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Author Topic: Mach 3 putting in offsets? HELP!  (Read 5431 times)

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Mach 3 putting in offsets? HELP!
« on: April 07, 2010, 03:29:42 PM »
Hello folks
 I'm trying my hand at doing some G-Code writing. the file I've attached is the problem. I have written all of the lines(copy and paste) the same, BUT when I bring it into mach 3, it shows all the cuts offset by .010. if I run the program, it does cut .010 off each cut. I've checked my offsets,(g54 etc) they are all zero, i removed any G41/42, I'm at a loss, can someone help me?
 Thanks!

BTW I'm having fun "making chips!"

Offline Graham Waterworth

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Re: Mach 3 putting in offsets? HELP!
« Reply #1 on: April 07, 2010, 07:29:45 PM »
Half you problem is that the code is in incremental, if it starts in the wrong place it will remain in the wrong place until an absolute command is issued.

Have you a picture of what you are trying to machine?

Graham
America gave us powered flight, England the steam train and Germany the car.  Who invented the first boat?

Offline Tweakie.CNC

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Re: Mach 3 putting in offsets? HELP!
« Reply #2 on: April 08, 2010, 02:57:09 AM »
It's an interesting shaped toolpath you have created there - Not sure it could ever be made using a 3 Axis machine (because of the undercut) but interesting none the less.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Mach 3 putting in offsets? HELP!
« Reply #3 on: April 08, 2010, 06:37:30 AM »
 First, The shape is basically  a letter "T" with a small knob on the end. as for absolute, I realize if it doesn't start in the same position it will go off, but if you notice, after each "Perimeter" move there is an X0 Y0 command. as for cutting it on a 3 axis machine, I don't want an undercut, the code is for the perimeter to "Cut it out" of a slightly larger piece. this is why I need it to go straight down and not off set
 Any further suggestions would be great, thanks for the help.

Offline Tweakie.CNC

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Re: Mach 3 putting in offsets? HELP!
« Reply #4 on: April 08, 2010, 07:08:41 AM »
OK. An alternative approach:-

Write the code for your letter 'T' once only and set the Z depth to the maximum you require.
Then use the Mach Wizard 'Multi Pass', setting your incremental depth to create the toolpath for the numerous passes.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Mach 3 putting in offsets? HELP!
« Reply #5 on: April 08, 2010, 07:11:21 AM »
okay, thanks I'll give it a try.
 Thanks again
BP
Re: Mach 3 putting in offsets? HELP!
« Reply #6 on: April 10, 2010, 10:10:58 PM »
Well I tried it, but to no avail. I thought it might be in the machine setup, so I went back checked everything, made the machine do 50 repetitions of each axis, everyone were within .002. I then programmed a 2 inch by 2 inch square on .250 alu. gave it the boundry then hit multi pass, it cut a perfect square. so I guess I messed something up some where in the code.

Offline ger21

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Re: Mach 3 putting in offsets? HELP!
« Reply #7 on: April 11, 2010, 09:03:52 AM »
Here's the problem.

g01 G91 X.75 f1.5
g01 G91 y-.31
g01 G91 X-.285
g01 G91 y-.32
g01 G91 X.08
g01 G91 y-.31
g01 G91 x-.33
g01 G91 y.31
g01 G91 x.08
g01 G91 y.32
g01 G91 x-.285
g01 G91 y.31
g01 x0y0

Assuming you start at X=0, you move to X.75. Then to .465 (-.285) Then to .545 (.08) Then to .215 (-.33) Then to .295 (.08) then to .01(-.285). Your in incremental, so the G01 X0Y0 doesn't do anything. So your off by .01 when you move down and start again.

I also noticed at least one spot where the first Y-.31 was actually -.30.

Also, it's much easier to read if you just use one G91, instead of on every line. It stays incremental until you do a G90.
« Last Edit: April 12, 2010, 05:40:04 PM by ger21 »
Gerry

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Re: Mach 3 putting in offsets? HELP!
« Reply #8 on: April 12, 2010, 07:27:36 AM »
Thanks, I'll give it a try and get back.
Re: Mach 3 putting in offsets? HELP!
« Reply #9 on: April 24, 2010, 06:12:58 PM »
Thanks folks, it worked !!!!!!!! and is working well