FreeCAD Lesson 08 - Inner Threads Video Lecture | Mastering FreeCad: Tutorial for Beginners - Design Softwares

hello and welcome to another video
tutorial about freecad in this video
tutorial we are going to discuss how to
model enough threads as an example we
will have a look at a hexagon not of a
size m6 and we will talk about different
kind of representation so to say
different kind of modeling ending up in
a swept profile along a helical path and
a boolean cut to get a fret like with
Reds we have in real life or knots or
other parts a free cat version we use
here is with 0.15 stable release on the
windows 7 64 bit system when it comes to
mechanical engineering and we have let's
say a quite complex technical machine of
some sort we have a lot of nuts and
enough frets on all parts but in most
cases you won't see the threads because
if you insert a bolt or screw or
something alike the thread becomes
invisible to you to save CPU performance
in mechanical engineering
we don't use a representation which
shows an enough thread remember we
talked about a 3d model showing a thread
on a virtual 2d sheet of paper is
something else but in mechanical
engineering for freedom model we use a
representation like this it's an
abstract
representation we have a flat
cylindrical inner face as you can see
here in the preview the model was done
using a part design work bench in
freecad we first made a sketch and
revolved it the sketch contains the in a
profile here it defines the eight of the
screw and the two slopes the slope here
and the slope here when varies a pocket
operation applied to get the six phases
which form the hexagon on the outer
shape of the model this kind of
representation is sufficient for
mechanical engineering somebody doing
mechanical engineering will have a look
at this model and say okay we are
talking about a hexagonal nut and maybe
he will use the measurement tools in the
C ad system to measure the width across
flats here to get an idea about the size
of a nut maybe he will also measure the
aid of a nut to get an idea if you are
talking about and not with normal aid or
reduced aid but in real life this person
would have to consult for example the
part list to get additional information
about the nut such as the material or
maybe there is also a surface treatment
applied to the not something like zinc
plating or nickel plating of course
there are a certain cases when you need
an optical representation of a fret
in this case you could use a model like
this as you can see in the tree view the
part design workbench was used for pet
operation doing the hexagon faces and we
also did a revolution if we look at the
sketch of a revolution here you can see
we have this zigzag like profile with a
polyline and if you revolve this each
and then do a boolean common operation
well at least talking about optical
representation it looks like a fret and
doesn't use that much CPU power and
therefore it doesn't use that much file
size on your hard disk
additionally there might be cases when
you need a real thread with all correct
dimensions for example for 3d printing
then you would use for the inner profile
a helix and of course some sort of a
triangular sketch being swept along the
helix and then doing a boolean cut on
the rest of the shape to get this helix
like shape I am now going to show you
how to do all of the free models step by
step so let's first close these
documents here let's insert a new
document and make sure that part design
workbench is activated
let's first create a sketch on the XZ
plane
applying ok let's zoom a little bit to
the origin and in my case I chose by
edit preferences display sketcher a grid
size to be shown of two millimeters so
each step here is 2 millimeter okay so
let's start with sketch by using the
polyline tool and starting on the
horizontal axis
let's first insert a slope like here
then let's insert a vertical line here a
slope in this direction horizontal line
slope here vertical line let's go back
in a slope to the horizontal axis and
then back to your first point of our
polyline if I would have caught a here V
horizontal axis the solver would have
shown an error message saying this point
on to this axis this point on this axis
and a horizontal constraint is one
constraint too much but in this case
everything is ok we have an under
constraint sketch with eleven degrees of
freedom so let's first begin with
constraining our angles here according
to the ISO
and we now need an angle of 150 degrees
we also need here an angle of 150
degrees because Dean ISO says that this
angle here should be in total 60 degrees
and this slope here can be Ryba tween as
far as I know if I recall correct 15 and
30 degrees so let's choose 30 degrees so
that this angle here is 150 degrees
because horizontal line would be 180
degrees
okay let's constrain this angle here to
be also 150 degrees and let's also
constrain this angle here to be 150
degrees
let's choose these two lines here and
apply an equality constraint and also
apply a quality constraint on these two
lines let's choose this point here and
the origin and apply a horizontal
constraint of 2.5 millimeters because
with an m6
Fred the inner bore diameter according
to Dean or to use the newer definition
to according to ISO is five millimeters
so the radius is 2.5 millimeters
also apply to these two points a
