How to mount limit switches?

[A_Camera]

There are as many ways to do things as there are folks that do them. Thant being said. you can avoid G54 commands and homing switches by simply using an exact spot on your vise or the actual work material as your "0". location. If you need to start the run again from some point in the program, Mach 3 will allow you to do that quite easily. I am not saying G offsets are right or wrong....but I find the more simple things can be done, the better. Dan

OK, thanks. I was not looking for help, but thanks anyway. I am not using G54, I don't know how did you get that impression.

Edit: The above was a bit misinterpreted and needs some clarification, my fault, sorry.

Of course I use G54 and don't want to avoid it at all, but...

I don't have a fixed position. When I start with something new I don't care about previous settings, everything is zeroed. Yes, THAT reference is important, but what I had for positions the day before or any specific fixed point on my table is totally irrelevant for me. Yes, G54-G59 are used, but only during the actual work, most of the time I don't care about them after the computer or the CNC is switched off or the software is closed. So, yes, I definitely use work coordinates, but work coordinates change all the time when I change the work. I don't have a fixed wise, so the work piece is located wherever I find it practical at the moment I fix the piece I plan to work on and if I use a vise I fix it somewhere on the table, but never keep it there longer than I have to, so homing on the vise is only practical for THAT specific work.

[109jb]

See, there is where you guys are wrong. You are using G54-G59 whether you know it or not. A CNC controller is always using one work offset. It has to unless you are using some goofy control software. In order to program in machine coordinates you would have to use G53 on every line of the G-code. The default work offset is G54 and if you haven't changed it then your programs are running in G54. Now the G54 work offsets can be exactly the same as the G53 machine coordinates, but that just means the offset is zero in all axes.

[MT_Pockets]

OK, thanks. I was not looking for help, but thanks anyway. I am not using G54, I don't know how did you get that impression.

Yes, this is a very good point. I've actually tested this already (actually the first switch I installed was broken) and the Y-axis just drives into the front of the bearing mounting plate and the servo motor skips. Since the Taig has pretty light steppers it doesn't do any damage but still something that should be avoided. Of course bad things can happen if switches fail in the NC position as well, I've had this happen to me once before on a different machine.

BTW, I am using G54.

[A_Camera]

See, there is where you guys are wrong. You are using G54-G59 whether you know it or not. A CNC controller is always using one work offset. It has to unless you are using some goofy control software. In order to program in machine coordinates you would have to use G53 on every line of the G-code. The default work offset is G54 and if you haven't changed it then your programs are running in G54. Now the G54 work offsets can be exactly the same as the G53 machine coordinates, but that just means the offset is zero in all axes.

Yes, but...

Like I said before, I don't have a fixed position. When I start with something new I don't care about previous settings, everything is zeroed. Yes, THAT reference is important, but what I had for positions the day before or any specific fixed point on my table is totally irrelevant for me. Yes, G54-G59 are used, but only during the actual work, most of the time I don't care about them after the computer or the CNC is switched off or the software is closed. So, yes, I definitely use work coordinates, but work coordinates change all the time when I change the work. I don't have a fixed wise, so the work piece is located wherever I find it practical at the moment I fix the piece I plan to work on. The "goofy software" I am using is UCCNC and Mach3, and of course, both work very similar in this respect.

[A_Camera]

Yes, this is a very good point. I've actually tested this already (actually the first switch I installed was broken) and the Y-axis just drives into the front of the bearing mounting plate and the servo motor skips. Since the Taig has pretty light steppers it doesn't do any damage but still something that should be avoided. Of course bad things can happen if switches fail in the NC position as well, I've had this happen to me once before on a different machine.

BTW, I am using G54.

I think your answer is not matching the quote and I assume the above is an answer to what I said in post #19:

Be careful with that sort of installation... what happens if your wire breaks or you get a lose connection...? Nothing. The Y continues off the edge until it hits the floor or something else nasty will happen.

Yes, perhaps your machine is a bit weak, so it is not critical. I would not like to hit the sides of my machine at full speed.

BTW, yes, I am also using G54, like it was pointed out before, everybody is using it. That comment I made was a bit too fast typed and misinterpreted.

[MT_Pockets]

I think your answer is not matching the quote and I assume the above is an answer to what I said in post #19:



Yes, perhaps your machine is a bit weak, so it is not critical. I would not like to hit the sides of my machine at full speed.

BTW, yes, I am also using G54, like it was pointed out before, everybody is using it. That comment I made was a bit too fast typed and misinterpreted.

Whoops, yes I quoted the wrong post. I'm using 270 oz-in steppers so not too torqy.

[Travspad]

Hi guys I hope this is a suitable thread to ask this question......
Iv'e read a lot online the most people will set up 2 x limit switches on each axis and wire them both to one input on the breakout board. In my design I have used only one switch on each axis that travels with the machine and have two configurable triggers on each end of the travel. In my mind this makes way more sense, have I missed something here?