Arm Construction

From Lofaro Lab Wiki
Revision as of 06:08, 11 May 2016 by Agoldsto (Talk | contribs)

Jump to: navigation, search

Required Parts

All parts for the Arm are Machined. The Arm is broken down into three major parts: the wrist, the forearm, and the upper arm. The required parts per arm are shown below:

Wrist

Machined Parts:

1x AX-12A Holster 1x Wrist

Additional Parts:

1x AX-12A Servo 1x MX-28T Servo 1x HN07-N101 Servo Horn

12x 2mm x 9mm machine screws 4x 4mm x 5mm machine screws 1x 4mm x 8mm machine screw 8x 2mm x 3mm machine screw 1x 3mm x 8mm machine screw 4x 4mm nuts


Forearm

Machined Parts:

1x Wrist Rotator 1x Lower Arm 1x MX-64T Servo Holster 1x Lower Arm Brace Front 1x Lower Arm Brace Back

Additional Parts:

1x MX-64T Servo 1x MX-106T Servo 2x HN05-102 Servo Horns

10x 2.5mm x 9mm machine screws 16x 2.5mm x 6mm machine screws 18x 4mm x 8mm machine screws 2x 3mm x 8mm machine screws 18 4mm nuts


Upper Arm

Machined Parts:

1x Rotating Upper Arm 1x Rotating Upper Arm Brace Front 1x Rotating Upper Arm Brace 1x Upper Arm 1x Upper Arm Brace

Additional Parts:

1x MX-106T Servo 3x HN05-101 Servo Horns

24x 2.5mm x 6mm machine screws 16x 4mm x 8mm machine screws 10x 2.5mm x 9mm machine screws 1x 3mm x 8mm machine screw 16x 4mm nuts


Wrist Construction

1. In all steps for the arm we attach the servo horn first before we mount the servo. The servo horn is attached to the wrist using 2.5mm x 6mm machine screws as shown in the figure below.

2. We then attach the wrist piece to the AX-12A servo holster using 4 4mm x 5mm machine screws with nuts securing them from the wrist piece.

3. After the wrist has been attached to the AX-12A servo holster we then attach the MX-28T servo to its horn and secure it using the 3mm x 8mm machine screw.


Wrist Assembly step 1.PNG Wrist assembly step 1 top view.PNG Wrist assembly step 1 side view.PNG


4. Next we mount the AX-12A servo into its holster and secure it using 2mm x 9mm machine screws as shown in the images below


Wrist assembly step 2.PNGWrist assembly step 2 side view.PNG


5. This completes the wrist piece. The Left wrist piece is constructed the same way but mirrored. Analyze the picture below to find what slight adjustments need to be made.


Right Wrist.PNG


Forearm Construction

1. First we place the MX-64T in the groove of the lower arm as shown in the picture below. We then mount it from below using 4 2.5mm x 9mm machine screws.

2. Next we place the MX-64T Servo Holster inside the lower arm and align it the proper holes on each side. The holster should be snug against the top of the servo with the raised part of the servo perfectly fitting through the hole in the holster. See pictures for details. We then use 6 2.5mm x 9mm machine screws to mount the holster to the top of the servo and place 2 4mm x 8mm screws in the MIDDLE holes to secure the MX-64T holster to the lower arm.

3. Now we mount the servo horn to the wrist rotator using 8 2.5mm x 6mm machine screws. Once secure we then attach the horn to the MX-64T servo and secure it using a 3mm x 8mm machine screw.


Forearm step 1.PNG Forearm step 1 side view.PNG Forearm step 1 top view.PNG


If assembled properly the top of the MX-64 Holster should look exactly like the image below. Make sure it is assembled properly before continuing as it will be hard to fix later on.


Forearm step 1 inside.PNG


4. Now we attach the lower arm brace front and lower arm brace as shown in the picture below. Be certain the orientation is correct, its extremely important that the front brace be attached facing the top of the MX-64 servo or else you cannot obtain full dexterity with the elbow. Both braces are attached using 8 4mm x 8mm screws each. They are attached with nuts internally for both aesthetic and safety purposes. However this makes it very hard to attached the nuts. I recommend securing the entirety of one brace first, and then for the other one start going bottom up. Secure both screws at the bottom before continuing upwards on either side. This will leave you enough room to use a tool to hold the nut in place while you screw in the screw from the outside.

5. Lastly we attached the servo horn to the top of the lower arm using the 8 2.5mm x 6mm screws and secure the servo to the horn using the 3mm x 8mm screw as shown below.


Forearm step 2.PNG


Below is an image of a properly constructed right forearm. The forearms can both be the same, it does not effect functionality. However a piece called 'left lower arm' has been provided in order to create a mirrored left arm for aesthetic purposes. Using the left lower arm piece the assembly is completed the exact same way. The only difference is the left lower arm is constructed to have the 106-T servo mount on the opposite side, thus mirroring the right configuration.


Right Forearm.PNG


Upper Arm Construction

1. First we place the MX-106T servo in the groove of the upper arm and secure it from below using four 2.5mm x 9mm machine screws, similarly to step 1 for the lower arm.

2. Next we add the upper arm brace and slide it snug between the branches of the upper arm and flush on the back of the 106T servo. We then use 6 more 2.5mm x 9mm screws to secure the upper arm brace to the 106T servo as well as use four 4mm x 8mm machine screws to secure attach the brace to the upper arm. Nuts are used to secure the screws as shown in the picture below.

3. After the servo is secure we attach the two servo horns to the arm using the 8 2.5mm x 6mm screws. We note that the shoulder construction and design is yet to be completed and these horns are not present in our current testing prototype.


Upper arm step 1.PNG


4.