Custom Printed Worm Gear Offers New Dimension in Lego Motion

You're probably thinking "a worm gear...big deal". Well actually you're right, it is a big deal. It offers a means of providing well defined and finite motion in Lego builds all wrapped up in a very small package. Better yet, if you have access to a decent 3D printer the cost of printing all you could ever need is truly negligible.

Step 1: The Serendipity Moment

The serendipity moment came with the realization the commonly available miniature N20 gear motors fit easily but snugly into the side of the Lego worm gear blocks and stay put with no additional mounting hardware. This made for a very simple plug and play method of creating motion with the Lego gears. Problem was that the D shaped shaft of the motor would not interface with the cross shaped opening of the worm gear. Sure you could drill out the Lego worm gear and glue the motor into place but that kind of defeats the plug and play potential the system offers. So time to put modern 3D printing to use and create a worm gear with a D-shaped input.

Step 2: Uses

The model shown above which includes a 100 RPM motor, a low voltage PWM generator and a 9V power supply probably represents the worst possible use of this concept as all it created was the world's slowest dune buggy but sadly that's about the extent of my remaining Lego collection. The intended use however was propelling a time lapse camera slider but as of this writing is still awaiting parts coming snail mail.

The reality is however that with motors available anywhere from 10 to 300 rpm this concept offers opportunities in a vast array of projects anywhere from robot armatures to steam shovel models as the motors are easily reversible and the main gear stays put where the worm gear stops. And with the N20 gear motors generally available in the $3-$5 range and coming in a wide variety of speeds combined with easy swapability, this concept offers a wide range of potential very inexpensively.

If you've already got a use in mind, please leave a comment and let us know what you envision.

Thank you for giving my instructable a moment of your time.

'tsallgood

Comments

[MakerStudioNZ]

the file doesnt works with tinekrcad, there is big gaps between the the thread and the cross axle column. btw, how do you print this small size object, esp with thread with your 3d printer. i had a try yesterday, without support, the part is totally a failure without any accuracy. but if i add on support, it will be hard to take the support out. any suggestion?

[tsallgood]

Sorry but I can't offer any help. My 3d printer was (and still is) garbage so I sent this out to one of the bigger printing services and had it done in resin.

[MakerStudioNZ]

no worry, just curious what 3d printing method did the 3rd party use. I use my fdm printer,it totoaly sucks, from your photo, it looks more like SLS (laser sintering technolog), can you confirm that? Thx mate

[tsallgood]

Yes, the grey one is SLS plastic and the white ones are polyjet resin.

[ByronW13]

Attracted to this site because of "custom printed" although you are talking about Legos. I'm interested in sizing up to add worm gears to a pontoon boat steering wheel column and throttle control (for a Minn Kota eDrive motor) and electric motors to be controlled by a handheld RC unit so I can be elsewhere on the boat. There's a third channel on some of the cheaper controllers so I guess it would be about mandatory to have a man-overboard emergency stop as well but that's an electrical not a worm gear issue.

The gear would have to be printed in at least 2 sectors to be bolted around the steering shaft, and the 200 degree turn throttle lever base. Very little turning force is required to turn the steering wheel and throttle/speed control on this boat. The worm would be attached to an appropriate DC electric motor. Spring mounting would snap the worm and motor out of the way for strictly manual control of the helm. I might add full autopilot control later through OpenPlotter/Raspberry Pi later.

[williamjt]

Nice!

[zposner]

Cool, i used to love hacking legos.