Kodak OAGM 2500 Off Axis Grinding Machine

Kodak OAGM 2500 - Off Axis Grinding Machine

The Kodak OAGM 2500 Off Axis Grinding Machine is a classic example of a special purpose machine.

This machine was built in a specially made facility in the UK for proving and acceptance testing before being shipped to the USA.

Read a case study on the Off Axis Grinding Machine here.

Machine concept

The initial concept of the OAGM 2500 machine shows how Cranfield Precision take a manufacturing problem, create a concept and a design and then turn it into a special purpose machine tool.

Machine Assembly

Assembly of the large machine structure shows the symmetry and nature of the stiff repeatable structure.

Ensuring the surfaces are correctly formed and alignments are correct is a key part of the highly skilled assembly process.

Mirror Segment Inspection

Technicians inspect the mirror segments that are manufactured in a controlled facility on the OAGM 2500 in Kodak's production facility.

High Precision Horizontal Boring Machine

High Precision Boring Machine

Cranfield Precision has produced a high precision horizontal boring machine. The machine was designed and developed to meet a need for our parent company Cinetic Landis Ltd where there was no commercially available machine that could achieve the required accuracy over the 4m³ work volume.

The machine is designed as a high accuracy finish jig boring machine capable of multi-purpose machining functions such as; mill, drill, ream, face and bore in one set-up

Read a case study on the design and development of the high precision boring machine here.

Initial 3D CAD Concept

The Principle of Determinism

Precision Machine Tool

Precision Machine Design adheres to the fundamental principle of determinism. The principle of determinism is that machine systems obeys cause and effect relationships. The principle of determinism does not accept the word random, it suggests that nothing is random and at some level there is a cause for the observed effect.

The repeatability of a machine tool is not driven by some inherent and seemingly random limiting process. With the ability to measure all of the influencing variables we can aim to better control them and therefore produce a more accurate machine tool.

Layton Hale's PhD Thesis (10mb PDF) talks about the principles of determinism and that the list of variables that cause errors in machine tools is not so long that we can't control them.

Cranfield Precision has a proven track record of producing highly accurate precision machine tools that are designed and produced using deterministic techniques.

Repeatability in Precision Machine Tools

Repeatable Machine Structure

Repeatability is one of the most important elements in precision machine tool design. The aim is to make a mechanical structure that is stiff and repeatable. Having a stable and stiff mechanical structure is the basis for a high precision machine tool.

Finite Element Analysis
of a machine element

At Cranfield Precision we design high precision machine tools with stiff and repeatable structures through advanced finite element analysis techniques and by obeying the key principles of precision machine design.


Once you have a stiff and repeatable mechanical system that will consistently repeat to a demanded position advanced control system and error compensation techniques can be applied to correct any measured errors. 


Precision metrology techniques are used to accurately measure machine error motions. The combination of a stiff repeatable structure, precision metrology and error compensation techniques produces a very accurate precision machine tool.

Error Budgets and Error Budgeting Techniques

An error budget is a method employed in ultra precision machine design that identifies the accuracies of individual machine elements and gives a useful value as to the over all machine accuracy. This technique can identify potential weak spots in a machine concept and be used to focus design effort into ensuring that every element of a machine tool is fully optimised.

6 degrees of freedom for a machine tool axis

Each machine element will have a potential error motion or influence in 6 degrees of freedom dependent on  the constraints in place.

Error budgets are used with a good deal of experience and where necessary previous results and test beds to prove a principle or concept.

Read more on error budgeting techniques here.