[Emc-users] jerk control for high speed machines

[andrew beck]

Hey guys

just a few thoughts here.

I have a high speed cnc machining center (cnc mill)

it has 16mm pitch ballscrews and weighs 6ton

linuxcnc is awesome and does a great job controlling it.  I make plastic
injection molds and lots of 3d machining all the time.  plus all the little
jobs that a cnc is great for.

I think the only thing lacking from linuxcnc for my use is some sort of
jerk control for corners.  there may already be something around that
solves the issue though without jerk control.  so what happens is when the
machine changes direction the whole machine vibrates and jumps around.  its
quite bad.  enough that I may rubber mount the electrical box lol.

I have accelerations of 750 (i think it is mm/sec2)

and max rapids of 8m/min

I would love to turn those up to like 25m/min rapid and 2000mm/sec2
accelerations

has any one tried any form of jerk control yet on linuxcnc?  or wants to
have a play and code it.  I have 3 6 ton cnc machines that will all use
linuxcnc so very keen to solve this jerk control issue.

regards

Andrew

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Re: [Emc-users] freecad, latest, starter tut?

[Martin Dobbins]

Can you select, copy, and paste the code you see on screen to a text file?

I don't know, I didn't try.

Martin



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Re: [Emc-users] freecad, latest, starter tut?

[Gregg Eshelman via Emc-users]

 How about HeeksCAD/CAM? https://sites.google.com/site/heekscad/
https://sites.google.com/site/heekscad/news/linuxversion
The only difference between the free and paid version is the free version puts 
a note at the start of the G-Code it outputs, which can easily be removed with 
a text editor.

On Sunday, September 20, 2020, 12:33:03 PM MDT, Bruce Layne 
 wrote:  
On 9/20/20 3:47 AM, Gene Heskett wrote:
> On Sunday 20 September 2020 01:50:10 Bruce Layne wrote:
>
>> Creating an STL from a FreeCAD part is about as simple as it can be.
>>
> How many times do I have to say it? Freecad has an export to linuxcnc 
> menu. It does not work.

You cropped the part of my reply that made it obvious that I was
replying to someone else's comment lamenting that it shouldn't be so
difficult to create an STL in FreeCAD.  I was merely demonstrating that
it isn't difficult.  I wasn't trying to tell you to create an STL to 3D
print your part.

I did try to generate G code for your part.  I drew your part by
subtracting one cylinder from another in a few seconds.  I then tried to
teach myself how to generate G code for LinuxCNC from FreeCAD.  I
thought I might be able to help you while learning a useful new tool. 
Nope.  The tutorial on the FreeCAD site was so out of date as to be
unusable.  I found a nine month old tutorial using FreeCAD 0.18 that I
thought might work with 0.19.

http://cadcamlessons.com/freecad-path-workbench-tutorial

Close, but no cigar.

The FreeCAD menus, icons and hot keys had changed but I mostly muddled
through that.  I was able to select the linuxcnc post processor and
create Default Tool 1 and set the following parameters:

horizontal feed speed
vertical feed speed
spindle speed
spindle direction
conventional milling

However, I was unable to set:

horizontal rapid speed
vertical rapid speed
tool diameter

The CAM process was clearly not ready for prime time.  It seemed buggy,
even by alpha code standards.  Some of the fields seemed to allow me to
enter a number but when I tried, the numbers were interpreted as hot
keys for the 3D view perspective.

I'll keep using FreeCAD for my 3D printers.  It's good at that.  I might
try CAM a year from now in FreeCAD, although I still prefer to write my
own G code by hand, occasionally using a G code generator for creating
pockets, bolt hole patterns, etc.



> the youtube screen is way too small to see what they are actually doing.

It's even worse for me as I'm inevitably trying to watch a FreeCAD
demo/tutorial on my cell phone, which is a frustratingly pointless exercise.  
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Re: [Emc-users] freecad, latest, starter tut?

[Gregg Eshelman via Emc-users]

Can you select, copy, and paste the code you see on screen to a text file? 

