CNC router bits and carbide cutting tools with tutorials and technical guides

Depth Setting Rings for 3mm and 1/8 in. Shank Cutters

Depth setting rings are plastic collars that are securely pressed onto the shank of a drill bit, end-mill, router bit, or similar rotary cutter. Their purpose is to accurately, and repeatedly, set the distance the collet face to the tip of the cutter. The shank side of the ring is accurately positioned ( relative to the tip of the tool. If the shank-side of the ring is pressed against the collet when the tool is loaded, the tip of the bit will be a known distance from the face of the collet. Knowing this distance, the programmer can plunge the tool, confident that the depth of cut will be as expected and will remain the same no matter how many times the tool is changed.

The thickness and positioning of the rings are chosen to insure that the shank of each bit is inserted into the collet (or chuck) deep enough for proper engagement and clamping between the shank and the collet bore. This serves to insure that the collet correctly centers during tightening and minimizes the chance that the tools will "walk out" of the collet under heavy cutting loads.

An additional function is to partially block the intrusion of dust and debris into the spindle/router chuck eliminating a significant cause of unpredictable bit runout.

NOTE: These rings are intended for installation by the end user. If you want rings pre-installed on your 1/8 in. and 1/4 in. shank tools, please indicate this during registration or checkout. 


  • Material: Nylon 6
  • Outer diameter: 7.5mm ±0.1mm (0.295 in.)
  • Thickness: 4.5mm ±0.1mm (0.177 in.)
  • Shank compatibility: Depth rings are available for:
    • 3mm shanks - DB03 family
    • 1/8 in. shanks - DB08 family
  • 3mm depth rings WILL NOT fit 1/8 in. shanks!
  • More information
3mm and 1/8 in. shank depth rings

Description UnitReviews Part Number Price
Depth ring for 3.0mm dia. shanks - black, blank (25 pack) 25 Pack DB03-RBLK-025


Depth ring for 3.0mm dia. shanks - dark green, blank (25 pack) 25 Pack DB03-RDGRN-025


Depth ring for 3.0mm dia. shanks - red, blank (25 pack) 25 Pack DB03-RRED-025


Depth ring for 3.0mm dia. shanks - violet, blank (25 pack) 25 Pack DB03-RVLT-025