J'utilise un petit PC portable. Je peu toujours essayer avec un PC plus puissant.

Tu peux partager ton gcode complet? Moi de mon coté je sèche complet face a ton problème.
Autre info qu'est ce ce que tu as comme broche et quel matière tu usines? Quelle fraise?
Bon serrage de la fraise sur la machine? Un essai en baissant la vitesse d avance. Pour grbl j'ai une acceleration plus faible (120) mais je suis en full nema17 et ma broche est tres lourde.
Serrage des poulies sur la vis du Z. Ne pas hesiter a faire un petit meplat sur la vis.
Tension de la courroie du Z

(Test)
(T1 D=5 CR=0 - ZMIN=-18 - fraise deux tailles)
G90 G94
G17
G21
(When using Fusion 360 for Personal Use, the feedrate of)
(rapid moves is reduced to match the feedrate of cutting)
(moves, which can increase machining time. Unrestricted rapid)
(moves are available with a Fusion 360 Subscription.)
(Poche 2D1)
T1
S5000 M3
G54
G0 X2.878 Y-2.035
Z10
G1 Z5 F800
Z0
G3 X5.372 Y2.007 Z-0.261 I1.247 J2.021 F333.3
X2.878 Y-2.035 Z-0.521 I-1.247 J-2.021
X5.372 Y2.007 Z-0.782 I1.247 J2.021
X2.878 Y-2.035 Z-1.042 I-1.247 J-2.021
X5.372 Y2.007 Z-1.303 I1.247 J2.021
X2.878 Y-2.035 Z-1.563 I-1.247 J-2.021
X5.372 Y2.007 Z-1.824 I1.247 J2.021
X1.75 Y-0.014 Z-2 I-1.247 J-2.021
X3 Y-0.014 I0.625 J0 F800
X-3 Y-0.014 I-3 J0
X7.75 Y-0.014 I5.375 J0
X-7.75 Y-0.014 I-7.75 J0
X12.5 Y-0.014 I10.125 J0
X-12.5 Y-0.014 I-12.5 J0
X12.5 Y-0.014 I12.5 J0
X11.432 Y0.883 I-0.911 J0
G1 X7.248 Y0.15
X7.144 Y0.138
X7.04
X6.954 Y0.139
X6.868 Y0.131
X3.235 Y-0.358
G3 X2.878 Y-2.035 I0.121 J-0.903
X5.372 Y2.007 Z-2.261 I1.247 J2.021 F333.3
X2.878 Y-2.035 Z-2.521 I-1.247 J-2.021
X5.372 Y2.007 Z-2.782 I1.247 J2.021
X2.878 Y-2.035 Z-3.042 I-1.247 J-2.021
X5.372 Y2.007 Z-3.303 I1.247 J2.021
X2.878 Y-2.035 Z-3.563 I-1.247 J-2.021
X5.372 Y2.007 Z-3.824 I1.247 J2.021
X1.75 Y-0.014 Z-4 I-1.247 J-2.021
X3 Y-0.014 I0.625 J0 F800
X-3 Y-0.014 I-3 J0
X7.75 Y-0.014 I5.375 J0
X-7.75 Y-0.014 I-7.75 J0
X12.5 Y-0.014 I10.125 J0
X-12.5 Y-0.014 I-12.5 J0
X12.5 Y-0.014 I12.5 J0
X11.432 Y0.883 I-0.911 J0
G1 X7.248 Y0.15
X7.144 Y0.138
X7.04
X6.954 Y0.139
X6.868 Y0.131
X3.235 Y-0.358
G3 X2.878 Y-2.035 I0.121 J-0.903
X5.372 Y2.007 Z-4.261 I1.247 J2.021 F333.3
X2.878 Y-2.035 Z-4.521 I-1.247 J-2.021
X5.372 Y2.007 Z-4.782 I1.247 J2.021
X2.878 Y-2.035 Z-5.042 I-1.247 J-2.021
X5.372 Y2.007 Z-5.303 I1.247 J2.021
X2.878 Y-2.035 Z-5.563 I-1.247 J-2.021
X5.372 Y2.007 Z-5.824 I1.247 J2.021
X1.75 Y-0.014 Z-6 I-1.247 J-2.021
X3 Y-0.014 I0.625 J0 F800
X-3 Y-0.014 I-3 J0
X7.75 Y-0.014 I5.375 J0
X-7.75 Y-0.014 I-7.75 J0
X12.5 Y-0.014 I10.125 J0
X-12.5 Y-0.014 I-12.5 J0
X12.5 Y-0.014 I12.5 J0
X11.432 Y0.883 I-0.911 J0
G1 X7.248 Y0.15
X7.144 Y0.138
X7.04
X6.954 Y0.139
X6.868 Y0.131
X3.235 Y-0.358
G3 X2.878 Y-2.035 I0.121 J-0.903
X5.372 Y2.007 Z-6.261 I1.247 J2.021 F333.3
X2.878 Y-2.035 Z-6.521 I-1.247 J-2.021
X5.372 Y2.007 Z-6.782 I1.247 J2.021
X2.878 Y-2.035 Z-7.042 I-1.247 J-2.021
X5.372 Y2.007 Z-7.303 I1.247 J2.021
X2.878 Y-2.035 Z-7.563 I-1.247 J-2.021
X5.372 Y2.007 Z-7.824 I1.247 J2.021
X1.75 Y-0.014 Z-8 I-1.247 J-2.021
X3 Y-0.014 I0.625 J0 F800
X-3 Y-0.014 I-3 J0
X7.75 Y-0.014 I5.375 J0
