Messages

1

General Mach Discussion / Re: parts are the wrong size

« on: March 17, 2013, 03:07:17 PM »

status update!

i have gotten it all sorted out. i finally had the time to sit down and properly calculate the steps per for the y axis. the reality of it is still off a small amount from the calculated, but i know have it very accurate and repeatable. there was also a small amount of backlash that i am now compensating for as well. between the 2 the machine is now right on the money. at least in the y axis.

now i need to fix the x axis. this was the better of the 2 but now that the y is so dialed in, x is now the problem child.

i already know the problem here as well. it is direct drive and can not make small enough steps for the accuracy i am trying to achieve. so gear reduction is in order.


Thanks again to everybody who helped along the way. much appreciated!

2

General Mach Discussion / Re: parts are the wrong size

« on: February 25, 2013, 09:02:33 PM »

here is a screen capture of the settings




the "clearance" setting was set to .2000" when the above g code was generated. so i could see that being part of the problem. but when i set it lower i get the message show at the bottom of the screen. "msg.clearance <= step depth"

3

General Mach Discussion / Re: parts are the wrong size

« on: February 25, 2013, 08:58:46 PM »

this is the code for a 3" square pocket 1/8" (.125") endmill. i don't think the code is right. the final pass should be at 1.375" i still think my y steps are off and possibly a small amount of backlash.

Code: [Select]

G00 X0 Y0
G0 Z0.199
G01 Z-0.001 F6
X0 F6
X0.025 Y0.025
Y-0.025
X-0.025
Y0.025
X0.025
X0.05 Y0.05
Y-0.05
X-0.05
Y0.05
X0.05
X0.075 Y0.075
Y-0.075
X-0.075
Y0.075
X0.075
X0.1 Y0.1
Y-0.1
X-0.1
Y0.1
X0.1
X0.125 Y0.125
Y-0.125
X-0.125
Y0.125
X0.125
X0.15 Y0.15
Y-0.15
X-0.15
Y0.15
X0.15
X0.175 Y0.175
Y-0.175
X-0.175
Y0.175
X0.175
X0.2 Y0.2
Y-0.2
X-0.2
Y0.2
X0.2
X0.225 Y0.225
Y-0.225
X-0.225
Y0.225
X0.225
X0.25 Y0.25
Y-0.25
X-0.25
Y0.25
X0.25
X0.275 Y0.275
Y-0.275
X-0.275
Y0.275
X0.275
X0.3 Y0.3
Y-0.3
X-0.3
Y0.3
X0.3
X0.325 Y0.325
Y-0.325
X-0.325
Y0.325
X0.325
X0.35 Y0.35
Y-0.35
X-0.35
Y0.35
X0.35
X0.375 Y0.375
Y-0.375
X-0.375
Y0.375
X0.375
X0.4 Y0.4
Y-0.4
X-0.4
Y0.4
X0.4
X0.425 Y0.425
Y-0.425
X-0.425
Y0.425
X0.425
X0.45 Y0.45
Y-0.45
X-0.45
Y0.45
X0.45
X0.475 Y0.475
Y-0.475
X-0.475
Y0.475
X0.475
X0.5 Y0.5
Y-0.5
X-0.5
Y0.5
X0.5
X0.525 Y0.525
Y-0.525
X-0.525
Y0.525
X0.525
X0.55 Y0.55
Y-0.55
X-0.55
Y0.55
X0.55
X0.575 Y0.575
Y-0.575
X-0.575
Y0.575
X0.575
X0.6 Y0.6
Y-0.6
X-0.6
Y0.6
X0.6
X0.625 Y0.625
Y-0.625
X-0.625
Y0.625
X0.625
X0.65 Y0.65
Y-0.65
X-0.65
Y0.65
X0.65
X0.675 Y0.675
Y-0.675
X-0.675
Y0.675
X0.675
X0.7 Y0.7
Y-0.7
X-0.7
Y0.7
X0.7
X0.725 Y0.725
Y-0.725
X-0.725
Y0.725
X0.725
X0.75 Y0.75
Y-0.75
X-0.75
Y0.75
X0.75
X0.775 Y0.775
Y-0.775
X-0.775
Y0.775
X0.775
X0.8 Y0.8
Y-0.8
X-0.8
Y0.8
X0.8
X0.825 Y0.825
Y-0.825
X-0.825
Y0.825
X0.825
X0.85 Y0.85
Y-0.85
X-0.85
Y0.85
X0.85
X0.875 Y0.875
Y-0.875
X-0.875
Y0.875
X0.875
X0.9 Y0.9
Y-0.9
X-0.9
Y0.9
X0.9
X0.925 Y0.925
Y-0.925
X-0.925
Y0.925
X0.925
X0.95 Y0.95
Y-0.95
X-0.95
Y0.95
X0.95
X0.975 Y0.975
Y-0.975
X-0.975
Y0.975
X0.975
X1 Y1
Y-1
X-1
Y1
X1
X1.025 Y1.025
Y-1.025
X-1.025
Y1.025
X1.025
X1.05 Y1.05
Y-1.05
X-1.05
Y1.05
X1.05
X1.075 Y1.075
Y-1.075
X-1.075
Y1.075
X1.075
X1.1 Y1.1
Y-1.1
X-1.1
Y1.1
X1.1
X1.125 Y1.125
Y-1.125
X-1.125
Y1.125
X1.125
X1.15 Y1.15
Y-1.15
X-1.15
Y1.15
X1.15
X1.175 Y1.175
Y-1.175
X-1.175
Y1.175
X1.175
X1.2 Y1.2
Y-1.2
X-1.2
Y1.2
X1.2
X1.225 Y1.225
Y-1.225
X-1.225
Y1.225
X1.225
X1.25 Y1.25
Y-1.25
X-1.25
Y1.25
X1.25
X1.275 Y1.275
Y-1.275
X-1.275
Y1.275
X1.275
X1.3 Y1.3
Y-1.3
X-1.3
Y1.3
X1.3
X1.325 Y1.325
Y-1.325
X-1.325
Y1.325
X1.325
X1.35 Y1.35
Y-1.35
X-1.35
Y1.35
X1.35
X1.375 Y1.375
Y-1.375
X-1.375
Y1.375
X1.375
X1.4 Y1.4
Y-1.4
X-1.4
Y1.4
X1.4
X1.425 Y1.425
Y-1.425
X-1.425
Y1.425
X1.425
X1.4375 Y1.4375
Y-1.4375
X-1.4375
Y1.4375
X1.4375
G00 Z0.1
G00 Z0.1
M5 M9
M30


