I'm trying to reverse engineer a set of spur gears that I have on a model RC car, but they are tiny, so there's a limit to what I can measure with my calipers. My plan is to create a new gear design with a few important changes that will mesh with these existing gears, then have it professionally 3d printed in nylon.
I've used this image as a reference for what data I might want to obtain:
And here's an image of the gears in question:
So far I have these measurements for each gear:
Pitch Diameter: 5mm
Outside Diameter: 6mm
Root Diameter: 4mm
Pitch Diameter: 11mm
Outside Diameter: 12mm
Root Diameter: 9.5mm
Note: I don't know how to obtain the base diameter, only the root diameter, since the base diameter doesn't seem to be directly measurable. Also, the pitch diameters are a guess, but I'm assuming for simplicity the people who designed them probably picked 5mm and 11mm to go with 10 and 22 teeth respectively. It's the sort of thing I'd probably do. Also it matches with the centre-to-centre measurement of the meshed gears being 8mm, which is the same as (5mm + 11mm)/2.
I'm thinking of using this OpenSCAD script to replicate the gear designs:
Do I have enough data to make a replica of these gears using that script? If not, what else do I need? The script's comments seem to indicate that I need to know the pressure angle, but looking at the diagram I linked, I can only figure that out if I have the base diameters.