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

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Depth Setting Rings

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. They serve multiple purposes, especially when applied to cutters used in CNC woodworking.

3 major benefits are:

  • 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 (d) from the face of the collet (or chuck). 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 position of the ring assures that enough of the tool shank is inserted into the collet (or chuck) to insure reliable centering and clamping. This minimizes the chance that the tools will "walk out" of the collet under heavy cutting loads. There is nothing worse than a solid carbide ballistic missile zipping across your shop. This assumes, of course, that the correct amount of torque has been applied to the collet nut during tool setting
  • When the ring is pressed against the face of the collet, it virtually eliminates (or, at least, reduces) the amount of airborne swarf that gets trapped in the spindle bore.

Make sure that you press the ring firmly against the collet / chuck face as you tighten the nut!

If all of the tools in the programmer's magazine have been fitted with depth setting rings, an automatic tool changer can load and unload tools with the tip of each one the same distance from the face of the collet. This distance is referred to below as the "Ring Set".

This is especially helpful with micro-tools where "touching-off" on some reference surface to calibrate the tool height can damage or break the tip of the tool. Rings also find widespread use in inlay pocket cutting where relatively large diameter cutters are used to "hog out" basic shapes, followed by much smaller diameter finishing bits that clean up the edges, sharpen the corners and add fine detail to the finished part.

Depth rings are available on both 1/8 in. and 1/4 in. shank tools.  There is no charge to add the rings, but the user is cautioned to make sure that their equipment is compatible with their use.

Ringset

Common Ring Settings

1/8 in. Shank

SHANK DIAMETER
(inch)		 OVERALL LENGTH
(inch)		 RING SET
(inch)
(±0.004)		 COLLET ENGAGEMENT
(inch)		 RING DIA. X LONG
(inch)		 NOTES
0.1250 1.50 0.800 0.70 0.30 X 0.18 drills, routers, end-mills, V-tip cut-out, counter sinks
0.1250 1.42 0.800 0.62 0.30 X 0.18 some stub end-mills
0.1250 1.42 0.800 0.62 0.30 X 0.18 V-tip engraving, tapered-stub
Notes:
  • Tools purchased for use in Plek™ Fingerboard Tuning Machines should be rung at 0.890 in. (22.61mm)
    • Most bits for Plek™ machines have 3mm shanks (available on special order)
    • 1/8 in. collets are available from spindle manufacturer

1/8 in. Shank (tools for PCB fabrication)

For PCB machines, the industry standard ring set is still 0.800". However, LPKF and T-Tech set the rings to different positions based on if the tool is used for through cutting (Drills, Routers, etc.), or surface cutting (Isolation/V-tip, Stub, Rubout, etc.). Typically these tools are 1.50" overall length for through cutting and 1.42" overall length for the surface cutting. However, as many tools have been developed for CNCs using industry standard ringing this may not always be the case.

It's assumed for the following tables that the overall lengths are 1.50" for through cutting and 1.42" for surface cutting. However, we ring tools for LPKF or T-Tech by their application even if the overall length is different. This will make them compatible with the machine but change the collet engagement from the tables below.

LPKF USERS: Please note that there are now 2 settings for LPKF V1 and V2. We started having reports in the beginning of 2023 that the LPKF V1 ring set was not working with some machines. This setting had been working for decades and validated both through LPKF rung tools and customer use. Through investigations with our customers, we found that the ring set was changed resulting in the LPKF V2 setting below. We are not entirely sure when this change took place or which software, firmware or machine versions use which ring set. Our best guess is that this change started somewhere around the middle of 2022. The best way to determine which version you need is to take a working tool and check it against the collet engagement length in the tables below (back of ring to back of tool).

1/8 in. Shank - Through Cutting

SHANK DIAMETER
(inch)		 OVERALL LENGTH
(inch)		 RING SET
(inch)		 TOLERANCE
(inch)		 COLLET ENGAGEMENT
(inch)		 RING DIA. X LONG
(inch)		 NOTES
0.125 1.50 0.800 ±0.004 0.700 0.30 X 0.18 STANDARD
0.125 1.50 0.800 ±0.004 0.700 0.30 X 0.18 T-Tech RINGING
0.125 1.50 0.787 (20mm) +0, −0.004 0.713 0.30 X 0.18 LPKF V1 RINGING
0.125 1.50 0.770 +0, −0.005 0.730 0.30 X 0.18 LPKF V2 RINGING

1/8 in. Shank - Surface Cutting

SHANK DIAMETER
(inch)		 OVERALL LENGTH
(inch)		 RING SET
(inch)		 TOLERANCE
(inch)		 COLLET ENGAGEMENT
(inch)		 RING DIA. X LONG
(inch)		 NOTES
0.125 1.42 0.800 ±0.004 0.620 0.30 X 0.18 STANDARD
0.125 1.42 0.720 ±0.004 0.700 0.30 X 0.18 T-Tech RINGING
0.125 1.42 0.709 (18mm) +0, −0.004 0.711 0.30 X 0.18 LPKF V1 RINGING
0.125 1.42 0.690 +0, −0.005 0.730 0.30 X 0.18 LPKF V2 RINGING
Notes:
  • LPKF and T-Tech users must specify the make and model number of their CNC routers to insure that the rings are properly positioned!
  • Applying rings to LPKF and T-Tech specifications may delay shipping
  • Depth rings should NOT be used on end-mills and other side cutters equal to, or less than, 0.005" (0.127mm) dia.. Think & Tinker will not apply rings to these tools.
  • Because of the limitations of our 1/8" shank ring setting equipment, we cannot apply rings to:
    • 1/8" shank tools longer than 1.50"
    • 1/8" shank tools with flute lengths or necked cutting depths greater than 0.50"
    • 1/8" shank tools for steel rule die fabrication

1/4 in. Shank

SHANK DIAMETER
(inch)		 OVERALL LENGTH
(inch)		 RING SET
(inch) (±0.0015)		 COLLET ENGAGEMENT
(inch)		 RING DIA. X LONG
(inch)		 NOTES
0.250 2.50 1.60 0.900 0.50 X 0.25 T&T PROPOSED STANDARD
0.250 3.00 2.100 0.900 0.50 X 0.25 T&T PROPOSED STANDARD
0.250 3.25 2.35 0.900 0.50 X 0.25 T&T PROPOSED STANDARD
0.250 3.50 2.600 0.900 0.50 X 0.25 T&T PROPOSED STANDARD
0.250 4.00 3.100 0.900 0.50 X 0.25 T&T PROPOSED STANDARD
0.250 4.50 3.600 0.900 0.50 X 0.25 T&T PROPOSED STANDARD

Note: Depth rings for 1/4 in. shank bits are not compatible with ER11 spindles or Dewalt 611 and Porter-Cable 450 routers without the use of a positioning spacer. The rings interfere with the operation of the collet nut during tool removal.

1/2 in. Shank

SHANK DIAMETER
(inch)		 OVERALL LENGTH
(inch)		 RING SET
(inch)(±0.0015)		 COLLET ENGAGEMENT
(inch)		 RING DIA. X LONG
(inch)		 NOTES
0.500 3.00 2.00 1.00 TBD T&T PROPOSED STANDARD
0.500 4.00 2.750 1.25 TBD T&T PROPOSED STANDARD