Dual Monitor Arm Sliding Down the Pole: Stop the Collar Slipping

Quick Answer: Support the arm, wipe the pole clean, and retighten the height collar as its guide directs. If it still creeps, add a stop collar under it or cut the load.

• Not sure the collar is really moving: Tape the pole and check after a day. Start with Step 1 to mark the pole
• The collar slid after the arm was moved or bumped: Reseat and retighten it. Use Fix A to reseat the collar
• A tight collar still creeps over days: Let it rest on a stop instead of friction. Use Fix B to add a stop collar
• Heavy screens or arms always fully extended: Reduce the load and the leverage. Use Fix C to cut the load

• Difficulty: Moderate. A loaded arm needs a second person while its collar is loose.
• Tools: Painter's tape, a clean dry cloth, a flashlight, and the hex keys supplied with the arm.

Jump to:

• Step 1 - Mark the Pole and Confirm What Moves
• Step 2 - Restore the Collar's Hold
• Step 3 - Check the Collar Stays at Its Mark
• Common Mistakes
• FAQ

Why an Arm Slides Down Its Pole

A dual monitor arm sliding down the pole means its height collar is losing its grip. The collar holds its height by friction, squeezed onto the pole by a clamping screw or set screw, and nothing else stops it.

Two forces work against that friction. The screen's weight pulls the collar straight down, and an extended arm also tips the collar outward, so it pinches the pole at one top edge and one bottom edge instead of gripping evenly.

The collar then creeps when the screw has backed off, when grease or a film on the pole lowers the friction, or when the load and reach are near the arm's limit. A collar that slips once after being bumped is a different case from one that creeps a little every day.

A collar that stays put while the screen drops is not slipping at all; the arm's spring is sinking. A fixed stop collar under the arm takes friction out of the job entirely, because the arm then rests on a solid stop.

Problem state: The collar's friction grip is weaker than the downward pull and tipping force, so it creeps down the pole.

Corrected state: The collar grips a clean pole at its specified tightness or rests on a stop collar, with the load and reach inside the arm's ratings.

Critical Safety Warning: A collar loosened under load can let the arm drop down the pole suddenly, and a spring arm with its monitor removed can snap upward hard.

Before you loosen any collar:

• Remove that arm's monitor, or have a helper hold the arm, before you loosen its collar.
• Keep hands off the pole below a loose collar.
• Never pull an empty spring arm down by hand.

Step 1 - Mark the Pole and Confirm What Moves

Test with your screens on and used normally, because the creep happens under your real load.

1. Tape above each collar: Wrap a strip of painter's tape around the pole right against the top edge of each arm's collar. If the collar slides, a gap opens between it and the tape.
2. Use the desk for a day: Work and adjust the screens as you normally would.
3. Check for a gap: Look for a gap between the top of each collar and its tape.
4. Check the screw: With a flashlight, see whether the collar's screw is backed out, and whether the pole has a flat or groove it should sit on.
5. Note the screens: Write down each screen's weight without its stand and how far each arm usually extends.

What your results mean:

• A gap opened and the screw was loose: Use Fix A to reseat the collar.
• A gap opened with the screw still tight: Use Fix B to add a stop collar, and check the load in Fix C.
• The collar stayed at its tape, but the screen is lower: The arm's spring is sinking, not the collar. See Monitor Arm Keeps Falling Down?
• The screw spins without tightening: It is stripped. See Stripped Allen Screw in a Monitor Arm Joint first.
• No gap after several days: The collar is holding. If a screen still drifts, look at the arm's joints, not the collar.

Step 2 - Restore the Collar's Hold

Use the arm's assembly guide for the collar's tightening method, whether a stop collar exists for your pole, and the weight limits per arm and per pole.

Fix A - Clean, Reseat, and Retighten the Collar

Use when: The collar slid with a loose screw, or it was moved or bumped recently.

Before you start: Have a helper hold the loaded arm, or take its monitor off, before you back the collar screw out (why a loose collar can drop).

What you need: A clean dry cloth and the arm's hex key.

