will this 4th axis work

[Robin Hewitt]

Surely you'll be using Anti-Backlash gears from HPC Gears as it would be a strange choice to add backlash in the primary drive (regardless of how small an error this would introduce) of a system designed specifically to avoid backlash?

Wow, it almost designs itself.

[magicniner]

Wow, it almost designs itself.

That's extremely fortuitous then ;-)

[Robin Hewitt]

I just took that harmonic drive apart, one screw head decided to snap off, one had to be drilled off.

Much as expected, only remarkable thing is how fine the gear pitch is.

These gears are about 28mm diameter...

[Edward]

Not just the fine pitch but also the fact that they are flexible to mesh and I am not totally sure about the inner workings, but I think they have one more tooth than the gears they mesh with, or vice versa. Incredible concept and I guess very difficult to machine such precision.

Edward

[johnsattuk]

Not just the fine pitch but also the fact that they are flexible to mesh and I am not totally sure about the inner workings, but I think they have one more tooth than the gears they mesh with, or vice versa. Incredible concept and I guess very difficult to machine such precision.

Edward

Need 2 teeth difference and because of the fine pitch, need a bit of care when reasemmbling as it is easy to be one tooth out, do not force.

[Robin Hewitt]

I have to get those headless screws out before I can reassemble.
M2.5 and darned close to the bendy cog. I don't have anything suitable to grab them with.
Any ideas?

[johnsattuk]

Have you tried two or three nuts locked together perhaps with heavy duty locktite retainer as well