Re: [Emc-developers] Trajectory planner shortcomings

2023-07-04 Thread Sam Sokolik 
Any movement involving the rotary axis is limited to the old
trajectory planner - 1 segment look ahead..

sam

On Tue, Jul 4, 2023 at 1:47 PM gene heskett  wrote:

> On 7/4/23 13:31, Marius wrote:
> > Hi
> >
> > I have been trying to get a rotary fourth axis setup going with the help
> > of regular and knowledgable contributors to LinuxCnc. We came up against
> > a brick wall as many other project developers have done.
> >
> > The problem seems to be that our trajectory planner lack the ability to
> > look ahead for any rotary axis. This means that a coordinated move that
> > includes a rotary move will be dysfunctional at best.
> >
> Not true Marius, if you are having problems, something about your config
> is wrong. I am presently carving a 2 start screw in wood with my B axis
> on the 6040 gantry mill.  And its accurate to a fraction of a degree
> anyplace in the 400mm length of that screw.  With no PID's in use on
> that machine.  All you should have to do is calculate the end points
> related to where it starts for the b axis and issue the two end points
> in the same command line. I carve a two start buttress thread by pre
> positioning at the shape point of the tooth, and carve that position for
> the length of that screw. That rotates the b axis in perfect sync with
> the y motion.  At the far end of the screw, I add 180 degrees to the b,
> move it that addition 180, then come back to the y starting point with b
> coming bavk to 180, which is about 6mm off the end of the screw, then I
> move b back to zero, reposition the tool for the next pass, and do it
> again till its done.  The 7 degree angle of the load bearing face of
> that thread is established by a wedge under the motor, an angle
> duplicated in the tooths shape. The nuts are printed on a 3d printer in
> PETG, with a dozen teeth engaged in the length of the nut.
>
> There are no PID's and my B axis is a 3NM, 3 phase stepper/servo driving
> a 5/1 worm which is driving a square socket that turns a 2x2 stick
> nearly 600 mm long.live center at the other end of the stick, shimmed to
> reduce the z motion required to do as close to a true cylinder the
> length of that thread.  And it all Just Works. My Z axis is also driven
> by a 1NM version of that stepper/servo.
>
> Start by checking your .ini file. under:
> [DISPLAY]
> you should have something like this:
> GEOMETRY = XYZA
> then down file a ways:
> [TRAJ]
> AXES = 4
> COORDINATES =  XYZA
>
> Now, that's wrong but my i/o channels are limited to 4 axis so my B axis
> is actually wired to what would be the A terminals in the interface as I
> am using a 5i25 and a 7i76 plus a std breakout for other functions. A
> 7i90HD would fix that but bring another wagon load of shekels for
> 7i42TA's, takes 3 of them as the 7i90 has no buffers to protect the fpga
> used from 5 volt stuff. I've forgotten how, but on screen in axis it
> does show as B.
> Check the above, the rest of my .ini has it as A and JOINT_3.
>
> Digging thru my .hal file will get more complex as its been a couple
> years since I first rigged a different B axis.
>
> So start with the above.
> And have a happy 4th Marous.
>
> > I understand that there is a free trajectory planner on offer to
> > LinuxCnc but it has not been integrated. It would seem that some lack of
> > skills or time has a role to play in getting it integrated.
> >
> > I unfortunately do not have the skills nor the time to tender to assist
> > with this however, someone made the suggestion that maybe the community
> > could embark on a fund raising project to enable us to pay for someone
> > to get the trajectory planner integrated. I am sure that many would
> > stand to benefit from this and other users that I have spoken to has
> > indicated that they would gladly contribute.
> >
> > I would at least want to start a discussion around the idea.
> >
> >
> > Regards
> >
> > Marius
> >
> >
> >
> > ___
> > Emc-developers mailing list
> > Emc-developers@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-developers
> > .
>
> 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 
>
>
>
> ___
> Emc-developers mailing list
> Emc-developers@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-developers
>

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Re: [Emc-developers] Trajectory planner shortcomings

2023-07-04 Thread gene heskett 

On 7/4/23 13:31, Marius wrote:

Hi

I have been trying to get a rotary fourth axis setup going with the help 
of regular and knowledgable contributors to LinuxCnc. We came up against 
a brick wall as many other project developers have done.


The problem seems to be that our trajectory planner lack the ability to 
look ahead for any rotary axis. This means that a coordinated move that 
includes a rotary move will be dysfunctional at best.


