A Mirror Stand is a free-standing furniture mechanism that suspends a mirror panel between two vertical uprights using horizontal trunnion pivots, letting the user tilt the mirror to a chosen viewing angle and hold it there by friction. A typical cheval frame holds tilt angles from -15° to +25° with a pivot torque of 4 to 8 N·m. The mechanism solves the problem of viewing the full body without wall-mounting, and you find it in named pieces like the IKEA KNAPPER, the Pottery Barn Sausalito, and tailoring fitting rooms at Savile Row houses.
Mirror Stand Interactive Calculator
Vary mirror mass, CoM offset, tilt angle, and available pivot torque to see the friction torque needed to prevent mirror drift.
Equation Used
The required holding torque is the gravitational moment of the mirror mass about the trunnion pivot. The calculator converts the CoM offset from mm to m and the tilt angle to radians, then reports the torque magnitude because friction must resist drift in either direction.
- Gravity is fixed at 9.81 m/s^2.
- CoM offset is measured from the pivot along the mirror frame centerline.
- Required friction torque is reported as a magnitude for either tilt direction.
- Pivot torque is the total available holding torque about the shared axis.
Operating Principle of the Mirror Stand
The Mirror Stand works on a simple principle — a rigid mirror frame hangs between two vertical posts on a single shared horizontal axis, and the friction at that pivot is tuned high enough to hold the mirror's weight at any tilt angle but low enough that you can adjust it with one hand. The pivot is usually a shouldered bolt running through a brass or nylon bushing, with a Belleville washer or wave washer compressing a friction disc against the upright. Tighten the bolt and you raise the holding torque. Back it off and the mirror swings free.
Geometry matters more than people think. The pivot axis must pass within 5 mm of the mirror panel's centre of mass, otherwise gravity creates a constant restoring moment the friction joint has to fight all day long. Get this wrong and the mirror creeps — you tilt it to 15°, walk away, come back an hour later and it's drifted to 3°. The classic fix on a cheval mirror is a counterweight bar at the bottom of the frame or a deliberately heavy lower rail to bias the centre of mass below the pivot, which gives you a stable resting angle when the friction lets go.
If the pivot bolt loosens — and it will, because every tilt cycle works the threads — you lose holding torque progressively. You'll notice the mirror sagging forward under its own weight after 6 to 12 months of daily use. The fix is a nylon-insert locknut (Nyloc) or a thread-locking compound at assembly, plus a pivot bolt torque spec the factory actually follows. We see cheap dressing mirror imports skip the locknut and use a plain hex nut, which is why those units fail first.
Key Components
- Vertical Uprights: Two parallel posts, typically 1500 to 1800 mm tall for a full-length cheval mirror, spaced wider than the mirror frame by 30 to 50 mm to allow tilt clearance. They carry the pivot load and resist the tipping moment when the mirror is angled — base footprint must be at least 0.35 × frame height to meet BIFMA stability.
- Trunnion Pivot Bolt: A shouldered M8 or M10 bolt passing through the upright into a tapped or bushed boss on the mirror frame. The shoulder sets the bushing compression — get the shoulder length wrong by 0.5 mm and you either crush the friction disc or leave the joint sloppy.
- Friction Disc and Belleville Washer: A fibre or nylon disc squeezed by a Belleville (conical spring) washer to provide the holding torque. Belleville stack height controls the torque curve — a single washer gives roughly 4 N·m, two stacked in series doubles travel, two in parallel doubles force.
- Counterweight Lower Rail: A weighted bottom rail, often a steel bar hidden inside the wooden frame, that drops the centre of mass below the pivot axis. Adds 1.5 to 3 kg and gives the mirror a natural resting angle around 5° forward — the angle most users want anyway.
- Base Feet or Cross Stretcher: Wide-set feet or a horizontal stretcher between the uprights that prevents tipping. For a 1.7 m tall stand the base must extend 500 to 600 mm front-to-back to keep the centre of pressure inside the footprint when the mirror is tilted to its 25° forward limit.
Industries That Rely on the Mirror Stand
The Mirror Stand shows up anywhere a wall isn't available, isn't allowed, or isn't appropriate — bedrooms, retail fitting rooms, theatre dressing areas, tailoring shops and photo studios. The freedom to angle the mirror without drilling makes it the default choice in rented spaces and in any environment where the user's height varies session to session.
- Domestic Furniture: The IKEA KNAPPER full-length cheval mirror — 48 × 160 cm, friction-pivot tilt, sold over 2 million units a year as a flat-pack standing mirror.
