[DonRotolo]

In the car world, the big advantage of spiral bevel gears are their much quieter operation and their somewhat longer life. The disadvantage is their higher production cost.

In your circumstance, I think ease of manufacturing would trump all that.

It is possible to make a flat straight-tooth bevel gear, but strength, durability and efficiency suffer. Really, the big gear is flat, and the pinion looks like a spur gear but with tapering teeth - the tooth profile is not constant, but gets thinner towards the far end. Generally the pinion is not very wide, maybe 1/2" - 3/4" for the kind of sizes I think you're working with.

Maybe try it with some machining wax, machining foam, or maybe soft brass?