Making scale gratings is probably the hardest job to do right in modelling. We all know how they fit together, but doing it accurately is another thing altogether. We have all seen the offerings produced by the mainstream manufacturers, but in many cases even the smallest scale is big enough for a crewman to lose his foot into one of the "holes".
In the past I have used a slitting saw blade of a width equating to the size of the square. That was OK, but moving the cutting tool to the next slot was always a "hitty-missy" thing. What was really needed was an adjustable feed that would "click-in" at a pre-determined distance.
Remember that no matter what scale you are building at, at full size the squares are always about 1" (Gulp). At 1:48 scale that equates to about the width of a piercing saw blade. Almost impossible without some sort of mechanical intervention. I came across an American journal that seems to solve the problem. Trust an American to come up with such a wonderful bit of lateral thinking.
Let's just hope that the resolution is good enough to be read (and understood).