Spider Robot With Chopstick Legs — Electronics | Make:

By OddBot
Time Required: 3-4 days

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Multi-limbed robots such as hexapods can be very complex and expensive. This is a relatively cheap and simple 8-legged robot made with chopsticks, Polymorph and an Arduino-compatible controller. Most of the servos cost under $8 if you shop around. I have seen the 12Kg/cm servos for as little as $13 at HobbyKing.

The construction is pretty easy but takes time as you often have to hold parts in position and wait for the Polymorph to cool. Patience is definitely a virtue. Cold weather will speed things up.

[youtube http://www.youtube.com/watch?v=d8_UKJKeZEI?wmode=opaque&w=560&h=315]

This project will show you how to make an 8-legged spider robot. As you need 3 servos for each leg the servos are the most expensive component. You can make fewer legs for a quadruped or hexapod if you wish to save money.

I used two pan/tilt kits fitted with IR compound eyes for close-range object tracking. These are relatively cheap and give your robot the ability to play with people which adds a lot to its personality. See the videos below.

[youtube http://www.youtube.com/watch?v=n92P7Cw3O7o?wmode=opaque&w=560&h=315]

[youtube http://www.youtube.com/watch?v=7hG6Amnb9Mo?wmode=opaque&w=560&h=315]

[youtube http://www.youtube.com/watch?v=Kd8g4NVy4gY?wmode=opaque&w=560&h=315]

[youtube http://www.youtube.com/watch?v=IfFbjXP8vd0?wmode=opaque&w=560&h=315]

December 18, 2012, 10:42 pm PST

Parts
/
Tools

Parts

Polymorph, granules (500)
Pan / Tilt kit, Dagu brand (includes miniature servos) (2)
disposable Chopsticks, Bamboo (20)
7.2V / 7.4V Rechargeable battery pack, 4500mAH or better (1)
Cable ties, heavy duty 200mm long (4)
High current switch, 20A or better (1)
self tapping screws, 2.3mm x 12mm (20)
self tapping screws, Small pan head 2 x 8mm (50)
Spider controller with HD servo shield (1)
Cable ties, light duty, 100mm long (24)
12Kg/cm servo, 7.2V with metal gears (8)
5Kg/cm servo, 7.2V if possible (16)
self tapping screws, Small pan head 2 x 6mm (200)
Fuse or circuit breaker, 15A (1)

Tools

#1 Phillips Screwdriver
Kettle
Side cutters
metal skewer or piece of thick wire

Steps

Step #1: Prepare your workspace.

NextPrev

A glass-top table is best when using Polymorph. You need a flat workspace that the Polymorph won't stick to. If you have a wood table then keep the top wet or put a sheet of glass on top.
You will need a rag, a constant supply of hot water, a bowl for the hot water (not plastic as the Polymorph may bond to it) and a cup of cold water (ice will speed things up) for cooling the Polymorph. Coffee is optional. :)
When you dip hot Polymorph in cold water for a few seconds the outside will cool rapidly forming a milky, flexible skin. This will prevent the Polymorph from bonding to your servos. The exact amount of time required will depend on how hot your Polymorph is and how cold the water is. A slightly milky appearance is your best indicator.
For each leg segment I used a 230mm chopstick cut in half, each segment being about 115mm in length. Cut 16 chopsticks in half with the side cutters now so they are on hand when the Polymorph is hot.
I have used pan-head self-tapping screws for this project. Polymorph is perfect for self-tapping screws and the pan heads eliminate the need for washers.

Conclusion

This project shows a relatively easy and low-cost approach to building robots. The combination of Polymorph and chopsticks will allow fairly complex robot chassis to be constructed that are strong, lightweight and low in cost.

OddBot

5 Responses to “Chopsticks” the Spider Robot

NPD on August 9th, 2013 at 9:58 am said:

I’m very up to the challenge of making this, but (from a person with very limited experience), the parts list seem so unspecific. It takes me a bit to find each, and often from different stores online – and some bits, e.g. the 5kg/cm servo I just can’t seem to find.

While I suppose you probably don’t feel you want to point people to specific brands and shops, why not specify the actual makers of the parts, so it all would be a bit easier to find for me and others?

Otherwise, great job – I love that robot!
Daen de Leon on August 27th, 2014 at 8:10 pm said:

Are the eight 12kg/cm servos for the hip joints, and the sixteen 5kg/cm servos for “thigh” and knee joints?
Wayne Kinne on December 16th, 2014 at 10:01 am said:

I am building a Hex-A-Pod with three servo’s per leg, this electronics and control look perfect to borg in! I am printing it all on the parts on my 3D printer. Is this OddBot covered anywhere else?
- Andrew Terranova on December 16th, 2014 at 3:29 pm said:
  
  OddBot is a long time member of http://letsmakerobots.com. You will find lots of great stuff from him and many others at the LMR website.
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