Box Angle Plates

UKAS Certified | BS 5535:1978 | Machine Setup

Manufactured in accordance with BS 5535:1978, Eley’s cast iron angle plates are manufactured from our well-aged, close-grained cast iron, and can be supported by a UKAS or Eley Metrology certificate of calibration.

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  • Supplied in Grade A or Grade B, with options for primary squareness only or both primary and secondary squareness, allowing the plate to be matched more closely to the accuracy and inspection demands of the application.

  • More rigidity and stable geometry than a standard angle plate. The box form helps maintain squareness during repeated setting, clamping and inspection operations.

  • Standard and custom sizes are readily available, for applications that require a specific configuration, improved versatility or a tailored workholding solution.

  • Layout, setting-out and machine setup tasks in precision engineering, toolrooms and general workshop environments.

  • Tooling and inspection applications where a rigid, accurately squared reference is needed for reliable workpiece positioning.

  • Use as right angles or squares for checking, supporting and orienting components during machining or inspection.

  • Workholding where the component can be fixed on one face and rotated through multiple positions without disturbing accuracy or alignment.

  • Special fixture and jig applications, including setups adapted with tenons, pins or stops to suit specific holding requirements.

  • Matched pairs used as parallels or height blocks when additional support, spacing or reference height is required.

Cast Iron Box Angle Plates to BS 5535 (1978) Primary and Secondary Squareness

GRADE
SIZE (mm)
PRIMARY ONLY (µm)
PRIMARY (µm)
SECONDARY (µm)
WEIGHT (kg)
A
150 x 122 x 115
10
10
13
9
A
225 x 175 x 150
12
12
15
21
A
300 x 250 x 225
15
15
17
44
B
150 x 122 x 115
50
60
75
9
B
225 x 175 x 150
60
60
75
21
B
300 x 250 x 225
75
75
85
44

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Industries Used In - Cast Iron Box Angle Plates -

Close-up of a high-power CNC laser cutter head piercing a reflective metal sheet, producing bright golden sparks.

Precision Engineering

Supporting and clamping precision components at 90° for machining, drilling, and inspection, and providing a stable reference for perpendicularity checks.


Precision engineering companies use cast iron box angle plates to hold workpieces square to machine tables and surface plates, ensuring accurate right‑angle machining and measurement.

A technician wearing a yellow hard hat and safety glasses using a calliper to check the precise inner dimensions of a machined metal component.

Machine Tool Manufacturing

Setting up test pieces, jigs and fixtures at precise right angles during machine build, alignment, and performance verification.


Machine tool manufacturers use cast iron box angle plates as rigid, machined reference faces for checking squareness between tables, saddles, columns and spindle orientations.

A female aerospace technician in blue overalls inspecting a complex aircraft jet engine component.

Aerospace Manufacturing

Supporting structural parts, precision brackets and complex machined components in a rigid 90° orientation for machining, CMM checks and surface plate inspection.


Aerospace manufacturers employ cast iron box angle plates where stable, vibration‑resistant right‑angle fixturing is needed to meet tight geometric tolerances on critical components.

Unfinished car bodies moving along an automated assembly line track inside an automotive manufacturing facility.

Automotive Manufacturing

Holding engine blocks, housings, brackets and fixtures square on machining centres and surface plates for accurate drilling, boring and measurement operations.


Automotive manufacturers use cast iron box angle plates in toolrooms and production to ensure consistent, repeatable right‑angle positioning of safety‑critical and high‑precision components.

A machinist wearing an orange hard hat and safety glasses operating a large industrial metal lathe machine.

General & Heavy Manufacturing

Fixturing large or heavy components at 90° for boring, milling and drilling, and maintaining squareness during fabrication and machining operations.


General and heavy engineering shops rely on cast iron box angle plates to support bulky parts securely while critical perpendicular features are produced or inspected.

FAQs

What is the difference between a cast iron box angle plate and a standard angle plate?

