Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Gene Heskett]

On Tuesday 14 July 2020 12:43:40 andy pugh wrote:

> On Tue, 14 Jul 2020 at 17:37, Les Newell  
wrote:
> > > No programmer will ever use machine-coordinates (G53) - only in
> > > case of trouble or for maintenance.
> >
> > Nope. G53 is pretty common.
>
> Fusion360 CAM assumes that a G53G0Z0 will retract the tool to the top
> of Z travel.  I have seen a number of posts on the forum where this
> has mashed a tool into the table.
IMO Fusion360 is correct. And its not open for discussion.  There is no 
valid reason for it to do otherwise.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Gene Heskett]

On Tuesday 14 July 2020 12:18:30 Les Newell wrote:

> On 14/07/2020 15:28, Reinhard wrote:
> > The machine moves (assuming it does not have absolute
> > encoders that are battery buffered) toward the home switch until the
> > switch signals contact. That's the axis origin - and I thought, this
> > is what the word "home"-position means.
> > With any professional cnc I know about it is the case.
> > Obviously not with linuxcnc :(
>
> Referencing is simply a way for the machine to identify it's position
> in space. Where the home switches are positioned is immaterial. They
> just say 'you are here'. It is up to the machine integrator to decide
> where the axis 0 is.
>
> > So if linuxcnc has different behaviour, it is far from being
> > flexible. It's just crap! Crap from people that don't know machine
> > behaviour.
>
> You can set up LCNC to use the home switch exactly as you describe.
> You can define your axis zero to be anywhere you like.
>
> > No programmer will ever use machine-coordinates (G53) - only in case
> > of trouble or for maintenance.
>
> Nope. G53 is pretty common. For example on a lot of machines Z0 is the
> highest point the Z axis can move. G53G0Z0 will give the maximum
> possible Z clearance without needing to know about any offsets.
>
> On my router for instance my parking sequence is:
> G53G0Z0
> G53G0x1250Y1300
>
> > And that a user needs to use negative tool offsets is bullshit.
>
> Tool offsets are added to the commanded position, just like any other
> control. They specify the position of the tip of the tool relative to
> some standardized reference position. For instance on a mill the
> reference may be the tool holder gauge line. On a mill or router you
> are very unlikely to need negative tool offsets. If you do, the
> problem is to do with how you have your work or fixture offsets set
> up.
>
> On a lathe however there are some situations where you would need
> negative offsets. For instance if you are using a lathe with two tool
> posts on one X axis. Everything will be negative for the tool post
> behind the spindle centre line. Some lathe controllers have have
> compensation built in for this but AFAIK LCNC does not.
>
> > Its very poor, that there are so many weird workarounds in linuxcnc
> > caused by ignorance, lack of knowledge or misunderstanding :(
>
> It strikes me that in this case the lack of understanding is on your
> part, not the LCNC authors.
>
> Les
>
I have to agree. Haveing a home_offset, conbined with logic that runs it 
toward the switch position is extremely handy if one sets up his switch 
activation so its never released if travel continues in the direction 
that closed the switch. On both of my lathes the switch is a bit left of 
center of the travel, so issueing a home, the switch is first checked 
and if closed it drives the carriage to the right in search of the 
switch opening.  If open, the carriage is right of the switch so it 
knows to move left to find it. So at the least, you don't have to 
manually move the machine to where you know the switch is open before 
starting to home it. It just goes in the right direction to find the 
switch autmatically.  Its called usability.

Whats not to like about that?
>
>
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Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Chris Morley]

The home position was just set at 6" arbitrarily.


That's what I said. But then the home position may not be called home
position. It might be a workpiece origin, a reference point, what ever.


Homing is complicated!

Not at all! But wordings and diagrams should be clear and understandable.
Arbitrary positions should be marked as such. The current picture is
misleading - especially if your unsure and look for help. It is a help page!


What would be a good description of the final position after homing then?

It's not a reference point or origin. In fact it has no significance 
other then that's where an axis will end up after homing.


Reference point is a reasonable description of the home switch offset - 
but I thought home switch offset was clear enough.


