Mechanical versus hydraulic thumb kind of depends on what you want to do with the backhoe. If you mostly want the ability to clamp on to something to move it to a new location then the mechanical one will be fine. If you see yourself picking up something - like a rock - so that you can place it carefully into position on top of a rock wall then that is better done with the hydraulic thumb.
I use the hydraulic thumb a lot because I do a lot of picking and placing rocks and logs for rock & log walls, to make neat edges or boundaries, or place rocks to walk on or for kids to climb on. It's kind of hard to explain the advantage of the hydraulic without actually showing it in motion...., but basically by using the hydraulic thumb I can keep pressure on the rock so that it is being held as the bucket uncurls. By holding onto the rock as I uncurl the bucket I gain another several eet of distance. And as the bucket uncurls, the side of the rock that was facing the operator when we transported the rock now becomes the bottom, so it is easy to place the rock exactly into position on top of others.
It's easier to go from a mechanical to a hydraulic thumb than from no thumb at all to a mechanical one, so if you want to break the project into two parts that makes sense.
What doesn't make sense is that backhoes should have the fittings for a thumb as part of the dipper stick. It would be a minor matter to make add thumb attachment points when the dipper is manufactured.
At one point, Amulet Bucket Accessories made a "Hoe Clamp" thumb that was connected to the bucket pivot by a system of links and levers so that curling the bucket cause the bucket thumb to move toward the bucket with a powerful clamping motion - all powered by the movement of the bucket itself. So as the bucket curled, the thumb moved to clamp the load.
Maybe some clever guy will market a version of that design for our Kubota TLBs.
rScotty
