Re: [Emc-users] where can I get the instant height of axis Z on amill?, a daa that was zeroed by the homing operation

2022-11-01 Thread gene heskett 

On 11/1/22 13:50, andy pugh wrote:

On Tue, 1 Nov 2022 at 14:36, gene heskett  wrote:


what I need is the number in the 5000 block, (or where ever it lives)
that is the "current height" as was established as zero when
the machine was homed but is now the actual height ack the g53 related
commands.

You need the value in HAL, so just use joint.3.pos-cmd
That won't jump around with changes in the co-ordinate map in use? G54 
to G57 for example?
That, if not affected by map changes (and its not) until a move is done 
ack the new map,

would be ideal.

It's in inches, going thru zero but not quite mid travel. and its seems 
dead stable. I'll use it, but Z is joint.2,
not joint.3, :) which is the bs-1. for an A axis.  I think I'm ready to 
carve a new .hal file.




If the offset is linear it doesn't matter where the origin is, so you
could use motor-pos-cmd, but I think this pin will be consistent once
homed.
And LCNC remembers that even thru shutdowns. Should not need disabling 
controls since Z
is the first axis homed just to stop tool breakage. That's simplifies 
the .hal a bit.

I won't need the switching mux or lut5.

Thanks Andy. Take care and stay well.

--
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 



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Re: [Emc-users] where can I get the instant height of axis Z on amill?, a daa that was zeroed by the homing operation

2022-11-01 Thread andy pugh 
On Tue, 1 Nov 2022 at 19:14, gene heskett  wrote:

> #<_abs_z>

How do you intend to use that in HAL?

You need a HAL pin, as I said earlier.

See. also: 
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ContributedComponents#millkins_trivial_kinematics_extended_by_XY_skew_correction

(But that won't work as-is, it would need work)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] where can I get the instant height of axis Z on amill?, a daa that was zeroed by the homing operation

2022-11-01 Thread gene heskett 

On 11/1/22 11:06, John Figie wrote:

Can't you just use kinematics to accomplish this?

John Figie

How would that be accomplished?

Since posting that question, I found on page 868 of masters docs, that 
what I want is a

named global:

#<_abs_z>

and it does change with running Z up and down the post. But it is not 
zeroed
by homing the axis. Which means I'll need to write a subroutine to set 
my own version
to arrive at a zero reference. It does appear to be none volatile as I 
got the same answer
from a debug output after 3 homing's from various resting positions. At 
Z home, 158.75.
 I ran it to the bottom limit and got -121.158. This with an 1/8th" 
mill about 10mm from the table


Since the thing leans from the bottom, I'd like to add that 121.158 to 
whatever I get from #<_abs_z>
so as to have a value that scales up from the bottom at zero. But that 
will change with the bottom
sw limit, not exactly consistent unless the upper, home switch is moved. 
That about a mm from the top

of the screw, and a very solid stop.

It also occurs to me that this correction should be disabled during 
homing, and only re-enabled
after all 4 axises has been homed, complicating things a bit, monitoring 
with a lut5 so it is only
enabled when  its all homed. So the two corrected axis's will have a 
scale-offset-mux2 each
with the mux2's controlled by a lut5.  The question then is will it 
throw a following error when

the correction is activated? IDK.

And explains why, if it can be corrected with kinematics, it might be 
the better way. So I'm interested

in investigating the idea.

Explain please how.

And thank you John.


On Tue, Nov 1, 2022, 9:35 AM gene heskett  wrote:


Greetings all;

I am about to straighten the post of my go704, which is not straight, it
leans and this causes problems
when rigid tapping because the tap if trammed correctly is being moved
sideways as it descends into the
hole its tapping. I now have a circular square to set on the table and
scan with a dial.

I intend to put a height derived offset, scalable, into the x and y
axises which will move the table as the head rises and
falls to compensate and make it effectively become vertical to the table.

I'll put the offset module at the pid input, and in just front of the
pid in the addf order, The correction scale I can adjust,
what I need is the number in the 5000 block, (or where ever it lives)
that is the "current height" as was established as zero when
the machine was homed but is now the actual height ack the g53 related
commands.

Thank you.

Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
   soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
   - Louis D. Brandeis
Genes Web page 



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Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 



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