JG
Juliean Galak
Mon, Feb 4, 2019 6:08 PM
I'm trying to figure out if there's any way to "automate" the computation
of a rotation and translation of a part to fit into an assembly.
For example, consider a clothespin, the kind with two pivoting arms and a
spring. Let's say I have designed the two arm object.. Further, suppose I
want to vary the distance between the pivot point and the outer surface of
the arms, but I want the "business end" to always be touching, as if the
clothespin is closed by the spring.
What I'd like is to specify in some way that the two arms must always touch
at the "business end" and at the pivot point, and have OpenSCAD somehow
figure out how to rotate and position the arms accordingly. I've found an
"attachment" library that seems to do this, but it appears abandoned and
poorly documented, at least in English. (yes, I've reached out to the
author, with no success).
Obviously I can do this by writing some trig functions, but I'd really
rather not have to do that. Is there another solution to this?
--
Juliean Galak
jgalak@gmail.com
I'm trying to figure out if there's any way to "automate" the computation
of a rotation and translation of a part to fit into an assembly.
For example, consider a clothespin, the kind with two pivoting arms and a
spring. Let's say I have designed the two arm object.. Further, suppose I
want to vary the distance between the pivot point and the outer surface of
the arms, but I want the "business end" to always be touching, as if the
clothespin is closed by the spring.
What I'd like is to specify in some way that the two arms must always touch
at the "business end" and at the pivot point, and have OpenSCAD somehow
figure out how to rotate and position the arms accordingly. I've found an
"attachment" library that seems to do this, but it appears abandoned and
poorly documented, at least in English. (yes, I've reached out to the
author, with no success).
Obviously I can do this by writing some trig functions, but I'd really
rather not have to do that. Is there another solution to this?
--
Juliean Galak
jgalak@gmail.com
JF
Joe Francis
Mon, Feb 4, 2019 6:22 PM
The key for this problem is to model the parts in an orientation that
matches your frame of reference for the desired motion. (Or move them
into such an orientation before you rotate them).
i.e., model your clothespin arm such that the point you want to touch to
always be on the y-axis, then when you rotate the part about the y-axis,
it'll always be touching there and you avoid the complex math for
rotating it. Then translate/rotate the whole clothespin assembly to
whatever point in space you need it at.
The same principal applies to mating surfaces of parts that are meant to
be assembled. If, for example, you're modeling a stepper motor, it's
very easy to place it in another assembly if you place the mounting face
on the X/Y plane and run the stepper shaft on the Z-axis. If you model
the entire stepper in the x/y/z-positive quadrant, it requires a lot of
thinking to place it correctly in another model. Even more so if you
change the stepper to a different size later on and the key features
move relative to the origin.
This general pattern is, IMO, critical for making good parametric models
in openscad and keeping the complexity to a manageable level.
Joe
On 2/4/19 12:08 PM, Juliean Galak wrote:
I'm trying to figure out if there's any way to "automate" the
computation of a rotation and translation of a part to fit into an
assembly.
For example, consider a clothespin, the kind with two pivoting arms
and a spring. Let's say I have designed the two arm object.. Further,
suppose I want to vary the distance between the pivot point and the
outer surface of the arms, but I want the "business end" to always be
touching, as if the clothespin is closed by the spring.
What I'd like is to specify in some way that the two arms must always
touch at the "business end" and at the pivot point, and have OpenSCAD
somehow figure out how to rotate and position the arms accordingly.
I've found an "attachment" library that seems to do this, but it
appears abandoned and poorly documented, at least in English. (yes,
I've reached out to the author, with no success).
Obviously I can do this by writing some trig functions, but I'd really
rather not have to do that. Is there another solution to this?
--
Juliean Galak
jgalak@gmail.com mailto:jgalak@gmail.com
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
The key for this problem is to model the parts in an orientation that
matches your frame of reference for the desired motion. (Or move them
into such an orientation before you rotate them).
i.e., model your clothespin arm such that the point you want to touch to
always be on the y-axis, then when you rotate the part about the y-axis,
it'll always be touching there and you avoid the complex math for
rotating it. Then translate/rotate the whole clothespin assembly to
whatever point in space you need it at.
