Rotation axis problem.

[Pavshi]

Hi @fra589 On my cnc the fourth axis is a tangential knife. when i send the command G2/3 like: G02 X46.336814 Y25.635248 Z-1.000000 I-8.700505 J3.892172 A-2.39463684581 the knife does not turn while moving in an arc, he turns after moving, at the end of the arc :-(( Can you help me with this problem? I'm trying to figure out gcode.c but so far without success.

I'd like to solve it with your help.

[fra589]

Hi @Pavshi,

Circular interpolation work like defined in the LinuxCNC documentation... But in this documentation, only a third axis is used for helix movement. So, I don't study other special cases like the one you need now... I think perhaps it will be possible, but not so easy :-$ Then, it only will be a time linear interpolation between the start position and the final position (at N% of circular movement, the 4th axis will have the same N% of his total movement). So, your knife will not be exactly tangent to the circle... Perhaps it will be better for you to make those movements with many linear movements interpolation.

@++; Gauthier.

By the way, dont forget to tell your exact version and config (output of $I and $$) when you ask for a new issue...

[fra589]

Hi @Pavshi,

I just tested the scenario that you ask, which I had not done before my previous answer, and the axis A moves well at the same time as the others (4 simultaneous axis, test without motors)...

Which version of grbl-Mega-5X are you using? Tapes $I to find out and post the answer. Also post the result of the $$ command, this will save us time...

@++;
Gauthier.

[Pavshi]

Hi, Gauthier! thank you very much for such a quick reply :-) Here is the version I last used: $I [VER:1.1h Atmega 2560 6-axis + Sync/MPG.20180311:] [OPT:VNM] ok

Now I uploaded your latest version to Arduino, but have some problems with pins. I don't use Ramps. And I'm a little confused. Only x,y,z in top of cpu_map.h.

$$ $0=10 $1=255 $2=0 $3=1 $4=0 $5=0 $6=0 $10=3 $11=0.010 $12=0.002 $13=0 $20=0 $21=0 $22=0 $23=0 $24=25.000 $25=500.000 $26=250 $27=1.000 $30=1000 $31=0 $32=0 $100=538.182 $101=1613.115 $102=133.124 $103=1152.377 $104=250.000 $105=250.000 $110=800.000 $111=800.000 $112=800.000 $113=1500.000 $114=500.000 $115=500.000 $120=50.000 $121=50.000 $122=50.000 $123=50.000 $124=10.000 $125=10.000 $130=200.000 $131=200.000 $132=100.000 $133=200.000 $134=200.000 $135=200.000 ok $G [GC:G0 G54 G17 G21 G90 G94 M5 M9 T0 F0 S0] ok

[fra589]

Hi @Pavshi,
Your $I output don't come from my own grbl-Mega-5X version!?
I can't debug other versions since grbl-Mega-5X already take me a lot of time!

For my own version: grbl-Mega-5X support more than 3 axis only with the CPU_MAP_2560_RAMPS_BOARD definition. So, even if you don't use the RAMPS board, you need to define in config.h:

#define DEFAULTS_RAMPS_BOARD
#define CPU_MAP_2560_RAMPS_BOARD

and use the section after the sentence #ifdef CPU_MAP_2560_RAMPS_BOARD, line 136 in cpu_map.h.

There, you will find where to plug your hardware or to change the definitions to conform to your need, see the wiki page: https://github.com/fra589/grbl-Mega-5X/wiki/Pinout-mapping-in-cpu_map.h

@++;
Gauthier.

[Pavshi]

Bonsoir, Gauthier! I finally figured out the ports and pins :-) And voilà :-))) It's working !!! Your version really do it (4th axis rotates by G2/3). I’m still testing it, but what I see is very good. Now I'm happy, I can say good buy to Windows and Mach3 :-))) Thank you so much for your work. $I [VER:1.1m.20200420:] [AXS:5:XYZAB] [OPT:VNMH,35,255,0] ok :1st_place_medal: