What should the rated load of a tool satchel be based on?

Answer: The heaviest load the job puts in, times a 2.5 dynamic factor, divided across the attachment points. A 20 kg bag lands at 250 N per point.

With a 22.8 L nominal compartment, how much goes in?

Answer: The nominal figure already applies the 85 percent factor, so loading reaches nine tenths of it.

Moving from 600D to 1680D, how much thickness is added?

Answer: The shell goes from 0.5 mm to 1.0 mm and the side wall to 4.45 mm, with the EVA core kept at 3 mm.

How much strap pull is enough?

Answer: Enough that the 4:1 working strength clears the peak: 587 N on a 25 mm strap, 470 N on a 20 mm strap, which is short.

Which dimensions can be loosened to ±5 mm?

Answer: Only class C sizes touching neither assembly, load nor appearance, such as pocket depth.

Tool Satchel Specifications: Dimensions, Wall Thickness and Load

Quick answer: Four lines fix a tool satchel specification: a size chain with datums, pocket tiers for volume, a laminate for wall thickness, and a load rating back-calculated to one attachment point.

How the Tool Satchel Size Chain Is Built
Pocket Tiers and Volume Allocation
Fabric and Liner Stack Thickness
Back-Calculating Load and Strap Pull
Tolerances and Measuring Tools
FAQ

1. How the Tool Satchel Size Chain Is Built

A size chain is more than three numbers. The body is soft, so its outline moves: measure the empty bag flat, then again 30 minutes after the rated load goes in. A depth difference above 8 mm means the mouth tape and side panels are out of proportion.

Four links carry it: mouth tape, body depth, base panel and corner guard, each with a datum and a tolerance. A 16-inch tool satchel runs 380 by 260 by 300 mm, with a 1,280 mm tape perimeter and a 60 mm guard.

Size chain link	Datum size	Tolerance	Measurement datum
Mouth tape perimeter	1,280 mm	±3 mm	Tape centre line
Body length	380 mm	±1.5 mm	50 mm below mouth
Body width	260 mm	±1.5 mm	Base fold ends
Body depth	300 mm	±2 mm	Mouth edge to base
Corner guard height	60 mm	±1 mm	Base to guard top

Volume is quoted twice. A 370 x 250 x 290 mm cavity gives 26.8 L geometric, but radii, seams and the folded mouth cut the usable figure to 85 percent, or 22.8 L.

2. Pocket Tiers and Volume Allocation

Pockets are a hierarchy, not a count. Six positions work: one main compartment, two internal flat pockets, one external flap pocket and a slot at each end, each with its own opening size and depth.

Tool Satchel: closed red hard case on a white van's ribbed metal floor, thick corner lugs, a side rib and a folded dark cloth

The internal pocket is 180 x 120 mm and 130 mm deep, the flap pocket 240 x 160 mm and 60 mm, each end slot 60 mm across. Clear every opening by 15 mm so a gloved hand can reach in.

Six positions total about 4.2 L, or 18.4 percent of usable volume.

3. Fabric and Liner Stack Thickness

Wall thickness means the whole laminate: 1680D polyester at 1.0 mm, 0.15 mm PU coating, 3 mm EVA foam, 0.3 mm 210D lining, giving 4.45 mm at the side wall; the base adds a 1.5 mm PP sheet for 5.95 mm.

Thicker foam is not better. At -10 C, 3 mm EVA takes five 180-degree folds without cracking; 5 mm shows a white line at the third. Coating sets water resistance: 0.15 mm holds 1,500 mm of hydrostatic head, 0.25 mm holds 2,500 mm.

4. Back-Calculating Load and Strap Pull

A rating starts at payload and ends at a proof force. At 20 kg: 196 N of weight, a 2.5 dynamic factor, a 490 N peak, split across two points at 245 N and rounded to 250 N.

Tool Satchel: red hard case standing on its side against a dark background, two front catches, a folding handle and a raised seam rib

A 25 mm polyester strap breaks at 2,350 N; at 4:1 it works at 587 N, covering the 490 N peak with 20 percent spare. A 20 mm strap breaks at 1,880 N and works at 470 N, under the peak.

Stitching is weaker: a double back-stitched seam at 3.5 stitches per centimetre reaches 80 percent of cloth break strength, a plain seam 55 percent.

5. Tolerances and Measuring Tools

Grade tolerances by function. Class A, touching assembly and load: ±2 mm. Class B, look and feel: 2 mm per 300 mm. Class C, free sizing: ±5 mm.

Match the gauge to the band: a 0-150 mm caliper at 0.01 mm for the 4.45 mm stack, a class I tape for the outline, a 0.02-1.00 mm feeler for mouth misalignment.

Ten repeats give a 0.03 mm standard deviation, 15 percent of a ±0.2 mm band, inside the one-third rule.

Item	Band	Gauge	Sampling point
Outline length and width	±1.5 mm	Class I tape	50 mm below mouth
Laminate thickness	±0.2 mm	Digital caliper	Side panel midpoint
Attachment spacing	±2 mm	Tape	Centre of D-rings
Mouth misalignment	≤0.5 mm	Feeler gauge	Either side of seam
Finished weight	±3%	0.1 g scale	Whole unit

Conclusion

A specification stands on three foundations: a size chain with real datums, a laminate drawn layer by layer, and a rating carried to a single-point force. Fill those in and the tool satchel specification is complete.

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.