Firky2010

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LEGO Facts

  • LEGO is an abbreviation of the two Danish words "leg godt", meaning "play well"
  • During the moulding process, the plastic is heated to 232°C until its consistency is that of dough
  • In 2003 LEGO  changed the minifigure's yellow facial colouring to a more authentic skin colour
  • In 2006 the LEGO  website had an average of 8,137,062 individual visitors a month
  • If you built a column of about 40,000,000,000 LEGO bricks, it would reach the moon

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845days since
Project Launch

360 Degree Wrist


After I had finished my grab I needed a good wrist to give the grab as much freedom as possible. After hours of looking all over the internet I again found a brilliant idea on youtube, as shown in the video below. This wrist gave me everything I was looking for so I built it. As soon as it was built I spotted numerous flaws in that particular design but the basis was there. This design allows for the freedom I was looking for with 360 degree rotation, and the 180 degrees of movement up and down or left to right, depending on the position of the wrist. The wrist's horizontal axis was weak and unable to support any real weight so I fine tuned this design until I was happy, although it took a while to eliminate the problems.


In the video of the Arm below you can see that I have slimed down the wrist by only using 4 Lego lift arms in stead of 8 and instead of all the gears making up the horizontal axis I replaced them with to LEGO Technic turntables. These are much stronger and a lot easier to work with. The gear box on the side of the wrist has changed several times too. Note the differences between the video and my new LEGO Digital Designer drawing each time I have eliminated weaknesses in the design, such as slipping gears and play in the axis.


This picture shows the set up used in the video above, just using two half beams and some axle bars holding the gears in place. This set up was simple and light but did allow some gears to slip when lifting heavy loads. The new set up is much stronger and does not allow any gears to slip.
The LEGO Digital Designer really shows how simple the wrist is - just a few pieces put together can make such a versatile part. I am currently toying with the idea of adding a Mindstorm NXT colour sensor to the wrist and a white block level with the turn table, to allow the NXT to easily find its home position. This would therefore allow me to build a program to prevent the Arm from entangling the cables, feeding the grab.



The next pictures show the wrist and grab in its current state ready for some more testing and fine tuning.