Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: aconstruction on April 17, 2013, 09:42:18 PM

Title: Random wrong direction axis moves
Post by: aconstruction on April 17, 2013, 09:42:18 PM

I am getting random axis moves in the wrong direction.
It can occur on any axis and seems to happen at random times.
Usually everything works as it should but a couple times a day it will go the wrong way in the middle of a program that usually runs fine.
My setup is: Mach3, windows XP, CNC4PC C11 breakout board, automation technology drives

Thanks for any suggestions
Title: Re: Random wrong direction axis moves
Post by: BR549 on April 17, 2013, 11:04:08 PM
Might want to post a copy of your XML for HOOD to double check.

(;-) TP
Title: Re: Random wrong direction axis moves
Post by: diyengineer on April 18, 2013, 06:58:00 AM
Is it when running a program, or your spindle is on? Maybe noise?
Title: Re: Random wrong direction axis moves
Post by: aconstruction on April 22, 2013, 10:38:51 AM
Is it when running a program, or your spindle is on? Maybe noise?

It happens only when running a program and right after a tool change. Yes the spindle is running and is under mach3 control.  It happens with programs that usually run correctly.
Title: Re: Random wrong direction axis moves
Post by: Hood on April 22, 2013, 11:16:49 AM
Attach your xml and I will check your setup.
Hood
Title: Re: Random wrong direction axis moves
Post by: aconstruction on April 22, 2013, 06:17:09 PM
Thank you Hood. Here is my XML file.
Title: Re: Random wrong direction axis moves
Post by: CalJet on April 22, 2013, 09:40:44 PM
At the risk of stepping on aconstruction's post.

I have a very similar problem.

Mach 3 while running a profile pass on a part has done two passes at different depths.

Then on the third pass which is exactly the same other than depth decides to change direction and cut into the part.

This always seems to happen on a radius.

I have attached my XML.
Title: Re: Random wrong direction axis moves
Post by: Hood on April 23, 2013, 02:56:52 AM
Ok, both aconstruction and CalJet can you tell me if, when the axis goes awry, the toolpath view shows it doing the correct motion and it is just the axis actually going wrong?

Hood
Title: Re: Random wrong direction axis moves
Post by: CalJet on April 23, 2013, 03:57:26 AM
Hood,

From memory (I usually hit the E stop to try and save the part) the tool path display shows what the tool is doing ie: it shows it going of course
not following the program.

Caljet
Title: Re: Random wrong direction axis moves
Post by: Hood on April 23, 2013, 02:13:31 PM
Ok if it is going off track on the toolpath then Mach is telling it to do so, so it would be good to know for sure. If you can try and take notes of what exactly has happened when it does so and also be sure to check the toolpath  view it would be a great help in hopefully finding the issue.
Hood
Title: Re: Random wrong direction axis moves
Post by: aconstruction on April 25, 2013, 01:10:00 PM
Hood,

I watched it closely this time.  The tool position was exactly where the toolpath display said it should be.

This is what happened today:

The first two parts ran flawlessly

The third part started off ok but then after a tool change mach3 executed the z move first, milling down into the part in the wrong location and then plowed through it to the proper x and y coordinate where it proceeded to mill the pocket

This is just one example sometimes the random moves can be far from their proper position.
Title: Re: Random wrong direction axis moves
Post by: Hood on April 25, 2013, 04:54:03 PM
Would it be possible for you to try something. Can you put
M5
M1
M3

In your code just before a tool change and then in General Config set it to ignore tool change and see if it runs ok. Obviously you will have to remember you have done that as all code you load with ignore tool change set will just run straight past a tool change unless you do as above on every single tool change.

With the above the spindle will stop and so will the code, once you have changed tools pressing start should start the spindle and the file will carry on.
Hood
Title: Re: Random wrong direction axis moves
Post by: aconstruction on April 25, 2013, 08:00:42 PM
Well I just made the changes you suggested and ran 5 parts without any problem.  That just might be the solution.

I am curious what is going on here behind the scenes.  Is the M6 command contributing to the random moves?

Another interesting thing happens with your code, After a tool change the spindle now starts at the previous speed and noticeably changes to the new tool speed. I don't remember this happening before.
Title: Re: Random wrong direction axis moves
Post by: Hood on April 26, 2013, 02:55:34 AM
I am thinking it may be something in the M6End macro that is being ignored  during the toolchange. The M6End macro is only used when in the Stop Spindle and wait for Start mode.
 It will likely need a bit of time before we can be sure this has solved matters but fingers crossed.
Regarding the spindle speed change, if you have always got a spindle speed and start after a tool change then you wont need to put the M3 in as I said above but it is a safety thing in case your code doesnt have a new spindle speed called. With the M3 there the spindle will start at the last commanded speed and then when another speed is called in the code it will do that speed. If there were no M3 in the lines I said to add then the spindle would start, when commanded later in the code, at the new speed. As mentioned however missing the M3 out could lead to trouble if there were no new M3 call further in the code.
 Hood
Title: Re: Random wrong direction axis moves
Post by: DeanoM on April 30, 2013, 08:46:37 AM
I have similiar problems every now and then. Always after a tool change. Usually the table will go to correct x/y position then before the z move it fires off in the wrong direction and cuts the part 6 or so inches away from the correct position. I just press stop, jog to a safe z then run from the last tool change and all is well. It never looses position it anything just has a brain fart
Title: Re: Random wrong direction axis moves
Post by: aconstruction on April 30, 2013, 10:35:58 AM
Hood, Thank you very much. I think telling Mach3 to ignore tool changes has solved the problem.  It has run lots of  parts now without a hitch. Thanks again.
Title: Re: Random wrong direction axis moves
Post by: Hood on April 30, 2013, 05:06:03 PM
Good to hear it seems to be working :)
Hood