4

General Mach Discussion / Re: parts are the wrong size

« on: February 24, 2013, 11:53:25 PM »

ill post the g code when i get a chance, although i am pretty sure now that it is not a g code problem, it is looking like it is mechanical.

5

General Mach Discussion / Re: parts are the wrong size

« on: February 24, 2013, 12:50:27 PM »

ok, i have been spending a little more time with the machine. i think the steps per unit for the y axis were off, and still are a little bit, but i am getting pretty close.

i have been working on getting a good drawing test, had to spend some time rigging up a pen mount, i think i have something workable for now.

here is a good example of the drawing test.



the g code is for a 1/8" end mill 3" square pocket, so the magic number should be 2.875" which the x axis is dead on in the left square.

i think several things happened on the right one.

the x axis motor was getting very hot.
the x axis did not move very smoothly at that speed.
the pen did not write as well at that speed.

as you can see in both the y axis is not quite the correct size. now the x axis (the one that is perfect) is a direct drive from the motor, while the y has a belt drive gear reduction. i am trying to determine if there is some backlash in that setup. any tips on how to measure this or work it out are welcome!

6

General Mach Discussion / Re: parts are the wrong size

« on: February 12, 2013, 10:00:43 PM »

ok, i get that. ill try it.


isn't there a test pattern tho, like a bunch of fractals strung together that is supposed to search out lost steps?

7

General Mach Discussion / Re: parts are the wrong size

« on: February 12, 2013, 09:50:45 PM »

where does one find that drawing test?

8

General Mach Discussion / Re: parts are the wrong size

« on: February 12, 2013, 12:19:20 PM »

The machine uses stepper motors. Sorry, I should have specified that.

9

General Mach Discussion / Re: parts are the wrong size

« on: February 12, 2013, 09:00:55 AM »

Backlash comp is off, but I will double check it again.

Both are being cut exactly the same. I have every thing set very low. Feed rate is 6 ipm  accel is set equally low. The g force is .009

10

General Mach Discussion / parts are the wrong size

« on: February 11, 2013, 07:23:50 PM »

hi, i have been using mach for a while now on a cnc router that i built myself completely from scratch.

here is the situation. i have calibrated all the axis. everything moves accurately. ie if i move the x axis 1" or 30" it goes exactly that far +/- .005"

when i use any of the mach wizards, or g code from a cam program. the parts come out the wrong size.

if i run a hand written g code program they come out the right size.

here is an example of a simple g code program i wrote to cut the inside of a 1" square. i am using a .125" (1/8") cutter

Code: [Select]

g01
m03
z-.125
x-.9375
y.9375
x.9375
y-.9375
x-.9375
y0
z.1
and here is an example of the squares it cuts.



and here is an example of what happens with the mach 3 pocketing wizard.



as you can see they are not the right size. i am at a loss as to what could be causing this to happen.

i have also cut some parts with multiple passes for depth. ie. .100" doc. 5 times for .500" total. all of the steps line up exactly so i dont think i am loosing steps. and the manual code is also right on.


any ideas or help are greatly appreciated.