The same principal applies to mating surfaces of parts that are meant to
be assembled. If, for example, you're modeling a stepper motor, it's
very easy to place it in another assembly if you place the mounting face
on the X/Y plane and run the stepper shaft on the Z-axis. If you model
the entire stepper in the x/y/z-positive quadrant, it requires a lot of
thinking to place it correctly in another model. Even more so if you
change the stepper to a different size later on and the key features
move relative to the origin.
This general pattern is, IMO, critical for making good parametric models
in openscad and keeping the complexity to a manageable level.
Joe
On 2/4/19 12:08 PM, Juliean Galak wrote:
> I'm trying to figure out if there's any way to "automate" the
> computation of a rotation and translation of a part to fit into an
> assembly.
>
> For example, consider a clothespin, the kind with two pivoting arms
> and a spring. Let's say I have designed the two arm object.. Further,
> suppose I want to vary the distance between the pivot point and the
> outer surface of the arms, but I want the "business end" to always be
> touching, as if the clothespin is closed by the spring.
>
> What I'd like is to specify in some way that the two arms must always
> touch at the "business end" and at the pivot point, and have OpenSCAD
> somehow figure out how to rotate and position the arms accordingly.
> I've found an "attachment" library that seems to do this, but it
> appears abandoned and poorly documented, at least in English. (yes,
> I've reached out to the author, with no success).
>
> Obviously I can do this by writing some trig functions, but I'd really
> rather not have to do that. Is there another solution to this?
>
> --
> Juliean Galak
> jgalak@gmail.com <mailto:jgalak@gmail.com>
>
> _______________________________________________
> OpenSCAD mailing list
> Discuss@lists.openscad.org
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
JG
Juliean Galak
Mon, Feb 4, 2019 6:35 PM
But how do you deal with two points of attachment? In my example, sure, it
makes sense to put the contact point of the jaws at the origin, oriented in
a normal way. But when changing the pivot distance, you'd still need to do
trig to figure out how much to rotate and translate each arm, depending on
said distance. Putting the contact point at the origin simplifies that
trig, but doesn't eliminate it.
Also, can you rotate around anything other than the origin? It'd be nice
to be able to specify that this part should rotate around this point on the
part, regardless of where the part is. I don't recall any way to specify
the point of rotation, which would also simplify the above. I guess you
could translate, rotate, and then translate back, but that's kind of cludgy.
On Mon, Feb 4, 2019 at 1:22 PM Joe Francis joe@lostapathy.com wrote:
The key for this problem is to model the parts in an orientation that
matches your frame of reference for the desired motion. (Or move them into
such an orientation before you rotate them).
i.e., model your clothespin arm such that the point you want to touch to
always be on the y-axis, then when you rotate the part about the y-axis,
it'll always be touching there and you avoid the complex math for rotating
it. Then translate/rotate the whole clothespin assembly to whatever point
in space you need it at.
The same principal applies to mating surfaces of parts that are meant to
be assembled. If, for example, you're modeling a stepper motor, it's very
easy to place it in another assembly if you place the mounting face on the
X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
place it correctly in another model. Even more so if you change the
stepper to a different size later on and the key features move relative to
the origin.
This general pattern is, IMO, critical for making good parametric models
in openscad and keeping the complexity to a manageable level.
Joe
On 2/4/19 12:08 PM, Juliean Galak wrote:
I'm trying to figure out if there's any way to "automate" the computation
of a rotation and translation of a part to fit into an assembly.
For example, consider a clothespin, the kind with two pivoting arms and a
spring. Let's say I have designed the two arm object.. Further, suppose I
want to vary the distance between the pivot point and the outer surface of
the arms, but I want the "business end" to always be touching, as if the
clothespin is closed by the spring.