horizontal constraint
of a horizontal dimension of three
millimeters let's the 6/2 we apply to
these two points a horizontal dimension
of four point 4 comma 9 millimeters and
we will pull slide a little bit inwards
and apply to these two points a
horizontal dimension of 6 millimeters we
can then place these dimensions a little
bit better for visibility and we will
apply two V's two points a vertical
dimension of four comma seven
millimeters that's it we have a fully
constrained sketch we close the sketch
and apply a revolution for vertical
sketch access let's say okay and we just
did the first sketch correctly okay
so the next operation is to use the
pocket operation to get the six hexagon
faces on the outer wall of the shape so
let's select the face here apply a
sketch to a face and let's select the
create regular polygon icon to get its
help in creating the hexagon so click on
the icon here select the origin and
let's select the point here so we have
now another constraint sketch with four
degrees of freedom left
so let's select this point here and
let's select the horizontal axis and we
will fix the point on to the axis with
this constraint here so let's repeat the
operation with this point here we then
have two degrees of freedom left so we
will apply to these two points in regard
to the horizontal axis a symmetry
constraint and then we will apply to
these two points a horizontal distance
of 10 millimeters
we will then insert a circle from the
origin here and we will click once again
here and remember that we did a radius
here of six millimeter so we apply a
radius to this circle of six millimeter
or more let's say we use seven
millimeters in this case to get an
overlapping for our boolean cut which is
mostly a good idea let's close the
sketch it is fully constrained and use
the pocket operation to say for example
through all or I could use dimension of
4.7 or more
remember v8 we defined with 4.7
millimeters I click on OK and we are
here complete with the whole model for
the first case so for the next case with
cylindrical a thread which I did show
you let's use a different design
approach just to practice modeling and
freak out a little bit more let's close
this document here let's create a new
document and we once more use the part
design workbench and in the end we use
the pot module workbench for our boolean
operation so first we apply a sketch to
the XY plane we do once more use my
create regular polygon icon we select
the origin here
we click here in a empty space we'll
apply a fixture constraint from this
point to the vertical axis let's try
what happens if we apply a vertical
constraint here and we still have two
degrees of freedom left so we could
apply a constraint of this point and the
origin being coincident this would have
been the same as applying for example
symmetry to these two points or these
two points or these two points so we
have still one degree of freedom left
this is the horizontal dimension of ten
millimeters between let's say these two
points
we closed the sketch and we pet it to a
height of four comma seven millimeters
we choose okay and we just completed the
first step of this model okay so the
next step is to draw the sketch which we
will use for evolution and the last step
would be to use the boolean common
operation on both solids to get the
resulting shape so first I'm going to
select a pet here doing a right click
and toggle its visibility to be able to
sketch a little bit better when I click
in empty space somewhere to deselect
everything I will apply a new sketch
this time to the XZ plane for reference
just look in right down corner we have a
small create with coordinate system is
always present and click on OK
so now we will draw once again our sweep
profile our revolve profile with a
polyline tool we will begin on the
horizontal axis doing a slope here going
vertical a little bit here do one zigzag
being once more vertical here doing a
second time a six egg being vertically
here doing once more an exact vertically
now one more zigzag and now one more
vertical one last slope in watts and
when we have a horizontal line slope
here a vertical line slope going back to
the horizontal axis and back to the
first point of a polyline we have our
well-known arrow in this case I'm going
to remove this constraint here by
selecting it and when you can press
Delete on your keyboard
or you could also for example do a right
click here on this constraint and choose
delete so the error message is now gone
and we will begin to constrain our
sketch so first thing we can do is
select this point and this line here and
apply a fixture of a point on to the
object this will cause these two lines
to be collinear or in line we will
repeat this operation here and we will
repeat the operation once more here and
once more here we will tell these free
inner lines to be equal or to be correct
of equal length we will tell all these
lines to be also
of equal length we will apply an
equality constraint to these two lines
and we will apply an equality constraint
to these two lines okay
so now we will use a small geometric
trick we will create a line from this
point here to this point here and apply
a vertical constraint to this line we
will then choose this line and we will
toggle a construction mode and then we
will apply a fixture constraint of Reath
