Does anyone know right off hand what screw size is normally used for the underside gear cover of an HO brass steam locomotive? I need to replace both of them and one of the two disappeared into oblivion. The brass company is NJ Custom Brass.
I’ll be heading over to Hobbytown either later today or tomorrow with the one screw I still have and can probably figure it out from the screws they have in stock. Using calipers, the major diameter of the screw is 0.0515". That’s smaller than 0-80 but larger than 0-90 and it doesn’t seem to match any of the metric sizes either.
You are assuming it is metric, unless you have this from the factory, this is a bad asumption. Found more than a few that were retaped by former owners.
Agree, my thing is restoration of eBay clunker locomotives and many have been re-tapped or worse yet the wrong screw forced into a hole.
Re-drilling and tapping the hole normally works much better if the threads are damaged. Having a good assortment of both SAE and Metric screws, washers and nuts is very helpful. I have a couple of assortments from Micro Fasteners in both brass and steel.
Sometimes you even have to make special screws.
The Rivarossi screw is 2.5mm. I was making a brass frame for a Rivaross