Racing Spider

Flexapod (Servo-less Octapod)

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A playfully terrifying mechanical spider with a unique drive system

I built this for the challenge, I was inspired to improve upon the ideas that (former Mythbuster) Jamie Hyneman shared in his project videos from 2015. 

The key my version of his creepy crawly is what I'm calling a Flexapod mechanism. An Arrangement of cams, shafts and bearings that enables super radpid movement and adaptability over rough ground. Also it is quite capable of making people's skin crawl and squirm.

It uses 3D printing and off-the-shelf  RC parts: battery, bearings, motors, controllers, screws, bolts aswell as a few custom bits. All of which I will explain as I endeavour to share this project for those who want to build one of their own.

So if you keen to build it, let me know and I will help you where I can.


All the 3D printing STL's

x-zip-compressed - 4.54 MB - 02/13/2020 at 13:34


  • Assembly graphics

    Russell Munro2 days ago 0 comments

    These are graphics of the machines assembly and operation. 

    Exploded view of the tray and left hand side. The right hand side is a mirror copy. Not show in drive belt between motor pulley and inner camshaft pulley. 

    Exploded View of the "hip" sub-assembly. 8 of these are assembled first, 4 left orientation 4 right. 

    The cams working together to create a walking gait. Notice how the main cam (show here as see through) rotates on the same axis that the leg pivots up and down on. This is the key to the independant suspension of the legs.

  • BOM and STLs

    Russell Munro4 days ago 0 comments

    Let's start with the bill of materials and STLs. The instructions are coming in a series of posts in the near future. 
    Link to the BOM. Most of the parts are off the shelf or 3D print. 2 of the parts (x2) are custom made, the camshafts, I will explain these in a future instruction post. 
    Link to STL zip. The STL parts where designed to print on my Lulzbot Mini 6" with 0.5mm nozzle. Your results may vary so I recommend you print one of each part before printing all the parts, just in case you need to make some printing adjustments.  
    Print ‘Cam Lift’ and ‘Cam Main’ with strong or stiff material like nylon or PLA. All the other parts use I used ABS. Use whatever material you like but the Cams need to be a strong material because the bearing impart a lot of cutting stress. 
    ‘Gears’ and the ‘60 tooth pulley’ may need a 0.5mm print nozzle. This is because of the detail required in the teeth. I've never tried so print them on a nozzle bigger than 0.5mm. If you try a bigger nozzle please let me know how it turns out. 
    Don't print all the Tray files, choose the '12 inch printer' file if you have that size print bed. Used the other 3 files if you have smaller print bed. 
    Print all the parts in the XYZ orientation that they come in. This is to maximise component strength. Also, some parts will require support material.  
    Except for ‘60 tooth pulley’, print all the parts with maximum fill. Be careful that sometimes 100% fill can bulge a part. So, you might be better off with 90-95% fill. ‘60 tooth’ can happily live with 10% fill. 
    If you find any mistakes please let me know. Thanks for following. 

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Russell Munro wrote a day ago point

Thanks Dejan! 

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Dejan Ristic wrote a day ago point

VERY cool. As an extra bonus it has that uncanny valley creepyness of the Boston Dynamics robots. Will follow this project for sure.

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