Messages

5571

SmoothStepper USB / Re: Which BOB for the smooth stepper

« on: October 18, 2009, 11:26:43 AM »

You got it correct, "slaving Z to the spindle", with the SS.  I have have questioned how that is going since it's been 9 months now. Don't hold your breath! 
RICH

5572

General Mach Discussion / Re: CNC or Mach3 calibration issue?

« on: October 17, 2009, 09:04:46 PM »

Glenn,
 Move your X, say x + 10, now zero your Dro's and also your scale.
Now using MDI do a X +500
Then do a X-500

You should be back to X=0Zero, and if not then you have some backlash, even if your steps are not correct.
If your steps per unit are correct then the difference is your backlash and that is the number you should use for setting the backlash amount in CONFIG>Backlash.
Save those setttings and then try the same thing above and you should return to zero.
Note that you used the same run of belt when you did that.
Now step from X=zero in 100 movements, in one direction, to 500, and see if they are all equal on your ref scale. If not then then there is error in the belt / pulleys.
RICH
MODIFIED: if you are in the absolute mode then you would do a ..... G0 or  G01 to X 0.0

5573

General Mach Discussion / Re: Problems threading on the lathe

« on: October 17, 2009, 08:34:13 PM »

ART,
Not sure what you posted on page page 56 reply 559 is valid report. Here is the readout i get from dry run.

RICH

5574

Show"N"Tell ( Your Machines) / Re: Success! Mini Machining Center under Mach3 control - Video link

« on: October 17, 2009, 05:38:27 PM »

Looking good Simpson, glad your happy with the outcome.
RICH

5575

General Mach Discussion / Re: CNC or Mach3 calibration issue?

« on: October 17, 2009, 05:24:08 PM »

Glenn,
Could be there is variation in the belt and even the pulleys. If you reverse the direction you sould get the same differences.
RICH
BTW: That's a long distance, due you also know for gact that the digital scale is accurate.
 

5576

SmoothStepper USB / Re: Which BOB for the smooth stepper

« on: October 17, 2009, 05:51:10 AM »

"and it could stream out the step signals for feed directly based on the encoder input from the spindle"

When?
Mach / SS - Just a quess, but the "horse and wagon may need to be able to travel together"
                and don't think you will see anything until Mach 4 is released.
                Only Warp9 can speak for itself.

There is a post on that site on requesting slaving the spindle to the Z axis, which could be done rather easily, but was limited to  only one direction and not both. Haven't pursued it since that posting which was months ago.

RICH

5577

Show"N"Tell ( Your Machines) / Re: 13x40 lathe conversion

« on: October 16, 2009, 10:11:26 PM »

Hey Zarzul,
 How about joining in on some thread testing?
Give her a test or two!
RICH

5578

General Mach Discussion / Re: Problems threading on the lathe

« on: October 16, 2009, 09:32:42 PM »

ART,
Thanks for the info as now i know how to interpret the data better.

I delibrately increased the rpm in the wizard becuase you could see the rpm float  in the threading diagnostics.

Yep, focus  on the crazy passes. They are the killers, since on a punny lathe you could "spiral down into the black hole"  and the resulting thread becomes hard to measure.

If the lead error can only be corrected within some tolerance, then a decreasing thread may be a better choice.
This way it starts out meeting some standard. The nut will go on and becomes loose. I will to post something practical as an example and think about it more.

Will try few with the last posting. That gives flavor to the tests i did were i varied the pitch some to get the lead error to zero.

BY the way, those crazycuts are really bad. ie; all of a sudden you go from just a a few tho cut to cutting
cutting .030" to .040" deep / full V cut. The force on a 1/4" dia rod is realy great including the carriage also.
If the material was hard you would probably break the insert.

Again thanks for stayng with this,
RICH

5579

General Mach Discussion / Re: Problems threading on the lathe

« on: October 16, 2009, 07:38:32 PM »

ART,
When i say i killed the program, what i have done is flip a switch which disables the drives and stops all switching activity. The drive will continue recieving inputs from the PP but nothing will be sent to the steppers.  That switch also kills the power for the Hall trigger. Then i stop the program.  So Mach will continue running the program and show that the rpm drops off.  That's why you see the velocity taper off in the data. The switch was flipped sometime after the thread pass but before it started the next threading cycle.

RICH

5580

General Mach Discussion / Re: Problems threading on the lathe

« on: October 16, 2009, 03:31:06 PM »

ART,
Just some more testing.
These three tests were run with VER .028 / posted version 54 - reply #539 with PP.

Testing was to look for a missing index pulse and relate when it happens and is it repeatable.
Full threading of the piece 1/4 - 20unc @ 404 RPM


TEST #1 - 40 PASSES - Pass # 23, 33 and 40 were bad! In fact #40 broke the piece.
                I din't have the end supported so thought that maybe a screwy lead happened and
               caught the end of it. So did another pass, very rigidly supported, and wondered if the
               lead would change at about the same pass.

TEST#2 - 40 PASSES - Pass # 21, 24, 28 and 32 were bad and stopped it at pass 33.
               By bad, i mean a visual change in the lead and thus a heavy cut.
               
TEST#3 - 18 PASSES -  I figured that since all the other passes got screwy at above 21 passes
              time / repeatitions, then i will change the threading code to fewer passes.
               18 PASSES @ .010" first pass and remaining at .005", no spring passes.
              Pass #9,10,12,14 were bad and the 18th pass cleaned up the thread and there was
             a .010" lead  increase / inch.

Attached are the velocity reports for the three tests. Spindle slow down is not a problem as the
lathe will just break or bend something and dosn't slow down. Maybe you can make something
more of the velocity tests by looking at the bad passes i noted for each test. It was interesting to
see a possible pattern happenng atapprox 22, 32, and 40 pass and the roughly 1/2 of that for pass
when the number of pass was changed.

I have attached a pic of the thread with some notes on it. It shows the change in lead at what i think
werethe passes. At 100x you can actualy see the small stepping of the cutting on the backside
flank per pass.So for the first 20 passes there is a rather even tappering.

If the lahe was a punny one like my Sherline, the RPMs would have dropped and you realy couldn't
get what i am finding.

RICH