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gnea / grbl-Mega

An open source, embedded, high performance g-code-parser and CNC milling controller written in optimized C that will run on an Arduino Mega2560
https://github.com/gnea/grbl/wiki
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Z Axis Not Homing Correctly ? #73

Open NEMA34 opened 6 years ago

NEMA34 commented 6 years ago

Hi , First off Thanks to GRBL Software Engineers for a great bit of Control Software

My Set Up : I am Running GRBL 1.1f on a Mega 2560 - Was Programmed using the Hex File Method.

I Connect to GRBL through UGS ( Nightly Build Latest )

My Machine is a CNC Router : See the Photo Attachment of my Limit Switch Positions & my Cartision Positioning Setup.

HOMING ISSUE DESCRIPTION

I have tested the Limit Switches Manually to make sure they are all working in UGS in Verbose Mode & they appear to be working Just fine - Here is the Output

[verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Pn:Z> - Me Manualy Triggering Z Axis Limit Switch [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Pn:Z|WCO:0.000,0.000,0.000> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Ov:100,100,100> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Pn:X> - Me Manualy Triggering x Axis Limit Switch- [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Pn:X> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Pn:Y> - Me Manualy Triggering Y Axis Limit Switch [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Pn:Y> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|WCO:0.000,0.000,0.000> [verbose]<Alarm|MPos:0.000,0.000,15.000|FS:0,0|Ov:100,100,100>

When i Run the Homing Cycle the Z Axis Moves slowly Upwards towards the Switch & I Hear the Switch Activate but the Z Axis Stepper Motor Continues to keep on Going up even though the switch has Triggered ?

So i Have to hit the Emegency Stop Panic Button to kill all power to the controller

My Limit Switches are wired ( Normally Open With 1K Pull Up Resistors to +5V & 100nf Ceramic Caps on the Grounds ) Making an RC Filter - I See no False Triggering in Vebose Mode.

My GRBL 1.1F Settings are as Follows

Grbl 1.1f ['$' for help]

$$ $G $0=10 $1=25 $2=0 $3=3 $4=0 $5=0 $6=0 $10=1 $11=0.010 $12=0.002 $13=0 $20=1 $21=0 $22=1 $23=7 $24=25.000 $25=50.000 $26=250 $27=20.000 $30=24000 $31=5000 $32=0 $100=159.426 $101=159.521 $102=100.000 $110=3000.000 $111=2400.000 $112=500.000 $120=25.000 $121=25.000 $122=10.000 $130=670.000 $131=1400.000 $132=200.000 ok [GC:G0 G54 G17 G21 G90 G94 M5 M9 T0 F0 S0] ok $I [VER:1.1f.20170802:] [OPT:VNM,35,255] ok

I Have Tried Re-Downloading the Hex File & Re-Flashing the 2560 Again - Still the same

Also i have put a mini scope on the Z Axis Limit Pin to see if there was any Noise Present, it is nice & clean.

Switch Untriggred it reads +4.870V (HI) & Triggred it Drops to 0.092V ( LOW ) with no apparent noise on the Z I/O Pin in ether Hi or Low ?

Is this a Bug with the Z-Axis or a config Error ?

Many Thanks in Advance

Dave528 commented 5 years ago

I was looking through your GRBL FW settings and setting $21 (Hard Limits) = 0 is incorrect for running homing cycles since this disables hard limits. I would change this to $21 = 1 to enable the hard limits. The $22 (Homing Cycle) setting is correct, but does not work with hard limits disabled. NOTE: I've only used GRBL on the Mega328 platform, so if I'm mistaken about this please let me know.

beautifulsmall commented 4 years ago

To confirm the workaround, Z switch showing in status but unresponsive during homing. I had $3=5 for direction invert on the X and Z ,

I set $3=4 and re-wired the X stepper to drive the opposite direction and it Homed perfectly in all directions. had ,boolean : $21 hard limits enabled =1 $20 soft limits disabled. =0 using NC switches with $5 invert on all limits discussion suggests X and Y direction inversion affects the homing switch polling.