We can change / add to the docs to make things clearer.

Chris



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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Jon Elson]

On 07/14/2020 11:00 AM, Reinhard wrote:
Last weeks I worked hard on linuxcnc and the deeper I dig, 
the more upset I get. Such a great project and nobody 
cares about quality ... That makes me mad. ... and when I 
see such things like the homing maze ... That was too much
Well, I've been using EMC/EMC2/LinuxCNC since 1998.  There 
were some stability issues in 1997.
But, since then, I have gone through 3 computers and a bunch 
of software updates, but LinuxCNC
just works.  I have NEVER, since 1998, had it crash on me.  
There have been a few issues, but they
are all related to operator error of one kind or another.  
There has been some grumbling about
the slow progress and long delays between updates, but it 
takes a while for issues to turn up and
be fixed.  So, I think that is the mark of quality --  take 
the time to be sure it is right before releasing it.
Yes, the documentation doesn't look like the product of a 
billion $ corporation, but it is being supported largely by 
ONE GUY!  And, we are so lucky to have John Thornton take 
over the docs, that ugly job that nobody else wanted to do!


There is a REASON homing is complicated, there are 
situations where you NEED to do it in several different 
ways.  Homing is needed for machines with tool changers, and 
accurate homing is needed where you will restart the machine 
with referenced fixtures in place, and expect the same 
reference as the day before.

LinuxCNC does all this quite well.

Jon


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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[andy pugh]

On Tue, 14 Jul 2020 at 17:37, Les Newell  wrote:

> > No programmer will ever use machine-coordinates (G53) - only in case of
> > trouble or for maintenance.
>
> Nope. G53 is pretty common.

Fusion360 CAM assumes that a G53G0Z0 will retract the tool to the top
of Z travel.  I have seen a number of posts on the forum where this
has mashed a tool into the table.

-- 
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-developers] problem understanding diagram from help-pages of pncconf

[Les Newell]

On 14/07/2020 15:28, Reinhard wrote:

The machine moves (assuming it does not have absolute
encoders that are battery buffered) toward the home switch until the switch
signals contact. That's the axis origin - and I thought, this is what the word
"home"-position means.
With any professional cnc I know about it is the case.
Obviously not with linuxcnc :(


Referencing is simply a way for the machine to identify it's position in 
space. Where the home switches are positioned is immaterial. They just 
say 'you are here'. It is up to the machine integrator to decide where 
the axis 0 is.



So if linuxcnc has different behaviour, it is far from being flexible. It's just
crap! Crap from people that don't know machine behaviour.


You can set up LCNC to use the home switch exactly as you describe. You 
can define your axis zero to be anywhere you like.




No programmer will ever use machine-coordinates (G53) - only in case of
trouble or for maintenance.


Nope. G53 is pretty common. For example on a lot of machines Z0 is the 
highest point the Z axis can move. G53G0Z0 will give the maximum 
possible Z clearance without needing to know about any offsets.


On my router for instance my parking sequence is:
G53G0Z0
G53G0x1250Y1300


And that a user needs to use negative tool offsets is bullshit.


Tool offsets are added to the commanded position, just like any other 
control. They specify the position of the tip of the tool relative to 
some standardized reference position. For instance on a mill the 
reference may be the tool holder gauge line. On a mill or router you are 
very unlikely to need negative tool offsets. If you do, the problem is 
to do with how you have your work or fixture offsets set up.


On a lathe however there are some situations where you would need 
negative offsets. For instance if you are using a lathe with two tool 
posts on one X axis. Everything will be negative for the tool post 
behind the spindle centre line. Some lathe controllers have have 
compensation built in for this but AFAIK LCNC does not.




Its very poor, that there are so many weird workarounds in linuxcnc caused by
ignorance, lack of knowledge or misunderstanding :(



It strikes me that in this case the lack of understanding is on your 
part, not the LCNC authors.


Les



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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Ed]

On 7/14/20 11:00 AM, Reinhard wrote:

On Dienstag, 14. Juli 2020, 17:31:20 CEST Chris Morley wrote:

I don't understand your hostility.