X-7.75 Y-0.014 I-7.75 J0
X12.5 Y-0.014 I10.125 J0
X-12.5 Y-0.014 I-12.5 J0
X12.5 Y-0.014 I12.5 J0
X11.432 Y0.869 I-0.899 J0
G1 X7.299 Y0.08
X7.202 Y0.067
X7.105 Y0.065
X2.858 Y0.166
G3 X2.051 Y-1.171 I-0.021 J-0.899
X6.199 Y1.143 Z-8.261 I2.074 J1.157 F333.3
X2.051 Y-1.171 Z-8.521 I-2.074 J-1.157
X6.199 Y1.143 Z-8.782 I2.074 J1.157
X1.75 Y-0.014 Z-9 I-2.074 J-1.157
X3 Y-0.014 I0.625 J0 F800
X-3 Y-0.014 I-3 J0
X7.75 Y-0.014 I5.375 J0
X-7.75 Y-0.014 I-7.75 J0
X12.5 Y-0.014 I10.125 J0
X-12.5 Y-0.014 I-12.5 J0
X12.5 Y-0.014 I12.5 J0
G1 Z10
(When using Fusion 360 for Personal Use, the feedrate of)
(rapid moves is reduced to match the feedrate of cutting)
(moves, which can increase machining time. Unrestricted rapid)
(moves are available with a Fusion 360 Subscription.)
(Contour 2D2)
G0 Z15
X29 Y6.159
G1 Z5 F800
Z0.5 F333.3
G18 G3 X28.5 Z0 I-0.5 K0 F800
G1 X28
G17 G3 X27.5 Y5.659 I0 J-0.5
G1 Y-19.833 Z-0.89 F333.3
G2 X20 Y-27.333 Z-1.302 I-7.5 J0
G1 X0 Z-2
X-20 F800
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y19.61
G2 X-20.042 Y27.11 I7.5 J0
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X0
X-20 Z-2.698 F333.3
G2 X-27.5 Y-19.833 Z-3.11 I0 J7.5
G1 Y5.659 Z-4
Y19.61 F800
G2 X-20.042 Y27.11 I7.5 J0
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y5.659
Y19.61 Z-4.487 F333.3
G2 X-20.042 Y27.11 Z-4.897 I7.5 J0
G1 X11.54 Y27.286 Z-6
X19.958 Y27.332 F800
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y5.659
Y19.61
G2 X-20.042 Y27.11 I7.5 J0
G1 X11.54 Y27.286
X19.958 Y27.332 Z-6.294 F333.3
G2 X27.5 Y19.833 Z-6.707 I0.042 J-7.5
G1 Y-17.199 Z-8
Y-19.833 F800
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y19.61
G2 X-20.042 Y27.11 I7.5 J0
G1 X11.54 Y27.286
X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-17.199
Y-19.833 Z-8.092 F333.3
G2 X20 Y-27.333 Z-8.503 I-7.5 J0
G1 X-20 Z-9.9
G2 X-22.789 Y-26.795 Z-10 I0 J7.5
X-27.5 Y-19.833 I2.789 J6.962 F800
G1 Y19.61
G2 X-20.042 Y27.11 I7.5 J0
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-17.199
Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-22.789 Y-26.795 I0 J7.5
X-27.5 Y-19.833 Z-10.312 I2.789 J6.962 F333.3
G1 Y19.61 Z-11.689
G2 X-22.804 Y26.566 Z-12 I7.5 J0
X-20.042 Y27.11 I2.804 J-6.956 F800
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y19.61
G2 X-22.804 Y26.566 I7.5 J0
X-20.042 Y27.11 Z-12.099 I2.804 J-6.956 F333.3
G1 X19.958 Y27.332 Z-13.496
G2 X27.5 Y19.833 Z-13.909 I0.042 J-7.5
G1 Y17.216 Z-14
Y-19.833 F800
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y19.61
G2 X-20.042 Y27.11 I7.5 J0
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y17.216
Y-19.833 Z-15.294 F333.3
G2 X20 Y-27.333 Z-15.705 I-7.5 J0
G1 X11.557 Z-16
X-20 F800
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y19.61
G2 X-20.042 Y27.11 I7.5 J0
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X11.557
X-20 Z-17.102 F333.3
G2 X-27.5 Y-19.833 Z-17.513 I0 J7.5
G1 Y-5.898 Z-18
Y19.61 F800
G2 X-20.042 Y27.11 I7.5 J0
G1 X19.958 Y27.332
G2 X27.5 Y19.833 I0.042 J-7.5
G1 Y-19.833
G2 X20 Y-27.333 I-7.5 J0
G1 X-20
G2 X-27.5 Y-19.833 I0 J7.5
G1 Y-5.898
G3 X-28 Y-5.398 I-0.5 J0
G1 X-28.5
G18 G3 X-29 Z-17.5 I0 K0.5
G1 Z15
G17
M5
M30