On Sunday, September 20, 2020, 8:07:24 AM MDT, Martin Dobbins 
 wrote: 
freecad has an export menu that claims to do gcode, but it does not
create the code, nor does it report any error I understand when going
thru the motions. freecad screenshot attached. A simple torus shape,
50mm in diameter, 35mm tall, with a 28mm center hole.

Good morning Gene,

I've looked through the midden heap of my drag knife folder and I have been 
unable to locate a file with g code.  This bugged me because I *know* I saw 
readable g code from that project, then i remembered how I had seen g-code (on 
screen) which is pretty much as described in this video:

https://www.youtube.com/watch?v=fWU621P0gZk

I know I expected to have human readable code at the end of this project (pity 
I didn't complete it) because I'm working on a desktop that is not connected to 
the CNC so I expected a text file at the end that I could edit and rename to a 
.ngc file to transfer to the CNC machine.

If you can wait, I'll have a go at replicating the torus you made and see if I 
can send the g code.  If that works I will (try) to tell you how I did it.  
Later today, I hope.

Martin  
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Re: [Emc-users] freecad, latest, starter tut?

[grumpy--- via Emc-users]

On Sun, 20 Sep 2020, Bruce Layne wrote:


I'm not a professional draftsman.? I was initially intimidated by
FreeCAD, as many people naturally are.? I knew when I was glomming parts
together using geometric primitives that I wasn't doing *real* CAD, but
that inelegant method allowed me to produce simple usable parts.? Some
complex parts need to be drawn in 2D and lofted or rotated, and that's
what I do when I need a complex shape, but if I was drawing Gene's
simple part in FreeCAD it's much faster to create two cylinders and
subtract one from the other, and it would be much faster and easier for
Gene to get the part he wants that way instead of trying to talk him
through using Draft mode to draw 2D shapes (which requires selecting
working planes, etc.) and then switching to Part mode to extrude the
shape into 3D.

I totally agree that restricting ourselves to simple 3D shapes would
severely limit our capabilities, but for simple 3D shapes it's easier in
FreeCAD to stay in the 3D Part environment and simply create the
parametric part I need.? The notion of drawing 2D parts and then lofting
or rotating them as THE way to work seems to have its origins in the
days when AutoCAD was trying to embrace 3D CAD but was barking up the
wrong tree because they were adding that capability to their legacy 2D CAD.

I assume Fusion360 and Solidworks make it much easier to work in 2D and
3D.? It's not terribly difficult in FreeCAD, but I find it cumbersome to
switch gears.? If I want a rectangular plate with some holes or a disk
or tube, it's much easier to use the 3D primitives.? It's certainly much
easier to talk a newbie through the 3D process than try to convince them
to draw 2D parts and then switch to 3D to extrude them, which is similar
to telling then to use a 2D CAD program to draw their part and then
export that to a DXF and import that into a separate program to loft the
part and create the G code.

And it IS surprising how complex parts can be when constructed using 3D
primitives.? Most of us aren't doing a lot of 3D surface machining for
injection molds or art objects.? Most of us are cranking out simple
parts that are readily machinable using 2.5D methods.? Gene's part is on
the simple side but is a good example.? Designing parts from 3D
primitives is quite amenable to the types of parts that hobbyists are
usually machining.? I don't have a five axis machining center in my
basement shop, so I had no need for complex 3D CAD until I had a 3D
printer that was much less restricted in the part geometry it could
create.? In fact, for the simple parts I machine on the mill, router and
lathes, I prefer to write my own G code from scratch rather than using
CAD and CAM.


an example of some of the different methods in freecad are demonstrated in the 
link below
i have used the "Part Workbench" method to create many different threads
https://wiki.freecadweb.org/Thread_for_Screw_Tutorial


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Re: [Emc-users] freecad, latest, starter tut?