Yes, I'm not smart enuf :(

Last weeks I worked hard on linuxcnc and the deeper I dig, the more upset I
get. Such a great project and nobody cares about quality ...
That makes me mad.

... and when I see such things like the homing maze ...
That was too much


The homing routine is no more complicated than the integrator makes it.

Set your switches where you want and leave "HOME_OFFSET" at zero in the 
ini file. If you are doing a retro fit and do not like where they are 
then change them.


The nice thing about  the system as it is now is you have the OPTION to 
change it, not a necessity. On my vertical mill I left them as is and 
leave home in that position. On my lathe it is handier to have home 
position away from the switch position.


Maybe this is more of a semantics problem, names here may be different 
than names elsewhere.



Ed.




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Jon Elson]

On 07/14/2020 10:31 AM, Chris Morley wrote:

I don't understand your hostility.
I didn't create the homing routine but it seems reasonable to me.
Linuxcnc is capable of doing exactly what you are used to, just set some of the 
settings to zero.

There is a case where the home position MUST be different 
than the switch position.  If you
use a limit switch for home, then the home position MUST 
cause the machine to back away from
the switch.  Also, when using encoder index pulses to make 
the homing more repeatable, then
the hole position will be slightly different from the point 
where the switch trips.  You then have the choice for the 
axis to continue toward the switch, or to back away, while 
searching for the index pulse.
I think all of these options are necessary for specific 
machine configurations.


Jon


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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

On Dienstag, 14. Juli 2020, 17:31:20 CEST Chris Morley wrote:
> I don't understand your hostility.

Yes, I'm not smart enuf :(

Last weeks I worked hard on linuxcnc and the deeper I dig, the more upset I 
get. Such a great project and nobody cares about quality ...
That makes me mad.

... and when I see such things like the homing maze ...
That was too much

> I didn't create the homing routine but it seems reasonable to me.

Well, I'm not as good a you

> but it also allows one to set the origin anywhere and adds an optional move
> after 'reference'

but why call that point "home-position"?

In my understanding, "home-position" is a machine internal and there is no 
place for interpretations or user wishes. "home-position" is machine origin.

> Also G28/30 move to origin by default so having origin somewhere particular
> may be useful.

Support lazyness? 
You're kidding!

Just need to save the parameters for G28 and it works the same.
So make things complicated for SOME users, that don't like to store a 
location? And all other users have to accept the complicated behaviour?
Well done!

That's like one person does not like the sunset and it stops earth rotation - 
all other beings have to accept the wish of this single person :/






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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Chris Morley]

I don't understand your hostility.
I didn't create the homing routine but it seems reasonable to me.
Linuxcnc is capable of doing exactly what you are used to, just set some of the 
settings to zero.

but it also allows one to set the origin anywhere and adds an optional move 
after 'reference'

Setting the origin in a certain stop could be useful in some situations, say to 
miss equipment while homing a particular axis.
Also G28/30 move to origin by default so having origin somewhere particular may 
be useful. ie I think G30 can be used as a tool change position.

Then also remembering linuxcnc doesn't always run machine tools - I'm sure 
robots have their own requirements.

If using the words 'reference offset ' rather then 'home switch offset' makes 
you happy I'm sure no one will say you have a crappy mind.

Chris


From: Reinhard 
Sent: July 14, 2020 2:28 PM
To: EMC developers 
Subject: Re: [Emc-developers] problem understanding diagram from help-pages of 
pncconf

On Dienstag, 14. Juli 2020, 06:09:38 CEST Chris Morley wrote:
> The problem seems to come from people thinking the contact with the homing
> switch is where home is. which is not surprising, as when you ask linuxcnc
> to home that's where it goes first.

May be its caused by the wording, or linuxcnc people are already accustomed to
crappy minds :/

The word "homing" does not reflect the importance of that issue. In german we
talk about referencing an axis. So referencing is completely off to users
wishes or likes. The machine moves (assuming it does not have absolute
encoders that are battery buffered) toward the home switch until the switch
signals contact. That's the axis origin - and I thought, this is what the word
"home"-position means.
With any professional cnc I know about it is the case.
Obviously not with linuxcnc :(

So if linuxcnc has different behaviour, it is far from being flexible. It's just
crap! Crap from people that don't know machine behaviour.