What I'd like is to specify in some way that the two arms must always
touch at the "business end" and at the pivot point, and have OpenSCAD
somehow figure out how to rotate and position the arms accordingly. I've
found an "attachment" library that seems to do this, but it appears
abandoned and poorly documented, at least in English. (yes, I've reached
out to the author, with no success).
Obviously I can do this by writing some trig functions, but I'd really
rather not have to do that. Is there another solution to this?
--
Juliean Galak
jgalak@gmail.com
OpenSCAD mailing listDiscuss@lists.openscad.orghttp://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
But how do you deal with two points of attachment? In my example, sure, it
makes sense to put the contact point of the jaws at the origin, oriented in
a normal way. But when changing the pivot distance, you'd still need to do
trig to figure out how much to rotate and translate each arm, depending on
said distance. Putting the contact point at the origin simplifies that
trig, but doesn't eliminate it.
Also, can you rotate around anything other than the origin? It'd be nice
to be able to specify that this part should rotate around this point on the
part, regardless of where the part is. I don't recall any way to specify
the point of rotation, which would also simplify the above. I guess you
could translate, rotate, and then translate back, but that's kind of cludgy.
On Mon, Feb 4, 2019 at 1:22 PM Joe Francis <joe@lostapathy.com> wrote:
> The key for this problem is to model the parts in an orientation that
> matches your frame of reference for the desired motion. (Or move them into
> such an orientation before you rotate them).
>
> i.e., model your clothespin arm such that the point you want to touch to
> always be on the y-axis, then when you rotate the part about the y-axis,
> it'll always be touching there and you avoid the complex math for rotating
> it. Then translate/rotate the whole clothespin assembly to whatever point
> in space you need it at.
>
> The same principal applies to mating surfaces of parts that are meant to
> be assembled. If, for example, you're modeling a stepper motor, it's very
> easy to place it in another assembly if you place the mounting face on the
> X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
> stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
> place it correctly in another model. Even more so if you change the
> stepper to a different size later on and the key features move relative to
> the origin.
>
> This general pattern is, IMO, critical for making good parametric models
> in openscad and keeping the complexity to a manageable level.
>
> Joe
>
>
> On 2/4/19 12:08 PM, Juliean Galak wrote:
>
> I'm trying to figure out if there's any way to "automate" the computation
> of a rotation and translation of a part to fit into an assembly.
>
> For example, consider a clothespin, the kind with two pivoting arms and a
> spring. Let's say I have designed the two arm object.. Further, suppose I
> want to vary the distance between the pivot point and the outer surface of
> the arms, but I want the "business end" to always be touching, as if the
> clothespin is closed by the spring.
>
> What I'd like is to specify in some way that the two arms must always
> touch at the "business end" and at the pivot point, and have OpenSCAD
> somehow figure out how to rotate and position the arms accordingly. I've
> found an "attachment" library that seems to do this, but it appears
> abandoned and poorly documented, at least in English. (yes, I've reached
> out to the author, with no success).
>
> Obviously I can do this by writing some trig functions, but I'd really
> rather not have to do that. Is there another solution to this?
>
> --
> Juliean Galak
> jgalak@gmail.com
>
> _______________________________________________
> OpenSCAD mailing listDiscuss@lists.openscad.orghttp://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
>
> _______________________________________________
> OpenSCAD mailing list
> Discuss@lists.openscad.org
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
--
Juliean Galak
jgalak@gmail.com
JG
Juliean Galak
Mon, Feb 4, 2019 7:23 PM
For example, consider this model:
https://pastebin.com/3fNius4L
I want to play around with pviotOffset, and have done so using a trig
function. Relatively simple, here. But I'd love to not have to dust off
my trig, especially in more complicated cases. That attachment library I
found purports to do just this, but I've not figured out how to use it...
I guess what I'm really looking for is some sort of equivalent to the "snap
to" functionality found in some other modeling packages, where I could
designate sets of points (or other items) and maintain their relationship.
Maybe it just doesn't exist in OpenSCAD. If so, so be it - I can make do.
