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Re: Bug in formulas
« Reply #10 on: November 30, 2010, 12:31:18 PM »
That driver version is the same as I have. Dated April 11, 2010 I believe.

I have just reloaded XP and installed nothing but XP SP2 and Mach 3 (latest stable release). It still hammers the drive and the DRO still jumps to the calculated position before the machine starts to move normally.

Another interesting symptom is that if you feedhold in the middle of a move (ie pause it in the middle of a 10" feed) and hit cycle start again the stepper locks up indicating that it is being hit with pulses at full speed instead of being ramped up.

I can't see how it's possible that I'm the only one seeing this problem. This is now running on a "virgin" XP SP2, is not connected to the net, and Mach3 has no plugins running and no modifications have been made whatsoever. I have confirmed it on a number of other machines by visually watching the DRO's in Mach3.

Anyone who can, please verify that this happens on your machine by putting in a formula f(y) = y + 0.1 . The problem should occur on the first move from the MDI or when you press Cycle Start. At the MDI if you want to make it happen again hit reset twice and move again. It is easiest from the MDI if you just move another axis so that the affect can be clearly seen. You may want to turn off your CNC if you don't want to hit the motor with pulses that are too fast for it.

Art, if you are reading this, any help or insight you could provide would be much appreciated!


Edit:
This also happens using the Verify button on the MDI screen, and oddly enough, if you set f(y) = y + 0.1 and set your jog step 0.0001 and step jog on the x axis it will hit the y motor with pulses the first 3 times you jog (I guess something is stopping it from making the full jump).

Again, if others could please test this I would appreciate it very much!
« Last Edit: November 30, 2010, 12:49:12 PM by Sargon »

Offline BR549

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Re: Bug in formulas
« Reply #11 on: November 30, 2010, 12:37:50 PM »
I would say that 99.99% of all users have never ran with a formula so I think you are a minority with that problem(;-).

(;-) TP
Re: Bug in formulas
« Reply #12 on: November 30, 2010, 12:52:59 PM »
Agreed ;(

However, this problem is almost bad enough to make the formulas completely useless! Surely this would wreak havoc if you were trying to drive a parallel machine with it!

Even if you don't use formulas, could you please test it and let me know? I really want to know if it's a problem with Mach3 or perhaps just with particular configurations or windows version.

Thanks!

Offline Tweakie.CNC

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Re: Bug in formulas
« Reply #13 on: November 30, 2010, 01:05:51 PM »
Just my opinion, but I think that a single drive on a 48" gantry is probably asking for problems way beyond this issue. Although, as you say, it is not easy it would perhaps be better to concentrate on getting your machine square and to use slaved drives to better distribute the torque.

There may well be a bug in formulas, so what, it's no big deal - move on and get your machine right, in the long term it is a far better solution than a software 'fix'.

Again, just my opinion.

Tweakie.
KEEP SAFE !
Re: Bug in formulas
« Reply #14 on: November 30, 2010, 01:56:59 PM »
I'm about 10 steps ahead of you, and the fact that mechanical solution is best is very, very obvious (to anyone who knows ANYTHING about machinery). I am well aware of the physics that this machine is working against. However, time right now does not permit me to rip the table apart as someone has already done that twice. The next time it comes apart it IS going to get dual drives (it just makes sense, doesn't it?), but that will not happen for a while. Also note I am only cutting plastic sheet and it puts virtually no load on the spindle or drives.

To be perfectly honest, a feature that does not work has no place in distribution software. I thank all who have worked to make this program as great as it is (I believe it is among the best because of it's flexibility), but this broken feature is out of place among the rest of the software that, for the most part, works flawlessly. I would say it needs to be fixed or removed. Just my honest, unbridled opinion. Of course, if it were to be removed it would eliminate native support for parallel machines. It is probably better to fix the feature because it is useful for a variety of applications (not just for correcting table error!) and makes the software much more versatile. The fact that there aren't many users making use of formulas does not negate it's usefulness to the users that would like/need to use it.

Thank you for your opinion, and I agree in principle, but in the practical world there are limitations, one being time, the other money, and I don't have much of either.

Offline ger21

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Re: Bug in formulas
« Reply #15 on: November 30, 2010, 03:14:22 PM »
I've helped a couple people a few years ago set up formulas to correct an out of square Y axis. Neither reported the problem you have, although it was a much smaller correction.

I'll see if I can test this tonight.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline BR549

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Re: Bug in formulas
« Reply #16 on: November 30, 2010, 03:25:34 PM »
Unfortunitly buggs in things that do not effect the majority are way down on the fix list as the squeaky wheel gets the oil. I think I would invest some time in correcting the aligment problem as a fix may be a long time down the road.

I am sure that is not what you want to hear but just the way it works.

Just a thought, (;-)
Re: Bug in formulas
« Reply #17 on: November 30, 2010, 05:52:31 PM »
Lol... I'm going to write a plugin to do it if it gives me enough control... the table will be dealt with next year. The workaround I now have in place works, I just can't use feedhold and continue... I have to rewind, then everything stays lined up perfectly.

Thanks for the input and for confirming that this is likely a bug in Mach3.

Cheers!

Offline ger21

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Re: Bug in formulas
« Reply #18 on: November 30, 2010, 07:59:07 PM »
I'll confirm that is a pretty nasty bug.
What I found was that jogging any axis other than the one with the formula would cause the one with the formula to not move when you did an MDI move. Doing MDI moves was OK, but jogging did it every time.

Like he said, the biggest problem is that nobody uses it. :)

I have a felling that this used to work OK, and crept in at some point and nobody noticed.

Actually, I'd always heard that it didn't work while jogging, so maybe it's always been like this? Reading this refreshed my memory.
http://www.indoor.flyer.co.uk/kinematic.pdf
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Bug in formulas
« Reply #19 on: December 01, 2010, 06:02:41 PM »
Yes, the formulas are only applied to MDI and G-Code commands. I think this may have been intentional, I'm not sure, but it should probably be an option. The only spare time I have is when I'm at home so I will delve into plugin programming and see if I can get it all working without bugs that way.

Anyone who has any suggestions as to the best way to modify the trajectory I would appreciate it very much as I assume that this will be somewhat difficult to accomplish and this is my first plugin attempt (I like a good challenge! :) ). Assuming I am able to make it work well I will release it free of charge for anyone who wants to use it for parallel machines, error corrections, rotations without mixing up the DROS, etc...