1. Loosen and set the height: Loosen the collar slightly and raise the arm to the height you want.
2. Clean the pole: Wipe the pole where the collar sits until no grease or film is left.
3. Line up the screw: If the pole has a flat or groove, turn the collar so its screw lands on it.
4. Tighten fully: Seat the key fully in the screw head and tighten as the guide directs, while the arm is still supported.
5. Release slowly: Let go gradually and watch the gap between the collar and the tape above it.

Check: The collar holds under load; confirm it over a day in Step 3. If it creeps again with the screw still tight, use Fix B.

Fix B - Add a Stop Collar Under the Arm

Use when: The collar creeps even when fully tight, and a stop collar is available for your pole.

Before you start: Take the monitor off that arm before you fit a stop collar, so the arm can't drop while you work under it.

What you need: A stop collar listed for your pole's diameter, from the arm's maker where possible.

1. Mark the height: With the arm at the height you want, put tape around the pole right under its collar.
2. Fit the stop collar: Clamp it on the pole right under the mark and tighten it as its instructions describe.
3. Lower the arm onto it: Loosen the arm's collar, rest it on the stop, and retighten.
4. Remount and retune: Refit the monitor and adjust the arm's tension if the screen now rises or sinks.

Check: The arm's collar sits flat on the stop with no gap; continue to Step 3. If no stop collar fits your pole, use Fix C.

Fix C - Reduce the Load and the Leverage

Use when: The screens are heavy for the arm, or the arms usually sit fully extended.

Before you start: Hold each screen by its frame with both hands while you move it, so a sudden drop can't catch your fingers.

What you need: Each monitor's weight without its stand, plus any accessories on it, compared with the per-arm and whole-pole limits.

1. Compare with the ratings: If either arm or the pole total is over its limit, stop using that setup and move to arms rated for the screens.
2. Bring the screens in: Pull each screen closer to the pole. Less reach means less tipping force on the collar.
3. Set the arms lower: A collar lower on the pole sees less leverage from the pole's own bending.
4. Check the clamp too: Heavier loads also load the desk clamp; see How Much Weight Can a Desk Clamp Hold?

Check: Both screens are within the ratings and the arms work with some reach to spare; continue to Step 3.

Step 3 - Check the Collar Stays at Its Mark

Re-tape each pole right against the top edge of each collar, then use the desk for several days, moving each screen through its range at least once a day.

1. Check the tape daily: Look for any gap between the top of each collar and its tape.
2. Push each screen: Press gently on each screen's side and watch whether the collar tilts on the pole.
3. Check the screws: Confirm the collar screws are still tight.

PASS: The top of every collar still touches its tape after several days, no collar tilts when its screen is pushed, and the screens hold their height.

This shows the collars hold your current load. It does not raise the arm's or the pole's weight limit.

FAIL: A gap opens between a collar and its tape, a collar tilts when you push the screen, or a screw has loosened again.

NEXT ACTION:

• A small gap, no stop collar: Add one with Fix B.
• The collar tilts when pushed: Bring that screen closer with Fix C.
• The screw keeps loosening: Retighten it with Fix A; if it loosens again within days, replace the screw with the maker's part.
• A cracked collar or bent pole: Stop using that arm and replace the damaged part.

Later check: After a week, check the tape once more. Collars that hold for a week under normal use rarely start creeping unless the load or the reach changes.

Common Mistakes

Mistake: Using a longer wrench to tighten the collar past the guide's direction.

What happens: The screw strips or the collar cracks, and then it can't hold at all.

Instead: Tighten as directed, then add a stop collar or reduce the load.

Mistake: Wrapping tape or rubber around the pole for grip.

What happens: The wrap compresses and slips, so the arm can drop suddenly.

Instead: Clamp onto a clean, bare pole.

FAQ

Why does only one arm slide?

That side usually carries the heavier screen or extends farther. Check that side's load and reach first.

Will a drop of thread locker stop the screw backing out?

Only if the arm's maker allows it for that screw. Otherwise a screw that keeps backing out should be replaced with the maker's part.

This guide covers pole-mounted monitor arms held at height by a collar. The desk clamp's grip and the desktop's strength are separate checks.

Written and edited by Lio Lim

Every guide on The ErgoDesk Lab is reviewed before it goes live so each step leads to a clear next action. Spotted something unclear or wrong? Let us know, or read how these guides are made.