End-of-stroke Design

The design of end-of-stroke detectors is a necessity in numerous mobile applications. These elements serve to prevent damage to the equipment, including stepper motors, while also ensuring the safety of operators and facilitating the management of travel strokes without the necessity for complex programming of associated control cards.

It is possible to purchase limit switch detectors from online sales sites for a few euros each. However, these have been developed for specific equipment, such as 3D printers. In the case of custom-made equipment, the limit switch must be redesigned.

A 6mm diameter aluminum rod or tube is a common element in our designs. This point serves as the basis for defining our end-of-travel detector. If the diameter of the tube or rod changes, the reference diameter can be simply modified. Furthermore, a versatile design is essential to enable the detector to operate in any direction, without the need for re-design for 3D printing. Our assembly must also respond to this point.

Finally, regarding the switch, we utilize a 3-way push button switch from the E-swich brand [ [i]] to facilitate the broadcasting of two distinct types of information contingent upon the switch's position.

In order to comply with the aforementioned constraints, we opted for a T-shaped and two-part design.

[i] https://www.mouser.fr/ProductDetail/E-Switch/TL2285EE?qs=7Bi7Dg8SEnxrzf04kzdLHA%3D%3D&mgh=1&vip=1&utm_id=18189909961&gad_source=1&gclid=CjwKCAjww_iwBhApEiwAuG6ccNncX3vGIQqVLexTw077FZctm-n93d8soqZy1u9ECOEn0djlSGgrCxoCJI4QAvD_BwE

• 2 colored wires (from recycled LAN cat 5 cables)
• E-Switch
• 2 3d printed elements (see supporting files attached)
• Cyanoacrylate (super glue)
• M3 screw and nut

The initial component will be positioned within the 6mm rod. With a length of 10mm, the component is able to slide into the 6mm rod via a cavity with a diameter of 6.2mm. One component permits the insertion of an M3 nut and the subsequent passage of an M3 screw, which will secure the component on the rod. A V-shaped protrusion 2mm high will allow the second component to slide.

The second part of the 3D-printed object is designed to house the E-switch. It is a cube with a depth of 10 mm and a hollowed-out section measuring 7 mm in length, which is the length of the E-switch. The cube also has two windows measuring 2.5 mm, which can be slided in to accommodate the switch connectors. The equivalent of the V-shaped protrusion of the first part is dug into this second part for assembly.

The two components are assembled by sliding the second component into the first, facilitated by the V-shaped protrusion. Depending on the desired outcome and the symmetry of the assembly, we obtain a component whose tightening is done on the right or left if the M3 screw is horizontal, top or bottom if the M3 screw is vertical, and top.

Once the assemblies have been affixed by means of cyanoacrylate glue (superglue), they are positioned in the equipment in a manner that is most appropriate in terms of safety or selected distance for limit switch, among other considerations.

Further Reading : « 100 Sensors In Action, Electronic For Chemists » - Gérard Bacquet- SciencExpert Edition - 2024