### Re: Morphing irregular shape while extruding?

T
Terry
Thu, Jan 19, 2023 4:55 PM

Even if I actually end up using my crude 'wooden trap' idea, I'll try
your suggestion shortly as a learning exercise. Well, when I can force
myself away from an engrossing Arduino project ;-)

On Thu, 19 Jan 2023 16:06:33 +0000 (UTC), you wrote:

I'm not going to say this is THE answer, but it might still work as desired. Your SVG tracing can be imported and extruded to a minimal height. A circle of the appropriate dimensions also created to a minimal height, then translated to the desired distance.
Hull() the pair twice, rescale the x/y for the second hull(), then difference them.
This idea stems from a web search for "OpenSCAD loft" which presented an Instructable that didn't really help, but twisted the alleged mind in this direction.

``````On Thursday, January 19, 2023 at 10:55:30 AM EST, Terry <terrypingm@gmail.com> wrote:
``````

Haven't done any printing for ages, and more than a bit rusty, so...

I have a garden 'blower' that I want to improvise for an unusual
purpose. I need to print a PLA add-on I can temporarily push inside its
open end. That end of the part must obviously roughly match the blower
tube's shape. Although not an OpenSCAD issue, any tips on the best way
to capture that closed curve would be welcome. The best two
I've come up with so far:

1. Wrap some stiff wire tightly around the blower near its end. Or
perhaps better, a long but thin strip of aluminium; slide that off and
make an SVG.in Inkscape (when I've relearnt how to do that).

2. Use the rough pencil trace I've made as the SVG basis. Then in
OpenSCAD reduce its 'x' coordinates appropriately. Presumably the factor
would be b/h estimated from the photo.

Precision won't be an issue as I'll glue some thin but flexible stuff to
the outside.

The more difficult aspect is that the other end of the print must be a
cylinder of about 2 inches (50 mm) in height and 5/8 inch (15 mm) inner
diameter. (I'll be attaching a hose or similar.) This would obviously be
trivial if the starting shape was circular, but what is the general
approach for extruding from an irregular shape to a circle?

While preparing this a simpler idea dawned, and it would take a fraction
of the time to prepare. A rectangular piece of plywood or similar
covering the entire end of the blower, secured by screws or velcro to
the adjacent plastic area. The 3d print (if an existing piece of tubing
cannot be found) would be a simple cylinder, friction fitted inside a
hole in the wood's centre.

But I'd still like to learn how to 'morph' from one 2D shape to another

Image attached, or here:
https://www.dropbox.com/s/tcj3g1f0zd4n1j7/Two-plus.jpg?raw=1

Terry, UK

To unsubscribe send an email to discuss-leave@lists.openscad.org

RW
Raymond West
Thu, Jan 19, 2023 5:09 PM

Not sure if you'd get much air from a blower into a 5/8 d hole, in
particular going into a hose. A simple test, get a plastic lemonade
bottle, cut off the bottom, the big end can be slit to fit around the
nozzle, and fit with duct tape. See if you get the air flow you think
you'll get. (I use said bottles to fit various sawa, dust collecting,
etc.  to the wood shop vac.

On 19/01/2023 16:55, Terry wrote:

Even if I actually end up using my crude 'wooden trap' idea, I'll try
your suggestion shortly as a learning exercise. Well, when I can force
myself away from an engrossing Arduino project ;-)

On Thu, 19 Jan 2023 16:06:33 +0000 (UTC), you wrote:

I'm not going to say this is THE answer, but it might still work as desired. Your SVG tracing can be imported and extruded to a minimal height. A circle of the appropriate dimensions also created to a minimal height, then translated to the desired distance.
Hull() the pair twice, rescale the x/y for the second hull(), then difference them.
This idea stems from a web search for "OpenSCAD loft" which presented an Instructable that didn't really help, but twisted the alleged mind in this direction.

``````On Thursday, January 19, 2023 at 10:55:30 AM EST, Terry <terrypingm@gmail.com> wrote:
``````

Haven't done any printing for ages, and more than a bit rusty, so...

I have a garden 'blower' that I want to improvise for an unusual
purpose. I need to print a PLA add-on I can temporarily push inside its
open end. That end of the part must obviously roughly match the blower
tube's shape. Although not an OpenSCAD issue, any tips on the best way
to capture that closed curve would be welcome. The best two
I've come up with so far:

1. Wrap some stiff wire tightly around the blower near its end. Or
perhaps better, a long but thin strip of aluminium; slide that off and
make an SVG.in Inkscape (when I've relearnt how to do that).

2. Use the rough pencil trace I've made as the SVG basis. Then in
OpenSCAD reduce its 'x' coordinates appropriately. Presumably the factor
would be b/h estimated from the photo.

Precision won't be an issue as I'll glue some thin but flexible stuff to
the outside.

