Yet another home/limit switch GRBL problem

Hey all,

I'm hoping for someone to give me some advice. I've build my own CNC machine which works well. Recently I decided to add home and limit switches, but I just cannot get them to work properly.

I have been googling all morning and completed a lot of testing - but bCNC just brings up a homing alarm as soon as Z axis has homed (It's homed, and moved 5 mm off the homing switch). It doesnt appear the X and Y even tries to move.

If I move any axis onto their home or limit switches, bCNC gives me limit alarms correctly.

I have used 47uf capacitors connect to the home switches, which are wired as suggested on sites I have seen (I could try using 330 ohm resistors, but I have seen both used so guessed they are both suitable).

I'm using GRBL 0.9j.

As far as testing as gone, Ive set $10=255 and testing the switched. The ? Lim: settings reflect the status of the home and limit switches correctly (they are all wired in parallel). So all off in a normal state - and each switch pair reacts as expected.

Any advice would be greatly appreciated, I can send pictures or explain the wiring in more detail if required.

My GRBL settings are :

Grbl 0.9j ['$' for help]
$0=10 (step pulse, usec)
$1=25 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=0 (dir port invert mask:00000000)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=255 (status report mask:11111111)
$11=0.010 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=1 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=3 (homing dir invert mask:00000011)
$24=25.000 (homing feed, mm/min)
$25=300.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=3.000 (homing pull-off, mm)
$100=50.000 (x, step/mm)
$101=400.000 (y, step/mm)
$102=400.000 (z, step/mm)
$110=1900.000 (x max rate, mm/min)
$111=300.000 (y max rate, mm/min)
$112=300.000 (z max rate, mm/min)
$120=100.000 (x accel, mm/sec^2)
$121=10.000 (y accel, mm/sec^2)
$122=10.000 (z accel, mm/sec^2)
$130=500.000 (x max travel, mm)
$131=500.000 (y max travel, mm)
$132=140.000 (z max travel, mm)

Thanks all,

Jammy

 

I've resolved this problem by creating a circuit as per attached picture.