[Bruce Layne]

On 9/20/20 3:47 AM, Gene Heskett wrote:
> On Sunday 20 September 2020 01:50:10 Bruce Layne wrote:
>
>> Creating an STL from a FreeCAD part is about as simple as it can be.
>>
> How many times do I have to say it? Freecad has an export to linuxcnc 
> menu. It does not work.

You cropped the part of my reply that made it obvious that I was
replying to someone else's comment lamenting that it shouldn't be so
difficult to create an STL in FreeCAD.  I was merely demonstrating that
it isn't difficult.  I wasn't trying to tell you to create an STL to 3D
print your part.

I did try to generate G code for your part.  I drew your part by
subtracting one cylinder from another in a few seconds.  I then tried to
teach myself how to generate G code for LinuxCNC from FreeCAD.  I
thought I might be able to help you while learning a useful new tool. 
Nope.  The tutorial on the FreeCAD site was so out of date as to be
unusable.  I found a nine month old tutorial using FreeCAD 0.18 that I
thought might work with 0.19.

http://cadcamlessons.com/freecad-path-workbench-tutorial

Close, but no cigar.

The FreeCAD menus, icons and hot keys had changed but I mostly muddled
through that.  I was able to select the linuxcnc post processor and
create Default Tool 1 and set the following parameters:

horizontal feed speed
vertical feed speed
spindle speed
spindle direction
conventional milling

However, I was unable to set:

horizontal rapid speed
vertical rapid speed
tool diameter

The CAM process was clearly not ready for prime time.  It seemed buggy,
even by alpha code standards.  Some of the fields seemed to allow me to
enter a number but when I tried, the numbers were interpreted as hot
keys for the 3D view perspective.

I'll keep using FreeCAD for my 3D printers.  It's good at that.  I might
try CAM a year from now in FreeCAD, although I still prefer to write my
own G code by hand, occasionally using a G code generator for creating
pockets, bolt hole patterns, etc.



> the youtube screen is way too small to see what they are actually doing.

It's even worse for me as I'm inevitably trying to watch a FreeCAD
demo/tutorial on my cell phone, which is a frustratingly pointless exercise.





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Re: [Emc-users] freecad, latest, starter tut?

[N]

> ...
> I assume Fusion360 and Solidworks make it much easier to work in 2D and
> 3D.  It's not terribly difficult in FreeCAD, but I find it cumbersome to
> switch gears.  If I want a rectangular plate with some holes or a disk
> or tube, it's much easier to use the 3D primitives.  It's certainly much
> easier to talk a newbie through the 3D process than try to convince them
> to draw 2D parts and then switch to 3D to extrude them, which is similar
> to telling then to use a 2D CAD program to draw their part and then
> export that to a DXF and import that into a separate program to loft the
> part and create the G code.

Might be cases there starting from a 2D drawing is rather useful. One nice 
thing with the sketcher is dimensions could be added and it tell then drawing 
is fully constrained.

You need to start with a sketch to use the hole feature which is useful for 
holes and threads.


Nicklas Karlsson


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Re: [Emc-users] freecad, latest, starter tut?

[Bruce Layne]

I'm not a professional draftsman.  I was initially intimidated by
FreeCAD, as many people naturally are.  I knew when I was glomming parts
together using geometric primitives that I wasn't doing *real* CAD, but
that inelegant method allowed me to produce simple usable parts.  Some
complex parts need to be drawn in 2D and lofted or rotated, and that's
what I do when I need a complex shape, but if I was drawing Gene's
simple part in FreeCAD it's much faster to create two cylinders and
subtract one from the other, and it would be much faster and easier for
Gene to get the part he wants that way instead of trying to talk him
through using Draft mode to draw 2D shapes (which requires selecting
working planes, etc.) and then switching to Part mode to extrude the
shape into 3D.

I totally agree that restricting ourselves to simple 3D shapes would
severely limit our capabilities, but for simple 3D shapes it's easier in
FreeCAD to stay in the 3D Part environment and simply create the
parametric part I need.  The notion of drawing 2D parts and then lofting
or rotating them as THE way to work seems to have its origins in the
days when AutoCAD was trying to embrace 3D CAD but was barking up the
wrong tree because they were adding that capability to their legacy 2D CAD.

