X-carve Grbl Default Settings - 500mm

X-Carve Assembly
1

I’ve been helping folks get their X-carve machines up and running. I’ve learned a lot. One of the things that I have noticed is that the grbl parameters seem to be inconsistent, especially when the Arduino has to be re-flashed.

Long story short I wanted to find out exactly what the defaults should be.

I took a new Arduino and used the EEPROM clear example program to clear the contents of the EEPROM (1024 locations), compiled the source code for Grbl 0.9j, downloaded to the Arduino, then ask for a $$ report,

Here are the results for a 500mm X carve with the ACME Z axis screw:

Grbl 0.9j [‘$’ for help]
$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=3 (status report mask:00000011)
$11=0.020 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=0 (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)
$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=100.000 (z max travel, mm)
ok

As you bring up your unit there are settings that will change. Most of the changes will be simple and usually are for homing/limit switch use. Some people have changed the steps per mm values to fine tune the accuracy of the machine.

For those who are bringing up their machines for the first time, many problems can be avoided if you check these values after you have run the machine setup procedure in Easel. You can do that with a terminal program like HyperTerminal or Putty. In Easel you can use the Machine Inspector to view the parameters.

If your machine is working the way you want it to then you don’t need to check this, but if you are having problems that don’t appear to be mechanical issues then this is a good place to start looking for the problem.

This link can help you decide what changes, if any, you would like to make to the Grbl settings:

2

You can also check these settings in Easel.

Machine > Advanced > Machine Inspector

You can even use the console input to change values.

3

Larry, I am the guy having issues with my Z axis not moving in the correct direction. I made the changes to the configuration per your suggestion but alas, the z still moves in the downward direction, no matter what. When I connect using the tty.exe the unit is found, it unlocks just fine. I send G90 for absolute moves, G21 for millimeters and the x and y move fine with a G01 X100 Y100 F8000. When I send the $H to start the homing, the Z moves for a split second, in the downward direction, and then it reports an error ALARM Homing fail with an OK on the next line.

I’m pretty frustrated at this point.

Just a note: my son purchased an X-Carve 1000mm x 1000mm unit which I setup up for him without ANY problems. I’ve triple checked all my hook up and all looks fine. I stumped!

Stepehn

4

20150930_094746_resized.jpg864×1536 812 KB

Larry, here’s a photo of how the pots looked when I opened the case cover. Seems to be in the proper orientation to me. I also marked the limit switch wires on the right for your viewing pleasure.

Tag, you’re it! :grinning:

5

Well, the first problem that I see is that your wiring is not correct.

Looking at your picture the inputs to the gShield should be (top to bottom) :

–NC
–Ground (spindle control ground)
–NC
–Z axis homing switch(positive)
–Spindle control(positive)
–Y axis homing switch(positive)
–X axis homing switch(positive)
–NC

where NC is no connection.

6

It also looks like the black wire for the Z terminal could be seated a little better, or maybe it just looks that way from having more insulation stripped back.

7

Larry, prior to making the connection changes, sorry for my dyslexic pin out, I checked the continuity as well as the switch switching properly and all was good.

But alas, I still get a ALARM: Hard Limit error as soon as I send the $X command to unlock: prior to the error, I get the [Caution: Unlocked] statement.

NON of the limit switches are made.

To try and isolate which switch might be the issue, I have disconnected one at a time And then do a crtl X to reset and then the $X and get the same error until all the switch lines have be disconnected.

just disconnected all switches and was able to access …

Could it still be something in my configuration?..listed below.

Grbl 0,9j [’$’ for help]
[’$H’|’$X’ to unlock]
$x
[Caution: Unlocked]
ok
ok
ALARM: Hard limit
[Reset to continue]

Grbl 0,9j [’$’ for help]
[’$H’|’$X’ to unlock]
$x
[Caution: Unlocked]
ok
ok
$$
$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=1 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=3 (status report mask:00000011)
$11=0,020 (junction deviation, mm)
$12=0,002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=1 (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=750,000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1,000 (homing pull-off, mm)
$100=40,000 (x, step/mm)
$101=40,000 (y, step/mm)
$102=188,976 (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=295,000 (x max travel, mm)
$131=790,000 (y max travel, mm)
$132=100,000 (z max travel, mm)
ok
ok

9

Do you have your homing/limit switches hooked up for Normally Open or Normally Closed?

Normally Open $5=0
Normally Closed $5=1

10

Larry, all is well in the Land of X-Carve!

I’m as happy as a little!.. snl Sprockets

Thanks for holding my hand… I did learn a lot dealing with my own stupidity… :stuck_out_tongue_winking_eye:

Later!
Stephen

11

@StephenLedak

I would recommend that you keep soft limits turned on, and turn hard limits off.
$21=0

If you don’t have limit switches on both ends of the X and Y axes, then you don’t gain much by having hard limits on.

With hard limits off and soft limits on the switches are only used during the Homing cycle. This prevents false triggers on the switches due to electrical noise interfering with your carve and checks your G code to make sure that you are not executing a command to take your spindle out of bounds.

12

Wouldn’t $130 need to = 790? (for a 1000?) or is it $131 is wrong? Is this a passive function?

13

Yes. I missed that.

These values are only used if you have soft limits turned on.

14

Thanks. Trying to get a hang on the details. Good to see I’m on the right track.

15

Thanks for this post. I just had to load GRBL onto my Uno, and this is going to come in very handy.

One question though…

What is the microstep setting that these values are the default for?

16

@BradT
Since you called out x and y - no jumpers on the gShield header block for x or y

If you are not using the gShield it is 1/8 stepping.

17

Thanks @LarryM ! Since you mentioned it…sort of. I read somewhere that the Z is 2x. Is that right?

I’ll be using a CNC shield V3 to start with. I have very similarly spec’d stepper drivers (DRV8825), but will need to set the jumpers. The driver I will be using has up to 1/32 microstepping. Do you think I would see any benefit from going finer?

18

@BradT

Yes. Different sources use different terminology. Z axis is 1/2 micro-stepped and some refer to it as 2x.

I haven’t done any testing with micro-stepping rates. You would get less rotation from using 1/32, but I don’t know if that would show up on the machine. You may get to a point diminishing returns.

You would just have to do some testing to see what you can get and where the best place is to run the machine for the performance that you want.

1 Like
21

@RizwanAsgar

Please delete your post and start a new thread. I’ll meet you there.

22

Hi! everyone good to be here @LarryM am having issues with my x-carve loosing steps on y-axis, have tried squaring , dialing the ref voltage but still won’t work , am very new to this machine so baby spoon me through . thanks

23

Larry passed away some time ago :cry:

What kind of controller/steppers do you use?
What is your Vref?
What machine load, like bit diameter, material, depth and feed rate?