Next is the articulated version of my Gen 2 thumb.
For this project, I actually made a full scale mockup out of OSB, so
I could plan the links and the extent of the articulation. Also, I had
to use the existing 25mm pivot at the lower end of the curl cylinder.
This sounds easy, but I needed an extra-long 25mm pin drilled for
grease and a way to drill a 25mm hole in the new link. Also, pin
rotation must be restricted, so a special pin had to be made. Links
are 3/8" x 1.5".
I took a 10 second video with my Nikon, but the file size is 3.2 MB.
I have dialup, so I can not post. Even 5 sec would be 1.6MB. Instead,
I am posting 4 series pix of the thumb articulating. I shortened up
my Gen 2 a bit so it clears the main boom by an inch at full open.
In use I find that I can switch from digging to grabbing very easily
without having to adjust or remove the thumb. Sweet.
Next modification will be to try a slave
hyd cylinder, connected in
parallel to the curl cylinder. That may work even better than the
this method.