I assume Fusion360 and Solidworks make it much easier to work in 2D and
3D.  It's not terribly difficult in FreeCAD, but I find it cumbersome to
switch gears.  If I want a rectangular plate with some holes or a disk
or tube, it's much easier to use the 3D primitives.  It's certainly much
easier to talk a newbie through the 3D process than try to convince them
to draw 2D parts and then switch to 3D to extrude them, which is similar
to telling then to use a 2D CAD program to draw their part and then
export that to a DXF and import that into a separate program to loft the
part and create the G code.

And it IS surprising how complex parts can be when constructed using 3D
primitives.  Most of us aren't doing a lot of 3D surface machining for
injection molds or art objects.  Most of us are cranking out simple
parts that are readily machinable using 2.5D methods.  Gene's part is on
the simple side but is a good example.  Designing parts from 3D
primitives is quite amenable to the types of parts that hobbyists are
usually machining.  I don't have a five axis machining center in my
basement shop, so I had no need for complex 3D CAD until I had a 3D
printer that was much less restricted in the part geometry it could
create.  In fact, for the simple parts I machine on the mill, router and
lathes, I prefer to write my own G code from scratch rather than using
CAD and CAM.





On 9/20/20 6:38 AM, andy pugh wrote:
> On Sun, 20 Sep 2020 at 06:52, Bruce Layne  
> wrote:
>
>>  It's amazing how much can be
>> accomplished by using geometric primitives (cube, cone, sphere,
>> cylinder, torus) and using Boolean operations to add or subtract these
>> components, then using chamfer or fillet on the edges.
> I would suggest that this probably isn't the best way to work.
>
> It is typically rather more flexible to start with a sketch then
> extrude it (for milling) or revolve it (for turning).
>
> The vast majority of lathe parts can be designed from a single
> dimensioned sketch revolved about an axis.
>


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Re: [Emc-users] freecad, latest, starter tut?

[Martin Dobbins]

In the meantime I've found that freecad treated my diameters as radii, so
the posted image is too big by 2x for xy.  Its a 50mm diameter pipe,
35mm long, with a 28mm diameter bore.  Makes sense, but big dummy at
work. :-)

That's a lathe job surely?  Why are you trying to mill it?

Hope you have better luck finding a more reliable vendor for your motor.

Martin



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Re: [Emc-users] freecad, latest, starter tut?

[Gene Heskett]

On Sunday 20 September 2020 10:04:48 Martin Dobbins wrote:

> freecad has an export menu that claims to do gcode, but it does not
> create the code, nor does it report any error I understand when going
> thru the motions. freecad screenshot attached. A simple torus shape,
> 50mm in diameter, 35mm tall, with a 28mm center hole.
>
> Good morning Gene,
>
> I've looked through the midden heap of my drag knife folder and I have
> been unable to locate a file with g code.  This bugged me because I
> *know* I saw readable g code from that project, then i remembered how
> I had seen g-code (on screen) which is pretty much as described in
> this video:
>
> https://www.youtube.com/watch?v=fWU621P0gZk
>
> I know I expected to have human readable code at the end of this
> project (pity I didn't complete it) because I'm working on a desktop
> that is not connected to the CNC so I expected a text file at the end
> that I could edit and rename to a .ngc file to transfer to the CNC
> machine.
>
> If you can wait, I'll have a go at replicating the torus you made and
> see if I can send the g code.  If that works I will (try) to tell you
> how I did it.  Later today, I hope.
>
> Martin

Not that big a hurry Martin, I don't have the motor in hand yet that I 
plan on using. I have found it from other vendors so all is not lost. 
This vendor I now recall burnt me several hundred dollars when I bought 
a 6040 mill for my Christmas present almost 2 years ago. I had to ditch 
the electronics and replace that whole box and its contents. Around $400 
of an $1200 purchase. Runs nicely now exceptfor an actual speed tally on 
the water cooled spindle which has no encoder, so its displaying the 
commanded speed to the vfd. Ought to be an echo from the vfd, but I 
don't know how to acquire it for linuxcnc.  Cheap clone vfd.

