Which Low RPM Gear Motor?

I am working on a robot that will have a grabbing claw, of sorts, and I'm not sure what gear motors to use to actuate the claw.  It needs to have significant gripping power, so the gear motor must be low-RPM and high torque.  The two best options I have found so far are these:

1. 12VDC Gear Motor, 7 Rpm 2-7/16" x 1-5/16" Dia.
2.  Tamiya 70110 4-Speed Crank-Axle Gearbox Kit 

 
If I used the Tamiya gearbox, I would also have to buy higher voltage motors, so the cost of the two is approximately equal.  Because of its layout, I think the Tamiya would be easier to use, but I'm worried about stripping the plastic gears.  Also, I have a smaller Tamiya gearbox, and the axle has some play in it and is extremely noisy.


The 12V gear motor, on the other hand, appears to be more robust and probably has metal internal gears, but it would make my robot a bit larger.

Does anyone have experience with Tamiya gearboxes?  How do they handle high loads?  If anyone has any input on these two choices, or other motors you think would be even better, I'd really appreciate the help.  Thanks!

Kiteman6 years ago
"Probably" has metal gears? You'd best check that first.
ben_k (author)  Kiteman6 years ago
I can't find anything that explicitly says that they are metal. I have done some sleuthing, and found these, which are metal:

http://www.pololu.com/catalog/category/116

The 37mm above motors are made by a company that makes 33mm gear motors like the 7 RPM one in my original post. If the 37mm ones are metal, then the 33mm ones are also probably metal.

http://www.igusa.com/pages/gearmotors.html