J'utilise une fraiseuse Makita RT0700C. Pour le test, j'utilise une fraise droite de 5mm pour usiner un bout de lamellé-collé relativement tendre. Tout est bien serré et la courroie est bien tendue. J'ai essayé plusieurs stats de vitesses et d'accélérations.

Petite observation que j'ai faite aujourd'hui : Pendant la plongée en hélice, le moteur de l'axe Z tourne pendant approximativement  2 sec puis s'arête de tourner 2 sec, puis repart pendant 2 sec, etc... alors qu'il devrait tourné de manière régulière sans s'arrêter jusqu'au premier plat qui se situe à -2mm. (ligne de code 21 à 28).

Bien sur l'erreur se reproduit à chaque reprise de plongée en hélice. (de -2 à -4mm... de -4 à -6mm... etc...)

Ok tu doit avoir un problème de chauffe alors, le driver fait tourner le moteur 2 secondes, puis se met en securité 2 secondes pour refroidir etc .. essaye de voir si ton driver est brulant ou pas 

Effectivement le driver est brulant mais j'ai déjà essayé avec un driver externe DM542T qui ne chauffe pas beaucoup et ça ne changeait rien. Tu pense que je devrais quand même mettre un dissipateur plus gros sur le DRV8825 ?

J'ai réglé le problème en changeant les cartes Arduino et CNC Shield. Peut être que le condensateur de l'axe Z était défectueux. En tout cas merci pour votre aide. J'espère pouvoir apporter mon aide un de ces quatre histoire de renvoyer l'ascenseur à ceux qui en ont besoin.

vraiment bizarre ton soucis. en tout cas tant mieux si le probleme est resolu