I think I may have come up with a way to get rid of the spring. It means adding another piece to the arm. I'm not convinced this is a good idea. My test showed it performing well on the lift, but poorly on the drop. This would probably be helped by gravity on the toolhead.
I also can't tell how much force can be exerted at either end, though the force in the middle of the range should be decent.
The url=https://www.youtube.com/watch?v=VVecj6CaC3s]idea[/url] is to add what amounts to a linear actuator between the two arms.
I think it would perform better on the drop if it had a decently powered motor, not this puny meccano motor.
I also can't tell how much force can be exerted at either end, though the force in the middle of the range should be decent.
The url=https://www.youtube.com/watch?v=VVecj6CaC3s]idea[/url] is to add what amounts to a linear actuator between the two arms.
I think it would perform better on the drop if it had a decently powered motor, not this puny meccano motor.