Checkers the Seven Servo Robot Arm!




Introduction: Checkers the Seven Servo Robot Arm!

In this instructable I'm going to show you how to make a 7 servo robot arm. I will release the the CAD file soon, on the 18th of September. Also this instructable only shows you how to build  the physical arm, so please do email me with control method suggestions.  Oh and by the way this only the so no wrist+gripper but not to worry for an update will be out soon! And now as I promise d but about a month late. Drum roll. The CAD files. 

Step 1: /*Parts List*/

This is just the list of super important components, don't worry if its a it vague since at each step I will give a list of components needed to complete the step.

The List:
4mm thick 1x1m sheet of acrylic.
This product called plastic weld.
1m of M3 rod (the one that has the coil round it).
5 Modelcraft RS-2 junior servos.
2 ES-05 junior servos.
60 M3 nut and washers + 5 nylock nuts.
4 M3x35mm bolts.
8 M3 butterfly bolts.
2 M3x20mm bolts.
2 springs that I wil show later.
Lots an I mean lots of 2x10mm screws.
10 servo lead extenders (optional).

Step 2: /*The Base*/

The Base is the part that the arm will sit on.
  /*Parts Needed*/
The three big circular pieces you've cut
5 M3 nylock nuts 
9 M3 nuts + washers 
1 modelcraft RS-2 junior servo
4 M3x35 mm bolts
5 pieces of M3 rod cut to size 
4 2x10mm screws
The tiny black screw that came with the servo

Step A of base:

With the the 4 M3x35mm bolts and 4 nuts + washers, the servo to the circular piece with the larger hole in the centre.

Step B of Base:

With the product of step A finished, now with the 5 pieces of M3 rod (cut to length), 5 M3 nylock nuts and 5 m3 nuts+washers bolt the product of step A to the circular piece with the four sticky out bits on it (see picture), to construct the majority of the base.

Step C of Base:

Use 4 2x10mm screws to screw the black cross thing that came with the servo onto the last circular piece.

Step D of Base:

Using the tiny black screw that came with the servo, screw the product of part C to the combine product of parts A and B.

Step 3: /*The "Feet"*/

The parts needed:

2 RS-2 servos 
2 of the acrylic piece shown in the picture
8 M3x20mm bolts
3 M3 butterfly nuts
5 M3 nuts+washers

Step A of feet:

Bolt on the acrylic piece to the servo, make sure that the servo is underneath the acrylic. See pictures for detail.

Step B of Feet:

Repeat step A but with a slight change to the butterfly nut configuration that is shown in more detail in the picture.

Step 4: /*Lollipops*/

All of this step can be done by looking at the pictures.

Step A of Lollipops (i):

Screw the servo mount plates to the ends of the lollipop shaped pieces as shown in the picture.

Step B of lollipops (i):

Cut off the sticky out bits of the servo mount plates if you have any.

Step C of Lollipops (ii):

Screw the second mount plate in, take note of all the pictures or you risk doing it wrong.

Step 5: /*The Fore Arm*/

You will need:
The acrylic pieces in the picture
8 M3x20 bolts 
16 M3 nuts+washers 
2 pieces of M3 rod (cut to size)
2 RS-2 servos
1/2 a pound of patience 

Step A of Fore Arm:

Bolt both servos as shown in the picture to either of the acrylic pieces, it doesn't matter which. What matters is to get them facing the same direction.

Step B of Fore Arm:

This isn't easy. Get the other piece of acrylic and force it onto both servos that are bolted onto the first piece of acrylic, Past where the cables come out of the servo, loosen/unbolt the servos if it helps.

Step C of Fore Arm:

Once step B is done you should see that second piece of acrylic is unable to slip away from the servos but at the same time able to move and jiggle about within its boundaries.  To prevent this use the two pieces of M3 rod (cut to size) and eight nut+washers (2 on the inside 2 on the outside) to fix the second acrylic piece see pictures for examples.

Now if done correctly it should look like in the first picture. 

Step 6: /*Connecting the Lollipops to the Feet*/

Parts Needed:

Both of the feet you previously made 
Both of the parts you made whilst following the lollipops steps
2 little screws that came with the RS-2 servos 

Step A

Look at the pictures as reference as to where the maximum backward-ness is and then just screw in.
Its really quite easy ;). 

Step 7: /*Feet+Lollipops to Fore-arm*/

Parts needed: 
The feet+lollipops
Fore Arm

Steps A:

Watch Video

The Video

Step 8: Your Done

You finished the arm. Soon there will be an update showing you how to make the wrist + gripper

3rd Annual Make It Stick Contest

Participated in the
3rd Annual Make It Stick Contest

Hurricane Lasers Contest

Participated in the
Hurricane Lasers Contest

Hack It! Contest

Participated in the
Hack It! Contest

1 Person Made This Project!


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14 Discussions


3 years ago

Can u upload the code for running this or can email me at


4 years ago

can anyone send me the PDF?


5 years ago on Introduction

Can u send pdf for me


5 years ago on Introduction

really awesome robotic arm! i'm in the process of building one, almost done with the electrical part of it, so this instructable came in just in time for some ideas. i have a problem tho. when i click on the cad file, it just opens a link and there's a really long list of stuff with some numbers. how am i supposed to open it??


6 years ago on Introduction

Hello! I have a doubt about the assembly, how did you glued the 2 bottom servos to the base? with what kind of glue?

Thanks and great tutorial!


Reply 7 years ago on Introduction

they are cheap and I am lazy.


7 years ago on Introduction

Nice project. I love the look of the acrylic. I built the same thing about two months ago from hardboard based on the original design by jjshortcut which can be found here:

Can't wait to see the rest of your build and the programming!


Reply 7 years ago on Introduction

The CAD file is a slight variation of jj shortcut's I will publish it soon.

wow, can you post a video of this thing in action? I'd love to see how it moves!