Ball Sorting Crane with Ultimate Grabber    Send article as PDF   
As mentioned in my previous post, I’ve been working on-and-off for a couple years now on a reliable LEGO Technics, Crane Claws which will pick up balls reliably. To show case my ‘Ultimate Crane Grab’, I’ve built a LEGO Mindstorms NXT Coloured Ball Sorting Crane, which runs along a geared tressel, which features my Ultimate Crane Grab mechanism! The Crane picks up coloured Ping-Pong Balls, and drops them into cells according to their colour.

Tressel Crane Set-up

Pictured below is a LDraw rendering of the Tressel Crane with my New Crane Claw Assembly attached. Note that the Small PowerFunctions Motor that Opens and Closes the Claw is missing. The RCX type Touch Switches used as ‘Limit Switches are also missing. There are two Limit Switches, one either side of the base which are Connected in Parallel to the NXT Port 1. These switches are used in calculating the travel distance along the Crane Track Assembly.


Ball Sorting Crane with Ultimate Grab in Action!

There are heaps of Colour Sorters around, but this one was built to show case my Ultimate Crane Grab. Because of the Grab’s design, it is great for handle Balls and other Round Objects. It also very efficient at collecting many other shaped objects as well.

Tressel Crane with New Crane Claw Assembly
Tressel Crane with New Crane Claw Assembly
Tressel Crane Claw Assembly
Tressel Crane Claw Assembly
Tressel Crane Claw Assembly

A third ‘Limit Switch’ connected to the NXT Port 2, is used in conjunction with the ‘Lenear Actuator’ to set the upper limit of the Actuators travel. From these three switches the Software calculates the length of travel.

Tressel Crane Claw Set-up
Tressel Crane Claw Set-up
Tressel Crane Claw Assembly Close-ups

The Small PowerFunction Motor for the Claw Operation, connects to the two Technic pins and drives the fingers. This connection point is shown in the top-center of the above Crane Claw Assembly image.

Tressel Crane Track Assembly
Tressel Crane Track Assembly

The Tressel Track Assembly shown above can be built to a greater length if you wish. The Software will automatically calculate, via the ‘Limit Switches, the distance to each Ball Bin along it’s length.

Tressel Crane Ball Delivery Assembly
Tressel Crane Ball Delivery Assembly

Ball Sorting Crane with Ultimate Grab Instructions:

Instructions: DownloadLEGO Digital Designer Format

NXC Source Code: Download NXC Format


NXC Source Code:



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