Hexagon shaped pieces elevator

Hi guys, I need to make some kind of gripper to elevate some heavy sutff (750g at max), hexagon shaped chunks of wood. I plan on using some Nema 17 motors which I already have, but idk which gripper design should I use. I already tried a 5:1 gearbox with a simple as hell gripper design, just two sticks with their respective helical gears, not enough power, the motor skips steps...

What gripper design would be ideal to have a ton of torque for those heavy wood chunks??

I'd use claws that fully encompass the pieces. Then you can lock the gripper and move the load around.

Stepper motors are available with various torque, Nema 17 may be a bit small for your load. I also would use a DC motor or powerful servo for more torque, not a stepper. The DC motor can be powered until it stalls, with high current or some other feedback for turning it off. Torque is primarily a matter of the gear transmission ratio.

If the jaws are smooth it may help to add some texture in the form of bumps or pointy things like the tips of screws or nails.  Think carpet tack strips.

Thanks for the answers, yes, they have a smooth surface so I might be using some 3d printer belt for the adhesion... Do you think using some pointy things would be better??

Talking about the gripping method, I've tested using a parallel grip with a Nema 17 and a lead screw from a 3d printer, I need to make an aligment mechanism but overall seems the way to go, the problem is that the sticks tends to bend at the end due to the force applied by the motor. Which encompassing nechanism do you mean? like making the grip with a hexagon shape?

If you can locate some, rough top conveyor belt material would make a good grip surface.

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Time to experiment.