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Author Topic: Strange motor speed on reversing....  (Read 13048 times)

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Offline RICH

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Re: Strange motor speed on reversing....
« Reply #10 on: April 30, 2009, 04:49:51 PM »
Hi All,
Just my 50-50-50 pitch ( easy to remember).

BACKLASH - set at 50%
Motor Velocity - set at 50% of the velocity they would start to skip steps
Shuttle Setting - set at .0050 or .050 value ( .5 is slow )

These are start values and then tweak upward. They all work in harmony.
RICH
Re: Strange motor speed on reversing....
« Reply #11 on: May 04, 2009, 06:43:51 AM »
Thanks Rich, I'll try that and see how it works out.

The motor "banging" wasn't the backlash comp.  I had the accel too high, or at least when I lowered it it stopped.  It happened mostly when I was jogging at start.
I made a part with a series of turned DIA at different lengths (-Z).  The final DIA were off by anywhere from .021 to .007" ....  I rechecked the motor steps with a dial indicator and jogged in .100" inc.... Moved .050" everytime, in either direction,, steps and backlash are good.  I made several parts,, rezeroing x at the DIA each time,, and each time it was off.  If I use MDI,,, the DIA are still off.


Last night I purchased the software registry codes and will work with it some more.
I'm still trying to wrap my head around a few setup tasks;
1.) Setting the machine coord home (without home switches)
2.) The MASTER Tool #1, Use it only to setup part stock?  Set every other tool from its location coord? 

Question.
In the manual screen-- The program, machine and part coord buttons/LEDs.  They are buttons for dro displays of the coord, NOT buttons for setting up each coord?
ie.  If you are setting your part coord, z 0.00 and x DIA of stock, the part coord button does / does not have to be activated during this setup?  And same for setting X and Z home limits?  Any of them can be activated when doing this.

What confused me was in the manual in the section of setiing up the machine home coord.  After setting my x and Z away from the part, the screenshot shows you to click the x and z home buttons,,, but in the screenshot the "program coord" LED is lit......?

Thanks again for everyones help
« Last Edit: May 04, 2009, 07:13:23 PM by thedude »
TheDude,

Offline RICH

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Re: Strange motor speed on reversing....
« Reply #12 on: May 04, 2009, 11:49:46 AM »
thedude,
Quote
1.) Setting the machine coord home (without home switches)

I just posted a little how to on this in "Members Docs". For a mill.

As far as all the other questions i'll get  back later on.
RICH
 
« Last Edit: May 04, 2009, 11:57:58 AM by RICH »
Re: Strange motor speed on reversing....
« Reply #13 on: May 04, 2009, 01:07:14 PM »
Thanks RICH.
I'm also going to post a better description of my setup, config and a few more questions.  I'm going to run some trial parts tonight and post the code and the measured results to be more clear.

Thanks again.
TheDude,

Offline RICH

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Re: Strange motor speed on reversing....
« Reply #14 on: May 04, 2009, 02:22:55 PM »
thedude,
Just a few comments.
Walk before you run. Make sure that motor tuning is right, steps per unit are correct, backlash is set setup properly.
Play around some with the lathe doing some simple stuff .........without any sophistication....................................
like fooling with the tool tables, setting up homing without switches, etc.
If you don't have an indexer, a repeatable tool changer the value of all that sophistication will only make doing something simple into a barrage of questions on why something is not comming out correctly.

What i am alluding to, is that if you make one of a kind stuff, constantly changing tools / the angle of the tool changer etc you can find the sophistication to be a pain in the neck.

RICH


 
Re: Strange motor speed on reversing....
« Reply #15 on: May 04, 2009, 09:54:15 PM »
Thanks RICH for the replies and help.
I should although be more clear about how I arrived at where I am on this.  I have made several parts, just playing mostly.  I've set the drives per calculations and verified with a dial indicator, also using it to verify backlash.  So far, I'm setup retty tight on steps and backlash as verified through a dial indicator,,,,,, but still,,, have a few lost steps through different actions taken through Mach3turn.

I spent some time tonight troubleshooting everything.  My wife stood by and took notes as I spoke what I was doing.
Here is some trials I was doing tonight.  This is only a part of what we did,, but I wanted to keep the post short,, and add as needed.

(Tool #1)
Setting Tool in Tool Table
Turning diameter = .7085   Z0
   Turned to a DIA of .7085 Clicked touch X
   Faced the end,  Clicked touch Z

DRO Access coordinates reading: X offset/X wear and Y offset/Y wear are all 0.000
Quit tool table screen
Returned to manual screen
Clicked Home X and Home Z
*SUCCESS*  (as best I can tell, it moved near where I originally set home limits)


To Verify part coord after tool setup.
   MDI
   Z0  X.7085 (diameter from setting part zero x)
   Tool was right on the OD and the end of the part.  (Visual)

   
To check programmed DIA cuts.
         
