My wife has a tiny orchard in our front garden, four fruit trees on dwarf stock. This year the espaliered pear tree has got a bit out of hand and has produced pears that are too high for us to reach and too far away to reach from a step ladder. In fact some are actually outside of our garden! The tree should really be 2D but it has gone a bit 3D on us.
So RepRap to the rescue, I made a device to cut pears at a distance and another device to catch them.
The cutter is based on a hook shaped Stanley knife blade No 1996. I made a sliding carrier for it with a hole to attach a string and a peg to take a spring.
This fits inside a casing with a tube to mount it on the end of a 16mm OD pipe. A spring keeps the blade extended. A string is pulled to retract it to cut the stem of the pear.
This drawing shows how the parts fit together inside.
There is a rib in the top that prevents the blade from lifting over its locating bumps. The casing was made upside down and makes heavy use of bridge spanning to avoid the need for support material.
As a mechanism it worked well, but useless for cutting pears as I completely underestimated how tough a pear stalk is. So onto plan B, a pair of secateurs clamped to a pole, with a piece of string threaded through an eye to pull them closed: -
The handle of the secateurs is a horrible shape for making something to mate with it because its surfaces are irregular curves (not arcs or ellipses) in two dimensions. Very difficult to model without a 3D scanner. I made use of a channel in the back to be able to grab it with simple flat parts.
This version works well, with a handle to make the other end of the string easy to pull: -
A cup mounted on a second tubular pole catches the pear.
It is a two person job to use both at the same time. A better design would be to mount both tools on the same pole somehow. A better catcher could be made by a plastic bag sandwiched between two circular hoops of plastic to hold the top open.
Here it is in use: -
The only design issue is that it is hard to see where the jaws of the secateurs are when looking along the length of the pole. Mounting the pole at an angle to the clamp would solve that.
Here are the extra out of reach pears that we cropped with the contraption.
The files are available on Thingiverse.