On Fri, 19 Mar 2021, Nicklas SB Karlsson wrote:
Date: Fri, 19 Mar 2021 19:07:50 +0100
From: Nicklas SB Karlsson <nk@nksb.online>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] Spindle rps and index
Den 2021-03-19 kl. 10:53, skrev andy pugh:
On Fri, 19 Mar 2021 at 01:46, John Dammeyer <jo...@autoartisans.com> wrote:
I take it then that you can't actually move the spindle to the index
position unless you have some sort of control beyond velocity?
Velocity control + PID = position control.
Here is a schematic of a typical LinuxCNC spindle orient setup:
https://wiki.linuxcnc.org/uploads/orient.svg
Yes schematic it is, once concluded .hal file is more or less a netlist
and have been able to use gschem to draw schematics and generate .hal file.
Think it is similar or same as VMC_toolchange among the simulation
machines in Linuxcnc. orient.N.position is a float and it will work if
it overflow each turn?
Otherwise then spindle rotate, position get larger, decimal point is
moved and after slightly more than 77 hours at 3 600 rpm resolution is
so bad it can't count a full turn. To get a resolution of 256 degrees
per turn 8 bits are necessary and this point is passed already after
slightly more than 18 minutes. Reason is for a float 24 bits are used
for digits, the other eight bits are used for sign and placement of
decimal point, there are also a few special cases like NaN/-Inf/Inf.
Often used float for analog values, there it have been great since
resolution have been known while scaling vary.
Nicklas Karlsson
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If spindle position is the same as other LinuxCNC axis, its a double precision
float so will take a _lot_ longer to lose precision.
That said, typical spindle orient routines use the index so the count gets reset
when orienting.
Peter Wallace
Mesa Electronics
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