Hello Guest it is November 21, 2019, 09:15:12 PM

Author Topic: Mill just wanders off  (Read 4351 times)

0 Members and 1 Guest are viewing this topic.

Mill just wanders off
« on: March 06, 2009, 05:33:39 AM »
Whilst machining under mach3 control my mill just wanders off, this just happens on odd occasions. I have checked the wiring etc and I am at a bit of a loss.
Can anyone help please?

Clive

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
Re: Mill just wanders off
« Reply #1 on: March 06, 2009, 06:03:25 AM »
Clive - does this just "happen" or have you done something just before like "start from here" or similar.

It sounds like Mach 3 looses it's memory, which it can do if you "start from here" without backing up enough for Mach to have full details of it's position
Not me driving the engine - I'm better looking.
Re: Mill just wanders off
« Reply #2 on: March 06, 2009, 06:58:54 AM »
It seems to happen at the start of a sequence, it happened twice today once while cutting a 25 way d type hole it started to ramp in then carried on down the ramp line. and the same with a circle.

BClemens

*
Re: Mill just wanders off
« Reply #3 on: March 06, 2009, 01:06:06 PM »
So this 'wander away' is happening during a circular interpolation? Are you programming in incremental or absolute?

You may be attempting to run an incremental I&J program with Mach set for absolute. That can certainly 'wander off' for sure!

Bill C.
« Last Edit: March 06, 2009, 01:08:37 PM by BClemens »
Re: Mill just wanders off
« Reply #4 on: March 06, 2009, 01:52:45 PM »
Yes it is wandering after/during  a circular interpolation.
I am using a D2NC generated program and I dont know whether it is absolute or incremental.
But I will have a look at my settings. I think my machine is running as incremental as I reset the zero position.
Although I have made a few things I am still a bit green.

BClemens

*
Re: Mill just wanders off
« Reply #5 on: March 06, 2009, 04:14:40 PM »
When you regenerate your tool path, what do you see in the toolpath screen? You ought to see the part.... 

If Mach is not set to interpret I&J according to the program you should see that effect in that screen as very enlarged circles - that is if the program is in incremental and Mach is set for absolute. Try a known bad (wandering off) program again but go to general settings and check theincremental box for the I&J circular interpolation and see what happens.... slow her down in feed and go for it!  Absolute is the default setting.

Bill C.

backwards again.....but corrected! A mind is a terrible thing!
« Last Edit: March 06, 2009, 05:00:48 PM by BClemens »
Re: Mill just wanders off
« Reply #6 on: March 06, 2009, 05:44:33 PM »
The program appears to run correctly ie. after it wandered off I unloaded the program and reloaded it with no changes and it ran correctly.
So it doesnt appear to be program related and that was the same for the hole. However I had previously changed the zero position as each of the features had been set at 0,0 in autocad/dxf/D2NC, which relates to the absolute and incremental theory.
Have I just cheated?
Thanks Bill

BClemens

*
Re: Mill just wanders off
« Reply #7 on: March 06, 2009, 05:55:45 PM »
Mach is smart but dumb about cheating...it then thinks you're smart!

Bill C.

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
Re: Mill just wanders off
« Reply #8 on: March 07, 2009, 03:08:36 PM »
I was going to answer this earlier today, but my server went down.

You must be sure, when you start, that your machine is properly zeroed. This means the machine co-ordinates, and the program co-ordinates. If you do not, any offsets introduced will not necessarily result in the right position.

The machine keeps position by using machine co-ordinates - displayed on the DROs when the Machine Co-ordinates button is pressed and the surround is illuminted. If you have home switches fitted, then the only way to alter these is to "home" the machine. If you do not have them fitted, or have them disabled, then pressing "RefAllHome" with zero the DROs.

So - the way to start (if you have no home switches) is to jog to the X0Y0Z0 position of the program. Press the Machine Co-ords button, and the "RefAllHome" the DRO's will all zero. If you then press the Machine Co-ords button so the led surround goes out, you can now zero the DRO's (if they are not zero) by pressing the zeroX zeroY and zeroZ buttons. This zeros the program co-ordinates. If you check the Config/Fixtures table you will see that G54 (the default offset) is now zero.

If G54 is not zero, then some other offset is selected, and you should select G54 and repeat the procedure. Unless you use offsets, all the table should be zero, and you can clear any figures that show in there.

Your machine-co-ords and your program co-ords now coincide with each other, and you can run your program, without any stray offsets value interfering. The problem is that Mach3 alters its Machine-Co-ordinates to reflect the actual machine position, with all the offset values added to it, whereas the program co-ords reflect the value of X,Y and Z in the program. The two are often miles apart.


Not me driving the engine - I'm better looking.
Re: Mill just wanders off
« Reply #9 on: March 07, 2009, 06:15:27 PM »
Thanks Jim
I had guessed it might be finger trouble.
Trouble is only using the machine occasionally doesnt help, I did read the manual but that was a while ago.
I will probably get back up to steam again as I am converting my lathe to CNC at present.
Doing the lathe seems to be more daunting than the mill from the mach 3 point of view.
From a mechanical point of view the lathe is far easier to modify than the mill and an awful lot cheaper.

Clive