MPCNC - Fusion360 CAM - XY axis go negative

Mostly Printed CNC - MPCNC Troubleshooting
1

Hi guys,

I have a problem with Fusion 360. I use this postprocessor: https://github.com/guffy1234/mpcnc_posts_processor. Whenever I generate the gcode from fusion the x and y axis have negative values.

Before I start the gcode, I position the tool head manually and home all axes with G92. Then I start the gcode and the machine instantly stops with the error “outside machine limits”.

Here’s an example of the gcode:
;Fusion 360 CAM 2.0.8407
; Posts processor: DIYCNC_RepRapFW.cps
; Gcode generated: Sonntag, 31. Mai 2020 17:23:07 GMT
; Document: Unbenannt
; Setup: Setup1
;
; Ranges table:
; X: Min=-372.45 Max=375.4 Size=747.85
; Y: Min=-357.948 Max=357.248 Size=715.196
; Z: Min=-2 Max=15 Size=17
;
; Tools table:
; T1 D=16 CR=0 - ZMIN=-2 - Schaftfraser

; *** START begin ***
G90
G21
M84 S0
G92 X0 Y0 Z0
; *** START end ***

; *** SECTION begin ***
;Planen1 - Milling - Tool: 1 -  Schaftfraser
; X Min: -372.45 - X Max: 375.4
; Y Min: -357.948 - Y Max: 357.248
; Z Min: -2 - Z Max: 15
M453 P2 I0 R30000 F200
; COMMAND_START_SPINDLE
; COMMAND_SPINDLE_CLOCKWISE
M291  P"Turn ON 5000RPM" R"Spindle" S3
; COMMAND_COOLANT_ON
M117  Planen1
G0 Z15 F300
G0 X375.4 Y-357.948 F2500
G0 Z5 F300
; MOVEMENT_LEAD_IN
G1 Z-0.4 F1000
G1 X375.396 Z-0.509 F1000
G1 X375.385 Z-0.618 F1000
G1 X375.367 Z-0.726 F1000
G1 X375.341 Z-0.832 F1000
G1 X375.308 Z-0.936 F1000
G1 X375.268 Z-1.037 F1000
G1 X375.221 Z-1.136 F1000
G1 X375.167 Z-1.231 F1000
G1 X375.107 Z-1.323 F1000
G1 X375.041 Z-1.41 F1000
G1 X374.969 Z-1.492 F1000
G1 X374.892 Z-1.569 F1000
G1 X374.81 Z-1.641 F1000
G1 X374.723 Z-1.707 F1000
G1 X374.631 Z-1.767 F1000
G1 X374.536 Z-1.821 F1000
G1 X374.437 Z-1.868 F1000
G1 X374.336 Z-1.908 F1000
G1 X374.232 Z-1.941 F1000
G1 X374.126 Z-1.967 F1000
G1 X374.018 Z-1.985 F1000
G1 X373.909 Z-1.996 F1000
G1 X373.8 Z-2 F1000
G1 X365 F1000
2

Based on the ranges, I’d guess you’re modelling with the origin at the center of your object, instead of out at the lower left edge. I don’t know if @guffy’s post processor can auto-correct that origin for you, but you should be able to move your object in F360 to get the origin out of the center.

3

Don’t even have to move the object. In the manufacturing setup, on the first panel, select stock box point and just click the corner where you want the cam origin to be. The little red /green/blue gimmick will move there. Re post. Done.

2 Likes
4

That doesn’t look normal. Is that normal? Is it possible you didn’t “select” the guffy pp?

5

Are you using the right post processor for the right board? That isn’t the right post processor if you’re using a Marlin board (e.g., Rambo or mini Rambo).

When I open the config in the post processor window I get this:

/*

MPCNC posts processor for milling and laser/plasma cutting.

*/
include(“DIYCNC_Common.js”);

description = “DIYCNC Milling/Laser - Marlin 2.0”;

mergeProperties(properties, properties3dPrinter);
mergeProperties(propertyDefinitions, propertyDefinitions3dPrinter);

function FirmwareMarlin20() {
Firmware3dPrinterLike.apply(this, arguments);
}
FirmwareMarlin20.prototype = Object.create(Firmware3dPrinterLike.prototype);
FirmwareMarlin20.prototype.constructor = FirmwareMarlin20;

currentFirmware = new FirmwareMarlin20();

1 Like
6

I haven’t encountered anything that sets the origin via post processor settings.

I concur that it is likely a need to select a WCS in the lower left using a stock box point as Turbomacncheese describes.

3 Likes
7

Might be spindle control automatic?

8

How do I do that? Didn’t mean to jump in here but there is no pp profile, that I can find, that’s able to be selected from within F360.

9

I don’t use fusion, but the guffy pp is linked at the bottom of milling basics. I am guessing the install instructions are there

10

Thanks for your time much appreciated!