What separates an Instrument Case from a protective case?

A: A protective case only survives the trip; an Instrument Case also provides a base that can be levelled and a lid angle that allows work.

Is a softer liner always better?

A: No. Soft liners densify under load and hard ones act as a rigid link. Twenty to thirty percent static compression, with lateral clearance, is the target.

Does an Instrument Case need levelling feet?

A: On concrete or a truck bed, yes. On a fixed bench, four pads and shims are enough; feet add weight and interrupt stacking.

How deep should the cavity be?

A: Deep enough to reach the floor, usually 250 mm or less. Taller equipment calls for a wider opening, not a deeper body.

Can the handle sit on the same face as the latches?

A: Better not. Fingers pass the latch as the lid opens, and both loads run the same way, which loosens the catch over time. ---

Instrument Case Design: Damping, Level and Working Height

Quick answer: An Instrument Case is specified by three measurable numbers, not by shell thickness. Damping needs an unbroken soft path between base and load, level needs coplanar support points, and working height needs the open case to sit inside arm reach. Fix damping first, then level, then height, because each one consumes the space the next one needs.

Why an Instrument Case Is Three Numbers, Not a Shell
Damping: Follow the Path, Not the Material
Level: Flatness Decides Whether the Reading Holds
Working Height: The Interface After the Lid Opens
When the Three Requirements Collide
FAQ

1. Why an Instrument Case Is Three Numbers, Not a Shell

An Instrument Case differs from a protective case in posture. The protective case is finished when it lands. The instrument case has to leave equipment able to work, so the box joins the measuring setup and vibration, flatness and reach matter as much as impact does.

All three appear on a drawing and can be checked at goods-in: liner compression, support-point coplanarity, and the height of the operating surface above the floor. Damping comes first because liner thickness eats internal depth, and depth drives outer height.

The same case closed and shot straight on, recessed corner pads, two latches along the lid edge, handle centred on top

2. Damping: Follow the Path, Not the Material

Damping is a path, not a material. Excitation enters the base, crosses the liner, reaches the load and returns through lateral restraints. Any rigid contact in that chain gives vibration a short cut, which is why soft foam under a load clamped by hard dividers isolates nothing.

Compression at rated load decides the result: below ten percent the liner is rigid, above forty it densifies and amplifies shock. Twenty to thirty percent, with three to five millimetres of lateral clearance, is the working range. The honeycomb ribs moulded into the lid are an impact feature, not a damping one.

Case open, lid standing, honeycomb ribs across the lid interior, empty base and a round pressure valve on the front wall

3. Level: Flatness Decides Whether the Reading Holds

Large rotomolded panels shrink as they cool, so the centre of a base often sits one to three millimetres below its corners and the case rocks. A bubble level on the equipment reads that rock as drift, and the instrument gets blamed for it.

Either recess the base into a rib grid that carries load on four edges, or mould four pads with height variation under one millimetre. Both rely on even cooling in the mould. An open lid used as a bench also needs a stay that holds it near vertical.

Closed case seen from the rear quarter, showing body depth, the side latch and the top handle

4. Working Height: The Interface After the Lid Opens

Working height is a sum of bench height, case height and the distance from the cavity floor to the operating surface. A 750 mm bench and a 150 mm case put the work at roughly 900 mm: right for standing, high for sitting.

Depth past 250 mm forces the wrist to rotate at the bottom; past 350 mm people pull the case closer instead. Lid angle matters too, since ninety degrees hides the rear of the cavity and 100 to 110 degrees does not. Keep the handle off the latch face, and under 450 mm of width for one-hand carry.

Case open at an angle, honeycomb lid ribs and empty base in one view, handle and two latches on the front wall

5. When the Three Requirements Collide

The three values fight each other. Thickness costs depth, depth costs height, height breaks the working limit. Work backwards from the load: equipment height plus compression gives internal depth, wall and rib height give the body, and the bench then checks the total.

If the check fails, move the bench, then the lid angle, and the liner last. Stacking is the other conflict, because every millimetre taken off the body removes a tier from a freight container.

Conclusion

Read the drawing in one order: liner, depth, body, then the surface the case will stand on. Change the bench before the liner when a check fails, and the Instrument Case keeps its three numbers intact.

This article covers container-side specifications and design intent only. It does not address any handling, loading or use of the contents.