- Bespoke Tailoring: Three-way fitting mirror stands at Henry Poole & Co, Savile Row — angled side panels on independent friction pivots so the cutter checks shoulder drape from any vantage.
- Retail Fitting Rooms: Free-standing tilt mirrors at Zara and Uniqlo flagship stores, used where tenancy rules forbid wall fixings into shared partition walls.
- Theatre and Film: Dressing-room mirror stands at the Royal Shakespeare Company's Stratford workshops, where actors need to check full costume silhouette and the room layout changes per production.
- Photography Studios: Posing mirrors on rolling stands in portrait studios — the model checks pose between frames, photographer wheels the stand out of shot in 2 seconds.
- Dance Studios: Portable barre-height mirror stands used by touring ballet companies for warm-up rooms when fixed mirror walls aren't available.
The Formula Behind the Mirror Stand
The critical calculation on a Mirror Stand is the pivot holding torque required to keep the mirror from drifting under gravity. At the low end of the typical operating range — a small 600 mm vanity mirror weighing 3 kg with the centre of mass 10 mm off the pivot axis — you need under 0.3 N·m of holding torque, which a single friction washer easily delivers. At the nominal point — a 1.6 m cheval mirror weighing 8 kg with a 20 mm offset — you need around 1.6 N·m. At the high end — an oversized 2 m floor mirror at 15 kg with 40 mm offset — torque demand climbs above 5.9 N·m and a single Belleville washer can't supply it without overtightening the bolt and crushing the bushing. The sweet spot sits where the centre of mass lands within 15 to 25 mm of the pivot axis — close enough that a standard friction stack handles it, far enough that the mirror has a definite resting position.
Variables
| Symbol | Meaning | Unit (SI) | Unit (Imperial) |
|---|---|---|---|
| Thold | Required pivot holding torque to keep mirror at angle θ | N·m | lbf·in |
| m | Mass of the mirror frame assembly | kg | lb |
| g | Gravitational acceleration (9.81) | m/s² | ft/s² |
| dcm | Perpendicular distance from pivot axis to centre of mass | m | in |
| θ | Tilt angle from vertical | degrees | degrees |
Worked Example: Mirror Stand in a boutique hotel cheval mirror
A custom furniture maker in Copenhagen is building a cheval Mirror Stand for a boutique hotel chain. Each unit holds an 8 kg mirror panel in a solid oak frame, with the pivot axis offset 20 mm above the assembly's centre of mass. The hotel wants the guest to be able to tilt the mirror with one finger but have it stay put once positioned, anywhere from 0° to 25° forward tilt.
Given
- m = 8.0 kg
- dcm = 0.020 m
- θmax = 25 degrees
- g = 9.81 m/s²
Solution
Step 1 — at the nominal worst-case tilt of 25° forward, calculate the gravity-induced moment the pivot has to resist:
That's the minimum static friction torque the pivot joint must supply to stop drift. In practice you size for 1.5× safety margin to account for friction decay over thousands of cycles, giving a target of roughly 1.0 N·m.
Step 2 — at the low end of the tilt range, 5° (a slight forward set, the typical resting position guests leave it at):
Almost nothing. Even a worn-out friction disc holds this. This is why mirrors that drift overnight always end up resting near vertical — the gravity moment falls toward zero as θ approaches zero.
Step 3 — at the high end, push tilt to 45° (beyond the design limit but useful to know for impact loading, e.g. a guest leaning on the frame):
The friction joint must hold this momentarily without slipping or you get a sudden swing-through — mirror drops forward and the lower rail clips the upright. Pivot stops at the upright limit are how you protect against this.
Result
The pivot needs roughly 0. 66 N·m of static holding torque at the 25° design limit, sized up to 1.0 N·m for service margin. At the 5° resting angle the joint barely sees 0.14 N·m, so the mirror feels solid at small tilts but progressively heavier as you push it forward — that's the operating-range feel built into every well-designed cheval mirror. If your finished build drifts after a week of use, the most likely causes are: (1) a missing or undersized Belleville washer letting the friction disc decompress as wood fibres in the upright relax, (2) a pivot bolt without a Nyloc nut backing off 1/4 turn under cyclic load, or (3) the centre of mass dcm coming out larger than the 20 mm spec because the lower counterweight rail wasn't fitted — check dcm on a balance fixture before final assembly.
