Topics

1

General Mach Discussion / semi circle problems

« on: March 06, 2011, 05:47:45 PM »

I am trying to generate a set of semicircles centered at x-2.8125 and y=16.25.
The first semicircle works fine but the code stops on the highlighted line with this error "Radius from end of arc is different from radius to start"
The radius from start in the first semicircle is 2.8126-1.5 =1.3125 and radius to end is 4.125-2.8125 =1.3125 and this semicircle works.
The radius from the start in the second semicircle is 2.8125-1.125=1.6875 and the radius to the end is 4.5-2.8125=1.6875 and it does not work.
I am confused.  Any help?

G0 x1.5 y16.25
z-0.3125
G02 x4.125 y16.25 i2.8125 j16.25
G1 x1.125 y16.25
G02 x4.5 y16.25 i2.8125 j16.25
G1 Z0.1

2

General Mach Discussion / g20/g21 and g70/g71 problems

« on: March 03, 2011, 04:25:12 PM »

I have a problem with the g20/g21 and g70/71 codes.  Whenever I use any of these in a program I get unpredictable results.
I use the following short programs to illustrate the problem.  I move my z axis to the top of my table, and move the x
and y to a convenient place on the table.  I the zero all three DRO's and run program test1.  The results are that the three axis
each moved the predicted one inch.

(test1)
g0 f30
g1 x1 y1 z1 (move to x=1, y=1 z=1)
m1 (stop, read DRO's first time - cycle start to continue) (DRO's read x=1 y=1 z=1)
x0 y0 z0  (move back to orgin)
m30

Next I edit the g code (using Mach 3) to add a g 20 and regenerate the path
resulting in the following code.

 (test 2)
g0 f30 g20
g1 x1 y1 z1 (move to x=1, y=1 z=1)
m1 (stop, read DRO's  - cycle start to continue) (DRO's read x=1 y=1 z=1)
x0 y0 z0  (move back to orgin)
m30

As soon as I put the g20 into the code my DRO's changed from 0 to
x =-16.7674
y = -388.7217
z = -53.7139

Since the position was previously at 0,0,0 I zero all three axis to read 0's and regenerate the path.
I start the code and the machine immediately moves to the y and z stops and tries to keep going until
 I stop it manually (using escape).

If I remove the g20 the axis are still screwed up when I run the program.

If I replace the g20 with a g 21 then everthing goes back to normal in terms of movement,
 i.e. the 3 axis move one inch
when the program runs, however the speed of movement appears to be much slower than normal for f30.

Closing Mach3 and and loading a program without a g20 seems to make things normal again.
If I close mach3 and reload the program with the g21 in the movement seems to be OK but
 the speed of movement is still slower, i.e. the movement at f30 is not as fast as normal.

If I reload the program with a g70 in place of the g20 it behaves as if I used g20, i.e. g20 and g70 behave the same.
  If I use g71 instead of g21 I get the same results except the speed of movement seems normal for f30.

Since I never use mm it does not seem to be a problem if I simply leave the g20 out, however
 I like to keep my code portable which dictates that you not assume any previous machine conditions.

Any suggestions?

3

General Mach Discussion / axis problems

« on: February 27, 2011, 08:13:10 PM »

I am trying to learn how to use my new machine.  I am having a great deal of difficulty getting any repeatability in the movement of axis'.  I have set my homing position to z=0, y=23, z=3/6 on a 24 x 24 inch by 3. 6 inch platform and saved the configuration.  If I home my machine and close mach 3 and then reopen it my DRO's do not reflect the home position that I left the machine in.  I have done nothing other than close mach3 mill.  When I reopen mach3 mill my DRO's read all zero. It seems to me that they should show the home position since I have done nothing except close and reopen mach3 mill.  What am I missing?  Another problem I have is that when I insert a g20 into my program the measure unit go haywire.  In a simple program that works fine the first two lines are;
g0 f80
g1 z2 x8.5 y16
This program works fine.  If I make the first line
g0 f80 g20
the the x and y axis movement (per the DRO's) is scaled by ~1/28 and the z by ~ 1/22.  I have changed nothing except to edit the g code in Mach3 saved it and regenerated the tool path.

Image 1 is the DRO's prior to adding the g20, image 2 is the DRO's after the g20 is inserted and the x and y axis are manually moved (tab) 1 inch and the z axis 3.5 inches.

Any Help will be appreciated.

4

General Mach Discussion / axis reference problems

« on: February 24, 2011, 04:23:09 PM »

I set my homing limits up at x=0, y=23, z=3.5.  This represents the rear left corner of my table, i.e. x=0, y=0 is at the front left of my table.  I home my machine and set the DRO's to read at my home limits.   After I make any kind of move and rehome my DRO's are not at my set up home limits.  Consequently when ever I try to repeat a machining operation the operation happens at a different location even though I have not changes the g code.  What am I doing wrong?  Thanks for any help.

5

General Mach Discussion / g code display

« on: February 22, 2011, 07:16:14 PM »

Yesterday my g code display looked like g code, today it looks like this. 

"solid model
facet normal 0.0 -1.0 0.0
outer loop
vertex 2.25 -0.75 0.575051000000001
vertex 2.16221543349139 -0.75 -0.011426
endfacet
etc. 
What have I done to change my displayed gcode?


"