Hello Guest it is March 28, 2024, 03:32:04 PM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - BrianW

Pages: 1 2 »
1
I don't have the link just now, but it was an explanation on the HSM Post Processor Forum by Bob Schultz dealing with "Multi Axis Feed Rates".

You are quite correct.  The "Mach3Mill" post processor has a line saying it is copyright by Autodesk, Inc.

2
Thanks for your considered reply.  I will duplicate the query on the Fusion forum, but I started here as the post processor selected is Artsoft's "Mach3Mill" from the Fusion library and the line about InverseTime is in Artsoft's copyrighted post processor. 

3
I'm trying to generate numbers around a handwheel dial.  Got Fusion to do the design and it simulates fine and even tells me how long it will take to machine.  But when I try to generate the G code, the standard Artsoft "Mach3Mill" post processor generates code with inverse time functions for A axis movement.  My Gecko 320X driver does not accept this and faults out, even if I slow the speed to 25%.  Does Artsoft provide a different post processor that will use G93 instead of G94?

I saw where it was possible to edit the Post Processor to change "var useInverseTimeFeed = true" to "var useInverseTimeFeed = false"  but this did not work for me.  The next attempt to post failed with the odd message "This post configuration has not been customized for 5-axis simultaneous tool path".  I see no reason why that change would introduce an extra axis.

Any help would be appreciated.

4
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 14, 2021, 11:53:21 AM »
Thanks Nick952.  I think that is exactly what happened and the screen shot confirms my opinion that there is a bug to be fixed.

5
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 13, 2021, 01:14:40 PM »
Thanks Cnckr.  That may be exactly the right solution.  I've noticed that occasionally and not related it to this problem.  It sure would be nice if the fix is as easy as that!  Appreciate your suggestion.

Brian

6
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 13, 2021, 01:09:12 PM »
Guys, I really do appreciate that you are trying to educate me about how Mach4 and ESS interact.  Despite being a mechanical engineer and having programmed NC mills since 1973, I'm still confused on Mach4's interaction with ESS.  Perhaps a numerical example will help me understand...

Let's deal with just one linear axis - the X axis.
Let's deal with a single screen button press to do a 0.001" jog
The speed slider on the jogging screen is set to 1% of maximum velocity

My X axis lead screw has 5 threads per inch
My X axis motor is accurately tuned at 10,000 pulses per rev
My X axis motor is tuned to a maximum velocity of 180 inches per minute (= 3.0 inches per second)
My X axis motor is set for an acceleration of 5 inches/sec-sec

So, 10,000 pulses to the servo generates 0.200" movement on the axis (1/5 inch)
Thus 0.001" movement requires 10,000 * 0.001/0.200 = 50 pulses  (This becomes a constant in this example.)

1% of the maximum axis velocity is 0.030 inches per sec.
.001" movement thus requires  .001"/.030 ips = .0333 sec (=33.333 milliseconds)

So, ignoring acceleration and deceleration, the 50 pulses will be sent in 33.333 milliseconds.
If the accel/decel happens within the 33.33 ms, then the 50 pulses will be spaced unevenly to accomplish this.
If the accel/decl is outside the uniform time of 33.33 ms, then the 50 pulses will be spaced over a longer than 33.33 ms time slot but again will be spaced unevenly.

If I understand Andrew's description correctly, it seems that Mach4 must be figuring out the accel and decel to predict the axis location at the end of the next time slice.
ESS then determines how many pulses to send and spaces them correctly for the time slice.


The Left Down action for this screen button is "Jog X-" and the Left Up action is "Jog X Off".  It is not explained what "Jog X-" is programmed to do.
If it is a "one shot" trigger, then presumably a command is sent to the core to generate 50 pulses on the X- axis.  If so, then there seems to be no need for the "Jog X Off".
If it is not a one shot, then it appears possible that holding down the jog button could generate more than one command to jog, hence requiring the "Jog X Off" on button release.  I've been repeatedly assured there is no bug in the Mach4 jogging function, so I have to assume there is some way to ensure there is only one set of 50 pulses being commanded and that the "Jog X Off" is merely there as a safety feature.

Andrew has been clear that "there is no such thing as an after run", but there is a (user determined sized) motion buffer which has to empty out.  (My buffer remains at the default size of 0.18 sec.)  But since ESS only creates pulses in accordance with the Mach4 determined position at the end of the next time slice, it would seem any additional (i.e. unwanted) pulses have been required by the Mach4 calculations.  (I hope we all agree on that.)

JoeAverage and Smurph are definite that the unwanted motion is due to some incorrect configuration setting on my machine.  I've turned off soft limits, hoping to ensure that potential cause is eliminated.  I have yet to try JoeAverage's experiment of increasingly small jog increments, but cannot get my head around his comment "when you want to touch off in incremental mode you effectively have to cycle through your programmed jog steps to find a more suitable number."  Would this not just put me back into exactly the same situation of too big a jog increment leading to unwanted motion?

As always, I appreciate the time you are all taking to help me understand.

Brian

 


7
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 12, 2021, 07:42:45 PM »
Thanks for the clear explanation.  I'll test that out.

8
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 12, 2021, 04:53:20 PM »
Hi Craig.  That sounds like an interesting experiment but I do not have a MPG.  It is one of the things I've been planning to get for some time.

I've got the jog steps at 0.001", so I'm not sure how small they have to be.  It is frustrating that I cannot repeat the incident on demand to test various parameter changes.

Do you know if there is a command that will flush the buffer to prevent "after-run"?

Brian

9
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 12, 2021, 02:46:36 PM »
Not to be argumentative, but rather to be sure we are all using the same facts...

1.  I do have an E-stop - I've mentioned a couple of time that I used it and it worked.  My point on that issue was that having a button labelled "STOP" on the screen that does not stop motion is, at best, misleading.  I get it that my expectation the button would work the same as in Mach3 was an erroneous assumption, yet perhaps reasonable for someone who has used Mach3 for a decade. (In Mach3, the "Feed Hold", the "Stop" and the "Reset" buttons all stop motion when pressed.)

2.  As you can see from the screen shot I posted in my first message, the soft limits were not enabled at the time (although they were configured).  So, my next question is, "if the soft limits are not enabled, is the issue of soft limit configuration even relevant?"

3.  I have verified that when the soft limits are enabled, X axis soft limits are configured correctly and work as expected.  Next question "what else should I check"?

Again, thanks for any assistance.

Brian

10
Mach4 General Discussion / Re: Hazardous Motion - Mach4 Software
« on: May 12, 2021, 12:56:59 PM »
Thank you Andrew.  It is reassuring to know there is no "buffer run on" with ESS.  So no issue with wondering how many uncompleted steps might still exist.

I have confirmed my X axis (the one where the incident occurred) is precisely tuned (within 0.001" over 6") and its velocity matches to under one second on a 60 second movement test.  I have not tested the other axes but I know the Y must be correct as I get perfect circles when I mill a circular hole.  I'm pretty sure I can say with confidence that the motor tuning is correct.

I get it that on a continuous motion movement there will be acceleration and deceleration components.  That is to be expected.  My incident occurred when requesting a 0.001" jog motion, so there would have been negligible time spent on accel/decel.  The issue was that the jog did not happen, the motion was continuous, even after the button had been released.

I'd really like to know what to do differently to ensure this type of situation won't happen again.

Again, thanks for your assistance.

Brian

Pages: 1 2 »