Proximity Switches

[CraftyGeek]

I'm starting to look at switch options for my design - are you using these proximity switches for homing?...are they accurate enough on a repeatable basis for that (ie, tool changes, flipping work piece etc)?

[kingcreaky]

I'm starting to look at switch options for my design - are you using these proximity switches for homing?...are they accurate enough on a repeatable basis for that (ie, tool changes, flipping work piece etc)?

In my opinion yes, sheerly because there is no mechanical parts. I cant talk from too much experience with flipping work etc but they were recommended to me by another forum member who does.

[CraftyGeek]

Thanks, i'm liking the look of this approach & I have basic electronics knowledge with plenty of soldering experience so should be easy enough to get them running - any chance of a pic showing how you've got one attached to your machine?

What are you using for limits?

[kingcreaky]

limits switches are for girls!!! the 'limit' is where the ballnut slams into the bearing housing

no pictures im afraid, however they are very simple... wave something metal infront of it... and it triggers

[JAZZCNC]

limits switches are for girls!!! the 'limit' is where the ballnut slams into the bearing housing

. . . .Ah ah obviously not bent a ballscrew yet Matt or ripped the teeth of a timing Belt..

Crafty Just buy some cheap-ish micro switches for limits and wire in series. Also arrange them so they get triggered by running over the switch and not into it. Same goes for Home/Proximity switches.

Also If you want to keep wiring and number of switches down then just have 1 limit switch per axis that travels with that Axis and gets tripped by some fixed but adjustable brackets at each end.

[CraftyGeek]

Crafty Just buy some cheap-ish micro switches for limits and wire in series. Also arrange them so they get triggered by running over the switch and not into it. Same goes for Home/Proximity switches.

That's pretty much what I did on my last crappy MDF machine...although the micro switches were a smidge too cheap
They've been retired...i'll be getting some new ones when the time comes.

[paulus.v]

I've got six nice inductive sensors, four of these and two of these. I'm not sure if and how I could use the last ones as they have only two connections. Do I need additional circuitry to be able to use them?

[EddyCurrent]

The four you have are Normally Open type, the preferred type for limit switches is Normally Closed.
Also take note when you mount them, if you notice they use brass, stainless, polypropylene mounts.
The last two may be normally closed, it does not say, some of these just change a voltage level so that the input decides if it's on or off.

This manual shows the wiring arrangements but obviously for their own board.
http://cnc4pc.com/Tech_Docs/C31R1_USER_MANUAL_REV1.pdf

You could wire the sensors so they operate the coil of a N/C relay then use the relay contacts as inputs to your breakout board but it's a backward as you have introduced more things to go wrong.

Personally I would replace them all for 3 wire N/C type.

[paulus.v]

If I use them only for homing with additional limit micro-switches will I have any issues being PNP?

[EddyCurrent]

PNP is the most common type used so you should have no issues.

Technical FAQs | Knowledge Base

yours are 5-10v so you should not require extra resistors as in this discussion but it makes interesting reading
http://www.mycncuk.com/forums/genera...-required.html