After referencing all axis (I use the german expression, which might describe
more exact what happens) the machine knows its origin and can move.
No programmer will ever use machine-coordinates (G53) - only in case of
trouble or for maintenance. So if you use G54 ... you don't have to know or
care about machine coordinates. The coordinates are as you like them to be.
And if you want the machine move to a different location after homing, that's
what stored locations (i.e. G28) are for.

And that a user needs to use negative tool offsets is bullshit. A machine
controller like linuxcnc should handle tool dimensions in any direction. A
tool length can never be negative and so you can't move an arc with negative
radius. Well, I talk about tool dimensions, not wear level parameters, which
of cause can be negative.

Its very poor, that there are so many weird workarounds in linuxcnc caused by
ignorance, lack of knowledge or misunderstanding :(

I don't wonna support that crap, so may be, its better some other guy cares
for translations ...


cheers Reinhard






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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

On Dienstag, 14. Juli 2020, 16:49:08 CEST Robert Ellenberg wrote:
> I agree that it's logical to use positive offsets for tools in a spindle
> (since a negative physical size is nonsensical). However, what if you have
> an auxiliary spindle with a tool tip above the zero height of the main
> spindle? I'm not saying that's a wise choice, but it would be physically
> correct to have a negative length offset.

At work we have multispindle lathe with revolver with turning tools and 
multiaxis milling head combined with tool changer. The auxiliary spindle can 
pick up the workpiece from main spindle and continue work ...

There you have any thinkable combination of tool dimensions and coordinate 
systems - but you as a user don't have to care about coordinate systems or 
positive or negative offsets.

Tool dimensions are always positive and coordinate systems are relative to the 
spindle. You have 2 controller instances (like linuxcnc) which can work 
independently or synchronized.
Revolver and Millinghead work for both spindles and each spindle can run in 
lathe mode or as indexed axis.

I guess, that kind of machine fits all thinkable situations - but none of them 
is illogical to the user.

We have a saying:
the genius of an invention reveals in its ease of use, 
not in the complexity of its structure


cheers Reinhard




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Robert Ellenberg]

Reinhard,

I agree that it's logical to use positive offsets for tools in a spindle
(since a negative physical size is nonsensical). However, what if you have
an auxiliary spindle with a tool tip above the zero height of the main
spindle? I'm not saying that's a wise choice, but it would be physically
correct to have a negative length offset.

Best,
Rob

On Tue, Jul 14, 2020 at 10:28 AM Reinhard 
wrote:

> On Dienstag, 14. Juli 2020, 06:09:38 CEST Chris Morley wrote:
> > The problem seems to come from people thinking the contact with the
> homing
> > switch is where home is. which is not surprising, as when you ask
> linuxcnc
> > to home that's where it goes first.
>
> May be its caused by the wording, or linuxcnc people are already
> accustomed to
> crappy minds :/
>
> The word "homing" does not reflect the importance of that issue. In german
> we
> talk about referencing an axis. So referencing is completely off to users
> wishes or likes. The machine moves (assuming it does not have absolute
> encoders that are battery buffered) toward the home switch until the
> switch
> signals contact. That's the axis origin - and I thought, this is what the
> word
> "home"-position means.
> With any professional cnc I know about it is the case.
> Obviously not with linuxcnc :(
>
> So if linuxcnc has different behaviour, it is far from being flexible.
> It's just
> crap! Crap from people that don't know machine behaviour.
>
> After referencing all axis (I use the german expression, which might
> describe
> more exact what happens) the machine knows its origin and can move.
> No programmer will ever use machine-coordinates (G53) - only in case of
> trouble or for maintenance. So if you use G54 ... you don't have to know
> or
> care about machine coordinates. The coordinates are as you like them to be.
> And if you want the machine move to a different location after homing,
> that's
> what stored locations (i.e. G28) are for.
>
> And that a user needs to use negative tool offsets is bullshit. A machine
> controller like linuxcnc should handle tool dimensions in any direction. A
> tool length can never be negative and so you can't move an arc with
> negative
> radius. Well, I talk about tool dimensions, not wear level parameters,
> which
> of cause can be negative.
>
> Its very poor, that there are so many weird workarounds in linuxcnc caused
> by
> ignorance, lack of knowledge or misunderstanding :(
>
> I don't wonna support that crap, so may be, its better some other guy
> cares
> for translations ...
>
>
> cheers Reinhard
>
>
>
>
>
>
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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

