What is the minimum depth of the conical hole used to center the top?

• A. 0.5 cm
• B. 1 cm
• C. 1.5 cm
• D. 2 cm

Answer: (B)

The idea is that the conical hole serves as a precise guide to place the top exactly on the center, and the depth of that hole determines how securely the cone can seat and align the top. You want just enough depth for the cone tip to engage fully so the top sits centered without any tilt, but not so deep that you risk binding or interference with other parts. If the hole is too shallow, the cone won’t seat properly and the top can drift or wobble, compromising accuracy. If it’s deeper than necessary, you add unnecessary contact, which can cause friction, misalignment, or damage and can limit how the top sits or is removed. Therefore, the best choice is the depth that is just sufficient to seat the cone securely and stabilize the center without extra interference.