A standard angle plate is an L-shaped tool providing two working faces — one horizontal base and one vertical face — at 90°.

 

A box angle plate is a hollow rectangular block with up to five usable precision faces, all square and parallel to one another within BS 5535:1978 tolerances.

 

This multi-face configuration gives the box angle plate far greater versatility: a workpiece can be rotated through multiple positions on a single setup without re-clamping or re-zeroing, and the closed box construction provides greater torsional rigidity under load than an equivalent open-section L-plate. Box angle plates are the preferred choice where components require inspection or machining across multiple faces in a single setup, or where a rigid, stable workholder is needed for heavy workpieces.

Size selection is driven by the envelope of the workpiece to be supported, the load applied and the clamping arrangement required. Eley cast iron box angle plates are available in standard sizes from 150 × 122 × 115 mm up to 300 × 250 × 225 mm, in both Grade A and Grade B.

 

The working face should comfortably accommodate the component being clamped or inspected without overhang, and the height should provide a stable squareness reference along the full length of the feature being checked. For applications outside the standard size range, Eley can produce bespoke box angle plates to customer-specified dimensions.

Reach out to one of our specialists to discuss your unique requirements.
Email: sales@eleymet.com
Phone: 01332 367475

Grade A is manufactured to the tighter squareness, flatness and parallelism tolerances of BS 5535:1978 and is the correct choice for quality department inspection, toolroom calibration work and any application where measurement uncertainty must be minimised. Grade B carries slightly wider tolerances and is well-suited to general machining setups, workshop fixturing and preliminary inspection tasks where Grade A precision is not a strict requirement.

 

As with all reference standards, a clear traceability hierarchy should be maintained, with verified Grade A artefacts used to check any Grade B working tools in routine use. Both grades are available with Primary squareness only, or with Primary and Secondary squareness verified, allowing the specification to be matched precisely to your application.

Calibration frequency should reflect usage intensity, application criticality and your QMS requirements.

 

As a practical guide, box angle plates in high-cycle inspection or machining environments benefit from calibration every 6–12 months; those used infrequently in controlled conditions may suit an annual interval. In regulated industries such as aerospace, nuclear or medical device manufacturing, more frequent calibration is commonly specified to prevent squareness deviations from propagating into product conformance decisions. Calibration should also be triggered immediately following any impact, suspected damage or anomalous measurement results.

 

All Eley cast iron box angle plates are supported by a UKAS or Eley Metrology certificate of calibration.

 

Contact us for maintenance or calibration assistance.
Email: sales@eleymet.com
Phone: 01332 367475

Consistent care is important to preserve both the working accuracy and the service life of cast iron box angle plates:

 

  • Cleaning: Wipe all working faces before and after use with a soft, lint-free cloth. Remove coolant, cutting fluid and moisture promptly to prevent surface corrosion.
  • Rust prevention: Apply a light coat of rust-preventative oil or petroleum jelly to all working faces when not in use, and inspect regularly for early signs of oxidation, particularly in humid workshop environments.
  • Burr and damage inspection: Check working faces for burrs or chips after use. Remove minor burrs carefully with a fine stone and clean the surface thoroughly before returning to service.
  • Handling: Use appropriate lifting equipment for larger sizes. Never drop or subject working faces to impact as cast iron is brittle and susceptible to chipping.
  • Storage: Store covered, on a stable, dry surface, away from temperature extremes and moisture. Keep T-slots and cored holes clean and free from debris to maintain clamping integrity.

Yes. All Eley cast iron box angle plates are supported by either a UKAS traceable calibration certificate or an Eley Metrology certificate of calibration, confirming squareness, flatness and parallelism values against BS 5535:1978 tolerances.

 

UKAS calibration, issued from our UKAS-accredited laboratory (No. 30213), is internationally recognised under ILAC mutual recognition agreements, providing the documented traceability evidence required for QMS frameworks.