point here on this line here we will
repeat the operation here we will repeat
the operation with this point here and
we will repeat the operation here
so the next thing to do would be to
constrain all four angles again
remember to choose each angle to be 150
degrees and apply here
fourth angle to be 100 now we don't need
a fourth one here s in this case it's it
would be over constrained as you can see
from the error message so let's break
let's press cancel and we are done with
the angles so let's then do another
geometric small trick let's draw a line
from here to be on the line here let's
choose the line to be of construction
mode let's select the line once more and
apply a horizontal constraint and let's
choose this point here for line and
let's also choose this line here and
apply a symmetry constraint
so now we are left with six degrees of
freedom so the next thing would be to
apply this dimension here which is also
regulated by Dean thirteen we apply in
this case a vertical distance of one
millimeter as we see ever solver
overreacted a little bit
so we choose to go back and we apply a
constraint once more
let's first beer for moment Wilfer
two-millimeter
that's been reduced to 1.5 very good
then let's reduce to 1 millimeter
now still overreacting a little bit so
let's use smaller reduction steps 1.2
and 1 millimeter okay this looks perfect
let's reduce
we ate Vanderbilt and let's apply our
first constraint to these two points
here the origin and this point here
let's use a horizontal constraint of 2.5
millimeters as before let's make sure
what per profile looks right
sometimes as it just have seen the
solver overreacts a little bit and finds
a different solution which is unwanted
so the next thing would be to reduce
here we ate a little bit and now apply a
constraint to these two points our
sample dimension constraint of remember
three millimeters as you can see here
solver we overreacted a little bit okay
let's go back choose these two points
apply our horizontal constraint
let's be R at the moment with 2.86 let's
change it to three millimeter and for
some reason we are good sometimes you
need to play around with values a little
bit in free cat to get free cat going
so the next thing would be to apply a
horizontal dimension constraint to these
two points off remember 4 comma 9
millimeters as you can see here once
more the solver overreacted a little bit
so we go back we pull this line a little
bit inside
okay we choose once more these two
points supply constraint here and when
we do a double click on with dimension
and when we choose small steps to reduce
to the value we like to have okay so now
we need to select these two points and
apply a horizontal constraint of
remember 6 millimeters when we choose
these two points to apply our last
constraint and we apply a total line 8
of 4 comma 7 millimeters let's let me
close my sketch we do a revolution we
say ok we select the pad do a right
click and toggle its visibility to get
both shapes shown here again in the 3d
view we choose part module workbench we
select both of these shapes here and
when we apply the boolean common
operation or in other words we make an
intersection of the to save shapes so
now we have resulting shape here and
this ends my demonstration of the second
showcase for optical representation of a
hexagonal nut now for the third case so
to say the real fret
I'll close this document here I will
create a new document and I will switch
back to part design workbench I will
begin with the same shape as used in the
first sketch so first I will apply my
revolution operation and then my pocket
operation so first I'm going to insert
once more on V X Z plane a sketch I will
zoom a little bit here I will use a
polyline tool I begin on the horizontal
axis and I'm doing my revolution profile
once more
so once more ideal eat with constraint
here let's apply equality let's apply
equality let's apply once more almost
four angles of remember 150 degree no it
was this angle here but needs 150
degrees 150 degrees
and once again 150 degrees so now I'm
going to apply all the horizontal
constraints once more which was 2.5
millimeters this one here was free
millimeters this one being 4 comma 9
millimeters
oops my solver overreacted a little bit
so I'm going to go one step back draw
the line inwards a little bit apply once
more horizontal what do you do here
let's say six millimeters and when doing
a double click and when correcting
finally 2 4 comma 9 millimeters when I
will apply here a horizontal distance of
6 millimeters and here I will apply a
vertical distance of 4 comma 7
millimeter and then I will do the
revolution once more and so we are done
with our first step and now I will
choose a pocket operation so I select
the face here once more I'm doing my
sketch doing a hexagon sketch let's say
this time I apply a fixture to this
point on V vertical axis I apply here
once more vertical constraint
I do apply a coincidence constraint on
these two points and I'm applying here a
horizontal distance of 10 millimeters
I will then need my circling site at the
origin and let's say we have a circling
once more of seven millimeters radius to
be sure to have an overlapping profile
here we close we apply the pocket
operation through all and now we all
have our basic shape and we are now able
to apply our hallux sweep and when our
