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Oct 10, 2017

Project March – making of the Crutch Handle

Guest

written by Guest

Innofil3D provided Project MARCH with choice of all the filament they have in stock in order to design, produce and iterate the products within the project.

General

Innofil3D provided Project MARCH with choice of all the filament they have in stock in order to design, produce and iterate the products within the project.

These materials helped us a lot in quickly validating certain design choices.
Together with our printers, we were able to create anything we needed to come to our best solutions for encountered problems.
One of the parts of the exoskeleton we designed and produced using material of Innofil3D is the crutch handle of the input device.

 

 

Crutch handle

The input device of the MARCH II enables the user to control the MARCH II exoskeleton. This is done via 2 buttons and a screen to provide the pilot with feedback on the current state. A state is a mode which can be executed by the exoskeleton (e.g. walking, climbing stairs, sitting etc. . . ), via the input device the pilot is able to choose the wanted state.

This crutch handle is completely custom made and fitted to the size and shape of our pilots hands, providing for an ergonomically grip. Next to provide comfort during operational actions, the crutch handle should provide for enough strength and stiffness in order to keep the integrated electronics intact and to not fail during walking!

A lot of design iterations had to be made in order to come to the best solution for our pilot. First we created a 3D model of a crutch handle based on the sizes of the hands of our pilot, and printed this in the provided PLA. We used this mock-up handle to check the sizes with ourselves and our pilot. Our pilot noted that the surface of the crutch handle was not very comfortable and thus we had to find a solution to make sure the surface provided a good grip as well as a smooth/soft touch for the pilot.

Within the range of printable rubbers Innofil3D provided us with Innoflex45. We thought a handle printed with Innoflex45 would provide a comfortable handle which gives a lot of grip. We found out we couldn’t get the same surface finish and detail in the print we got with PLA. Therefor we decided to not use the Innoflex45 material for the handle. To give the handle a better surface finish and create more grip we decided on using a couple of layers of Rubberspray to provide the 3Dprinted handle with some extra comfort and grip.

Next to having good surface properties for the interface with our pilot, the handle should thus provide a platform for electronics to be attached to (screen and buttons) and should it be mounted to the crutch. It also should be able to carry the entire load of the pilot (90 KG!) without failing. PLA would not suffice for these criteria and printing with ABS would bring along some printing issues regarding heat control. Together with Innofil3D we thought about this problem and they recommended us trying out a new material called the PRO1 series. This material has the simple printing compatibilities as PLA, but better structural properties and better surface finish.

With this material we printed a crutch model and tested it for its properties by mounting it onto a crutch and let our pilot walk with it. No issues came along and thus this material would do for printing a suitable crutch handle!

When printing our models we were able to use Innofil3D’s water soluble material. We used this material to build support structures for our products. This way we could print complex parts and made sure that no ‘support scars’ were visible on our products.

With those materials we were able to create a crutch handle which is smooth in it’s surface, and still providing for enough strength and stiffness in order to withstand all the forces acting upon the crutch during walking in an exoskeleton.

 

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