In the meantime I've found that freecad treated my diameters as radii, so 
the posted image is too big by 2x for xy.  Its a 50mm diameter pipe, 
35mm long, with a 28mm diameter bore.  Makes sense, but big dummy at 
work. :-)

Thank you Martin.

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)
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] freecad, latest, starter tut?

[Martin Dobbins]

freecad has an export menu that claims to do gcode, but it does not
create the code, nor does it report any error I understand when going
thru the motions. freecad screenshot attached. A simple torus shape,
50mm in diameter, 35mm tall, with a 28mm center hole.

Good morning Gene,

I've looked through the midden heap of my drag knife folder and I have been 
unable to locate a file with g code.  This bugged me because I *know* I saw 
readable g code from that project, then i remembered how I had seen g-code (on 
screen) which is pretty much as described in this video:

https://www.youtube.com/watch?v=fWU621P0gZk

I know I expected to have human readable code at the end of this project (pity 
I didn't complete it) because I'm working on a desktop that is not connected to 
the CNC so I expected a text file at the end that I could edit and rename to a 
.ngc file to transfer to the CNC machine.

If you can wait, I'll have a go at replicating the torus you made and see if I 
can send the g code.  If that works I will (try) to tell you how I did it.  
Later today, I hope.

Martin

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Re: [Emc-users] freecad, latest, starter tut?

[Gene Heskett]

On Sunday 20 September 2020 05:36:36 Lester Caine wrote:

> On 20/09/2020 08:34, Gene Heskett wrote:
> > BUT when I fill in that blank, github
> > says that address exists
>
> Have you tried simply asking it to reset your password? It will send
> it to the email address you are trying to use.
>
> When I first started playing with the 3D printer I registered with
> various sites providing models and promptly forgot that I had. The
> problem *I* find with github is that it is relied on too much by many
> projects and quite often I find myself there and automatically logged
> in as I have got the password saved :(

Story of my life too, Lester. And I tend to use and reuse pw phrases 
based on unusual names I've encountered in my 85 years, variations on a 
theme so to speak, but which variation did I use on this site? I can't 
remember that with a 38 in my ear.  Then the next site screws you up 
because they won't take a pw that long. A pox on sites still stuck on a 
6 character pw. Or even 20 chars, that was obsolete by 1995.

Thanks Lester. 

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)
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] freecad, latest, starter tut?

[Gene Heskett]

On Sunday 20 September 2020 05:31:13 Lester Caine wrote:

> On 20/09/2020 08:47, Gene Heskett wrote:
> >> Type in the filename, select the directory where you want it
> >> (defaults to the current location), and select STL from the list of
> >> many export options.
> >
> > And that part works fine. BUT I NEED A SOLID METAL PART! >
>
> Going back 15 or or years, creating gcode to produce a solid metal
> part needed substantial help from the machinist. And not much has
> changed today. A few years back I was given a very nice STL model of a
> train wheel with the request to cut one. Bottom line ... totally
> pointless exercise. What I needed was the original objects that were
> used to create the model, and the ability to select both faces and
> construction lines which can THEN be used to build a set of gcode. At
> that time I was using tools like vcarve and cut3d and feeding in 2D
> drawings which provided the various profiles to be cut. Now I have
> FreeCAD in the toolkit, essentially I'm following the same process but
> in the one package of tools. Certainly the older packages are much
> better at some elements of the process such as say 'engraving text
> around the curve of the wheel', but FreeCAD has a growing library of
> tools that take elements of the object and produce the relevant gcode.
>
> At some point in the future we may well be able to tell a machining
> suite 'I have an XYZ mill and here is the part I need to machine'. It
> spews out a list of tools to use, cutting feed rates, and either
> individual gcode files for each tool change, although if you have one
> of those million pound machining centres with an unlimited tool
> changer then it could be a single file. At the moment we still need to
> provide the intelligence to decide - appropriate to our available
> tooling - just what order of machining is appropriate, and FreeCAD
> today does allow me to create parts from a scrap of paper with a
> sketch on to a finished part.
>
> Personally I find the drafting side of FreeCAD cumbersome coming from
> some 30 years of Autocad style drawing and THAT side needs some more
> intuitive developments especially when taking existing drawings as a
> starting point. However as a framework to build on it is doing a good
> job and with more people working on niche areas it can only improve?
> In much the same way that LinuxCNC has ...