On Dienstag, 14. Juli 2020, 06:09:38 CEST Chris Morley wrote:
> The problem seems to come from people thinking the contact with the homing
> switch is where home is. which is not surprising, as when you ask linuxcnc
> to home that's where it goes first.

May be its caused by the wording, or linuxcnc people are already accustomed to 
crappy minds :/

The word "homing" does not reflect the importance of that issue. In german we 
talk about referencing an axis. So referencing is completely off to users 
wishes or likes. The machine moves (assuming it does not have absolute 
encoders that are battery buffered) toward the home switch until the switch 
signals contact. That's the axis origin - and I thought, this is what the word 
"home"-position means.
With any professional cnc I know about it is the case.
Obviously not with linuxcnc :(

So if linuxcnc has different behaviour, it is far from being flexible. It's 
just 
crap! Crap from people that don't know machine behaviour.

After referencing all axis (I use the german expression, which might describe 
more exact what happens) the machine knows its origin and can move.
No programmer will ever use machine-coordinates (G53) - only in case of 
trouble or for maintenance. So if you use G54 ... you don't have to know or 
care about machine coordinates. The coordinates are as you like them to be.
And if you want the machine move to a different location after homing, that's 
what stored locations (i.e. G28) are for.

And that a user needs to use negative tool offsets is bullshit. A machine 
controller like linuxcnc should handle tool dimensions in any direction. A 
tool length can never be negative and so you can't move an arc with negative 
radius. Well, I talk about tool dimensions, not wear level parameters, which 
of cause can be negative.

Its very poor, that there are so many weird workarounds in linuxcnc caused by 
ignorance, lack of knowledge or misunderstanding :(

I don't wonna support that crap, so may be, its better some other guy cares 
for translations ...


cheers Reinhard






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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Gene Heskett]

On Tuesday 14 July 2020 06:38:57 Ed wrote:

> On 7/13/20 11:09 PM, Chris Morley wrote:
> > There _is_ only one home position. But it doesn't need to be at the
> > origin or switch trip point. The problem seems to come from people
> > thinking the contact with the homing switch is where home is. which
> > is not surprising, as when you ask linuxcnc to home that's where it
> > goes first. But it's where the machine stops _after_ homing that is
> > actually home and it doesn't have to be the origin.
> >
> > You can of course set it up as you described, but that is only one
> > of a million different ways. Here the two switch exmple show home at
> > the origin and home at 3:
> > http://linuxcnc.org/docs/2.8/html/config/ini-homing.html
> >
> > I might point out this is machine coordinates which most people
> > don't normally work in.
> >
> > As I said homing is actually complicated - through linuxcnc's
> > flexibility.
> >
> > Chris
>
> To illustrate what Chris is saying. On my Hardinge CHNC lathe the X
> cross slide home switch activates when the slide is in the full
> positive position. The minor problem to this is all tool offsets are
> negative from that point. By changing the .ini file "HOME_OFFSET=0" to
> "HOME_OFFSET=4.5" the machine goes to the home switch, activates, then
> moves 4.5 (lathes set up in radius)  and calls that home. This gives
> me tool offsets with positive numbers on the X axis, much easier when
> fine tuning the last couple of tenths.

