Scratch built 66 project

[Michael [Blefuscu]]

Here's a bit of progress on the 66 idea I introduced in my introduction.
As a starting point I have used the gears suggested in "3D printable traction motor case", posted here by Melbournesparks . I had a problem with the 2mm bearings. After 'coaxing' them onto my axles they are no longer bearings, but the duplex gear is free running anyway so I will just print some solid bearings.

This design is running a bit fast for these tiny brushed motor and wheel diameter. (driven at 7.4V) So I'm going to have to change things around a bit.
The weight of the chassis is going to be taken by the axle boxes via 4 6mm springs. At least that is the plan at present. The little tail on the gearbox will be anchored to the bogie frame to stabilise the gearbox

 

[Michael [Blefuscu]]

Today I have been playing around with the gear configurations. This should achieve something like 500rpm...




I also drew up a configuration for 6x 500rpm N20 motors, driving the axle with M0.6 alloy gears



I like this enough that I just ordered some N20 motors and gears, but I also added the extra duplex gears to complete the other design. As all the parts are pretty cheap.

Space is tight, laterally, on both designs, so I am considering the idea of printing the final drive gear as part of the wheel. The only gears I have printed before I chunky affairs, and certainly not run at 500rpm, these gears might be a bit too fine.