Why must a jewellery display case fix the window before the lock?

Answer: The window takes 70% of the lid, leaving 30% of rim for catches. Lock first and the rim often drops under 25 mm, putting the point 6 mm from the glass, where pull falls from 300 N to 260 N.

Can the lid open to 120° instead of 105°?

Answer: Yes, with a thicker stop or a friction hinge. At 120° the lid centre of gravity sits 15 mm past the hinge and any knock tips it further, while a 3 mm stop holds the 1.8 kg lid at 105°.

How long does a 3H window last?

Answer: At two wipes a day under 500 g, haze rises from 2% to 2.6% in a year on 3H and to 4.2% on 2H. The window is a service part, swapped in 15 min rather than returning the lid.

Is a 15 kg handle enough for counter handling?

Answer: Yes with care. Loaded weight is 11.8 kg, and a 1.3 dynamic factor gives 15.3 kg, so two rivets per side at 60 mm centres keep a two-handed lift inside rating.

Jewellery Display Case

Quick answer: In a jewellery display case the order is window, then lock, then lining: a 4 mm PC window fixes visibility, a 300 N lock fixes security.

Order of decisions: window, lock, lining
Setting the 105° display angle
The 4 mm PC window and 3H hardness
Cam lock or combination: proving 300 N
2 mm flocking and a 15 kg handle
FAQ

1. Order of decisions: window, lock, lining

Seeing and locking compete for the same rim, so the order cannot be reversed. Fix the window and the rim width follows; fix the lock and you learn how much rim is left; the lining only fills what those two leave.

Reverse it and the lock ends up in a window that shrank by a ring: every 10 mm of rim a lock body takes is 10 mm off the display face.

On a 400 × 300 mm lid, a 320 × 220 mm window leaves a 40 mm rim. That rim has to carry both hinge pockets and latch catches, and two 20 mm stiffening bands are just enough.

Order	Item	Key figure	What breaks if missed
1	Window	4 mm PC, 70% of lid	Rim too thin for the catch
2	Lock	300 N per point	Lock eats the window, rim splits
3	Lining	2 mm flock, 12 mm well	Shallow well, pieces slide

The three items are hard-linked: below a 25 mm rim, the latch screw lands on the window gasket groove, lifting the seal by 1 mm and losing dust and water protection at the same time.

2. Setting the 105° display angle

105° splits the difference between visibility and stability. At 90° the lid stands vertical and the customer has to bend to see the tray; at 120° the lid centre of gravity passes the hinge and a knock on the counter keeps it falling.

Jewellery display case shelf with three black cases open, black divider pockets, white foam blocks, a white tray of orange sachets and an empty liner

Work the angle from the person: at a 900 mm counter and 1500 mm eye level, a 105° lid puts the tray at 35–55° to the eye, readable without stooping.

The stop belongs inside the hinge, not in a strap. A 3 mm stop block carries the 1.8 kg lid, wears 0.2 mm over 5000 cycles and loses only 2° of angle.

Lighting runs in an 8 × 6 mm channel along the rim, and a 12 V strip at 4 W/m hides behind the window, so no cable shows from the front.

3. The 4 mm PC window and 3H hardness

4 mm is where stiffness and weight part company: over 400 mm, a 3 mm window deflects 2.1 mm under a finger and 4 mm only 0.9 mm, and past 1.5 mm the finger reaches the goods.

3H is measured as pencil hardness. A 3H sheet survives 500 g without marking, and a ring edge leaves a polishable trace; a 2H sheet takes a 0.05 mm scratch that costs 4 min to polish out.

Read transmission and haze together. A 4 mm sheet gives 89% transmission and 2% haze against 91% and 1.5% at 3 mm, which is the price of stiffness; an anti-glare coating lifts haze to 4% and softens the spotlights.

The window seals to the lid on a double-sided tape gasket at 25% compression, so a 320 × 220 mm sheet can be changed in 15 min without stripping the whole lid.

4. Cam lock or combination: proving 300 N

300 N is the pass line. A tensile tester pulls the catch at 10 mm/min and the bolt must stay engaged with no rim split; two lock points flank the window and each carries 150 N.

Jewellery display case showroom wall of white shelves holding blue, orange, yellow and red cases, with open black and orange cases on lower tiers

The real difference between a cam lock and a combination lock is opening speed and who carries responsibility. One key opens every case in 3 s; a four-digit code per person removes key handover but locks out for 30 s after three wrong entries.

Item	Cam lock	Combination
Pull per point	300 N	300 N
Opening time	3 s	8 s
Access control	One key	Four digits per person
Best fit	Back-room storage	Counter handover

Lock position beats lock model: a point 12 mm from the window edge gives the shortest load path, while at 6 mm the rim splits at 260 N with the lock still intact.

Leave 0.5 mm between catch and bolt. The lid expands at 45 ℃ in summer and jams without it, while more than 1 mm rattles and makes staff think the case is unlocked.

5. 2 mm flocking and a 15 kg handle

2 mm flocking balances thickness and wrap. At 1 mm the board edge prints through the fabric; at 3 mm it eats 1 mm of well depth and the tray sits proud.

Well depth follows the piece. Rings take a 12 mm well, necklaces 8 mm, with 2 mm flocking in the bottom and 1.5 mm flocked board for the walls, chamfered 0.5 mm at the lip so chains do not catch.

Piece	Well depth	Well width	Load per cell
Ring	12 mm	25 mm	0.3 kg
Necklace	8 mm	180 mm	0.5 kg
Bangle	15 mm	90 mm	0.8 kg

The handle is rated at 15 kg. The case weighs 6.2 kg empty and 11.8 kg loaded, and the handle holds 15 kg for 1 h without set, on two rivets per side at 60 mm centres.

Set the display height too: a 900 mm counter with a 120 mm case puts the open lid at 1050 mm, 450 mm below eye level, clear of the face.

Conclusion

Display and security split into two lists ticked off on one drawing. Display: window at 70% of the lid, 105° opening, 4 mm PC, 2 mm flocking over 12 mm wells. Security: 300 N per point, points 12 mm from the glass, 0.5 mm catch clearance, rim never under 25 mm. Both lists share one rim, and neither may take more than its share. Do that and the jewellery display case lets a customer read the tray standing up, staff open it in 3 s, and still passes 300 N.

This article discusses container-side specifications and design implications only, and does not cover any handling, loading or use of the contents.