I am doing a similar thing with the 11x56 Sheldon, except I've a 
relatively large QCTP on a fixed base, no compound because LinuxCNC 
drives the cross slide to give the effect of the compound. Without the 
compound, its considerably more rigid. BUT with a BXA wedgeing toolpost, 
and the outer limit set a bit more restricted than OEM. My offset is a 
hair under 4". I can still reach stuff hanging outside of an 8" chuck by 
turning the tool post around and mounting the tools on the back side of 
the post, just did it this past week makeing a nema-23 motor mount out 
of the end of a 3.5 by 8" piece of half inch alu. I'm motorizing a BS-1 
clone. That will make my 3rd motorized A axis for my milling machines.  
Had to buy a hoist, by the time its finished its right at 200lbs. I 
shoulda started with a BS-0... 
>
> Ed.
>
>
>
>
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Ed]

On 7/13/20 11:09 PM, Chris Morley wrote:

There _is_ only one home position. But it doesn't need to be at the origin or 
switch trip point.
The problem seems to come from people thinking the contact with the homing 
switch is where home is.
which is not surprising, as when you ask linuxcnc to home that's where it goes 
first.
But it's where the machine stops _after_ homing that is actually home and it 
doesn't have to be the origin.

You can of course set it up as you described, but that is only one of a million 
different ways.
Here the two switch exmple show home at the origin and home at 3:
http://linuxcnc.org/docs/2.8/html/config/ini-homing.html

I might point out this is machine coordinates which most people don't normally 
work in.

As I said homing is actually complicated - through linuxcnc's flexibility.

Chris


To illustrate what Chris is saying. On my Hardinge CHNC lathe the X 
cross slide home switch activates when the slide is in the full positive 
position. The minor problem to this is all tool offsets are negative 
from that point. By changing the .ini file "HOME_OFFSET=0" to 
"HOME_OFFSET=4.5" the machine goes to the home switch, activates, then 
moves 4.5 (lathes set up in radius)  and calls that home. This gives me 
tool offsets with positive numbers on the X axis, much easier when fine 
tuning the last couple of tenths.



Ed.




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Chris Morley]

Did you read the text in pncconf about homing- it shows when you are on an axis 
page and press the help key.
help text changes for most pages when you press the help key.

I thought it did a decent description of the basics - it's old text so I could 
add more to it.

Chris

From: Chris Morley 
Sent: July 14, 2020 4:09 AM
To: EMC developers 
Subject: Re: [Emc-developers] problem understanding diagram from help-pages of 
pncconf

There _is_ only one home position. But it doesn't need to be at the origin or 
switch trip point.
The problem seems to come from people thinking the contact with the homing 
switch is where home is.
which is not surprising, as when you ask linuxcnc to home that's where it goes 
first.
But it's where the machine stops _after_ homing that is actually home and it 
doesn't have to be the origin.

You can of course set it up as you described, but that is only one of a million 
different ways.
Here the two switch exmple show home at the origin and home at 3:
http://linuxcnc.org/docs/2.8/html/config/ini-homing.html

I might point out this is machine coordinates which most people don't normally 
work in.

As I said homing is actually complicated - through linuxcnc's flexibility.

Chris

From: Reinhard 
Sent: July 14, 2020 2:44 AM
To: EMC developers 
Subject: Re: [Emc-developers] problem understanding diagram from help-pages of 
pncconf

On Montag, 13. Juli 2020, 23:33:35 CEST Chris Morley wrote:
> X home position in the diagram is referring to the final home position.

??? There could be only ONE home position and that's in my understanding the
origin in machine coordinates. Or with other words: home position is where the
home switch signals contact.

> The home position was just set at 6" arbitrarily.

That's what I said. But then the home position may not be called home
position. It might be a workpiece origin, a reference point, what ever.

> Homing is complicated!

Not at all! But wordings and diagrams should be clear and understandable.
Arbitrary positions should be marked as such. The current picture is
misleading - especially if your unsure and look for help. It is a help page!


cheers Reinhard




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Chris Morley]

There _is_ only one home position. But it doesn't need to be at the origin or 
switch trip point.
The problem seems to come from people thinking the contact with the homing 
switch is where home is.
which is not surprising, as when you ask linuxcnc to home that's where it goes 
first.
But it's where the machine stops _after_ homing that is actually home and it 
doesn't have to be the origin.

