Mud

I went through a couple of iterations of design for the turntable mechanism, one of which used the inner teeth and the 16/24 tooth differential (single axle through the turntable). I don't have any of the old 14 teeth gears, and from my recollection of them, I don't want any! With a single axle going through the turntable your options really open up I think Rook may be confusing studless and SNOT...or I am

I made you a video: Hopefully that's clear - the axles going into each differential correspond to the two outputs passed through the turntable and are 1:1 (i.e., no gearing up or down). I lock the inputs solid to represent the load a (unused) motor has on the input, and you can see that the turntable and outputs don't move relative to eachother (lash from all the gears aside). This is as small as I managed to make this mechanism, but I think there's room for improvement. I couldn't work out an easy way of gearing the 24/16 tooth differentials to match the 56 tooth turntable, so if I'm missing a trick please let me know I might've misunderstood the term as it's used on this forum. I thought 'studless' simply referred to creations using liftarms rather than the old studded beams edit: got confused there for a second.

I guess I could take a video of it running over and shooting my son's baby-toys before I dismantle it, but not tonight ;) Too kind...Sariel's tanks set a high water mark that got me spending money on lego, and having seen some of the studless creations on this board I can see plenty of room for improvement though :)

First build after a ~15 year dark age, and my first studless build. This started off as a tank, but my studless skills failed me on the turret...so I went for a fun working missile launcher rather than aesthetics. The 'tank' has XL motors for each track, an XL motor for the turret rotation (over-specced really), and M motors control the missile launcher pitch and turn the crankshaft to fire the missiles. My aims were to make the tank as small as possible, whilst incorporating full turret control. To that end, I based the tracks loosely on the Japanese type 95 light tank, although I found the bogeys worked better unsprung. I also sent two drive shafts through the turntable to control the turret rather than use a second battery box. This required a couple of differentials to keep these drive shafts stationary relative to the top plate of the turntable - I can rip this chunk out and detail it further if anyone is interested, and if anyone can further simplify my design I'd be eager to see how :) I'm classing this as a learning experience, I'm happy with parts of it but think I've hit the point where I need to start again if I'm to improve it. Frankly I'm bored of tanks now, I want to rip this apart and make something more interesting. Sorry for slightly poor photos, I'm not really into this kind of photography and lego bricks are more reflective than I was expecting! Now with video:

Quite tidy, but there's no real need for the second differential as evidenced by you locking one of the shafts. You may be intentionally using the differential for a more desirable gearing on the second motor, but you could do this with plain gears. This would be arguably less pretty though!

Agree 100%. Granted, I'm coming out of a 12+ year dark age...but I'm a Dr. of engineering () and to me, building with lego is more like doing a crossword puzzle. You need to come up with lots of synonyms (albeit of a mechanical nature) until you find one that fits your specific constraints.