But it'd be nice :) . Especially when I am working on more complex
assemblies that have more complex interrelationships.
Thanks,
Juliean.
On Mon, Feb 4, 2019 at 1:35 PM Juliean Galak jgalak@gmail.com wrote:
But how do you deal with two points of attachment? In my example, sure,
it makes sense to put the contact point of the jaws at the origin, oriented
in a normal way. But when changing the pivot distance, you'd still need to
do trig to figure out how much to rotate and translate each arm, depending
on said distance. Putting the contact point at the origin simplifies that
trig, but doesn't eliminate it.
Also, can you rotate around anything other than the origin? It'd be nice
to be able to specify that this part should rotate around this point on the
part, regardless of where the part is. I don't recall any way to specify
the point of rotation, which would also simplify the above. I guess you
could translate, rotate, and then translate back, but that's kind of cludgy.
On Mon, Feb 4, 2019 at 1:22 PM Joe Francis joe@lostapathy.com wrote:
The key for this problem is to model the parts in an orientation that
matches your frame of reference for the desired motion. (Or move them into
such an orientation before you rotate them).
i.e., model your clothespin arm such that the point you want to touch to
always be on the y-axis, then when you rotate the part about the y-axis,
it'll always be touching there and you avoid the complex math for rotating
it. Then translate/rotate the whole clothespin assembly to whatever point
in space you need it at.
The same principal applies to mating surfaces of parts that are meant to
be assembled. If, for example, you're modeling a stepper motor, it's very
easy to place it in another assembly if you place the mounting face on the
X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
place it correctly in another model. Even more so if you change the
stepper to a different size later on and the key features move relative to
the origin.
This general pattern is, IMO, critical for making good parametric models
in openscad and keeping the complexity to a manageable level.
Joe
On 2/4/19 12:08 PM, Juliean Galak wrote:
I'm trying to figure out if there's any way to "automate" the computation
of a rotation and translation of a part to fit into an assembly.
For example, consider a clothespin, the kind with two pivoting arms and a
spring. Let's say I have designed the two arm object.. Further, suppose I
want to vary the distance between the pivot point and the outer surface of
the arms, but I want the "business end" to always be touching, as if the
clothespin is closed by the spring.
What I'd like is to specify in some way that the two arms must always
touch at the "business end" and at the pivot point, and have OpenSCAD
somehow figure out how to rotate and position the arms accordingly. I've
found an "attachment" library that seems to do this, but it appears
abandoned and poorly documented, at least in English. (yes, I've reached
out to the author, with no success).
Obviously I can do this by writing some trig functions, but I'd really
rather not have to do that. Is there another solution to this?
--
Juliean Galak
jgalak@gmail.com
OpenSCAD mailing listDiscuss@lists.openscad.orghttp://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
For example, consider this model:
https://pastebin.com/3fNius4L
I want to play around with pviotOffset, and have done so using a trig
function. Relatively simple, here. But I'd love to not have to dust off
my trig, especially in more complicated cases. That attachment library I
found purports to do just this, but I've not figured out how to use it...
I guess what I'm really looking for is some sort of equivalent to the "snap
to" functionality found in some other modeling packages, where I could
designate sets of points (or other items) and maintain their relationship.
Maybe it just doesn't exist in OpenSCAD. If so, so be it - I can make do.
But it'd be nice :) . Especially when I am working on more complex
assemblies that have more complex interrelationships.
Thanks,
Juliean.
On Mon, Feb 4, 2019 at 1:35 PM Juliean Galak <jgalak@gmail.com> wrote:
> But how do you deal with two points of attachment? In my example, sure,
> it makes sense to put the contact point of the jaws at the origin, oriented
> in a normal way. But when changing the pivot distance, you'd still need to
> do trig to figure out how much to rotate and translate each arm, depending
> on said distance. Putting the contact point at the origin simplifies that
> trig, but doesn't eliminate it.
