Why is the inside of a Portable Tool Box 6 mm larger than the tool?

Answer: That is handling clearance. Three millimetres per side lets fingers in and absorbs shrink; below that a full box jams in cold.

Is a 3.0 mm wall worth it over 2.6 mm?

Answer: Only if tier count demands it. Weight goes 2.4 to 2.9 kg, the cycle 74 to 92 s, deflection just 1.1 to 0.9 mm.

Why rate the handle at three times the load?

Answer: Lift acceleration, one-sided carry and swing all stack up. At three times, a 20 kg rating becomes 590 N with set under 1 mm.

Can an IP65 Portable Tool Box stay out in the rain?

Answer: The class only describes the test. Class 5 spray runs 3 min per face, and long exposure creeps past an ageing seal.

Can a pallet layer hold six boxes?

Answer: Not at 460 × 340 mm. Six need offsetting with 6 mm of gap, and forklift entry clips the corners.

Portable Tool Box: Sizing, Wall Thickness and Load

Quick answer: A Portable Tool Box is specified from the inside out: fix internal space and tray grid, work back through wall, rim step and envelope, then check handle rating and stack tiers.

How the Dimension Chain of a Portable Tool Box Runs
Wall Thickness, Ribs and Self-Weight
Single-Box Load and Handle Rating
Stack Tiers and What the Base Really Touches
Sealing Class and Pallet Module
FAQ

1. How the Dimension Chain of a Portable Tool Box Runs

A Portable Tool Box drawing usually carries the outer envelope only, yet internal space decides fit. Build from the inside: tool outline, 6 mm clearance, then wall, rim step and draft.

Take 460 × 340 × 190 mm outside, 2.6 mm wall, 3.2 mm rim step per side, 3.0 mm base, 2.8 mm lid, 8 mm rim overlap, 0.3 mm shut-off. Internal length lands at 448.4 mm, called 448 ±1.0; width 328 ±1.0; height 176 ±0.8.

Dimension	Nominal	Tolerance
Outer length	460 mm	±0.8 mm
Inner length	448 mm	±1.0 mm
Inner height	176 mm	±0.8 mm

Inside gets plus tolerance, outside minus. At 1.6 percent PP shrink the 460 mm direction moves 7.4 mm, so cavity steel is cut to measured values.

2. Wall Thickness, Ribs and Self-Weight

Wall thickness is derived from a weight ceiling, not picked for strength. One-hand carrying tops near 12 kg, leaving the body 2.4 to 3.0 kg; a 2.6 mm wall with a 3.0 mm base lands at 2.4 kg.

Portable Tool Box: a grey case open on a bench, a compartment tray of screws and drill bits, two metal draw latches at the front

Ribs follow at 0.6 of the wall, so 1.6 mm at the root: heavier roots sink onto the stacking face, lighter ones fill halfway. Ribs 5 mm tall at 80 mm pitch, crossed, take a 500 N centre load from 3.6 to 1.1 mm.

Main wall	Body weight	Cycle
2.2 mm	2.1 kg	62 s
2.6 mm	2.4 kg	74 s
3.0 mm	2.9 kg	92 s

3. Single-Box Load and Handle Rating

Load takes two paths: base and walls carry contents as distributed pressure, the handle carries the box as a point load. At 20 kg the floor sees 0.05 MPa, the handle root ten times that.

Size the handle at three times the rating, 60 kgf or 590 N. The grip is 26 × 14 mm, roots stay at R5, and the hinge pin is 6 mm stainless in an H8 bore.

4. Stack Tiers and What the Base Really Touches

Tier count comes from the lid of the bottom box. At five high it carries four full boxes, about 785 N, or 196 N per corner, spread over 2828 mm² of pad contact at near 0.28 MPa.

Portable Tool Box: a blue case standing open in a van, lid upright, a black strap crossing above the opening, road and traffic behind

A base never sits flat: shrinkage lifts the middle, so a new box touches on four corners with 1.5 mm of air and the footprint overstates capacity threefold. A 1.5 mm reverse crown lands the centre only under load.

In a van, 400 N of strap tension must run in the 2 mm deep side channels; a 190 mm box stops at eight tiers.

5. Sealing Class and Pallet Module

A sealing class means nothing without test conditions. Dust class 6 uses talcum at 2 kg/m³ for 8 h; water class 5 a 6.3 mm nozzle at 12.5 L/min for 3 min per face. A Portable Tool Box passes on an 8 mm rim depth and a seal set 25 to 30 percent.

Latch count is a perimeter sum: a 1600 mm rim needs 960 N for 0.6 N/mm, so four 350 N latches are the minimum.

Item	Value	Note
Rim depth	8 mm	25–30% seal set
Latches	4	from 0.6 N/mm
Pallet module	1200 × 1000 mm	four per layer

A 1200 × 1000 mm pallet takes four boxes per layer, four tiers with dividers reach 796 mm. The grid follows the inside: 448 × 328 mm split 4 × 3 gives bays of 108 × 106 mm.

Conclusion

The specification of a Portable Tool Box is a closed chain: inside sets envelope, envelope sets wall, wall sets weight, and weight with tier count pushes back on height. Settle those four and the Portable Tool Box stacks as drawn.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.