Even though the PT-2 has been discontinued by Canadian Curling Tools in favour of their new “Smartbroom” device, a number of curling associations and individual coaches continue to use PT-2 instrumented brushes with their teams. A characteristic of the PT-2 that coaches must be aware of is the frequent need to “zero” the PT-2 brush to ensure that the force readings from the brush are as accurate as possible. The need for this is because the PT-2’s load sensors are cemented into the brush’s EQ brush pad, and over-tightening of the bolts that fix the brush pad in place can result in skewed measurements.
As I’ve been asked a few times about the zeroing method for the PT-2 I decided to post this article. PT-2 documentation is no longer available on the Canadian Curling Tools website.
To zero a PT-2 brush, follow these steps:
- Ensure that the brush head is plugged into the PT-2’s display unit, and the unit is charged.
- Loosen the bolts on the brush head assembly to disconnect the brush pad from the brush head. It isn’t necessary to completely loosen the bolts and detach the pad; note that there are wires that will still connect the pad to the head assembly and these wires should be managed carefully.
- From the PT-2’s home screen, press the Utilities menu item at the bottom of the screen:
- From the menu on the left-hand side of the Utilities screen, select “Sensors”:
- Note the sensor reading displayed on the screen. A typical value will be between 1.40 and 2.80 – each PT-2 brush has a different base value, so your brush may not reflect the value shown here (1.60):
- Re-attach the brush pad if you completely separated the pad from the head assembly in Step 2.
- Gently tighten the bolts to attach the brush pad to the head assembly. Do so evenly so that the top of the brush pad is even with the bottom of the head assembly. Tighten the bolts until the sensor reading on the display is 0.02-0.04 higher than the base value from Step 5:
- Return to the PT-2’s home screen. The brush is now zeroed and ready for use.