You can of course set it up as you described, but that is only one of a million 
different ways.
Here the two switch exmple show home at the origin and home at 3:
http://linuxcnc.org/docs/2.8/html/config/ini-homing.html

I might point out this is machine coordinates which most people don't normally 
work in.

As I said homing is actually complicated - through linuxcnc's flexibility.

Chris

From: Reinhard 
Sent: July 14, 2020 2:44 AM
To: EMC developers 
Subject: Re: [Emc-developers] problem understanding diagram from help-pages of 
pncconf

On Montag, 13. Juli 2020, 23:33:35 CEST Chris Morley wrote:
> X home position in the diagram is referring to the final home position.

??? There could be only ONE home position and that's in my understanding the
origin in machine coordinates. Or with other words: home position is where the
home switch signals contact.

> The home position was just set at 6" arbitrarily.

That's what I said. But then the home position may not be called home
position. It might be a workpiece origin, a reference point, what ever.

> Homing is complicated!

Not at all! But wordings and diagrams should be clear and understandable.
Arbitrary positions should be marked as such. The current picture is
misleading - especially if your unsure and look for help. It is a help page!


cheers Reinhard




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

On Montag, 13. Juli 2020, 23:33:35 CEST Chris Morley wrote:
> X home position in the diagram is referring to the final home position.

??? There could be only ONE home position and that's in my understanding the 
origin in machine coordinates. Or with other words: home position is where the 
home switch signals contact.

> The home position was just set at 6" arbitrarily.

That's what I said. But then the home position may not be called home 
position. It might be a workpiece origin, a reference point, what ever.

> Homing is complicated!

Not at all! But wordings and diagrams should be clear and understandable. 
Arbitrary positions should be marked as such. The current picture is 
misleading - especially if your unsure and look for help. It is a help page!


cheers Reinhard




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

Hi,

On Montag, 13. Juli 2020, 22:11:53 CEST Rod Webster wrote:
> Data redundancy should be avoided at all costs. There must be only one
> single point of truth!

That's a very nice theory :D

If you look at the code of linuxcnc, or even at language texts you'll note, 
that reality is different ;)
I only translated small part of the language file, but you see pretty the same 
message appear again and again and again ...


cheers Reinhard




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Chris Morley]

If HTML docs were included for offline, I would have Pncconf load them.
PDF docs suck.

Those diagrams you reference are included in pncconf help page too.


From: Rod Webster 
Sent: July 13, 2020 8:11 PM
To: EMC developers 
Subject: Re: [Emc-developers] problem understanding diagram from help-pages of 
pncconf

There is a separate heading about homing
http://linuxcnc.org/docs/devel/html/config/ini-homing.html
I don't  think pncconf docs should include anything about homing except a
reference to the homing configuration docs.
Data redundancy should be avoided at all costs. There must be only one
single point of truth!

Rod Webster
*1300 896 832*
+61 435 765 611
VMN®
www.vmn.com.au<http://www.vmn.com.au>



On Tue, 14 Jul 2020 at 01:14, Reinhard 
wrote:

> On Montag, 13. Juli 2020, 16:55:28 CEST andy pugh wrote:
> > On Mon, 13 Jul 2020 at 15:31, Reinhard 
> wrote:
> > > So when the home-switch signals contact, then that is my home position,
> >
> > The home switch can be anywhere on the axis. It does not have to be at
> > a position called "0".
>
> Sure! I know that. But the picture shows the home-switch of the x-axis is
> at
> the min-position of the x-axis, which is the origin of the x-axis.
>
> The current position of the table shows a distance of 6" from the trip pin
> to
> the home switch. But the table could as good be placed at 5" or 7"
> distance
> between trip pin and home switch.
> What gives the 6" distance the right to be called home position?
>
>
> cheers Reinhard
>
>
>
>
>
>
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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Chris Morley]

X home position in the diagram is referring to the final home position.
The measurements 4 and 10 are the trip pin to limit switches measurements, 
which is an easy way to physically measure them.

The home position was just set at 6" arbitrarily.

