[Help] Cannot get Akiyukys' pneumatic GBC module to work properly

[NoEinstein]

Currently I am trying to build a pneumatic GBC module based on the videos of

and

.

Somehow I keep having issues with a full 180 degrees turn. When not attached to the base, the turntable turns a full 180 degrees (like in the final part of Akiyuky his video). Once attached to the base my grabber does not turn fully, but only about 150-160 degrees. This way my version will not grab new balls but crash horribly due to not being aligned properly. Somehow the pneumatic piston does not push the turntable enough when fully extended. The only way it works ‘properly’ is when I operate the pneumatic pump as a madman so the swing speed turns the grabber fully but it should not have to operate on insane speed as shown in both linked videos.

It might be that the module is not properly balanced but I copied most from Akiyuky and analyzed Michael Speelgoeds’ one too and they seem to work fine, although I must admit that the use of all the black pieces make it hard to see every detail so I might have missed something.

Another reason might be the friction between the gear rack 1x13 and the outside of the module. As shown in the LDD file I made, there is a lot of free space between the gear rack and the outside of the module (all marked lime green) so I originally had a half bush on the lime green peg with cross axle closest to the grabbing arm so the gear rack would not ‘jump’ over the 16 tooth gear. LDD does not accept a half bush, due to not having enough free space which made me think maybe it gave too much friction. I removed it and pressed the lever 3M tight against the gear rack, but it does not stick so after a while the rack starts to slip on the 16 tooth gear. More importantly the grabber still will not turn a full 180 degrees.

I am currently at a complete loss on what I can try next and was hoping someone had some pointers.

[hknssn]

Have you tried to replace the 16 tooth gear with a 12 tooth gear? It will be a better fit for the gear rack and it migh solve the 180 degree problem since it should increase the turn movement.

[NoEinstein]

Thanks a lot for the suggestion hknssn.

I used it in my first version but could not get the gripper to work correctly then. I just tried it again on my current (third) version and everything seems to work fine. The only thing is that because of the larger turn it can make and therefore is stopped "early", the whole module (including base) is now turning on my glass table due to the impact on the L stopper. This is using the big hand pump, with the small motorized pump it works like a charm.

Akiyuki and Michael Speelgoed use the 16 tooth which theoretically (and for them practically) can make an exact 180 degrees turn with a pneumatic piston. I am not sure how much additional stress is put on the turn stopper but time will tell.

For anyone using my LDD with hknssns' solution, compensate the pneumatic piston position so the turntable turns 1 more teeth when the stopper L is removed in either direction.

It works like a charm so thanks again.