First Proper CNC Router

[diycnc]

Turns out there was a mig welder sitting no less than 5m away from my machine in my neighbours shed!
Just waiting on a new mask and gloves before I can start welding.

Whilst I wait, im thinking about my limt/home switch setup. I currently have 3 NPN proximity sensors.
For the X and Y I will use 1 sensor mounted on the moving parts as both the limit and home switch.

For Z do i need both limit and home?

Also thinking about cable chain sizes. Will the 37x18mm stuff be big enough?

[Clive S]

For Z do i need both limit and home?

Generally you don't use a bottom limit switch but you can use soft limits. on all axis.

[Kitwn]

Generally you don't use a bottom limit switch but you can use soft limits. on all axis.

I've gone with common sensors for limits and homing plus soft limits. Sooooo easy in LinuxCNC. I have a low limit switch on my Z axis, but that's because on my design there's a crash risk with the gantry ends if it gets too low. There is a soft limit as well so it's really belt and braces.

In practice you should never need limit switches to prevent a crash as long as you have the soft limits set correctly and always home the machine before you do anything else after switching it on.

BUT. There may be a risk if you have a pendant for manual control of the machine which does not operate through the controlling software and therefore moves the machine without the software knowing. I think this is possible with some of the cheap Chinese break-out boards and is a train-wreck waiting to happen for the blissfully ignorant.