The boards and the card frames that hold them in the Acorn System Computers follow the dimensional standards set out for 19" racks and Eurocards in IEC60297. Fortunately we don't need to read these standards in order to build Acorn System Computers ! The VeroTec Product Handbook has a very useful section at the beginning which provides drawings showing all the key dimensions of the Subracks, Panels and Eurocards, I have used this information to produce a set of reference drawings for making replica boards.
Note: I generally use the term 'card frame' to refer to the chassis system holding Acorn System Eurocards, the term 'rack' refers more generically to a system for mounting equipment in a vertical racking system e.g. the '19" rack' however both terms are often used to refer to Acorn System enclosures.
The key dimensions of the standard are:
Eurocards
Acorn Eurocards are sized to fit in a 3U high Subrack with a depth of 160mm i.e. 100 x 160mm and are drilled to accept a DIN41612 64-way AB right angle plug at the rear and at the front brackets for a panel.
Here is a drawing showing the dimensions of the board and positions of the mounting holes:
Front Panels
The width of front panels are in multiples of 1HP minus an allowance for clearance of 0.4mm.
Acorn System boards are fitted with panels of width 5HP (or 5E) which equates to exactly 25.00mm.
Here is a drawing showing the detail of a 5HP wide 3U high Front Panel:
The Front Panel mounting brackets (vero part number 173-12525B) were originally black, unfortunately Verotec now only supply them in green. For those wanting to make accurate replicas the only other option is to print your own, here's an OpenSCAD design and the .stl file required for printing: