bounce off home switch.

[boldford]

As I've no need to machine metals I'm thinking of Hall Effect devices. I'm concerned mechanical switches or slotted opto devices might be affected by dust. No firm decision made yet.

[irving2008]

As I've no need to machine metals I'm thinking of Hall Effect devices. I'm concerned mechanical switches or slotted opto devices might be affected by dust. No firm decision made yet.

No need to use hall effect... simple magnetic reed switches work well although need debouncing just as a microswitch would. A hall effect device might just be too sensitive. With modern high-strength mini-magnets I found for one application I needed the hall effect device over 5cm away from the magnet before it stopped recognising it. Also the reed switches in burglar alarm sensors are ideal and not expensive £3.99 from maplin or £1.45 on ebay

[Jonathan]

I think the inductive switches I linked to in post 12 sound a lot easier than using reed switches, unless there's some advantage to using reed switches over them? SN04-N are the same ones DMM-tech use with their servo systems.

[boldford]

With so many ideas to choose from it will probably come down to cost v repeatability.

Hummm. . . . . So many design decisions. . . . . .