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Author Topic: 0 return not precise.  (Read 3161 times)

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rcjarvis

• 19
0 return not precise.
« on: June 25, 2008, 02:55:13 PM »
Hi, I've tried to find a solution to this problem on the forum but no luck so far.
This is the first time I work on a part that is 123 inches long. My tool will not come back to 0 origin when it travels all the way to the right of the 0 (Center of workpiece) . When it goes the whole 62.5 inches to the left, it comes back to 0. When it travels the same distance to the right, it comes back about 1/4 inch to the left of 0. does Mach3 have limitations on X and Y travel ?, I checked and cleaned all rollers and rails, usually, i don't detect any lost steps, lost steps are easily heard and felt.
The problem occurs both manually or g-code driven.

Daniel G.
A good day starts with how you see it....

jimpinder

• 1,232
• Wakefield, West Yorks, UK
Re: 0 return not precise.
« Reply #1 on: June 26, 2008, 04:00:32 AM »
I am just musing, because I don't know the answer on such limited information :-

Logic tells you that the system is loosing steps when moving to the right ( it cannot gain steps). I do not know what your steps per inch is set at, therefore it is difficult to follow that much further , other than to say 1/4 of an inch in 62.5 is 40 thou per inch - how many steps is that..

What if you start the tool on the left and move the whole 123 inches, and back - does it finish where it started.
Similarly, if you start the tool on the right and go 123 left and back does it return to where it started.
I assume you have measured the movement left and right to see if the table is travelling short in one direction. You can certainly measure to 1/4 inch with a tape measure.

Logic says that the table must stop short, and the most likely place is to the extreme right of travel - is there any movement past the 62.5 inch mark or are you approaching limits - I know you have cleaned it all, so you have thought of that.

I think you need to do a little bit more detective work to find where the movement is being lost, before we can point to a solution.

There is no limit on Mach 3 to my knowledge - certainly not in one direction only.
Not me driving the engine - I'm better looking.

rcjarvis

• 19
Re: 0 return not precise.
« Reply #2 on: June 26, 2008, 08:27:19 AM »
This has  to be a Murphy's law type of thing. as I was running "detective" tests, the diiference was shorter and shorter. I loosened-up the  step-motors to see if everything was running smooth, I could run the whole distance with thumb and index...Throughout the testing( I was running 61"X 124"  X'S and squares The gap went from .285 to .024. I'm gonna close this thread for now, I feel like I spent a day between hell and the twilight zone (with many signs looking at me, waiting to be carved on time !!!) Hate when this happens in the rush season:(
Brian Barker from Artsoft suggested switching on the sherline 1/2 step mode wich I will try today. What does that sherline thing do (Note: I'm really not familiar with all the bling blings in mach3, Usually just pop in the gcode and start))
Daniel G.
« Last Edit: June 26, 2008, 08:31:09 AM by rcjarvis »
A good day starts with how you see it....

• 4,908
Re: 0 return not precise.
« Reply #3 on: June 26, 2008, 08:40:19 AM »
Hmmm.....You spent a whole day where I live, and I didn't even see ya.
If you are sure it's not missing steps, I'd check all of the mechanical connections. Something may be slipping. Shaft, pulleys and couplings.
Also, I've seen problems with the wiring in cable tray/tracks and festooning. The electrical connections can become intermittent at certain points in the travel if the machine has been is service for a while.
Good luck....I'll look for ya the next time you visit.
We'll keep the light on for ya.
RC

• 4,908
Re: 0 return not precise.
« Reply #4 on: June 26, 2008, 08:52:38 AM »

rcjarvis

• 19
Re: 0 return not precise.
« Reply #5 on: June 26, 2008, 08:52:55 AM »
Sorry, I was scratching my head all day and was hiding under a pile of ripped hair !!!

Daniel G.
A good day starts with how you see it....