>
> Also, can you rotate around anything other than the origin? It'd be nice
> to be able to specify that this part should rotate around this point on the
> part, regardless of where the part is. I don't recall any way to specify
> the point of rotation, which would also simplify the above. I guess you
> could translate, rotate, and then translate back, but that's kind of cludgy.
>
> On Mon, Feb 4, 2019 at 1:22 PM Joe Francis <joe@lostapathy.com> wrote:
>
>> The key for this problem is to model the parts in an orientation that
>> matches your frame of reference for the desired motion. (Or move them into
>> such an orientation before you rotate them).
>>
>> i.e., model your clothespin arm such that the point you want to touch to
>> always be on the y-axis, then when you rotate the part about the y-axis,
>> it'll always be touching there and you avoid the complex math for rotating
>> it. Then translate/rotate the whole clothespin assembly to whatever point
>> in space you need it at.
>>
>> The same principal applies to mating surfaces of parts that are meant to
>> be assembled. If, for example, you're modeling a stepper motor, it's very
>> easy to place it in another assembly if you place the mounting face on the
>> X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
>> stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
>> place it correctly in another model. Even more so if you change the
>> stepper to a different size later on and the key features move relative to
>> the origin.
>>
>> This general pattern is, IMO, critical for making good parametric models
>> in openscad and keeping the complexity to a manageable level.
>>
>> Joe
>>
>>
>> On 2/4/19 12:08 PM, Juliean Galak wrote:
>>
>> I'm trying to figure out if there's any way to "automate" the computation
>> of a rotation and translation of a part to fit into an assembly.
>>
>> For example, consider a clothespin, the kind with two pivoting arms and a
>> spring. Let's say I have designed the two arm object.. Further, suppose I
>> want to vary the distance between the pivot point and the outer surface of
>> the arms, but I want the "business end" to always be touching, as if the
>> clothespin is closed by the spring.
>>
>> What I'd like is to specify in some way that the two arms must always
>> touch at the "business end" and at the pivot point, and have OpenSCAD
>> somehow figure out how to rotate and position the arms accordingly. I've
>> found an "attachment" library that seems to do this, but it appears
>> abandoned and poorly documented, at least in English. (yes, I've reached
>> out to the author, with no success).
>>
>> Obviously I can do this by writing some trig functions, but I'd really
>> rather not have to do that. Is there another solution to this?
>>
>> --
>> Juliean Galak
>> jgalak@gmail.com
>>
>> _______________________________________________
>> OpenSCAD mailing listDiscuss@lists.openscad.orghttp://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>
>>
>> _______________________________________________
>> OpenSCAD mailing list
>> Discuss@lists.openscad.org
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>
>
>
> --
> Juliean Galak
> jgalak@gmail.com
>
--
Juliean Galak
jgalak@gmail.com
JB
Jordan Brown
Tue, Feb 5, 2019 1:37 AM
On 2/4/2019 10:22 AM, Joe Francis wrote:
The same principal applies to mating surfaces of parts that are meant
to be assembled. If, for example, you're modeling a stepper motor,
it's very easy to place it in another assembly if you place the
mounting face on the X/Y plane and run the stepper shaft on the
Z-axis. If you model the entire stepper in the x/y/z-positive
quadrant, it requires a lot of thinking to place it correctly in
another model. Even more so if you change the stepper to a different
size later on and the key features move relative to the origin.
When I'm starting with a module, the very first question (documented in
the comments) is what the origin and rotations are for that module.
For the stepper motor example, I would say that the origin is at the
mounting face, centered on the shaft, with the shaft along the Z axis.
(Rotation around the Z axis left to author's discretion.)
Mostly I design model furniture for my model house, and so usually the
base of the model is at Z=0. X=0 is usually the left-right center of
the model so that symmetry is easy. Y=0 is usually the "front" of the
model, but (for instance) knobs usually extend into negative Y.
Rotation-wise, "up" on the model is almost always positive Z, left is
usually negative X, right is positive X, the front is toward negative Y,
and the back is toward positive Y.