On manual screen:   MDI to X.670
   Manually jogged Z to cut
   Diameter = .670
On manual screen:   MDI to X.650
   Manually jogged Z to cut
   Diameter = .650

Opened tool table to check tool info, closed and went back to manual screen

On manual screen:   MDI to X.60  (From last DIA of .650)
   Manually jogged Z to cut
   Diameter = .631   ?????
   *FAIL*

   Re-zeroed part in X
   Made facing cut
   Diameter = .609
   Typed in .609 in part zero
   Clicked part zero X button
On manual screen:   MDI to X.580
   Manually jogged Z to cut
   Diameter = .597   ?????
                *FAIL*

Attached Mechanical Dial Indicator to measure movement of X axis  (NO Part Machining)
   Jog increment = .1 inch
   Diameter mode, result should be .050
   Jogged positive X 6 times and each time resulted in .050 each time
   Jogged negative X 4 times and each time resulted in .050 each time, (backlash comp verification,, set correct)

Verifying turnings with Dial indicator attached.  (Part Machining)

   On manual screen:   MDI to X.609
   X.609
   zero the indicator.   
   MDI X.58
   Should go .0145 inches but it went .0055  (DIA Mode)
   Told it to go back to .609 and it went to 0
   
Went back to test this in jog increment of  0.100
   Indicator Readings
   1.   X.048        ????
   2.   X.091        ????

Zeroed indicator and repeated jog increment 4 times  1) .050,  2).  .050   3)  .050  4.) .050
Moved to Home X and Home Z.  Home X crashed slightly in negative.

I have no conclusions to any of this.....

My settings are below.

Current Config Setup.

Motors
   Both motors are 4.2v, 3 amp, 305 oz/in
   X axis = 1/8 step, Direct Drive of a 20 TPI Lead screw, (.050 per turn)
      Steps per revolution = 32,000
      Velocity = 30
      Accel = 1
      Step pulse = 0 (I never set this)
      Direct pulse = 0 (I never set this)
   
   Z axis = 1/8 step (Using threading lead screw on lathe, 16 TPI, two timing pullys 1:1.5,  38400 calculated, Indicated to 38,360)   
      Steps per revolution = 38,360
      Velocity = 25.002
      Accel = .75
      Step pulse and Direct pulse = 0 (?)
   
   Backlash Comp
      Backlash X = .0012 (Per Dial Indicator)
      Backlash Z = .0185 (Per Dial Indicator)
      50%
   
   Both motors are 4.2v, 3 amp, 305 oz/in

   Shuttle excel = .1 second
   
   Motion mode = Constant velocity
      CV Control
      CV distance tolerance = 60
      G100 adaptive nurbs is checked by default
      Stop CV on angles is unchecked
   
   Distance mode = absolute
   IJ mode = incremental

Ports & Pins

   Port enabled is checked
   Kernel speed = 25,000Hz

EStop Checked,,, Low active Unchecked
X and Z axis Low active and Step Low active both Unchecked.

Hope I have provided enough info for a guru to see the problem,,,  any questions please ask,,,

Thanks!  Any help is appreciated greatly.



« Last Edit: May 05, 2009, 12:09:06 PM by thedude »
TheDude,
Re: Strange motor speed on reversing....
« Reply #16 on: May 05, 2009, 10:34:32 PM »
I hope I haven't worn out my welcome with that last post.  It is long, but I wanted to give enough info to promote a fix.
The short of it is that,,, when Inc jogging, by .100 in this case, the X axis is dead on.  When using MDI it varies.  Also, not listed in my post is running a program, it varies too.

Again,, thanks for everyones help thus far,,, and I hope some suggestions will continue.

Thanks again.
duder,,,
TheDude,

Offline RICH

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Re: Strange motor speed on reversing....
« Reply #17 on: May 06, 2009, 01:06:16 AM »
thedude,
You have not worn out your welcome. I would have to carefully look at what you posted
and see if i could find the problem. Right now I'm  just caught up in a problem  myself
( at least your machine is running ).  ;)  Others will chime in.

RICH
Re: Strange motor speed on reversing....
« Reply #18 on: May 07, 2009, 09:07:40 PM »
Tonight I decided to run a rew more trial pcs.
The part was a series of DIA, each cut in less -Z.
Basically, the part looked like a mini DEVO hat,,, Whip It!!  haha.  Simple.

The DIA were finishing at .020-.026 oversized each time.
I decided to adjust my X axis stepper setting from the calculated, 32000.  (1/8 step, 20 TPI) and see what happens.

Here is my workflow.
Part stock is .75" DIA Delrin
I'm working in Diameter mode.
Tool 0 (as I am setting the part zero manually)

Load the stock.
Make a facing cut
Type zero, enter, click zero part Z.
Make a turning cut.
Measure, type the measured DIA, click zero part X.
Run program.
Measure.
.020-.026 more than programmed DIA.

Adjust Stepper setting a bit, repeat. (several times, adjust, repeat.  I must have made 15 mini Devo Hats tonight)
Strangely,, it would get within .006 to DIA,,, then,,, when I tweaked just a hair more to dial it in,,,,
It would go back to giving me an error of the .020-.026" !!!!  Regardless of the stepper setting.
My stepper setting ranged from 32500 to 31025 during this troubleshoot.

I'm wondering if I have narrowed it down to my hobbycnc controller box??

Anyone think that I should now mount the "Y" axis motor, reset the Y pin outputs to the Z outputs and retry???

Any help,,, thanks
TheDude,
Re: Strange motor speed on reversing....
« Reply #19 on: May 07, 2009, 10:16:34 PM »
Wondering if I should abondon this thread.  I've taken everones advise so far and it has proved to be helpfull.  Now I'm stuck on the X travel Variance issue.
I will keep reading, troubleshooting, and searching.

Thanks everyone for your help thus far.
TheDude,