boolean cut on this shape here okay so
for the next step we switch to a part
module workbench and we will create a
geometry primitive we choose the hallux
we want to have a pitch of one
millimeter that's okay we want to have a
total of more than 4.7 let's say we want
to have to be real sure six millimeters
complete eight and we want to have a
radius of let's say 2 comma five
millimeters we leave the angle at 0
degrees and right hand it is okay so we
create V Alex and now we close this
dialogue here we select the pocket shape
and we targeted specifically to be able
to draw a little bit better when we
switch back to a part design web bench
and we apply a sketch to the xz-plane
say okay we do zoom here and then we
will draw a triangle with its let's say
base point on the horizontal axis having
here are a vertical line and going back
to my first point so now we have to
apply equality constraint to these two
lines we have to apply an angle of 60
degrees and we have to apply a
horizontal dimension of well we want to
have an overlapping so we apply a little
bit less than 2.5 millimeters so let's
try it with two point or two comma point
to two gamma 4 millimeter to be real
correct
and this here should get the horizontal
distance of three millimeters and that's
it we have fully constrained sketch we
closed the sketch and then we go back to
a part module workbench we click an
empty space to make sure to have
everything be selected and we choose the
utility to sweep we want to sweep sketch
0:02
we click once more here in empty space
and a sweep path we select we do a multi
select a tube to then press control on
the keyboard on windows in this case and
we select all these segments here say
done we want to create a solid and we
want the beginning face and the end face
to be coplanar so we select the Fred an
option we click on OK and visit our
swept profile we talk about visibility
or for not here
and then be select the pocket and then
the sweep a shape and then we apply a
boolean cut we can toggle the visibility
of three Alex and as you can see the
sketch is also visible we talk about
visibility of a sketch here and here we
go this is for complete Fred with
everything made since you may encounter
a problems in 3d modeling so to say you
may encounter situations where boolean
operations especially boolean cuts will
fail so let's talk a little bit about
troubleshooting in 3d modeling for
talking about troubleshooting we have to
talk a little bit about the background
of 3d see ad with your personal computer
you need a basic operation system to run
it this could be one of the different
versions of Windows or Linux
distribution of your choice or one of
the products from Apple with 3d see ad
you also need a basic software it is
called kernel there are a well known see
ad kernels on the market of course
commercial ones
speaking of licenses the biggest free
are the Katia kernel the step kernel and
the Asus kernel whose native file format
is SAT free cat is set atop on as far as
I know the only existing open source
3 DC ID Colonel open cascade Colonel or
in short OCC this kernel provides free
care the ability to do 3d operations
it's providing whenever needed
mathematics and geometric a basis to do
that as our technical products it has
some limitations and sometimes you need
one or two let's say small tricks to get
everything going so the best advice is
if you're doing boolean cuts be sure to
have overlapping geometry coplanar faces
are not very good for boolean cuts it
may work but the operation is also quite
likely to fail a second trick would be
to use part primitives instead of
revolve or extruded profiles at least
with earlier free versions of freecad I
was thinking that free cut or these the
geometric kernel was reacting more
robust when doing boolean operations
with primitives rather than revolved or
extruded profiles I also encountered one
time a situation with an earlier version
of freecad that occ so to say the
geometric kernel didn't seem to like the
fact that the hallux and a profile to be
swept we're lying on the same plane so
in this case we XZ plane asthma revolved
profile which was responsible for the
outer geometry so in that case I applied
we are placement a 90-degree turn to the
hallux Andrus we profile so the hallux
and miss be profile begin on the Y Z
plane and suddenly the boolean cut
worked this would be another trick you
can use another trick would be well a
little dirty one we are talking here
about mathematics if free - free is zero
well when we have to cheat a little bit
so maybe you could have success with a
boolean cut if you do a shift for
position of one of the two solids you
want to cut by a very small amount let's
say one thousandth of a millimeter in
real life this is in most cases beyond
all accuracy of milling machines
measurement tools and even beyond
normally all accuracy of 3d printing but
shifting positions a B a placement for
example of one of the solids by one
thousandth of an millimeter will result
in a mathematic result of not being zero
and so maybe the boolean operation will
succeed in this case so with these
tricks for troubleshooting we have
reached the end of today's lesson I hope
that I showed some new things and what
you did learn something feel free to
leave any comments here on youtube and
mel maybe see you in another video bye