The more difficult aspect is that the other end of the print must be a
cylinder of about 2 inches (50 mm) in height and 5/8 inch (15 mm) inner
diameter. (I'll be attaching a hose or similar.) This would obviously be
trivial if the starting shape was circular, but what is the general
approach for extruding from an irregular shape to a circle?

While preparing this a simpler idea dawned, and it would take a fraction
of the time to prepare. A rectangular piece of plywood or similar
covering the entire end of the blower, secured by screws or velcro to
the adjacent plastic area. The 3d print (if an existing piece of tubing
cannot be found) would be a simple cylinder, friction fitted inside a
hole in the wood's centre.

But I'd still like to learn how to 'morph' from one 2D shape to another

Image attached, or here:
https://www.dropbox.com/s/tcj3g1f0zd4n1j7/Two-plus.jpg?raw=1

Terry, UK

To unsubscribe send an email to discuss-leave@lists.openscad.org

To unsubscribe send an email to discuss-leave@lists.openscad.org

T
Terry
Thu, Jan 19, 2023 5:23 PM

Thanks Ray. Don't think I have any plastic bottles around of large
enough diameter. But making a hole in any large enough piece wood or
cardboard should be easy and if my junk box tube is too small then
gaffer tape should fix it, as well as securing the platform..

If anyone's curious, I'm trying to get my car's windscreen washer
working. Apparently the likely cause is gel from the additive gunging
things up. Sucking it out, or blowing it around are what I have in mind.

On Thu, 19 Jan 2023 17:09:55 +0000, you wrote:

Not sure if you'd get much air from a blower into a 5/8 d hole, in
particular going into a hose. A simple test, get a plastic lemonade
bottle, cut off the bottom, the big end can be slit to fit around the
nozzle, and fit with duct tape. See if you get the air flow you think
you'll get. (I use said bottles to fit various sawa, dust collecting,
etc.  to the wood shop vac.

On 19/01/2023 16:55, Terry wrote:

Even if I actually end up using my crude 'wooden trap' idea, I'll try
your suggestion shortly as a learning exercise. Well, when I can force
myself away from an engrossing Arduino project ;-)

On Thu, 19 Jan 2023 16:06:33 +0000 (UTC), you wrote:

I'm not going to say this is THE answer, but it might still work as desired. Your SVG tracing can be imported and extruded to a minimal height. A circle of the appropriate dimensions also created to a minimal height, then translated to the desired distance.
Hull() the pair twice, rescale the x/y for the second hull(), then difference them.
This idea stems from a web search for "OpenSCAD loft" which presented an Instructable that didn't really help, but twisted the alleged mind in this direction.

``````On Thursday, January 19, 2023 at 10:55:30 AM EST, Terry <terrypingm@gmail.com> wrote:
``````

Haven't done any printing for ages, and more than a bit rusty, so...

I have a garden 'blower' that I want to improvise for an unusual
purpose. I need to print a PLA add-on I can temporarily push inside its
open end. That end of the part must obviously roughly match the blower
tube's shape. Although not an OpenSCAD issue, any tips on the best way
to capture that closed curve would be welcome. The best two
I've come up with so far:

1. Wrap some stiff wire tightly around the blower near its end. Or
perhaps better, a long but thin strip of aluminium; slide that off and
make an SVG.in Inkscape (when I've relearnt how to do that).

2. Use the rough pencil trace I've made as the SVG basis. Then in
OpenSCAD reduce its 'x' coordinates appropriately. Presumably the factor
would be b/h estimated from the photo.

Precision won't be an issue as I'll glue some thin but flexible stuff to
the outside.

The more difficult aspect is that the other end of the print must be a
cylinder of about 2 inches (50 mm) in height and 5/8 inch (15 mm) inner
diameter. (I'll be attaching a hose or similar.) This would obviously be
trivial if the starting shape was circular, but what is the general
approach for extruding from an irregular shape to a circle?

While preparing this a simpler idea dawned, and it would take a fraction
of the time to prepare. A rectangular piece of plywood or similar
covering the entire end of the blower, secured by screws or velcro to
the adjacent plastic area. The 3d print (if an existing piece of tubing
cannot be found) would be a simple cylinder, friction fitted inside a
hole in the wood's centre.

But I'd still like to learn how to 'morph' from one 2D shape to another

Image attached, or here:
https://www.dropbox.com/s/tcj3g1f0zd4n1j7/Two-plus.jpg?raw=1

Terry, UK

To unsubscribe send an email to discuss-leave@lists.openscad.org

To unsubscribe send an email to discuss-leave@lists.openscad.org

To unsubscribe send an email to discuss-leave@lists.openscad.org

JB
Jordan Brown
Thu, Jan 19, 2023 6:26 PM

On 1/19/2023 9:23 AM, Terry wrote:

If anyone's curious, I'm trying to get my car's windscreen washer
working. Apparently the likely cause is gel from the additive gunging
things up. Sucking it out, or blowing it around are what I have in mind.

I don't think a garden blower produces all that much pressure.  For a
small diameter, you might be able to get more pressure just blowing with