That would seem to still be true Lester. I was somewhat surprised it 
didn't want more info than just linuxcnc flavor.  To be fair, I may as 
well have a paper napkin sketch at this stage, but I was a bit put off 
when I can see the first stage of what I need on-screen, as shown in the 
screen snap I posted, and it couldn't even put that on paper. Because of 
the length of shaft sticking out of the BS-1, I made it 35mm long, and 
that alone takes it out of the one setup category due to the practical 
length of tool stickout needed. So the first step is to bore it thru so 
theres a locator hole to center it with when its turned over to do the 
other side. I understand that, but the code generator more than likely 
does not. It also would be much easier to make if the motor was already 
driving the bs-1, classic chicken v egg problem. :-)  At this stage, I 
don't even know how to add the dimensions so they would be output in an 
engineering drawing format as that would serve as a handy source of info 
while writing the code by hand. And it looks to me like I'll need to src 
a boreing head, something I don't own yet, or do it on the Sheldon, 
which may be the fastest to a usable part.

I fine tuned my ebay search a bit and found other vendors besides that 
jerk, selling the same thing, so if he doesn't ship and I have to do the 
chargeback, all is not lost as I should be able get it from other 
on-shore vendors.  The other wish is to locate and acquire some 2" or 
2.5" alu rod in 7078-t6. Hell on tooling but sure makes nice stuff. It 
also holds threads well, where 6061 is gone by the time you've tightened 
the bolt 10 times.  Even helicoils won't hold in that crap.

A railroad wheel? I'll not live long enough to own a machine that big.

Thank you Lester.

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)
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] freecad, latest, starter tut?

[andy pugh]

On Sun, 20 Sep 2020 at 06:52, Bruce Layne  wrote:

>  It's amazing how much can be
> accomplished by using geometric primitives (cube, cone, sphere,
> cylinder, torus) and using Boolean operations to add or subtract these
> components, then using chamfer or fillet on the edges.

I would suggest that this probably isn't the best way to work.

It is typically rather more flexible to start with a sketch then
extrude it (for milling) or revolve it (for turning).

The vast majority of lathe parts can be designed from a single
dimensioned sketch revolved about an axis.

-- 
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] freecad, latest, starter tut?

[Lester Caine]

On 20/09/2020 08:34, Gene Heskett wrote:

BUT when I fill in that blank, github
says that address exists


Have you tried simply asking it to reset your password? It will send it 
to the email address you are trying to use.


When I first started playing with the 3D printer I registered with 
various sites providing models and promptly forgot that I had. The 
problem *I* find with github is that it is relied on too much by many 
projects and quite often I find myself there and automatically logged in 
as I have got the password saved :(


--
Lester Caine - G8HFL
-
Contact - https://lsces.uk/wiki/Contact
L.S.Caine Electronic Services - https://lsces.uk
Model Engineers Digital Workshop - https://medw.uk
Rainbow Digital Media - https://rainbowdigitalmedia.uk


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Re: [Emc-users] freecad, latest, starter tut?

[Lester Caine]

On 20/09/2020 08:47, Gene Heskett wrote:

Type in the filename, select the directory where you want it (defaults
to the current location), and select STL from the list of many export
options.

