hall effect home switches

Dr. wrote:

While trying to conceive of an appropriate cam mechanism to effect this, I realized that the easiest and most reliable mechanism for achieving this would be a hall-effect switch and a magnet. !

Depending on what you are machining, magnets can be a poor choice. Certainly if you intend to machine steel I would avoid them. (it seems fair to assume that you are unlikely to be machining Nickel or Cobalt)

Inductive proximity switches work well.

OT-CNC wrote:

Inductive proximity switches work well.

What repeatability are you guys getting with these switches when used for precision homing? I have mainly used optical switches for home switches and sealed roller micro switches for limits.

Ah, well, I should probably have said that my machines all have encoders or resolvers, so I can home to index and the home is exactly as accurate as the feedback is capable of measuring.

Adding a second prox that senses the motor-shaft flat (or whatever) for an emulated index would be possible for open-loop machines.

Dr. wrote:

Thanks guys for your help. It's clear to me now.

The thing that you might want to keep in mind is that some of us are approaching their CNC project without previous CNC experience, but with experience from other areas. So, when we ask a noobie question like this one, it might be with complete naivete relative to you guys. Hence the question in this forum.

...

The problem is in the documentation. For those of us who are just starting out, it's hard to find what you need, and the information is often presented in a way that is from an insider's view rather than an outsider's view. It's a natural problem. Developers often don't understand the needs of users, especially those who come from a different background.

I've thought of trying to help by generating some noobie friendly documentation (which I'm doing for myself so, if necessary, I can accomplish the same thing again without the same pain). I've yet to complete a document for my small configuration, so contemplating trying to complete one that might be applicable to all of the different configurations that LinuxCNC is capable of supporting is a bit overwhelming at the moment. But, maybe when I'm further along, and if there is interest from you guys...

There is always interest in improving the documentation!

One of the problems with making "noobie" friendly documentation is that every noobie is different and has different experience and knowledge. It's not merely a problem of developers not understanding the needs of users - it's a problem of users not understanding the needs of other users. Your approach will undoubtedly help some noobies, but might hopelessly confuse others In the current case - I have seen quite a few machines which have home switches - and have never seen one that operates as you mention in this thread - they all work using one of the methods supported by linuxcnc. I think a truly noobie friendly documentation would be several thousand pages and would probably need to start with a tutorial on the English language!

Don't let that dissuade you in any way however from contributing better documentation!

Holly Moses !!!