bearing and an O-Ring

The O-Ring makes the biggest difference for performance because it is soft and grips the surface best when using the measuring wheel (especially on hard smooth surfaces). To rank the options from best to worst: Plate 4 - Best, Plate 2 - 2nd Best, Plate3 - 3rd best, Plate 1 - worst (but still works). 

Assembly: 

After printing the desired wheel and installing the optional o-ring and/or bearing. Be sure to align the bump on the wheel (above the #10) with the clicker on the wheel cover. Spread the cover open and align the humps on the inside of the cover with the center of the wheel. 

Accuracy: 

Accuracy of measurements will depend of the printer, filaments, and o-ring stretch. I have tried all these wheel combinations and have been within 4mm on a 1 meter measurement which is an error rate of 0.4%.