RE: [CAD_CAM_EDM_DRO] Stepping motor skipping

Bob:

Hi, Bob:

A couple of comments:

First, how are you determining that your system is dropping steps? If you're
touching a dial indicator to one of the tables and using that indication,
don't forget to account for backlash in the system. One good way to check
the "reliability" of your system is to set the backlash in TurboCNC to zero
and use the calibration on the handwheels to determine if the motion is
correct.

As Alan mentioned, use a clean version of DOS. I've encountered problems
with the EMM386 driver making the pulse train nonuniform (EMM386 sometimes
takes a large amount of time during the 18.2 millisecond timer interrupt on
a PC so that the pulse train jitters).

You mention jogging and then acceleration and deceleration. Generally, I'd
not expect enough steps in a jog for acceleration and deceleration to play a
part in the equation. How large a distance are you moving?

It sounds as if your motors are not yet connected to the mill. Sometimes,
motors need the damping that the mechanical system provides for stability.
You might want to connect the motors to the mill and try your experiment
again.

As a point of reference, I've experienced problems with the motors stalling
when using a relatively low power (486DX2-50) processor when I had included
the EMM386.EXE driver in my config.sys file. Prior to removing EMM386, the
fastest speed I could move the motors reliably was about 900 steps/second.
After removing EMM386, the fast speed I could move was 2600 for Y and 4000
for X and Z. This speed was limited by the mechanical system, and not the
computer's ability to generate a pulse train.

Hope this helps.

-- Carol & Jerry Jankura
Strongsville, Ohio
So many toys, so little time....


|-----Original Message-----
|From: bobmaggi [mailto:bobmaggi1@...]
|Sent: Friday, March 29, 2002 10:29 AM
|To: CAD_CAM_EDM_DRO@yahoogroups.com
|Subject: [CAD_CAM_EDM_DRO] Stepping motor skipping
|
|
|I have just completed putting together a system for my 5400 Sherline
|mill using the Camtronics 2A 3 axis board. I am trying out the
|TurboCNC program but the steppers keep skipping steps (during manual
|jogging the system, no load). It seems to skip primarily during
|accelleration and decelleration portions of a move, although it also
|skips some once it is up to max speed (just not as frequently).
|
|I have searched the archives and tried many of the initial settings
|suggested and have tried varying the parameters one at a time but I
|haven't seen any improvement. My setup is currently (as of last
|night) as follows:
|
|Power - 18VDC
|160 oz-in steppers - the step is set to 0.000125
|pulse width - 50
|min speed - 100
|Max speed - 1000
|Running TurboCNC in DOS mode on a P90.
|
|Any additional advice is very welcome!
|
|Bob Sweeney
|
|
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