The voind robot concept was developed virtually in great detail even before a single part was produced, enabling us to work out the best arrangements to achieve a compact footprint (9 cm in height) for the sliding carriage assemblies. This part of the design was done using the excellent open source 3d design and animation package blender.

Once the overall chassis dimensions were established we produced the technical drawings and sourced the chassis fabrication and welding – stainless steel and tig welding.

We chose to use a low profile linear guide system from igus, allowing us to fit the entire X-Y carriages and motors within a 90 mm height.

For the aluminum parts we produced the 2.5d drawings using DraftSight

These drawings were then combined and laid down for cutting and machining from stock aluminum bars.

The parts were machined from 6060 aluminum bars with the help and resources of fablab Lisboa, in particular using their Ouplan milling machine.

First attempts at cutting aluminum were disastrous!

After some tests we settled on conservative settings and HSS/CO 3mm cylindrical end mills:

• Spindle: 5500 rpm
• Feed rate: 5mm/s
• Stepover: 1.2mm
• Stepdown: 0.75mm

A sequence of machining sessions followed – totaling around 20 hours – during which the majority of aluminum parts were cut.

 

We tried to keep the maximum possible dimensional accuracy with the tools at our disposal. This meant that sometimes we would be positioning a part for over 10 minutes only to perform a single drilling operation.

As soon as the first aluminum parts were fabricated we proceeded into initial tests of the assembly fits. These tests validated the dimensional correctness of the parts and the overall clearances which were calculated during the early stages of the design.

For example the clearance between the ballscrew and the surface of one of the parts is less than one millimeter across the entire width of the robot. This is one of several design decisions which allowed us to cram three DOFs (degrees of freedom) with motors and associated mechanics within a 9 cm height footprint.

The control electronics is being built and tested side-by-side with the mechanical components. In due time it will be attached to the robot chassis but until then it is laid out on an area of the assembly zone protected by a plastic transparent cover.

One of the challenges that we faced since the inception of the voind concept was how to control and use audio equipment that has no MIDI interface nor any other means of being controlled electronically. This is especially relevant for audio vintage equipment which, as the surveys conducted during our participation on the Energia de Portugal 2013 acceleration program showed us, is an interesting application of the “remote use of audio equipment” concept.

After evaluating a number of options based on hobbyist and industrial robotic arms, and collaboration scenarios with local engineering universities, we decided to design and build it ourselves.

some of the early design concepts

We settled on a design based on a rotating arm suspended from a horizontal guide in which the robot chassis would also provide the rack rails for 4Us of 19” rack equipment.

This project is being developed since August 2013. We will try to post regular progress updates on this same blog.