And that part works fine. BUT I NEED A SOLID METAL PART! >


Going back 15 or or years, creating gcode to produce a solid metal part 
needed substantial help from the machinist. And not much has changed 
today. A few years back I was given a very nice STL model of a train 
wheel with the request to cut one. Bottom line ... totally pointless 
exercise. What I needed was the original objects that were used to 
create the model, and the ability to select both faces and construction 
lines which can THEN be used to build a set of gcode. At that time I was 
using tools like vcarve and cut3d and feeding in 2D drawings which 
provided the various profiles to be cut. Now I have FreeCAD in the 
toolkit, essentially I'm following the same process but in the one 
package of tools. Certainly the older packages are much better at some 
elements of the process such as say 'engraving text around the curve of 
the wheel', but FreeCAD has a growing library of tools that take 
elements of the object and produce the relevant gcode.


At some point in the future we may well be able to tell a machining 
suite 'I have an XYZ mill and here is the part I need to machine'. It 
spews out a list of tools to use, cutting feed rates, and either 
individual gcode files for each tool change, although if you have one of 
those million pound machining centres with an unlimited tool changer 
then it could be a single file. At the moment we still need to provide 
the intelligence to decide - appropriate to our available tooling - just 
what order of machining is appropriate, and FreeCAD today does allow me 
to create parts from a scrap of paper with a sketch on to a finished part.


Personally I find the drafting side of FreeCAD cumbersome coming from 
some 30 years of Autocad style drawing and THAT side needs some more 
intuitive developments especially when taking existing drawings as a 
starting point. However as a framework to build on it is doing a good 
job and with more people working on niche areas it can only improve? In 
much the same way that LinuxCNC has ...


--
Lester Caine - G8HFL
-
Contact - https://lsces.uk/wiki/Contact
L.S.Caine Electronic Services - https://lsces.uk
Model Engineers Digital Workshop - https://medw.uk
Rainbow Digital Media - https://rainbowdigitalmedia.uk


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Re: [Emc-users] freecad, latest, starter tut?

[Gene Heskett]

On Sunday 20 September 2020 01:50:10 Bruce Layne wrote:

> Creating an STL from a FreeCAD part is about as simple as it can be.
>
How many times do I have to say it? Freecad has an export to linuxcnc 
menu. It does not work.

> Highlight the part by clicking on it in the left hand Application
> window. Click File-Export
> Type in the filename, select the directory where you want it (defaults
> to the current location), and select STL from the list of many export
> options.
And that part works fine. BUT I NEED A SOLID METAL PART! >
> There are a few aspects of FreeCAD that still aren't intuitive. 
> Engraved text is one.  It's not too difficult, but it's not very
> intuitive.  Like GIMP, now that I've used FreeCAD for some time and
> have figured out its quirks, I'm fairly productive.  Not productive in
> the manner of a CAD draftsman, but pretty good for a maker who does
> CAD an hour or two a week on average.  It's amazing how much can be
> accomplished by using geometric primitives (cube, cone, sphere,
> cylinder, torus) and using Boolean operations to add or subtract these
> components, then using chamfer or fillet on the edges.
>
> The YouTube FreeCAD tutorials are often out of date and the user
> interface improvements and new features make those out of date and
> useless (and frustrating), although the current 0.19 version seems to
> be stabilizing the basic features.  Another issue that confuses people
> is the different navigation modes that determine the mouse functions.
> Allowing the user to switch to the mouse navigation that they already
> learned in a previous CAD program makes FreeCAD flexible, but unless
> you use the same navigation mode as the person making the tutorial,
> you'll be lost.  Finally, way too many alleged tutorials on YouTube
> are actually demos.  I can see that someone is able to do something,
> but the quick clicky demo without any narration to tell me what
> they're doing is closer to a magic trick than a tutorial.  Slow down,
> and tell us what you're doing and why.

that too. the youtube screen is way too small to see what they are 
actually doing.

> The best way to learn FreeCAD would be to have someone who knows it
> walk you through a design.  Figuring it out on your own is probably 1%
> as efficient so there's a high frustration factor.  The lack of
> training materials is seriously holding back the growth of FreeCAD.