If the model is to be printed in one shot, that's the end; I rotate to
the desired print orientation in the slicer. If it's to be printed in
multiple pieces and then assembled, as I noted in another thread I've
been setting up an animation between the two positions.
On 2/4/2019 10:22 AM, Joe Francis wrote:
> The same principal applies to mating surfaces of parts that are meant
> to be assembled. If, for example, you're modeling a stepper motor,
> it's very easy to place it in another assembly if you place the
> mounting face on the X/Y plane and run the stepper shaft on the
> Z-axis. If you model the entire stepper in the x/y/z-positive
> quadrant, it requires a lot of thinking to place it correctly in
> another model. Even more so if you change the stepper to a different
> size later on and the key features move relative to the origin.
When I'm starting with a module, the very first question (documented in
the comments) is what the origin and rotations are for that module.
For the stepper motor example, I would say that the origin is at the
mounting face, centered on the shaft, with the shaft along the Z axis.
(Rotation around the Z axis left to author's discretion.)
Mostly I design model furniture for my model house, and so usually the
base of the model is at Z=0. X=0 is usually the left-right center of
the model so that symmetry is easy. Y=0 is usually the "front" of the
model, but (for instance) knobs usually extend into negative Y.
Rotation-wise, "up" on the model is almost always positive Z, left is
usually negative X, right is positive X, the front is toward negative Y,
and the back is toward positive Y.
If the model is to be printed in one shot, that's the end; I rotate to
the desired print orientation in the slicer. If it's to be printed in
multiple pieces and then assembled, as I noted in another thread I've
been setting up an animation between the two positions.
NH
nop head
Tue, Feb 5, 2019 9:52 AM
I often use $preview so that F5 shows the assembled item and F6 produces
just the printed parts arranged for printing.
On Tue, 5 Feb 2019 at 01:38, Jordan Brown openscad@jordan.maileater.net
wrote:
On 2/4/2019 10:22 AM, Joe Francis wrote:
The same principal applies to mating surfaces of parts that are meant to
be assembled. If, for example, you're modeling a stepper motor, it's very
easy to place it in another assembly if you place the mounting face on the
X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
place it correctly in another model. Even more so if you change the
stepper to a different size later on and the key features move relative to
the origin.
When I'm starting with a module, the very first question (documented in
the comments) is what the origin and rotations are for that module.
For the stepper motor example, I would say that the origin is at the
mounting face, centered on the shaft, with the shaft along the Z axis.
(Rotation around the Z axis left to author's discretion.)
Mostly I design model furniture for my model house, and so usually the
base of the model is at Z=0. X=0 is usually the left-right center of the
model so that symmetry is easy. Y=0 is usually the "front" of the model,
but (for instance) knobs usually extend into negative Y. Rotation-wise,
"up" on the model is almost always positive Z, left is usually negative X,
right is positive X, the front is toward negative Y, and the back is toward
positive Y.
If the model is to be printed in one shot, that's the end; I rotate to the
desired print orientation in the slicer. If it's to be printed in multiple
pieces and then assembled, as I noted in another thread I've been setting
up an animation between the two positions.
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
I often use $preview so that F5 shows the assembled item and F6 produces
just the printed parts arranged for printing.
On Tue, 5 Feb 2019 at 01:38, Jordan Brown <openscad@jordan.maileater.net>
wrote:
> On 2/4/2019 10:22 AM, Joe Francis wrote:
>
> The same principal applies to mating surfaces of parts that are meant to
> be assembled. If, for example, you're modeling a stepper motor, it's very
> easy to place it in another assembly if you place the mounting face on the
> X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
> stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
> place it correctly in another model. Even more so if you change the
> stepper to a different size later on and the key features move relative to
> the origin.
>
>
> When I'm starting with a module, the very first question (documented in
> the comments) is what the origin and rotations are for that module.
>
> For the stepper motor example, I would say that the origin is at the
> mounting face, centered on the shaft, with the shaft along the Z axis.
