[Chunky]

Are limit switches optional? Are they only there in case the stepper develops a mind of its own and travels outside the prescribed toolpath? Need to know whether to figure them into my building budget.

[CNCRob]

I beleive thats pretty much what they are for. Just to make sure the machine doesn't go past its limits and crash into itself. You can even crash the machine into itself when jogging it. I think servo motors have more of a tendancy to run away more than steppers but I could be wrong. The limit switches can also be useful for homing the machine.

[sol]

Just noticed that your age jumped a year; Happy Birthday!
Limit switches...Put them in. It only takes one mistake to make a mess of things. Cheap micro switches from RadioShack are better than nothing.

[buscht]

Chunky, Limit switches are important on high powered servo driven machines. I think that they are optional on low powered stepper driven machines.

My reasoning is that on a low power stepper, the motor will simply stall out when you get to the end of travel. On a high powered machine, something will break.

More important might be the homing switches. When you power up the CNC, it doesn't really know its position. You can't count on everything staying the same from run to run. An axis might have been bumped while power is off, or you may have lost some steps over time.

Home switches allow you to move the router to a known postition (X and Y) and zero out the coordinates. The Z axis is trickier because you have the added variables of the router bit length and work height. On this forum are threads that talk about a touch height sensor.

Some people use their home switches as limit switches (double duty to save costs). Other people have seperate ones. This is useful if you want to cut around the outside of a board for example. You can fixture it against the zero axis in X and Y and if your limit switch is outside this envelope say 1", then you have room to cut around the board.

All that being said, I still haven't put limit switches on any of my machines yet. They run fine without them, you just have to be more careful.

[Chunky]

Good thourough, understandable answer. Awards should be given for them. Thank you.