Limit switches

[itsme]

Hi there,

At last I think I've figured out exactly how limit switches are set up with pull-up resistors etc. All I need now is to find out what kind of switches everyone uses. I'd quite like something that is normally closed and is opened when the table reaches its limit (good for safety if a wire breaks etc...).

Does anyone know of good, cheap switches that would do this job? I've seen some 'proper' limit switches, but at over £10 a piece, I thought that was a bit steep.

Finally, would it make sense to have 2 switches per axis that are wired in series, and then the three axes (or 3 sets of 2 switches) wired in parallel?

Thanks
Warren

[Bubba]

Itsme,
Don't know what kind of machine you are using, but if it has coolant, make sure they will not get contaminated by coolant.
On my mill/drill, I use "AAP minature Din limit switches" which I get from Automation Direct here in the states, but feel sure they are available on your side of the pond. I get them for 12 USD ea.
I use one on the X, and one on the Y axis, for the Z axis, I use micro switches as they are out of the path of coolant.
for a fine precision, I am also using optical switches. All are setup as NC (and where necessary, are in series).

Hope this helps.

[10bulls]

http://uk.farnell.com/jsp/endecaSear...=gensearch&y=0

[itsme]

Hi there,

The machine is a Sieg X1. It's not going to have coolant to start with, but I'm planning on adding it at some stage.

I think I might just go with microswitches to start off with, simply because of the price. When the time comes, I will get some 'decent' switches that can handle the coolant etc. I think I will use 2 switches per axis and will definitely go with NC.

Thanks for the help.

Warren

[pauls]

I'm new to limit switches. I've got several micro switches-Radio Shack- but no info on what terminal is what. These are roller lever switches with 3 solder pins labelled 1,2,3. What's positive, ground? How to wire?

[da21]

Originally Posted by pauls I'm new to limit switches. I've got several micro switches-Radio Shack- but no info on what terminal is what. These are roller lever switches with 3 solder pins labelled 1,2,3. What's positive, ground? How to wire?

you will find the microswitch is a single pole changeover (spco)
i.e one pin is common and switches ( toggles ) between the other two depending if the lever is depressed or not

if you have a multimeter set on restance it's easy to find which is the common