> (Rotation around the Z axis left to author's discretion.)
>
> Mostly I design model furniture for my model house, and so usually the
> base of the model is at Z=0. X=0 is usually the left-right center of the
> model so that symmetry is easy. Y=0 is usually the "front" of the model,
> but (for instance) knobs usually extend into negative Y. Rotation-wise,
> "up" on the model is almost always positive Z, left is usually negative X,
> right is positive X, the front is toward negative Y, and the back is toward
> positive Y.
>
> If the model is to be printed in one shot, that's the end; I rotate to the
> desired print orientation in the slicer. If it's to be printed in multiple
> pieces and then assembled, as I noted in another thread I've been setting
> up an animation between the two positions.
>
>
> _______________________________________________
> OpenSCAD mailing list
> Discuss@lists.openscad.org
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
Tue, Feb 5, 2019 12:50 PM
I find that the code in attach.scad works well, the key is really the
orient operator. Simply define the connection points on each part (and the
direction), and you can attach them together.
On Tue, Feb 5, 2019 at 10:53 AM nop head nop.head@gmail.com wrote:
I often use $preview so that F5 shows the assembled item and F6 produces
just the printed parts arranged for printing.
On Tue, 5 Feb 2019 at 01:38, Jordan Brown openscad@jordan.maileater.net
wrote:
On 2/4/2019 10:22 AM, Joe Francis wrote:
The same principal applies to mating surfaces of parts that are meant to
be assembled. If, for example, you're modeling a stepper motor, it's very
easy to place it in another assembly if you place the mounting face on the
X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
place it correctly in another model. Even more so if you change the
stepper to a different size later on and the key features move relative to
the origin.
When I'm starting with a module, the very first question (documented in
the comments) is what the origin and rotations are for that module.
For the stepper motor example, I would say that the origin is at the
mounting face, centered on the shaft, with the shaft along the Z axis.
(Rotation around the Z axis left to author's discretion.)
Mostly I design model furniture for my model house, and so usually the
base of the model is at Z=0. X=0 is usually the left-right center of the
model so that symmetry is easy. Y=0 is usually the "front" of the model,
but (for instance) knobs usually extend into negative Y. Rotation-wise,
"up" on the model is almost always positive Z, left is usually negative X,
right is positive X, the front is toward negative Y, and the back is toward
positive Y.
If the model is to be printed in one shot, that's the end; I rotate to
the desired print orientation in the slicer. If it's to be printed in
multiple pieces and then assembled, as I noted in another thread I've been
setting up an animation between the two positions.
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
I find that the code in attach.scad works well, the key is really the
orient operator. Simply define the connection points on each part (and the
direction), and you can attach them together.
On Tue, Feb 5, 2019 at 10:53 AM nop head <nop.head@gmail.com> wrote:
> I often use $preview so that F5 shows the assembled item and F6 produces
> just the printed parts arranged for printing.
>
> On Tue, 5 Feb 2019 at 01:38, Jordan Brown <openscad@jordan.maileater.net>
> wrote:
>
>> On 2/4/2019 10:22 AM, Joe Francis wrote:
>>
>> The same principal applies to mating surfaces of parts that are meant to
>> be assembled. If, for example, you're modeling a stepper motor, it's very
>> easy to place it in another assembly if you place the mounting face on the
>> X/Y plane and run the stepper shaft on the Z-axis. If you model the entire
>> stepper in the x/y/z-positive quadrant, it requires a lot of thinking to
>> place it correctly in another model. Even more so if you change the
>> stepper to a different size later on and the key features move relative to
>> the origin.
>>
>>
>> When I'm starting with a module, the very first question (documented in
>> the comments) is what the origin and rotations are for that module.
>>
>> For the stepper motor example, I would say that the origin is at the
>> mounting face, centered on the shaft, with the shaft along the Z axis.
>> (Rotation around the Z axis left to author's discretion.)
