VALVE TYPES & MANUFACTURING TECHNIQUES (ix) - MORE ABOUT GRIDS -

As we have previously seen in this blog series, grids were produced in continuous  4 feet lengths and then cut to size for valve assembly - just like in the photo below: -

As Mullard used millions of grids annually - all of which were cut by hand - in order to increase consitency and throughput, something had to be done.   Accordingly, the Mullard Engineering Department developed an automated grid cutting machine in which grid lengths are loaded into glass hopper tubes which allow whole strips to be cut to length sequentially.  All an operator needed to do was keep the glass tubes filled and use the shadowgraph screen to monitor the quality of the cut lengths.  As needed, a limited range of adjustment was allowed for the operator to optimise the correct length of cut grid.

Here we see Trudy Firbush operating the automated grid cutting machine at the Blackburn works: -