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Author Topic: Is This A Bug In Mach3 ver 2.60  (Read 9253 times)

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Is This A Bug In Mach3 ver 2.60
« on: November 24, 2007, 11:47:13 AM »
Hi I had a problem the other day in which I thought I was losing steps in a canned drilling cycle and this was the first time I had run a canned drilling cycle. I came on here and asked for advice in that in the canned cycle I could not use CV mode only Exact Stop and I thought this was the reason I was losing position. Graham Waterworth helped me out with some example code for a subroutine, I wrote the code “Very Similar In The Amount of Moves In The Canned Cycle” and lo and behold I got the same sort of error.

I then just tried to test the axis and not scrap any more metal.

I then changed my code to move Z up then down by 60mm in a subroutine 60 times I ran the code and got an error of +0.1359mm

I then thought that my motor settings were incorrect “My Motors Are Running At Only Half Speed” I slowed it down some more and reran the code same result.

I then changed the acceleration value from 300mm per min to 150mm per min and ran the code again I got an error of  +0.1283mm

I then changed the acceleration value to 75mm per min and again ran the code this time I got an error of +0.1308mm

I the came to the conclusion that there was something wrong with the mechanics of the Z axis so I was about to start redesigning the Z axis when I thought I would try the Y axis

It should be noted that I use 795 steps per rev on this axis and 400 on the Y axis

I changed the code to suit the Y axis and ran the code starting from Zero to -60mm

This time I got an error of -0.2585mm

Then I changed the code to run from Zero to +60mm I got an error of  -0.2575mm

I then changed the code to run from +30mm to –30mm I got an error of  -0.2550mm

My conclusion now was that there is nothing mechanically wrong with my machine and that I was not losing steps as the results were pretty much the same except one axis was losing and one was gaining I then checked the motor direction, one is reversed compared to the other and that the fact that one axis error is double the other axis is down to the steps per rev being double in these two axis and it just can’t be a coincidence.

My motors are configured as

Dir Low Active X
Step Low Active X

The Drivers are from Motion Control Products, which are very popular and highly thought of in the UK model MDS980

So is this a bug, I am using version Mach3 2.60 by the way

Here is the last version I ran on the Y axis

Starting with my dial indicator nearest to me at Zero on the dial the Y DRO reading +30 I then run the code “Thanks Graham for the help”

F100
G90
G1 Y28
Z15 F1000
M98 P123 L50
Y28
Z0
M30
O123
Y-30
Y30
M99

If someone also using 2.60 could run that code using a driver other than the one i am using say a Gecko and check the results.

Or maybe someone can tell me another reason i am getting this error, i am all ears. ;D

Phil_H


 
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: Is This A Bug In Mach3 ver 2.60
« Reply #1 on: November 25, 2007, 08:44:30 AM »
Nobody got any ideas what the problem could be  ??? I'm desperate to get this working correctly.

Please I'm begging.

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

vmax549

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Re: Is This A Bug In Mach3 ver 2.60
« Reply #2 on: November 25, 2007, 10:12:19 AM »
Have you rechecked the steps per unit>>>

If you command a move in one direction does the axis move that "exact" amount?

(;-) TP
Re: Is This A Bug In Mach3 ver 2.60
« Reply #3 on: November 25, 2007, 10:28:00 AM »
Thanks vmax549

I did check that the distance moved was correct before i came to this problem.

You see that there  is an adjustment to the Z axis to get it correct so i just changed it to 780 from 795 i got the same error result.

I don't know how all this stuff works but to my mind it seems as if every time a move is it sent it will move the correct distance, but the next move it either adds or subtracts some steps depending on the motor direction settings, if that makes sense.

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: Is This A Bug In Mach3 ver 2.60
« Reply #4 on: November 25, 2007, 11:13:50 AM »
Could this be the reason.

In theory my system is zero backlash but no system could be totally backlash free.

So i have just had a thought, with some backlash that hadn't been compensated for i start off thus.

I move my table onto a dial indicator, set indicator to zero, set DRO to ZERO and if i then continue in the same direction and go 100mm it would in my case go 100mm. But if i instead go back and forth 100mm say 100 moves would a tiny amount build up to give the sort of error i am getting.

Could this turn into a backlash calculator ;D

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Chip

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Re: Is This A Bug In Mach3 ver 2.60
« Reply #5 on: November 25, 2007, 01:53:32 PM »
Hi, Phil_H

Have you tried Dir & Step Low Active to "Checked", Some Controls are sensitive to leading and trailing pulse''s.

If you change it then you'll need to change in Config, Home & limits, Reversed coll um's around for correct axis Direction.

Backlash should  not be cumulative.

Hope this Helps, Chip
Re: Is This A Bug In Mach3 ver 2.60
« Reply #6 on: November 26, 2007, 05:40:44 AM »
Hi afn09556.

I changed first DirLowActive to ticked same result

I then changed StepLowAcxive to ticked "Both Now Ticked" same result

I then unticked  DirLowActive same result

So that means i tried all combinations always ends up -0.255

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: Is This A Bug In Mach3 ver 2.60
« Reply #7 on: November 26, 2007, 07:02:06 AM »
Phil,
How far of a move did you make? I have found that the closer to full machine travel you can move & measure the more accurate the machine will be.
One other thought, If the machine worked correctly on an older version of Mach, just reinstall that version.
Hopethat helps.
Cutmore
Re: Is This A Bug In Mach3 ver 2.60
« Reply #8 on: November 26, 2007, 07:30:56 AM »
Hi CUTMORE thanks for the help

When i set my steps per rev i did it over 100mm

Even if that was incorrect i should still end at the same place i started. IE go 100mm goes 99 come back 100mm comes back 99.

I didn't do this particular check on an earlier version so it may have been wrong then as well.

Getting more desperate by the hour.

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline N4NV

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Re: Is This A Bug In Mach3 ver 2.60
« Reply #9 on: November 26, 2007, 08:10:01 AM »
What break out board are you using?  I had one that was opto isolated and whenever you changed direction, it would cause a crosstalk on the step channel and add a step.  So just about every change in direction caused an increase in steps.

Vince