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Messages - jid2

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1
SmoothStepper USB / Re: LUV-N the ESS!!!
« on: May 12, 2012, 03:40:13 PM »
Its the one by power in.

2
Ok, I got it, thanks.

I found the section in the manual that states mach will create the motion based on the acceleration and velocity of each axis, supporting linear rates in all axes, and arc based in your choice of two. So it was a bug, that in theory is fixed.

I agree that X and Y should always be the same, and mine are. Its Z that wants lower acceleration. I plan on keeping with my  35 for X and Y, and 20 for Z.

Thanks for the infoz.

3
OK. What you are saying is that Mach does not calculate realtime velocity during the acceleration ramp and look to keep each axis on path based on that acceleration/velocity.  Do you know this for a fact?  I'm not arguing, just looking to understand the math behind this  performance characteristic.  This isn't really about the weak system link, it's about the system architecture.  The architecture could support each axis having unique velocity and acceleration, but it sounds like it doesn't have that in the algorithym. 

4
Sure, that is what you deal with if needed.

I guess my question is this: does the Mach 3 toolpath generation algorithme account for each axis having a unique velocity and acceleration profile?  Or does it assume that all accelerations are set equal?

5
General Mach Discussion / Acceleration set the same for all axes?
« on: May 03, 2012, 04:49:03 PM »
There's a post on Bob W's CNCCookbook site about him running into an issue he felt was related to uneven accelerations on the axes.  He noted poor contour following with uneven accelerations and a marked improvement at the visual level by setting the accelerations the same across the three axes.

Is this a confirmed  phenomena, do the axes really need to have very similar accelerations?

Seems like it would be more apparent in the X-Y axes, which the accelerations are easy to get the same.  For most of us it's the Z axis that is difficult to maintain the same accelerations.  Right now my servo based RF45 conversion can support acceleration of 50 on X and Y, and 20 on the Z even with gas springs to assist the head.  I'm planning on running the X and Y and around 35 for acceleration and was going to leave Z at 20.  It's a little harder to find the issue when looking to couple it with Z moves.

Anyway - insights are welcomed, I searched and found nothing on the subject.

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SmoothStepper USB / Re: LUV-N the ESS!!!
« on: May 03, 2012, 03:52:06 PM »
I could not get the USB Smooth Stepper to work reliably on my machine, an axis motor fault would lock-up Smooth Stepper and freeze Mach 3.  This was without even turning the spindle on, just the DC Servo motors controlled by Gecko 320X's and a PMDX 126 breakout board.  I tried every version of Mach and Smooth Stepper driver and plugin.  I rewired and re-grounded my system two times, the 2nd time with pain staking detail and all components mounted to a steel plate and the PC sharing a common ground.  The system was not reliable enough for me to even tune the motors, and I would get a run-away table from time to time.

After fighting that for a while I finally just moved to the ESS and installed it at the beginning of the week.  No more crash or lock-ups of Mach 3.  I finally have a working control system.  I know others have used the USB SS with success , but mine was absolutely non-usable.  I'm very happy that the ESS exists and solved my problems, allowing nice motion control with Mach 3 and fantastic integration with the PMDX 126 board.

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