Robobot hardware

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Hardware

All 3D-printed parts are designed in Onshape and are public. They can be accessed at https://cad.onshape.com/documents/fef8699fcafb8aea780c8981/w/ce38e7fdd6cf8533b65e2c3c/e/eefdcf481faf2a4b03f5058c

For students, a free account can be created at https://www.onshape.com/en/education/

All items can be exported (in e.g. step format) for import in other CAD tools.

Mounting holes

The hardware is 3D-printed plastic (except for the electronics and screws)

All 3D printed parts have holes for mounting additional parts. These holes have:

• Individual hole distance of 1cm.
• Hole diameter of 2.5mm, intended for 3mm plastic screws.
• Plastic thickness is 6mm in most cases.

Screws

Screws for plastic (PT screws)

Mounting items on the 3D-printed thermoplastic should use plastic (PT) screws.

Plastic (PT) screws:

• Cut into the plastic with a sharp high-pitch thread.
• Gets locked into the plastic.

Plastic (PT) screw selection:

• Pan-head 2.5mm for PCB mounting, length 8mm, Torx 8IP/TX8.
• Countersunk 3mm length 10mm, TX8, for the most plastic-plastic mount, where head height is important.
• Pan head 3mm, length 10mm, TX10, for the most plastic-plastic mount, with space for the head.
• Pan head 3mm, length 16mm, TX10, for servo arm 'axle'.
• Countersunk 3mm, length 25mm, TX8, box lit 'bearing' and camera mount.

Pan head screw for thermoplastic.

Screws for metal

Mounting of motors and other metal parts should use screws for metal.

Metal screw selection:

• M3 pan head (servo horn 16mm, Torx TX10)
• M3 countersunk (motor mount 12mm, Torx TX10)
• M5 bolt (For the main wheel fastner, 16mm, Hex/Umbraco 4mm)
• M5 nut (For the main wheel fasten).
• M6 bolt (Castor axles, length 50mm, Hex/Umbraco 5mm)

Axles

Castor wheel axles are made from

• 2mm piano thread, length 25mm (e.g.: https://www.hobbydirect.dk/shop/modelskibe-af-trae/tilbehoer/piano-traad-pianotraad.htm).

NB! This is hardened steel and can not be cut by normal cutting tools, use e.g. a Dremel cutting disk.