Introduction: Electronic Wolverine Claws

By
About: Mechanical engineering student at Purdue University. 3D printing, robots, and various mechanisms.

My name is Aaed Musa; I'm 18 years old; from Jacksonville, Florida; and part of the high school graduating class of 2022. I'll be attending Purdue University as a first-year engineer in the fall. More specifically, I plan on pursuing Mechanical Engineering. Ever since I was a child, I have always been a huge Wolverine fan. The idea of retractable claws is so cool! My chances of becoming a mutant are pretty low so I'll have to resort to engineering for my powers. In this project, I'll show you how I made electronic wolverine claws. Whether you use it for cosplay or just for fun, I think this is a really simple and enjoyable build that can be done in a weekend. I also want to mention that I got this idea from Make Magazine.


To view all the files related to this project check out my GitHub repository

Supplies

Tools:

  • allen wrench for m3 screws
  • gorilla glue
  • soldering iron and solder
  • pliers
  • wire strippers
  • wire cutters
  • heat shrink tubing
  • electrical wire
  • dremel tool

Electronics

Other Material:

The total cost ≈ $80

For a more detailed breakdown of the bill of materials go here.

Step 1: 3D Print the Parts

First, we will need to 3D print 12 parts for this build. To download the parts, visit my Thingiverse Page.

If you own a 3D printer:

I used PLA to print all of the parts, but other filaments may work just as well. Total printing time was about 21 hours and total filament usage was about 246g.

  • 25% infill for all parts
  • auto-generated supports on all parts
  • 210º C extruder (for PLA)
  • 50º C heated bed (for PLA)
  • no rafts

If you don't own a 3D printer:

I would recommend getting the parts printed via a 3D printing service such as Shapeways

Wolverine Claws

Step 2: Glue the Knuckles On

Glue the three knuckles onto the areas shown in the image.

Step 3: Add the Threaded Inserts

Add 26 threaded inserts into 4 of the 3D printed parts shown. To add the inserts:

  • plug in a soldering iron
  • place the insert on the hole it needs to go into
  • push the insert with the heated soldering iron so that it is pressed into the plastic

This process is demonstrated in image#1.

Step 4: Assemble the Linkage

Let's now assemble the linkage

Image #1: Screw on 2 tie rods to both ends of the pushrod connector

Image #2: Take both servo horns and connect them in the placement shown using:

  • 2 x m3 by 8mm screw
  • 2 x m3 locknuts

(I found the holes on the servo horns quite small so I had to use a drill with a 1/8 bit to widen it)

Image #3: Connect one of the tie rod ends to the servo horn in the placement shown using

  • 1 x m3 by 12mm screw
  • 1 x m3 locknut

Image #4: Shave off the shown sides of the tie rods with a dremel tool. This is done so that the whole mechanism can slide easily. You want these sides to be completely flat. A before and after picture is further shown in image #5.

Image #6: Press an m3 locknut in the claw at the area shown.

Image #7: Screw the other tie rod to the claw using an m3 x 12mm screw

Step 5: Assemble the Case

Image #1: Using the two side connectors and 12 x m3 by 6mm screws, connect the front and back parts of the case.

Image #2: Insert the linkage assembly made in step 4 into the front part of the case.

Image #3: Screw the top-front part of the case onto the bottom part of the case to cover the claws.

Step 6: Upload the Program

Before connecting the Arduino nano to the other electronic components, let's upload the sketch. Download the Arduino sketch below and upload it to the Arduino Nano. No changes need to be made to the sketch.

Attachments

Step 7: Install the Electronics

Image #1: This is the complete circuit diagram. I have also added it as a pdf file below. Some important things:

  • make sure to connect the servo pwm pin to digital pin 3
  • make sure to connect one lead of the pushbutton to digital pin 6
  • it doesn't matter what lead of the push button connects to where
  • the 10k resistor connects ground to digital pin 6
  • the battery both powers the Arduino Nano and the servo in parallel

Image #2: Solder two wires to both leads of the SPST switch.

Image #3: Put the servo and switch into the areas shown.

Image #4: Solder two wires to both leads of the momentary pushbutton. Make sure the wire is about 14".

Image #5: Push the pushbutton into the wrist support. Screw on the nut that the push button comes with so that the pushbutton doesn't come out.

Image #6 and #7: Using the schematic, create the circuit and put the battery and Arduino Nano inside the back of the case.

Attachments

Step 8: Finishing the Case

Image #1: The servo horn needs to be screwed onto the servo, but the servo must first be moved to a known position. To do this, turn on the whole circuit by flipping the switch. This should move the servo to a certain position. After this, go ahead and screw the servo horn onto the servo with an m3 x 4mm screw while making sure that the servo claws are fully in the case.

Image #2: Screw on the back-top part of the case. Make sure the push button wires and the battery charging leads come out of the case as shown in images #3.

Image #4: Using 4 x m3 by 6mm screws Screw on the top-case connector to the top parts of the case.

Image #5: Using 4 x m3 by 20mm screws, attach the wrist support to the front of the case.

Step 9: Final Touches

Image #1: Remove the metal supports from the forearm wrist support.

Image #2 and #3: I decided to cut the wrist section of the support but I leave that to your discretion.

Image #4: Add two velcro straps to the bottom of the case. The case will attach to the forearm support that already has velcro to attach onto.

Step 10: Using the Claws

To use the claws:

  • Turn on the circuit by flipping the switch. The claws will automatically retract.
  • To extend the claws, press the momentary push button. To retract the claws, release the push button.
  • To have the claws extended permanently, hold the push button for a couple of seconds. To then retract the claws, press the push button again.

Step 11: A Note on the Design

I used Fusion 360 to design this project. My main goal was to make the project simple and sleek. A couple of notes on the design:

  • All components were designed in the CAD model (screws, nuts, battery, servo, Arduino, tie rods etc......)
  • I incorporated tolerances into all the parts so no sanding should be needed.
  • I based the design on the classic wolverine costume design and color scheme.
  • the claws extend to about 131mm (5.16")
  • this whole project can be printed with a quarter of a 1kg roll of filament
  • any medium-sized servo can work with this build
  • the wrist support may not fit everyone so you may want to modify the design
  • the whole thing case is about 11.75" long.
  • the case is composed of two hemispheres since my printer cannot print 11.75" long parts

If you would like to modify the design download the Fusion 360 file or the step file below.

Attachments

Step 12: Advancing This Project

If you would like to advance this project, I would recommend making it muscle-activated. As I mentioned before, I got this idea from Make Magazine. This original version used an EMG muscle sensor that allowed the claws to be activated by flexing your forearm. My claws use a switch. I would recommend taking a look at the Make Magazines article on how to make a muscle-activated wolverine claw and then adapting it to this design. Doing this would remove the need for a push button and would make the project more superhero-like.