Nails it solidly right there.

> On 9/20/20 1:25 AM, Gregg Eshelman via Emc-users wrote:
> > Ugh. Why can't it just do all that automatically to whatever is the
> > currently selected part of what's on the screen, or all of it if all
> > of what's on screen is one object?Save > Export > .STL and the
> > software does the rest behind the scenes.
> >
> > On Saturday, September 19, 2020, 12:03:07 PM MDT, grumpy--- via
> > Emc-users  wrote: i have used
> > freecad enough to be a middle'n noib
> > this is how i do it
> > save my .fcstd so i can come back and re-edit
> > in the top row select "Mesh design" in the drop down
> > in the left top panel select your design, "Cut"
> > in the top menu click "Meshes"
> > select "Create mesh from shape"
> > select "Standard"
> > select "OK"
> > in left top panel click on "Cut (Meshed)"
> > right click and select "Export mesh"
> > this creates a .stl
> > then use cura to slice

What for? The plastic has .1% of the strength needed. And takes at least 
31 hours and nearly 50 meters of filament would be wasted.

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)
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] freecad, latest, starter tut?

[Gene Heskett]

On Sunday 20 September 2020 01:25:34 Gregg Eshelman via Emc-users wrote:

> Ugh. Why can't it just do all that automatically to whatever is the
> currently selected part of what's on the screen, or all of it if all
> of what's on screen is one object?Save > Export > .STL and the
> software does the rest behind the scenes.
>
> On Saturday, September 19, 2020, 12:03:07 PM MDT, grumpy--- via
> Emc-users  wrote: i have used freecad
> enough to be a middle'n noib
> this is how i do it
> save my .fcstd so i can come back and re-edit
> in the top row select "Mesh design" in the drop down
> in the left top panel select your design, "Cut"
> in the top menu click "Meshes"
> select "Create mesh from shape"
> select "Standard"
> select "OK"
> in left top panel click on "Cut (Meshed)"
> right click and select "Export mesh"
> this creates a .stl
> then use cura to slice

as I have stated several times now Gregg, an .stl and cura is not the end 
target, it has zero chance of making me a serviceable part as this will 
be attached to the side of a 90Kg BS-1 clone. So I want gcode to drive a 
cnc'd G0704 working on about a pound of solid alu. Or, since I've a 
mister on the 6040, possibly that mill since it can turn 24000 revs and 
probably do a better job with the mister keeping the tool free of gummy 
alu.

freecad has an export menu that claims to do gcode, but it does not 
create the code, nor does it report any error I understand when going 
thru the motions. freecad screenshot attached. A simple torus shape, 
50mm in diameter, 35mm tall, with a 28mm center hole.  The terminal 
freecad is running on says:

Path workbench activated
PathScripts.linuxcnc_post gcode postprocessor loaded.
the object Cut is not a path. Please select only path and Compounds.
the object Cut is not a path. Please select only path and Compounds.
Traceback (most recent call last):
  File "", line 4, in 
: The given file is not a path
Stack Trace: Traceback (most recent call last):
  File "", line 4, in 

Which might as well be swahili to me. To me the "path" is to the location 
where its to write the code file to, which does exist and has other 
content.  But to freecad, apparently "path" is something else entirely.

As for using github to register for the freecad irc channel, I apparently 
am not doing that right either. their registration sends me to github, 
but github wants my email address BUT when I fill in that blank, github 
says that address exists and refuses to proceed as I use github to pull 
LinuxCNC updates to master, and build it on my rpi4 to drive the 11x54 
Sheldon.  So github definitely knows who I am, so how does that supposed 
to be done? IDK.  All I understand is that I am blocked from asking for 
freecad help on their IRC channel. They also have two other ident 
choices, but I don't feed the social media vacuums what s/b private 
info. My name is not Trump so I don't do twitter and I don't trust 
Zuckerburg, full stop there too.

Thanks Gregg.

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 
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