Originally posted by Cobra81li200
Horatio : there are tools existing that does drill and countersunk in only one operation.
It's not a big problem for a car with aluminium bulkheads like the X-Ray (or the Mi2 
it's a bad example, or maybe a good one in my point of vue).
But when you have molded plastic parts, like on the SD, the TC3 and the Pro4, CAD/CAM is an help but won't solve the problem, as when the plastic cools down it deformates NOT EVENLY and according to a lot of parameters.
This requires prototyping in order to find the proper shape for the mold. Knowing that a mold costs a minimum of £10000 ($20000) but for a RC car's gearbox it might be much more, you now understand why it's expensive.
Tool up costs for injection moulding machines are well known to be very high. I knew this already. Careful design of the moulded parts ensures that any deformation is kept to a minumum. If drive shafts, gears, spur adapters and gear cases can be moulded accurately enough, I don't see why getting a few M3 holes to line up correctly should be a problem
Machining components from solid Alloy will always be more precise, but just to use counter sunk screws?
That said, if Alloy gear cases came out for the SD I'd be sure to try them. And use Countersink screws
Personally, I'll be using a counter sunk upper deck and I don't envisage any problems at all. Past experience tells me that counter sunk screws are, in general, the least problematic you can use - whether they be used for 1/8th or 1/10th, on or off road.