>>
>> Mostly I design model furniture for my model house, and so usually the
>> base of the model is at Z=0. X=0 is usually the left-right center of the
>> model so that symmetry is easy. Y=0 is usually the "front" of the model,
>> but (for instance) knobs usually extend into negative Y. Rotation-wise,
>> "up" on the model is almost always positive Z, left is usually negative X,
>> right is positive X, the front is toward negative Y, and the back is toward
>> positive Y.
>>
>> If the model is to be printed in one shot, that's the end; I rotate to
>> the desired print orientation in the slicer. If it's to be printed in
>> multiple pieces and then assembled, as I noted in another thread I've been
>> setting up an animation between the two positions.
>>
>>
>> _______________________________________________
>> OpenSCAD mailing list
>> Discuss@lists.openscad.org
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>
> _______________________________________________
> OpenSCAD mailing list
> Discuss@lists.openscad.org
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
JF
Joe Francis
Tue, Feb 5, 2019 3:38 PM
On 2/4/19 12:35 PM, Juliean Galak wrote:
But how do you deal with two points of attachment? In my example,
sure, it makes sense to put the contact point of the jaws at the
origin, oriented in a normal way. But when changing the pivot
distance, you'd still need to do trig to figure out how much to rotate
and translate each arm, depending on said distance. Putting the
contact point at the origin simplifies that trig, but doesn't
eliminate it.
I don't think there is a way to totally eliminate the need to solve that
yourself in OpenSCAD. The strategy I outlined is just meant to simplify
it to solving for that one angle, rather than solving for 2 at a time.
From my (admittedly limited) understanding, attach.scad lets you chain
together a set of attached parts based on a point of attachment, but it
doesn't let you say "I want my part to touch two other surfaces, rotate
it to match". I think the inability to do that is a fundamental
limitation of a CAD kernel like OpenSCAD that's built on constructive
geometry - vs a system like Fusion360 that can also operate in terms of
geometric constraints.
Also, can you rotate around anything other than the origin? It'd be
nice to be able to specify that this part should rotate around this
point on the part, regardless of where the part is. I don't recall
any way to specify the point of rotation, which would also simplify
the above. I guess you could translate, rotate, and then translate
back, but that's kind of cludgy.
That kind of operation is ripe for wrapping in a simple module to do
what you need. Something like:
module rotate_around(angle, point) {
translate(-point)
rotate(angle)
translate(point)
children();
}
rotate_around([0,45,0], [10,0,10]) {
cube(5);
}
On 2/4/19 12:35 PM, Juliean Galak wrote:
> But how do you deal with two points of attachment? In my example,
> sure, it makes sense to put the contact point of the jaws at the
> origin, oriented in a normal way. But when changing the pivot
> distance, you'd still need to do trig to figure out how much to rotate
> and translate each arm, depending on said distance. Putting the
> contact point at the origin simplifies that trig, but doesn't
> eliminate it.
I don't think there is a way to totally eliminate the need to solve that
yourself in OpenSCAD. The strategy I outlined is just meant to simplify
it to solving for that one angle, rather than solving for 2 at a time.
From my (admittedly limited) understanding, attach.scad lets you chain
together a set of attached parts based on a point of attachment, but it
doesn't let you say "I want my part to touch two other surfaces, rotate
it to match". I think the inability to do that is a fundamental
limitation of a CAD kernel like OpenSCAD that's built on constructive
geometry - vs a system like Fusion360 that can also operate in terms of
geometric constraints.
>
> Also, can you rotate around anything other than the origin? It'd be
> nice to be able to specify that this part should rotate around this
> point on the part, regardless of where the part is. I don't recall
> any way to specify the point of rotation, which would also simplify
> the above. I guess you could translate, rotate, and then translate
> back, but that's kind of cludgy.
>
That kind of operation is ripe for wrapping in a simple module to do
what you need. Something like:
module rotate_around(angle, point) {
translate(-point)
rotate(angle)
translate(point)
children();
}
rotate_around([0,45,0], [10,0,10]) {
cube(5);
}
