I have just signed up to this forum. I have about 11 servos around from my RC plane days. I want to use what I have to design a 5 DOF arm, it doesn't need to lift a huge amount of load, and the servos i have, do not have a particularly high torque. This is what I have:
4 x JR NES-511 3500g p/cm 0.24sec p/60
4 x Futaba FP-S148 3024g p/cm 0.22sec/60
3 Hitec HS-300A 3500g p/cm @ 6v 0.19sec/60°
Don't have much other information, the specifications I assume are reasonably accurate. I also have an Arduino duemilnove which I will use as the controller.
As this is my first project I essentially want to copy a design from a small commercial hobby arm. this is the one I was looking at: http://www.crustcrawler.com/products/arm6.php?prod=11
I have drawn up an FBD based on the information from their Web site:http://i210.photobucket.com/albums/bb176/Mingzhus/FBD.gif
I chose this one because it has a great detailed assembly manual online, which will be a great help in designing.
Obviously my servos are not as strong. What modifications would you recommend to the design? Could I for example use 2 servos for the bicep. is it possible to add gears ( externally to the servo) in order to get more torque at a reduced speed? I used the robot arm calculator, I doubt mine would be able to lift much more than 100g, but I guess that's okay for experimenting with. I think the crust crawler arm uses 2mm thick aluminium sheet, perhaps I should go with something lighter like 1.5mm. I have a mill & lathe so building is not a problem. I'm going to design in solidworks, if I can work out how to stress test assemblies Rather than just individual parts. I am definitely no engineer, I just like to mess with various software
I look forward to hearing from you.