Universal gCode Sender / Fusion 360 Issues

I have had this issue come up a few times. I would zero the machine, pressed send then craziness ensues… The machine would move from zero to Z-.25" X -5" then Y+2" at 200+ipm. This only happens maybe one out four times, but it is devastating when it happens. Also, this has only happened when Fusion 360 is generating my code.

This is the instruction lines from my gCode that was created from Fusion 360 when using grbl settings in the post processor.

G28 is confusing me, as I am not setting a reference point other then zero. I am thinking either GRBL is not processing this command all the time or its a perimeter that I am somehow setting by mistake in ugs only sometimes…??? I also could be completely wrong and going down some mystery rabbit hole!! I am hoping someone with much more experience can help with this.

%
(Dust Shoe V2)
(T2 D=0.25 CR=0 - ZMIN=-0.665 - flat end mill)
G90 G94
G17
G20
G28 G91 Z0
G90

Thanks!

For Reference.

Dust Shoe V2 (NEW V2).nc (14.6 KB)

Yep. G28 is a command that takes the spindle to a particular location. This value is saved in EEPROM and doesn’t change, even through a power cycle.

UGCS “Return to Zero” uses the G28 command to send the spindle to that location.

You can set the location that you want for G28.

Don’t have to, but good practice to home your machine, jog to the location that you want G28 to go to and enter the command G28.1

That will establish your G28 location. If you have never set this before then your machine goes into lolla land when G28 is encountered in the G-code stream.

2 Likes

I have never set G28, nor have I had a gcode that has included it.

Thanks for the reply LarryM! I will look into this now.

That was it!! I set G28 and now the program runs as expected. I really appreciate the help LarryM.

Thank you.

1 Like

I’m kinda getting what you’re saying here, but let me run thru in a prac app, which is blowing up my wood everytime i try to start one.

I have generated 3 files in fusion 360.

  1. Position my machine at the starting point for file 1. Everything carves correctly.
  2. Change bits for the second file and reset my Z Axis (Machine Z doesn’t change - I think this is where it gets ready to self destruct… I don’t want to mess anything up so I only want to reset my z, and leave my xy in the right place)
  3. Run code for 2nd piece. It gouges into the wood sometimes or scrapes across the wood, even if i lift it up to clear.

So, should i move everything to rezero? Is there a way to reset the machine location for Z as well, or should I run G28.1 to get it to reset there, or should i move everything to the zero position xyz and then run the G28.1 command and keep repeating that for each of the files/bit changes.

Thanks. I looked in my GCode, and i don’t see the G28x command anywhere.
File 1:

    (1001)
(T1  D=0.85 CR=0. - ZMIN=-1.016 - FLAT END MILL)
G0 G90 G94 G17
G21
G53 Z0.

(MAJOR CARVE)
M5
M9
T1
S20000 M3
G54
M9
G0 X-46.922 Y112.494
Z10.
Z5.
G1 Z2.5 F333.
Z-0.931

File 2:

(20DEGVBIT - HOPS)
(T1  D=3.175 CR=0. TAPER=20DEG - ZMIN=-0.508 - CHAMFER MILL)
G0 G90 G94 G17
G21
G53 Z0.

(TRACE2 2)
M5
M9
T1
S20000 M3
G54
M8
G0 X-34.213 Y117.837
Z15.
Z5.
G1 Z-0.508 F1000.

Keep in mind that this is just a guess.

The G53 Z0. line resets your Machine Zero point for the Z axis. I don’t think you want to do this. You could try taking the G53 line out and see if that fixes the problem.

i am using UGS and grbl v1.1 cnc. i using fusion 360 for cad cam
i am begninner …
I have problem my z axies moves to milling poistion then back to where its start to moving down
My code is…
%
(1001)
(T1 D=3.175 CR=0 - ZMIN=-1 - flat end mill)
G90 G94
G17
G21
G28 G91 Z0
G90

(Face1)
M9
T1 M6
S10000 M3
G54
M8
G0 X17.064 Y-8.697
Z16
Z5
G1 Z-0.683 F762
G18 G3 X16.746 Z-1 I-0.317
G1 X15
X-15
G17 G2 Y-5.838 J1.43
G1 X15
G3 Y-2.978 J1.43
G1 X-15
G2 Y-0.118 J1.43
G1 X15
G3 Y2.742 J1.43
G1 X-15
G2 Y5.602 J1.43
G1 X15
G3 Y8.462 J1.43
G1 X-15
G18 G3 X-15.318 Z-0.683 K0.317
G0 Z16
G17
M9
G28 G91 Z0
G28 X0 Y0
M30
%
Pease help me

I’m not sure I’m understanding your issue, but I think the problem is most likely the lines with G28. Do you have homing switches? Do you know your G28 location? What post processor are you using?