[Pampop34]

Hello,

I have a cnc wood lathe and currently I only use g-code to program it, which is enough since I only produce simple things. The problem is that I cannot control acceleration or deceleration of the axes' movements. For example I want the Z axis start at a certain speed (say F15000) and I want it to slow down until F5000 when it moves 800 mm away. I read somewhere about this and it says we just write the speed code at the end of the line where we specify the end point as coordinates; for instance G01 F15000 / G01 Z825 X-110 F5000 (slash stands for next line). Supposedly it starts at F15000 and it is at Z70 X-80 for example, and it becomes F5000 when came to Z825 X-110. But this doesn't work! It just perceives the F code at the end of the last line as the speed of the whole movement. So I couldn't manage to observe any acceleration or deceleration that way.

Anybody has any knowledge about this and a suggestion? Even if you have any idea, please tell, I most probably need it!

[sinha_nsit]

As far as I know, continuous change if feedrate is not possible. It can be changed in steps.

[Pampop34]

As far as I know, continuous change if feedrate is not possible. It can be changed in steps.

By steps you mean each code line?

[sinha_nsit]

By steps you mean each code line?

Yes

[CNCFr]

It depends on the controller you are using.
There are controllers which support this feature and there are others which don't.

[ProToZyKo]

Im thinking a macro would help you here if there aren't any other functions, i have a simple program you can try, might need to adjust it for your machine and function.

(A=#1 NUMBER OF STEPS)
(Z=#26 Z DISTANCE TO GO)
(X=#24 X DISTANCE TO GO)
#104=#5003 (CURRENT Z)
#105=#5001 (CURRENT X)
#106=#4109 (CURRENT F)

#101=ABS[[#26-#5003]/#1] (Z MOVEMENT FOR EACH STEP)
#102=ABS[[#24-#5001]/#1] (X MOVEMENT FOR EACH STEP)
#103=ABS[[#9-#4109]/#1] (F CHANGE FOR EACH STEP)

N1
WHILE [#104 GE #26] DO1
#104=#104-#101
#105=#105-#102
#106=#106-#103
IF [#104 LT #26] THEN GOTO9999 (SAFETY CHECK)
IF [#105 LT #24] THEN GOTO9999 (SAFETY CHECK)

G1Z#104 X#105 F#106
END1
N9999
M99

[Pampop34]

It depends on the controller you are using.
There are controllers which support this feature and there are others which don't.

I am using Mach3 software on my PC, if it is what you mean as controller. If so, does it support this feature?

[Pampop34]

Im thinking a macro would help you here if there aren't any other functions, i have a simple program you can try, might need to adjust it for your machine and function.

(A=#1 NUMBER OF STEPS)
(Z=#26 Z DISTANCE TO GO)
(X=#24 X DISTANCE TO GO)
#104=#5003 (CURRENT Z)
#105=#5001 (CURRENT X)
#106=#4109 (CURRENT F)

#101=ABS[[#26-#5003]/#1] (Z MOVEMENT FOR EACH STEP)
#102=ABS[[#24-#5001]/#1] (X MOVEMENT FOR EACH STEP)
#103=ABS[[#9-#4109]/#1] (F CHANGE FOR EACH STEP)

N1
WHILE [#104 GE #26] DO1
#104=#104-#101
#105=#105-#102
#106=#106-#103
IF [#104 LT #26] THEN GOTO9999 (SAFETY CHECK)
IF [#105 LT #24] THEN GOTO9999 (SAFETY CHECK)

G1Z#104 X#105 F#106
END1
N9999
M99

Thanks for this. But I don't know anything about what this is. Is it another type of code for CNC like g-code?

[ProToZyKo]

A macro is a routine or sub-program that includes non-G-code commands. It is typically used for common operations that will be called many times in a program.
So the program works like a sub program, so put that in program O8000 or something then change G01 Z825 X-110 F5000 to G65 P8000 Z825 X-110 F5000 A1000(this value can be bigger og smaller depends on how often you want the feed to change)

[ger21]

Mach3 does not support If...Then and While in g-code.