Hello Guest it is September 20, 2019, 06:40:15 AM

Author Topic: Losing zero by alot and can't cut a circle  (Read 7580 times)

0 Members and 1 Guest are viewing this topic.

Losing zero by alot and can't cut a circle
« on: December 21, 2007, 10:10:26 PM »
I have a Dyna 2800 with steppers and I have two problems. First I have spent all day playing with the motor tuning trying to get it to cut a circle with out jumping around when it rounds on either end of the X movement. At a point on either side of the maximum X travel the motors growl and vibrate. I have read every post and made every adjustment I can think of. Do I need to replace the stepper boards and/or the motors???

The second problem started today; it now loses it "0" setting. If I try to cut a circle it will first run off and start cutting it off to the side and I mean almost an inch off of center. I also noticed when I zero the X setting it always has a - (negative) in front of it and not a + like the others.

I have burned out with this, anyone have any ideas? Help!!!!
Re: Losing zero by alot and can't cut a circle
« Reply #1 on: December 22, 2007, 11:58:01 AM »
I would check with an indicator if the is any side to side movement in your table. I say this because it sounds like something is binding.  Put an indicator on the end of the X axis and hang it off the head or table, something not connected to the table.  And with your hand see if you can move the X axis table front to back.  If so you need to adjust the gibs.

Just a guess.
Re: Losing zero by alot and can't cut a circle
« Reply #2 on: December 22, 2007, 03:35:47 PM »
dfurlano

Thanks for the reply and I will  re-check for physical binding, but I can grab the stepper motor shaft between my thumb and forfinger and turn it with no problem. The screws look like new and are protected by bellows,the gibs are set about perfect and this machine has an automatic oiler which keeps everything smooth.

When I went to the motor tuning and changed the pulse to 8 as they recommend 1-5 it did seem to get a little better. Can someone explain the function of the pulse setting. Does it have to do with the computer, the motors or the driver boards?

Offline Chip

*
  • *
  •  2,056 2,056
  • Gainesville Florida USA
    • View Profile
Re: Losing zero by alot and can't cut a circle
« Reply #3 on: December 22, 2007, 06:42:17 PM »
Hi, Ffulmer

It give your stepper control more time to see the Pulses from Mach3.

Thanks, Chip

Offline Chip

*
  • *
  •  2,056 2,056
  • Gainesville Florida USA
    • View Profile
Re: Losing zero by alot and can't cut a circle
« Reply #4 on: December 22, 2007, 10:14:10 PM »
Hi, Fred

Have you tried a smaller circle, Maybe your actually hitting the X max/end's.

Call me or email your phone #.

Thanks, Chip

Offline Whacko

*
  •  239 239
  • Happy Days
    • View Profile
Re: Losing zero by alot and can't cut a circle
« Reply #5 on: December 23, 2007, 04:20:11 PM »
Depending on the lenght of your cables and the drivers for your motors, there is a good chance that your problem stems from the drivers. Stepper motors have resonance at certain phase angles. Advanced stepper drivers use algorithms to dampen this resonance. Any play in the drive mechanism will result in a loud chatter of the motors. The cable length is also a factor as is the conducter size. The fact that the chatter is at vector changes indicates free movement in the drive mechanism. In some cases it would require the change of your drivers. Also the fact that the chatter is less with increase of microstep ratio points to the resonance as the most probable cause.

Whacko
Nothing's impossible
Re: Losing zero by alot and can't cut a circle
« Reply #6 on: December 23, 2007, 06:13:07 PM »
Hello again Whacko

This appears to be the best answer so far. I do appreciate all the help I have gotten from everyone. But if their is any play in the table or ball screws on this machine I can't find it, at least not what I can see on a dial indicator. I can move the tables by just my thumb and forfinger grabbing the motor shaft. With the exception of the motor clogging they move smooth and free. The motors appear to be very high end 1.8 degree, 8 wire Escap (Swiss made) disk which I believe use rare earth magnets. But the driver boards are the old original ones and I too think this is the root problem.

The wire on this machine is all shielded cable, I'm not sure of the length, I will say it's not much over 4 feet. I am going to order new driver boards and pick up a faster computer. Thank you.

Fred

Offline Whacko

*
  •  239 239
  • Happy Days
    • View Profile
Re: Losing zero by alot and can't cut a circle
« Reply #7 on: December 24, 2007, 01:33:09 AM »
You should try a driver board with a higher step resolution. I will pm you with some info

Whacko
Nothing's impossible

Offline Whacko

*
  •  239 239
  • Happy Days
    • View Profile
Re: Losing zero by alot and can't cut a circle
« Reply #8 on: December 24, 2007, 04:17:25 AM »
Fred, I sent you a pm

Whacko
Nothing's impossible
Re: Losing zero by alot and can't cut a circle
« Reply #9 on: December 31, 2007, 08:58:35 AM »
Hi,
If it is any reassurance, I can tell you that I am experiencing the same problem as you do. Only not with cutting a circle but by doing an angled movement (the worst with a movement to the up and left). Halfway through the machine stops dead in its track and makes a lot of noise, after that it continues its program but Mach3 thinks it is way ahead so the whole thing is ruined. This behavior happens when moving in G0, in G1 movement this hasn’t occurred as far as I know. A solution or help to get to the solution will be appreciated by more persons than just the topic starter so if you guys know anything, please put it here :)
Thanks in advance and excuses for the bad English (I’m Dutch :P )