What's inside
As an Amazon Associate I earn from qualifying purchases. This post may contain affiliate links at no extra cost to you.
What we cover
What a depth stop does
A depth stop limits how far a drill bit can travel into a workpiece. That matters when you need several holes the same depth, such as pilot holes for screws, holes for wall anchors, or a row of holes in a jig. Without a stop, it’s easy to make the first few holes consistent and then drill one too deep as you tire or lose track.
There are two common types. A collar stop clamps around the drill bit and physically meets the surface when the set depth is reached. A depth rod or depth gauge attaches to a drill or hammer drill and stops travel when its end contacts the surface. Either can work well, but the collar is often the simpler choice for ordinary drilling in wood or metal. A drill-mounted rod is useful when the tool has one fitted, especially for masonry work.
Choose the right stop for the job
For occasional holes, an inexpensive collar set is usually enough. Check that the collar matches the bit’s shank diameter and clamps securely; a loose collar can slide and let the bit go deeper than intended. A drill bit depth stop collar set is a practical buy if you use several bit sizes.
If you regularly drill into concrete or brick, use a compatible hammer drill’s depth rod when available. It’s quick to adjust and doesn’t need to be moved from bit to bit. For repeatable work in wood, a stop collar is often more precise because it touches the work surface directly. A hammer drill depth gauge rod is useful only if it fits your tool and can be locked firmly.
| Stop type | Best for | Trade-off |
|---|---|---|
| Bit stop collar | Repeat holes in wood, plastic, or metal | Must match the bit and be tightened securely |
| Drill depth rod | Masonry holes, especially with a hammer drill | Measures from the tool body, so surface position and tool angle affect accuracy |
| Tape flag on bit | A few rough holes when no stop is available | Can shift, and it does not physically stop the bit |
Set the depth accurately
First decide whether the measurement means total hole depth or usable depth for the screw or anchor. For a wall plug, follow its instructions: the hole may need to be slightly deeper than the plug so dust and debris don’t prevent it from seating. A common small plastic anchor may call for a hole around 25–40 mm deep, but the anchor packaging and wall material take priority. For a pilot hole in wood, set the depth to the screw’s required pilot length rather than guessing from its overall length.
Measure from the cutting tip of the bit, not from the start of the flutes. Set a collar by measuring from the tip to the collar’s contact face, then tighten its screw firmly with the supplied hex key. If the bit is fluted close to the collar, place the collar on the smooth shank where possible. A collar sitting on the flutes can tilt or clamp unevenly.
Before drilling the work, test the setup on scrap of the same thickness. Drill one hole, measure it with a depth gauge or a marked rod, and adjust. Allow for the shape of the bit: a pointed twist bit makes a deeper point than the flat bottom left by a Forstner bit. If the depth must be exact, measure the actual hole rather than relying only on the collar setting.
Drill the repeated holes
Mark each center clearly and clamp the workpiece so it cannot shift. Hold the drill as close to perpendicular as the job allows. A stop controls depth, not angle; a slanted hole can still be too shallow on one side and too deep on the other. On a cordless drill, start at a steady, moderate speed and ease off as the stop approaches the surface. Don’t force the tool to keep cutting once the collar contacts the work.
For holes in wood, clear chips periodically, especially in deep or narrow holes. Packed chips increase heat and can bind the bit. In masonry, use a suitable masonry bit and the correct drill mode. If the bit is overheating or the hole fills with dust, withdraw it occasionally to clear debris. Keep a firm two-handed grip where practical; a binding bit can twist a cordless drill sharply.
Drill a first hole, check it, then continue. Recheck the collar after several holes: vibration can loosen its screw, and a collar can also slip if it was clamped over oil, dust, or a damaged shank. If you change bit sizes, reset the stop—the same collar position does not guarantee the same depth when the bit’s cutting tip or geometry differs.
Avoid common mistakes
A stop rod that touches a rough or uneven surface may produce inconsistent depths. If the work face varies, use a stable reference surface or a collar that contacts close to the hole. A stop collar also cannot protect against drilling through a thin panel if the panel flexes under pressure; support the back of the work or use a sacrificial board.
Don’t treat tape as a reliable physical stop. It can be a visible warning for one-off work, but it may move as the bit rubs against the hole. Likewise, don’t use a drill’s clutch as a depth control. The clutch limits torque, not travel, and it may slip before the bit reaches the intended depth—or not slip at all.
For a handful of noncritical holes, a tape flag and careful measuring can be adequate. For a row of holes that must accept identical screws or anchors, a properly tightened collar or compatible depth rod is inexpensive insurance. The key is to test the first hole, keep the tool square, and verify the stop has not moved before finishing the batch.