When to Use a Mirror Stand and When Not To
A Mirror Stand isn't always the right answer. Wall-mounted mirrors, ceiling-suspended mirrors and motorised tilt mirrors all compete in the same problem space, and each wins on a different axis. Here's how they stack up on the dimensions that actually matter when you're specifying or buying.
| Property | Mirror Stand (Cheval) | Wall-Mounted Tilt Bracket | Motorised Tilt Mirror |
|---|---|---|---|
| Tilt adjustment effort | One-finger push, 1-2 second adjust | Requires ladder or step access for high mounts | Push-button, 5-10 seconds full sweep |
| Holding torque source | Friction disc + Belleville washer, 1-8 N·m | Cam-lock bracket, infinite hold once locked | Worm-gear actuator, self-locking up to 50 N·m |
| Installed cost (8 kg mirror) | $80-300 retail, no install | $25 bracket + $60-150 install labour | $400-1200 plus 12 V wiring |
| Footprint required | 500-600 mm base depth, mobile | Zero floor footprint | Zero floor footprint, requires power |
| Typical service life | 10-20 years, friction joint refresh at year 5-8 | 20+ years, no moving parts to wear | 5-10 years, actuator gearbox limits |
| Best application fit | Rented spaces, dressing rooms, retail fitting | Bathrooms, fixed-position vanities | Accessibility installs, smart-home bedrooms |
Frequently Asked Questions About Mirror Stand
Drift toward vertical means your friction holding torque is below the gravity moment at 20° but above the moment at smaller angles. As the mirror creeps, θ shrinks, and so does the restoring moment — drift slows asymptotically as it approaches the angle where friction equals gravity. The mirror always ends up resting just past that crossover point.
The fix is to raise pivot torque. Tighten the pivot bolt 1/8 turn at a time and re-test. If you've already bottomed out the Belleville stack and it still drifts, the friction disc has glazed — replace it with a fresh fibre or nylon disc. Don't keep cranking the bolt or you'll crack the upright at the boss.
Your centre of mass is above the pivot axis, not below it. That makes the mirror metastable in the vertical position — any tiny disturbance and it falls forward or backward, and friction has to fight gravity continuously rather than just holding a tilt.
Check dcm by removing the mirror from its uprights and balancing the frame on a knife edge. The balance point should sit 15-25 mm below the pivot axis. If it's above, you forgot the counterweight rail or fitted a heavier mirror panel than the design called for. Add ballast to the lower frame rail until dcm drops below the pivot — usually 1-3 kg of steel bar hidden inside the frame solves it.
Plain friction bushings every time. Ball bearings remove the very friction you need to hold the tilt position — you'd then have to add a separate brake mechanism, doubling the parts count.
For high-cycle use (50+ adjustments per day in a busy fitting room), specify an oil-impregnated bronze bushing or an acetal (Delrin) bushing running on a hardened shoulder bolt. Those handle 100,000+ cycles without measurable wear. The friction disc itself is the wear part — plan to replace it at the 3-5 year mark in commercial settings.
Calculate the tipping moment for a 200 N horizontal push at the top of the mirror (typical user lean force). The base must extend far enough that the resultant force vector — combining mirror weight straight down and the push horizontally — still falls inside the rear edge of the foot.
Rule of thumb for a 1.7 m tall cheval: minimum 550 mm front-to-back base depth, with at least 60% of the stand's total mass in the base assembly. BIFMA X5.5 furniture stability is the formal test — 10° tilt with 30 kg dead load applied at the top edge must not overturn. If you're under-spec on footprint, add splayed feet at 15° outward rather than just lengthening straight runners. Splayed feet add tipping resistance without enlarging the visual footprint as much.
Wood in the uprights swells with humidity, compressing the friction disc and bushing harder against the pivot bolt shoulder. Holding torque rises, the mirror gets stiff, and the joint stick-slips with a creak as you force it.
Two fixes. First, use a metal sleeve insert in the upright at the pivot boss so the bolt shoulder bears against steel, not wood — wood movement no longer changes the friction stack compression. Second, specify a wave washer instead of a Belleville for marine environments — wave washers tolerate dimensional change with less torque variation across the working range. We see this failure most on solid timber frames in places like Florida and the Mediterranean coast where summer relative humidity climbs above 80%.
Yes — a rotary friction damper installed coaxially with one pivot bolt smooths the motion considerably. Look for a 1-3 N·m rotary damper rated for bidirectional drag (ACE Controls and Bansbach both make suitable units around 30 mm diameter). Install it on one side, leave the other side as a plain friction pivot for holding torque.
The damper provides velocity-dependent resistance that kills the stick-slip jerk without adding to the static holding torque. Result is a Mercedes-style smooth tilt instead of the typical IKEA-style notchy feel. Adds about $25-40 in parts to a build.
References & Further Reading
- Wikipedia contributors. Cheval glass. Wikipedia
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