I am new to this kind of CNC, 20 years ago I worked on the big machines installing the computer interfaces, so I have a general knowledge and now I'm getting the details together. I seem to remember there being limit switches on either end of each axis. when I was watching the videos of installing the limit switches, they only had one on each axis. what are the advantages or disadvantages of using 1 or 2. I always thought they were for protecting the machine against limit crashes. Are there other reasons ? Connecting 2 switches is easy enough in parallel using NO switches. FYI i will be using the xtension limit switches, but id like to know the pros and cons of 1 or 2 per axis Thank You
You can wire two switches if you wish to (remember to order extras) , or you can use single switches along with Soft Limits. See gnea/grbl
Thank you for your quick response, So as i understand it, you use the limit switches to "Home" the machine and then the "soft" Limits are defined in the control software based on your work area defined by the operator/equipment? Soft limits cause an alarm or warning, and could allow for continuing the job if it is erroneous or correctable and won't cause a shutdown and need to reset? Whereas a Hard limit causes the machine to alarm and cease to operate until reset and the job is wasted (probably).So my next question is, if I do use 1 switch per axis (which if the aforementioned is true, I will be) where are the best places to put the limit switches on X,Y, and especially Z. In these scenarios, where does the X,Y,Z probe come into play ? Also, I failed to mention some of my hardware, mostly Openbuild hardware, Blackbox, IOT Relay, Meanwell 24v PS and a Router11, X and Z gantry are Openbuild C-beam hardware, and some other non Openbuild hardware on the Y Axis that I got in 2019. the motors are Nema 23 Hi torque series Thank you again Tim
Excellent observation, though do keep in mind hard limits also protect against runaways caused by faulty settings etc. You can also enable both functions. Soft limits do the checking, but should something go wrong, hard limits is in place as a backup. Worth the cost of 3 switches i'd say Standard is top, right, far back. Ie at the Maximum ends of travel. But XY can be anywhere. Z at the top is critical though, down crashes endmills. Upward is a safer direction to home toward See gnea/grbl Switches homes and sets the Machine Coordinates. Probe sets the Work coordinates (where the Stock is, relative to the machine)
