1/72nd Uboat Gearbox; just about done

[steve nuttall]

Here is the assembly pic
The motor drives a 12 tooth steel gear
1st reduction is 12 (motor) to the plastic 31 tooth; part of this same gear is a brass 8 tooth which forms the driver part of the 2nd reduction
The next plastic gear is 34 tooth; and this drives an 18tooth
This gear drives 3 steel 13 tooth shaft gears arranged so the outer 2 revolve opp directions
I still need to add the actual shafts and seals etc; the gears are riding on 1/8" diameter carbide cuttershanks for testing



Motor is rated 9-18volt 18,0000rpm it seems to run well on 12

[turbobearcat]

Here is the assembly pic
The

Here is the assembly pic
The motor drives a 12 tooth steel gear
1st reduction is 12 (motor) to the plastic 31 tooth; part of this same gear is a brass 8 tooth which forms the driver part of the 2nd reduction
The next plastic gear is 34 tooth; and this drives an 18tooth
This gear drives 3 steel 13 tooth shaft gears arranged so the outer 2 revolve opp directions
I still need to add the actual shafts and seals etc; the gears are riding on 1/8" diameter carbide cuttershanks for testing



Motor is rated 9-18volt 18,0000rpm it seems to run well on 12

That's the radio shack motor I use!


it powers my Uboat and IJN Musashi,maybe my son's Blue Devil
Destroyer...

good choice..

Mark

[steve nuttall]

cheap enough too

cheap enough too

[turbobearcat]

cheap enough too
true true!

cheap enough too

true true!

[steve nuttall]

shafts are now done too
I

shafts are now done too
I used silicon bronze for the output shafts; the gears are lock-tight'ed on after i knurled the outside diameter of the shaft to make sure there was plenty to grip; the gears I bathed in Acetone to remove every drop of grease-oil etc
They should stay put
I did add a safety device; between the 34 and 18 tooth plastic gears there is a 1mm shear pin
My clearance from the hard nylon rear seal to the output shafts is about 0.0005" with melted grease added as i inserted the shafts (just warmed the shafts up a bit to melt the grease)
I'm hoping this is close enough to stop any water getting in; I don't like the idea of o-rings (too much drag)
If i need to; there is enough shaft length outside to add custom teflon lip seals i can make and fix to the rear seal

[tennesseejim]

What did you use for

What did you use for the bushings? Also, where did you get the gears & bushings?

Thanks -

[steve nuttall]

Bushings; what bushings?

I use brass

Bushings; what bushings?

I use brass to steel contact or plastic to steel/brass where ever there is rotation
The silicon bronze is very tough

[steve nuttall]

Gearbox installed into the WTC;

Gearbox installed into the WTC; I just added model AC fuel tube in place of the dogbones i'll make
I wanted to test the shaft supports and prop thrust; all seems well; the small amount of defection from the propshaft to the gear shaft is quite small hardly anything to a set of dogbones
I was thinking of inboard bearings; but it just seems fine without

[anonymous]

Freaking excellent Steve!

Steve

Freaking excellent Steve!

Steve

[collins class]

Wow, impressive piece of work!

[color=#000000]Wow, impressive piece of work! ]

[steve nuttall]

still need to make the

still need to make the rudder pushrod or screwshaft exit
I'm really thinking a high speed screw for the rudder; like a worm and quadrant setup; not sure yet (the advantage would be the servo output shaft could drive it direct)

Anyway thanks guys; if 2 experts liek you think it's good; I must be on the right track