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Topics - abhi

Pages: 1
General Mach Discussion / quick question re axis formulas
« on: August 02, 2012, 05:14:30 AM »
can anyone tell me if the axis formula(s) operate from machine coordinates or from G54 offset?

General Mach Discussion / How far can I push axis formulas?
« on: July 22, 2012, 07:46:09 AM »
Im wanting to attempt something of a large equation and in axis formulas and wondering if anyone has tried something like this.

this is what it looks like in code with variables, it would get a bit longer (lol) without the variables due to repetition. Am I barking out the wrong tree?

for iy in 1 to 10 do
   for ix in 1 to 10 do
      Ymax = 10
      Xmax = 10
      Tx = x/Xmax
      Ty = y/Ymax
      X_1a= 0.0
      X_1b= 5.0
      X_1c= 0.0
      X_3a= 20.0
      X_3b= 500.0
      X_3c= 10.0
      X_5a= 5.0
      X_5b= 200
      X_5c= 10.0
      X_2a= X_3a*0.1+X_1a
      X_4a= X_3a*0.1+X_5a
      X_2b= X_3b*0.1+X_1b
      X_4b= X_3b*0.1+X_5b
      X_2c= X_3c*0.1+X_1c
      X_4c= X_3c*0.1+X_5c
      Y_1= (1.0-Tx)^4.0*X_1a+4.0*(1.0-Tx)^3*Tx*X_2a+4*(1.0-Tx)^2*Tx^2*X_3a+4.0*(1.0-Tx)*Tx^3*X_4a+Tx^4*X_5a
      Y_3 =(1.0-Tx)^4.0*X_1b+4.0*(1.0-Tx)^3*Tx*X_2b+4*(1.0-Tx)^2*Tx^2*X_3b+4.0*(1.0-Tx)*Tx^3*X_4b+Tx^4*X_5b
      Y_5 =(1.0-Tx)^4.0*X_1c+4.0*(1.0-Tx)^3*Tx*X_2c+4*(1.0-Tx)^2*Tx^2*X_3c+4.0*(1.0-Tx)*Tx^3*X_4c+Tx^4*X_5c
      Y_2 = Y_3*0.01+Y_1
      Y_4 = Y_3*0.01+Y_5
      zPos =(1.0-Ty)^4.0*Y_1+4.0*(1.0-Ty)^3*Ty*Y_2+4*(1.0-Ty)^2*Ty^2*Y_3+4.0*(1.0-Ty)*Ty^3*Y_4+Ty^4*Y_5
      Point pos:[ix*10,iy*10,zPos] size:1
 this code makes an array of points using a modified bezier equation in 3DSmax. Im also thinking of ways to shorten it but keep on wishing for arbitrary variables.

Is is possible to do this with VB, I've not tried my hand with that so I don't really know how difficult it would be.


Ive been doing lots of tests/measurements to correct machine geometry. Both my x and y slump in the middle due to gantry weight and the z also gradually rotates around the y axis apexing in the middle. My linear slides are round bar, for the moment I cant afford to change or add rigidity to the arraignment so I put my thinking cap on and it occurred to me that I could correct these curved looking problems with a parabolic equation. I don't have to correct by much but enough for things to not fit together very well at all.

the standard equation looks like this, so I still have to alter it to get the arc I'm looking for.
Y=(x-a) 2 +b

where a and b are the apex offset of the deflection the "a" term is also has to be inverted (+/-) to give proper cartesian placement.
I haven't tried this yet but wanted to know if there is any reason why it wouldn't or I shouldn't.

General Mach Discussion / M03 code causeing seamingly random problem.
« on: July 09, 2012, 04:46:38 AM »

okay ive been using the 2010 screen set under mach 3.042.040. After it completes an M06 and goes back to the last position before the M06 call then does the M03 mach doesn't always pause for the spindle spin up and instead executes the next move (usually a G0) and very soon after stalls my x and often my Y motors. Anyone else run into this? also looking at the code the execution line looks something like this.

N300 G00 X233.05 Y130. S2000 M03

The error does not happen every time which has made it hard to trouble shoot. I've been through checking the motors, made some inertial dampers, set the max speed to something reasonable 3000mm per sec (around 118ips) and accel at 150 (0.01g).

Any help or doughnuts welcome.

hi, im just setting up a new machine, its a gantry with ball screws driven by steppers (3.5a 387 oz.inch), gecko g540 and of course mach3 running under winXP. Im still working out the right tuning for the motors but everything works well when jogging around.

the thing that is giving me trouble is getting any kind of smoothness out of the machine when running gcode, it seems to be behaving as though its in exact stop mode. after exhausting all the recomended setting then trying rediculous settings, i thought is could be an issue with accel/decel values so i tried real slow through to almost painful.

the file im running is the road runner so i dont think its the gcode, the settings i gave are holding between restarts of mach3. Ive also added the G64 code to make sure that its turned on. ive hunted across the interweb trying to find the same issue but havent found anything the same save for when people are running it in exact stop mode.

...could it be an inch/mm thing? im running mm for units.

 any help would be very appreciated  :)

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