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Faze4 Robotic arm

Faze4 is 3d printable 6 axis robotic arm . It uses stepper motors and 3d printed cycloidal reducers.

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This is still work in progress.All info about the project is on : https://github.com/PCrnjak/Faze4-Robotic-arm I have been building robot arms for around 7 years now. Every one better then next one , and this is my latest arm. It came to be when i made a working 3d printable cycloidal gearbox and saw some potential in it. After that i designed whole arm around it .It uses 6 stepper motors , 3 nema 23 , 2 nema 17 and 1 nema 14 . Joints 1-5 use planetary gearboxes and belts while joint 6 uses planetary gearbox. Joints 1 and 6 are homed on inductive sensors .All other joints are homed on limit switches. The arm was tested with costum code on stm32, but soon will switch to teensy and better software . Total cost of the arm is around 1000 -1500 dollars . It depends on component choices you make.

So the whole project started with cycloidal drives. Why cycloidal drives?

  • They are really easy to 3d print
  • can have large reduction ratio
  • cheap
  • low backlash even when 3d printed

When 3d printing them there are few things to keep in mind , but i might make video about that later.

They were all designed using this great tool , and them in solidworks. There are 3 versions of cycloidal drives in this arm 11:1 version , 15:1 version and 27:1 version.

Design of the arm.

Esthetic design was inspired by FANUC’s LR Mate 200iD. 

Goal was also to hide all wires in the arm like most industrial arms do. Only visible wires ( or pipes ) would be ones for gripper. 

Weight of the arm is around 14-15 kg , but it can be reduced by printing with less infill.

Motor position

Firstly i wanted to move all motors to the base of the arm to reduce weight each motor should carry. First idea was to just copy the design of this kuka arm. I decided against that design and just went with probably most basic design where every motor is directly on the joint of actuation ( Except for joint 5 that i moved a little bit away).T his is not good idea actually and if I was redesigning this arm I would try to move atleast joint 3 to the bottom of the arm, but what is done is done.

Joints 1,4 and 5 use belts in addition to cycloidal reducers. Belts are mostly used to offset the place where joint will be rotating so that we can route wires thru the body of robot. They also give some additional reduction ratio. For example Joint 1 has 15:1 cyclo but with belt our reduction ratio jumps to 25:1.


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  • 1
    assembly instructions of arm

    Whole instruction is in pdf file .

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Discussions

dekutree64 wrote 08/23/2019 at 15:36 point

Impressive!

Looking through the assembly guide, are you sure all those bearings on the cycloidal ring pins are necessary? I thought the disc shape was calculated to have rolling contact on cylindrical pins, so the bearings should theoretically never turn anyway. I've seen several other people use bearings on the pins too, but no explanation of why. Is it a different tooth profile than hypocycloidal, or just a way to compensate for inaccuracy in fabrication, or something else?

  Are you sure? yes | no

Petar Crnjak wrote 08/24/2019 at 11:35 point

They are necessary , i made few designes with 3d printed roller pins and they work but can get jammed and have more backlash. I only used bearing because they were cheap , better choice would be screw and metal sleeve ( like this : https://www.youtube.com/watch?v=yBckAoqNQx4) but i could not find suitable components.

  Are you sure? yes | no

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