How many degrees of rotation do you normally get from wide open to full close on a thumb without linkage, and installed on the main bucket pin? Thank you for your reply! Ronald!
Assuming it is a hydraulic thumb. It depends on the length of the hydraulic cylinder stroke. Also where and how the rod is attached to the thumb.
Tinkerer, usually, what is the average result ... in degrees?
I think mine is 150° give or take a few. It is on a tractor/ loader/ backhoe, but it would be the same on a mini ex I would think.
If you go with a progressive link you can get at or close to 180.
What it depends on is the length of the stick. The thumb cylinder on a direct connect can only extend to the working length of the barrel. A long barrel thumb cylinder on a short stick will hit the boom when curled under.
The three thumbs I have or had went around 150 I'd say. My big one is pin mounted with the bucket and still moves about the same as the boom mounted thumbs. I had a 12,000 excavator with a cheap thumb that I put a longer cylinder on and made greasable pins but still around the same movement. Just guessing that's about the max with a straight mounted cylinder.
John C just reminded me of an important part of the fabrication of a thumb mount. When I mounted mine I had to be very careful about the travel length of the rod stroke. If it had been too long the rod could hit the dipper when it was fully extended. That would cause the rod to be slightly to severely damaged. Moving the barrel mount further up the dipper will eliminate that problem.