Tangent Knife

[migoupil]

Hello Nick and all of us,

I'm trying somme tests with Tangent Knife but the result is acceptale for the moment but i'm not sure of my parameters on Gcodetools.
For the moment I'm asking if it's normal, when the metric unit is used in Inkscape that i must use a scale number for the 4th axis for having the result in degree. I've found on internet that someone put a scale of 180 to convert in degree from Inch. For me in metrics I've found a scale around value of 57,3. It's correct?
And in second time I see that there is a problem of velocity. When i write 400 for feed, this is the celerity for linear advance and the same celerity for the rotation, but in the reality we need two different feed.So is there a solution for controlling the 2 different speed? Post Processing for example? (I don't have any idea about post processing method or programming....)

I hope that i'm not too confused to explain my interrogation.

[NightV]

For me in metrics I've found a scale around value of 57,3. It's correct?

to convert Radian in Gradus use this formula
Grad = Rad * 180 / Pi
scale= 57,296321247

[migoupil]

Thank you NightV for your answer!

I see that i am lucky man. I'have an another question ; can i put 180/Pi in the Tool's scale? I'm going to try this.

Thank you again!

[NightV]

no. write the numbers in the parameter
as here

Grad.jpg (8.97 КБ) 16182 просмотра

[migoupil]

I do it like your example. I've tried with 180/math.pi but i think that there is a problem with "," symbol instead ".". So with the number it's correct.
For the second matter, I think that for rotation speed there one Gcode instruction S. I will try tomorrow, and then i will tell you if it works.

Thank's

[NightV]

yes, you are right, my mistake, of course point (.)
more accurately be
57.295779513082320876798154814105
although this will be enough... Even with an excess of
57.295779513

which feed? rotary axis (tangent knife)?
it is automatically specified. knife just follow of the XY trajectory

[migoupil]

I talk about the rotation speed of the A axis, for me it's the rotary axis of my tangent Knife( it's a cutter made with a step motor ). I didn't have enough time to try the 'S' Gcode instruction yesterday, but i will do today (I hope ). Perharps, S is for the spindle motor, so i want to verify. Then if it's not the way, i'll try G02 instruction or an another solution to have to different speed for linear and rotaion motion.

I will tell you what i found or not!!!!!

[Nick]

S is not for A-axis. S is for spindle!

Why do you want to change rotation speed for the tangent knife?
Motion controller will change it automatically to make axis move synchronous.

If you want to change maximum rotation speed - then you should do it in machine config in LinuxCNC or Mach3...

[migoupil]

Hello Nick,
Yes, i note that that S command will affect the spindle speed . In fact, i use EMC2. There is a button for controlling, manually, the rotation speed for the A axis. But, there is a But (French joke), I don't find a command to control the speed rotation of an axis in GCODE. So the question is there one or should i complete a command for a speed rotation to 16000 deg/min like this :
Original command
A180
to
A180 F16000

If this solution is the only one, I should i find a solution with a post processor command?

Thank you

[migoupil]

Hi Nick,

I need your help. Do you think that with the regex command post-processor i can make a insert line before and after line of A rotation.I explain by an example of the result that i expected.
Original code
G01 A180

After Post
G01 F16000
G01 A180
G01 F400

I try many time with the example i found in a post in this forum but i don't succeed! Like in the post as time i don't understand the regular expression. if there a post about it or a tuto i want to read it for understand!

Thank's

[NightV]

I think no problem. postprotsesor in writing, that if we meet the A10 (for example) after the insert F multiplied (eg 20) obtain F200.
that is, just the speed of rotation multiplied by ... something. as I understood

[migoupil]

Hi,
I have found my solution . With a command regex, i just transform G01 A to G00 to G00 A. Then i have create an entry in the gcodetools_path-to-gcode.inx with the information i have found in this forum.
my command regex , put in the inx file is that :

<_item value='regex("G01 A","G00 A");'>Tangent Knife</_item>

It works well as i wanted!!!

Thank you for your advice

[NightV]

anytime

[badger]

Migoupil -

Excellent solution with the regex! I have been dealing with this issue in the thread "gearing of axis for stitch regulation". I think most of the issue has to do with LinuxCNC dealing with all "units" as equal. 400 inches per minute may be a fast machine, but 400 degrees per minute is very slow for rotation of a knife. Using your regex to get the rotation to be G00 gives a lot of flexibility in speeding things up in the ini file.

- Badger