When you hit the home switch you establish the origin (which everything is 
referenced from) but the origin can be anywhere, it doesn't have to be at the 
switch trip location.
The other two homing switch diagrams are newer and should give more detail.

Homing is complicated!

Chris

From: Reinhard 
Sent: July 13, 2020 2:31 PM
To: EMC developers 
Subject: [Emc-developers] problem understanding diagram from help-pages of 
pncconf

Hi,

I just tried to translate the help-pages of pncconf, when I realized, that I
don't understand the mill picture.

In my understanding, homing an axis means, that the axis moves until the home-
switch signals contact. No matter what or where the home-switch is - whether
it is shared limit switch or separate ...

So when the home-switch signals contact, then that is my home position, which
according to the picture of pncconf is identical to the axis origin. I don't
see the 6" home position.

The value of 6" is based on capriciousness, as it can't be measured.
How can I explain that position to a newcomer of linuxcnc if I don't
understand it?

I would understand the picture, if the home position would be called predefined
position (which could be reached with G28 or G30), but Home Position is quite
different from that.


cheers Reinhard




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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Rod Webster]

There is a separate heading about homing
http://linuxcnc.org/docs/devel/html/config/ini-homing.html
I don't  think pncconf docs should include anything about homing except a
reference to the homing configuration docs.
Data redundancy should be avoided at all costs. There must be only one
single point of truth!

Rod Webster
*1300 896 832*
+61 435 765 611
VMN®
www.vmn.com.au



On Tue, 14 Jul 2020 at 01:14, Reinhard 
wrote:

> On Montag, 13. Juli 2020, 16:55:28 CEST andy pugh wrote:
> > On Mon, 13 Jul 2020 at 15:31, Reinhard 
> wrote:
> > > So when the home-switch signals contact, then that is my home position,
> >
> > The home switch can be anywhere on the axis. It does not have to be at
> > a position called "0".
>
> Sure! I know that. But the picture shows the home-switch of the x-axis is
> at
> the min-position of the x-axis, which is the origin of the x-axis.
>
> The current position of the table shows a distance of 6" from the trip pin
> to
> the home switch. But the table could as good be placed at 5" or 7"
> distance
> between trip pin and home switch.
> What gives the 6" distance the right to be called home position?
>
>
> cheers Reinhard
>
>
>
>
>
>
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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

On Montag, 13. Juli 2020, 16:55:28 CEST andy pugh wrote:
> On Mon, 13 Jul 2020 at 15:31, Reinhard  
wrote:
> > So when the home-switch signals contact, then that is my home position,
> 
> The home switch can be anywhere on the axis. It does not have to be at
> a position called "0".

Sure! I know that. But the picture shows the home-switch of the x-axis is at 
the min-position of the x-axis, which is the origin of the x-axis.

The current position of the table shows a distance of 6" from the trip pin to 
the home switch. But the table could as good be placed at 5" or 7" distance 
between trip pin and home switch. 
What gives the 6" distance the right to be called home position?


cheers Reinhard






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Re: [Emc-developers] problem understanding diagram from help-pages of pncconf

[andy pugh]

On Mon, 13 Jul 2020 at 15:31, Reinhard  wrote:

> So when the home-switch signals contact, then that is my home position,

The home switch can be anywhere on the axis. It does not have to be at
a position called "0".

-- 
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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[Emc-developers] problem understanding diagram from help-pages of pncconf

[Reinhard]

Hi,

I just tried to translate the help-pages of pncconf, when I realized, that I 
don't understand the mill picture. 

In my understanding, homing an axis means, that the axis moves until the home-
switch signals contact. No matter what or where the home-switch is - whether 
it is shared limit switch or separate ...

So when the home-switch signals contact, then that is my home position, which 
according to the picture of pncconf is identical to the axis origin. I don't 
see the 6" home position. 

The value of 6" is based on capriciousness, as it can't be measured.
How can I explain that position to a newcomer of linuxcnc if I don't 
understand it?

I would understand the picture, if the home position would be called predefined 
position (which could be reached with G28 or G30), but Home Position is quite 
different from that.


cheers Reinhard




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