Not true Marius, if you are having problems, something about your config 
is wrong. I am presently carving a 2 start screw in wood with my B axis 
on the 6040 gantry mill.  And its accurate to a fraction of a degree 
anyplace in the 400mm length of that screw.  With no PID's in use on 
that machine.  All you should have to do is calculate the end points 
related to where it starts for the b axis and issue the two end points 
in the same command line. I carve a two start buttress thread by pre 
positioning at the shape point of the tooth, and carve that position for 
the length of that screw. That rotates the b axis in perfect sync with 
the y motion.  At the far end of the screw, I add 180 degrees to the b, 
move it that addition 180, then come back to the y starting point with b 
coming bavk to 180, which is about 6mm off the end of the screw, then I 
move b back to zero, reposition the tool for the next pass, and do it 
again till its done.  The 7 degree angle of the load bearing face of 
that thread is established by a wedge under the motor, an angle 
duplicated in the tooths shape. The nuts are printed on a 3d printer in 
PETG, with a dozen teeth engaged in the length of the nut.


There are no PID's and my B axis is a 3NM, 3 phase stepper/servo driving 
a 5/1 worm which is driving a square socket that turns a 2x2 stick 
nearly 600 mm long.live center at the other end of the stick, shimmed to 
reduce the z motion required to do as close to a true cylinder the 
length of that thread.  And it all Just Works. My Z axis is also driven 
by a 1NM version of that stepper/servo.


Start by checking your .ini file. under:
[DISPLAY]
you should have something like this:
GEOMETRY = XYZA
then down file a ways:
[TRAJ]
AXES = 4
COORDINATES =  XYZA

Now, that's wrong but my i/o channels are limited to 4 axis so my B axis 
is actually wired to what would be the A terminals in the interface as I 
am using a 5i25 and a 7i76 plus a std breakout for other functions. A 
7i90HD would fix that but bring another wagon load of shekels for 
7i42TA's, takes 3 of them as the 7i90 has no buffers to protect the fpga 
used from 5 volt stuff. I've forgotten how, but on screen in axis it 
does show as B.

Check the above, the rest of my .ini has it as A and JOINT_3.

Digging thru my .hal file will get more complex as its been a couple 
years since I first rigged a different B axis.


So start with the above.
And have a happy 4th Marous.

I understand that there is a free trajectory planner on offer to 
LinuxCnc but it has not been integrated. It would seem that some lack of 
skills or time has a role to play in getting it integrated.


I unfortunately do not have the skills nor the time to tender to assist 
with this however, someone made the suggestion that maybe the community 
could embark on a fund raising project to enable us to pay for someone 
to get the trajectory planner integrated. I am sure that many would 
stand to benefit from this and other users that I have spoken to has 
indicated that they would gladly contribute.


I would at least want to start a discussion around the idea.


Regards

Marius



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Emc-developers mailing list
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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-developers] Trajectory planner shortcomings

2023-07-04 Thread andy pugh 
On Tue, 4 Jul 2023 at 18:34, Marius  wrote:

> The problem seems to be that our trajectory planner lack the ability to
> look ahead for any rotary axis. This means that a coordinated move that
> includes a rotary move will be dysfunctional at best.

It's not as bad as that.

There is a 9-axis blending planner in Tormach, but it's not trivial to
merge it with Linuxcnc due to divergence in the codebase.

If we could get hold of the patches that introduced it to Tormach then
we could look at integrating it, but doing it just from comparing the
code sounds hard.

-- 
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] Trajectory planner shortcomings

2023-07-04 Thread Marius 

Hi

I have been trying to get a rotary fourth axis setup going with the help 
of regular and knowledgable contributors to LinuxCnc. We came up against 
a brick wall as many other project developers have done.


The problem seems to be that our trajectory planner lack the ability to 
look ahead for any rotary axis. This means that a coordinated move that 
includes a rotary move will be dysfunctional at best.


I understand that there is a free trajectory planner on offer to 
LinuxCnc but it has not been integrated. It would seem that some lack of 
skills or time has a role to play in getting it integrated.


I unfortunately do not have the skills nor the time to tender to assist 
with this however, someone made the suggestion that maybe the community 
could embark on a fund raising project to enable us to pay for someone 
to get the trajectory planner integrated. I am sure that many would 
stand to benefit from this and other users that I have spoken to has 
indicated that they would gladly contribute.


I would at least want to start a discussion around the idea.


Regards

Marius



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Emc-developers@lists.sourceforge.net
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