Limit switch not recognised and Z has mind of own

21

This what I need to see. This will tell me the health of your sytem

grbl 1.0c [’$’ for help]
modified by Larry Mayberry
[’$H’|’$X’ to unlock]

$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=3 (dir port invert mask:00000011)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=115 (status report mask:01110011)
$11=0.020 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=1 (soft limits, bool)
$21=0 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=3 (homing dir invert mask:00000011)
$24=25.000 (homing feed, mm/min)
$25=750.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$30=1. (rpm max)
$31=0. (rpm min)
$32=0 (laser mode, bool)
$100=40.000 (x, step/mm)
$101=40.000 (y, step/mm)
$102=188.947 (z, step/mm)
$110=8000.000 (x max rate, mm/min)
$111=8000.000 (y max rate, mm/min)
$112=500.000 (z max rate, mm/min)
$120=500.000 (x accel, mm/sec^2)
$121=500.000 (y accel, mm/sec^2)
$122=50.000 (z accel, mm/sec^2)
$130=290.000 (x max travel, mm)
$131=290.000 (y max travel, mm)
$132=90.000 (z max travel, mm)
ok

[G0 G54 G17 G21 G90 G94 M0 M5 M9 T0 F0. S0.]

[G54:0.000,0.000,0.000]
[G55:0.000,0.000,0.000]
[G56:0.000,0.000,0.000]
[G57:0.000,0.000,0.000]
[G58:0.000,0.000,0.000]
[G59:0.000,0.000,0.000]
[G28:0.000,0.000,0.000]
[G30:0.000,0.000,0.000]
[G92:0.000,0.000,0.000]
[TLO:0.000]
[PRB:0.000,0.000,0.000:0]
ok

22

$132=88.000 (z max travel, mm)
$131=290.000 (y max travel, mm)
$130=290.000 (x max travel, mm)
$122=50.000 (z accel, mm/sec^2)
$121=500.000 (y accel, mm/sec^2)
$120=500.000 (x accel, mm/sec^2)
$112=500.000 (z max rate, mm/min)
$111=8000.000 (y max rate, mm/min)
$110=8000.000 (x max rate, mm/min)
$102=188.976 (z, step/mm)
$101=40.000 (y, step/mm)
$100=40.000 (x, step/mm)
$27=1.000 (homing pull-off, mm)
$26=250 (homing debounce, msec)
$25=750.000 (homing seek, mm/min)
$24=25.000 (homing feed, mm/min)
$23=3 (homing dir invert mask:00000011)
$22=1 (homing cycle, bool)
$21=0 (hard limits, bool)
$20=0 (soft limits, bool)
$13=0 (report inches, bool)
$12=0.002 (arc tolerance, mm)
$11=0.020 (junction deviation, mm)
$10=1 (status report mask:00000001)
$6=0 (probe pin invert, bool)
$5=0 (limit pins invert, bool)
$4=0 (step enable invert, bool)
$3=3 (dir port invert mask:00000011)
$2=0 (step port invert mask:00000000)
$1=255 (step idle delay, msec)
$0=10 (step pulse, usec)
ok
[0.9j.20160726:]
$$
$I

23

Just an update. Checked board as suggested by Haldor and Z limit is now on pin 12. Made a temporary connection and can now go through homing cycle. Supplier has confirmed that engraver shield is up to GRBL 0.8 and asked if they can supply for GRBL 1.1f. Tried going back to 0.8 but was very retrograde and not worth the effort (70+ student with brain fade)
With the movement in the Z axis I added jumpers in the micro step configuration which is nearly there. GRBL did not allow me to change $102=188.947 downwards although it said ok it did not happen.
When I ran the Easel carve it appeared way out of scale. I did not cut anything but when get various matters resolved will try with pen and paper.
Going to make brackets and fit limit switches so I can accurately home the machine.

Again thanks for all help and will update when I have these bits sorted out

Hamish

24

Progress, that is good :slight_smile:

Calibrating the step/mm GRBL-parameters should be straigth-forward through Easel->MachineInspector->Console
You may be required to reset the UNO beofre change happen (disconnect/reconnect USB)

If UNO is not acting as expected, using a known-good method => UNO clone, some behave funky.

25

Good progress today. Made brackets for limit switches and temporarily wired up, until I get some screened two core. First homing operation was a bit alarming to say the least with X & Y thundering about and appearing to crash into end stops.
Did simple calibration and can get X &Y to move 10mm when I ask for 10mm. My settings for $100 & $101 are 3.5 steps/mm. I assume that to achieve suggested steps of 40 steps/mm it will be a case of inserting jumpers to utilise micro stepping? What benefit does this achieve?
I inserted jumpers into the Z axis micro stepping and it now gives what I ask. This axis runs much smoother than the others which are a bit jerky, so this an advantage of micro stepping?
Managed to attach a Sharpie and got a drawing which when measured was spot on.
Will be spending some time finishing the project as It is just strung together and looks very heath Robinson, much like many U-tube examples.
A far as the 0.8 engraver shield, the supplier suggested I amend GRBL back to pin 11, which sounds simple but may be outwith my abilities. I was impressed with the technical reply from him and will use again.
Again thanks for your help and no doubt I will be back.

26

Well rather than being spoon fed, which I find annoying, I did some homework and when I get some shorting links, ordered, as bits of wire pushed over pin not to impressive, will then experiment to get a smoother operation.
Thanks again

27

The suggested (40step/mm) value is just what is needed for “that particular system” and is not something universal to aim for. You use the value required for your machine, to achieve what you want.

Ideally one would want to use full step (1/1) because this will provide optimum torque at speed.
But since 1/1step = 200 steps per revolution each step is a little coarse, also in terms of mechanical “smoothness”.
1/1 may sound rough and “hard”.
So one use micro stepping 1/2, 1/4, 1/8 etc, which ever give you “smooth enough” operation.

I would use a smaller sprocket to gain a higher full step value (per mm) as at the moment you have like 0.3mm resolution which is rather coarse. You do, in theory, increase resolution by utilising micro stepping, but the actual micro step position is less accurate than the full step position relative to the magnetic field of the motor.

Full step position may be with say 5% but this increase with part step positions.
Say you use 1/2 step, the rotor may be off by +/- 5% in full pole position while mid-position may be +/- 20% (Numbers are arbitrary)

28

Thanks for that info Haldor. Once I get jumper pins will experiment.
Looking at how to set up Z probe came across site which indicate the Z limit switch was just plugged into the Spindle Enable pins with GRBL 1.3, so simple and I am making soldered joints to the pcb. Removed these and now connect Z limit to Spindle Enable with no problems.
Found my homing was freezing when complete. Altered $27=1 to 5 as limit switches have a lot of movement and now homing works ok.
Great this learning curve and hope others will learn from my ramblings.

29

Hello Haldor,

Well I am up and running but now come to a sudden stop. I thought Easel was free software and I repeatedly got request to purchase Easel Pro which for my use is not going to happen. Are you aware of any genuine free software?

30

Just discovered that it is charging me because I am using a V bit???

31

You have Easel which is free
Easel Pro have free 4 days per month for all users. (4x 24hrs)
You can purchase additional days or run a monthly subscription.

What require Easel Pro is V-bit carving and access to added fonts.
If the top right of Easel suggest “Easel Pro” one or two of the above is used.

32

Thanks Halfords, I had worked that out eventually with my mistake in thinking all things in life are free. The expensive V bit and collet will sit unused until the free days or I take out a day pass which is doubtful.
Big problems with A4988 drivers as it looked like one faulty wiped out other three. Have some Easydrivers so will set them up to maintain progress.