On Mon, 13 Jul 2020, Ralph Stirling wrote:
Date: Mon, 13 Jul 2020 13:15:27 +0000
From: Ralph Stirling <ralph.stirl...@wallawalla.edu>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Because the hardware store was 4 miles away...
Perhaps Peter could write a hostmot2 axis offset module that would run in the
fpga. No base thread needed.
-- Ralph
Oh No, thats definately the wrong design path, the philosophy here is to
push all the hard work into someone elses domain... :-)
On Jul 13, 2020 12:24 AM, Gene Heskett <ghesk...@shentel.net> wrote:
CAUTION: This email originated from outside the Walla Walla University email
system.
On Sunday 12 July 2020 22:44:05 Leonardo Marsaglia wrote:
Currently - there is no way to adjust it. I do run the
acceleration and velocity as high as I can. (on the emco it is in
above 50in/s^2) I do have some math that calculates the following
error of the shape (actual shape vs axis position) and decide how
fast to run the spindle to get the tolerance I want. There should
be some sort of trajectory planning - but that might be above my pay
grade
(mostly academic for me - just wanted to see how well it works...)
Thanks for the feedback Sam. I'll have to dig in a little more to
improve what I've done surely, but I guess only for the jobs I need to
do from time to time the live tool is justified. I usually do 6 mm
lift cams but sometimes I need to reach 9, 10 and even 11 mm of lift
wich are almost dynamically impossible to turn with conventional
tooling.
I find trying to imagine the method intriguing, as I already have an
offset module in use on the Sheldon, doing compensation for bed wear vs
z position, something that can be done very cheaply in the 200 hz jog
thread, but thats obviously too slow for this. No reason I couldn't map
an offset vs spindle, usable at backgear speeds or maybe even in 1st
gear direct. Something I could feed into the offset thru a sum2 from a
lookup table based on a MOD of encoder by scale function for the table
index. Something like a 240 tap deep lincurve, but can the pi4 handle
that in real time. Doubtfull as I can see other timeing problems Despite
the newer power supply giving me 40+ ipm at the x axis, I doubt the pi4
has enough processing power to pull that off. The ultimate limit would
be reached by adding a base-thread, which I don't have now, because that
sort of thing would need response at per encoder edge. That speed limit
then would be the 1 kilohertz servo-thread write to the stepgen.
One might experiment to find what those limits are with a siggen module
if it could be synched by a phase locked loop running at 6x spindle
index. Since its default is 1 hertz, it might make more sense for
testing to go to backgear and turn the spindle at 1/6th turn per second,
increaseing the gain of the triangle until a following error occurs. And
finding the minimum time for the phase-locked loop to stabilize the
spindle speed before advanceing the tool into cutting position, I can
imagine cutting a bolt head compatible with a 12 point box end wrench,
but not the pretty flats Sam got. That would require running a sine
signal thru an ABS function in real time adjusting the gain for flatness
of facets. Since thats a floating point function, servo-thread at 1
kilohertz would be its speed limit. But is that speed limit usable?
IDK. :(
Middle of the night thought experiments, darned things cost me sleep but
never get done... Ought to be a pill for that.
El dom., 12 jul. 2020 a las 15:52, Sam Sokolik (<samco...@gmail.com>)
escribió:
Currently - there is no way to adjust it. I do run the
acceleration and velocity as high as I can. (on the emco it is in
above 50in/s^2) I do have some math that calculates the following
error of the shape (actual shape vs axis position) and decide how
fast to run the spindle to get the tolerance I want. There should
be some sort of trajectory planning - but that might be above my pay
grade
(mostly academic for me - just wanted to see how well it works...)
sam
On Sun, Jul 12, 2020 at 1:32 PM Leonardo Marsaglia
<ldmarsag...@gmail.com>
wrote:
Excellent job Sam.
One question to the list in general. How are you managing the
atenuation and phase displacement you get when you increase
spindle rpm using eoffsets? Other than increasing the speed and
accel of the axis I mean.
I could cut cams with some success but I really can't follow the
shape
and
the phase with the same success and that's why I'm building a live
tooling
jig to cut at really low spindle RPM to avoid this effect as much
as possible. My particular problem is worse because all the
machining of the cams has to be aligned with a keyway in the
camshafts.
El dom., 12 jul. 2020 a las 5:12, John Dammeyer
(<jo...@autoartisans.com )
escribió:
So question.
1. would you post the G-Code that made that?
2. I take it virtually 0 backlash on the cross slide?
3. I was also impressed with how well the parting off went.
Mine tends
to
dig in.
John
-----Original Message-----
From: Sam Sokolik [mailto:samco...@gmail.com]
Sent: July-11-20 7:39 PM
To: Enhanced Machine Controller (EMC)
Subject: [Emc-users] Because the hardware store was 4 miles
away...
Right? Am I right?
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