Originally Posted by mlbco

I've had success building gearboxes from 1/8" plywood and gears mostly from Stockdrive products.
http://shop.sdp-si.com/catalog/?cid=p305
I use 32P gears and the motor has a spur gear with 1/8" shaft size that fits many brushless motors.

The bearing seats are just holes in the plywood and could be reinforced with a carbon layer glued to the plywood.

The crank arms are cut from an aluminum block using a bandsaw. Holes are made with a drill press.

These units are heavier than carbon plate versions with plastic gears, but my models are designed to be heavier so I'd rather have a robust gear drive than a lightweight fragile one.

Steve

Why not Steve ,
Horst Rabiger have made way more complicated gearboxes using plywood . Plywood is easy to work with espetially when making everithing by hand tools .
You still have a lot of room to make it more nerower and respectively light . I will draw a sketch for you .

This way you can achieve much beter aerodinamic quality because everithing is inside the fuselage including springs and conrods . Springs are stretched by strings which are pulled by pulleys mounted firmly to spar holders .This way pull force on the springs is more even thru the stroke . By profiling the pulleys ( making them other than round and center coaxial)the spring force can be modulated .

Flapping mechanism for full size ornithopter made by Mr Harris for DeLaurier ( University of Toronto engine powered )Ornithopter

Originally Posted by ZTEX

CF for the main gear shaft wouldent last long ,it develope micro cracks on some point delaminates and fail( the same as wing spars ) .

Are you suggesting not to use CF for the wing spars? I was planning to do so since this is what many popular models use. If not CF, what material would you suggest? Also I don't have a clear idea how to design the joints where the spar meets the flapping mechanism - the ferrules. Just any aluminum or ABS ferrule? Does the length matter? How should the spar be fixed, with a set screw? I have seen nested ferrules, but I am not sure why people do that. Any recommendations to minimize the risk of spars breaking?

Originally Posted by Jenzinger

Are you suggesting not to use CF for the wing spars? I was planning to do so since this is what many popular models use. If not CF, what material would you suggest? Also I don't have a clear idea how to design the joints where the spar meets the flapping mechanism - the ferrules. Just any aluminum or ABS ferrule? Does the length matter? How should the spar be fixed, with a set screw? I have seen nested ferrules, but I am not sure why people do that. Any recommendations to minimize the risk of spars breaking?

No ,for spars CF is OK , the perfect spar would be tapered CF rod ( poltruded ) or tube( but not poltruded , will crack and fail) . Also the spar can be made by few pieces with different diameters (4.3,2 mm ) For shafts CF isn't good idea and espetially when the CF shaft must to transmit torque , using set screws for fixing the gears to the CF shafts is unacceptable ( you already introduce the faluare points on the shafts this way ).
For the high performance sports cars CF Drive Shafts are used but there spetiall method for winding the threads are used and the shaft forks are glued to the CF tube .

Steel Shaft Vs Carbon Fiber Shaft (5 min 32 sec)

The best design for those ferrules is similar to the clevis design but with one more hole for the pivot point .
Will make a sketch for you later . https://www.ebay.com/p/2-Brake-Throt...769a2affe03744
The length , longer is better ( usually the spars broke at the point where they come out of the ferrules ) so probably long ABS tapered ferule will be beter ( the flexibility of the material and the taper will help as well for the longevity of the spars ) .
If the ferules are made from aluminum then at least you have to round the edge of the ferules holes where the spars come out of the ferules . The best way to conect spars to ferules is the spars to be pressed in to ferules holes and / or to be glued to them. The problem is that such a solutions are more dificult for repairs in case of faluare .
Using set screws for fixing spars to ferules isn't good idea as well and because of the reason which I already explained .

Wing Gear Linkage (0 min 31 sec)

Hi,
from the university Delf in the Netherlands , a very agile insect inspirated flapper.

DelFly Nimble - an agile insect-inspired robot (1 min 34 sec)

.

Happy Amps Christian

Originally Posted by Christian Lucas

Hi,
from the university Delf in the Netherlands , a very agile insect inspirated flapper.
https://youtu.be/CEhu-FePBC0 .

Happy Amps Christian

Thanks Christian , it’s already here https://www.rcgroups.com/forums/show...&postcount=170
Flapping mechanisms are from 20 $ I bird pigeon from eBay or Amazon. The ingenious thing is the way this enthomopter is controlled .
Independent flapping frequencies on left / right wings pairs , variable anhedral/dihedral and differential variable angle of attack on both wings .