Symmetry in Action


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Recently I’ve been working exhausting on a presentation for the
upcoming 3D Basecamp in Steamboat Springs, Colorado. I’ll be
presenting some concepts I’ve collected over time about how
to make correct and environment friendly fashions in SketchUp. In fact
this presentation may be very a lot in my ideas for the time being. A
starting SketchUp person contacted me a few undertaking he’s
engaged on. It’s a riser or extension block which shall be 3D
printed from the SketchUp mannequin. He obtained caught on creating the
holes for the screws. So in fascinated about how one can get this job
executed, I used to be fascinated about how one can create the mannequin effectively
and precisely.

For the reason that fellow making this half is a newbie utilizing SketchUp
Make, I’ve restricted the operations to native instruments. There are
some extensions that may very well be used however I believe it’s a good suggestion
to get conversant in what the native instruments can do first.

He provided the mannequin as above prepared for the holes. The
underside of the highest holes have to have hexagonal recesses for
hex nuts and the decrease holes have to be counterbored for the
heads of the cap screws.


For the reason that form is symmetrical, it makes it attainable to work on
half of the half and make the opposite half from the primary. This
is extra environment friendly and reduces the alternatives for errors.

With the block break up down the center, I made it a element and
positioned the middle of the holes on the highest and backside faces.

When creating geometry for issues such because the holes on this
block, I prefer to work outdoors the element. This permits me to
use the element’s geometry for reference with out the concern of
damaging the element.

The opening slicing shapes are drawn in situ. I made the
hex and counterbore parts further lengthy to make the clear up
simpler later. After drawing the shapes for the outlet cutters, I
reversed the faces. A part of this geometry will grow to be of the
holes themselves and reversing the faces now means the face
orientation shall be appropriate once we get completed.

With the geometry of the outlet cutters chosen, hit Edit>Lower
(Ctrl-X or Command+X) to position the geometry on the clipboard.

Subsequent, open the element for enhancing and use Edit>Paste in
place to stick the outlet cutters into the element geometry.

Once you paste the geometry into the element, you’ll discover
that there aren’t any edges the place the outlet cutters move by means of the
angled faces. You’ll have to create these edges with Intersect
Faces. I desire to pick out solely the concerned faces and run
Intersect Faces>With Choice as a result of this limits the
variety of faces that have to be checked out for intersections.

It would seem to be it will be simpler to skip the minimize/paste in
place step and as a substitute simply use Intersect Faces>With Mannequin.
The issue with that’s whilst you’d get the intersection edges
on the angled face, you wouldn’t have any faces contained in the
holes. The method I’m displaying not solely cuts the angled
surfaces of the block however it additionally cuts the outlet cutters off at
the angled surfaces.

After the intersect routine has run, delete the surplus geometry
from the outlet cutters and the faces skinning over the holes.
Switching to X-ray is an efficient technique to see all the mannequin at a
look so you’ll be able to search for remaining unneeded edges or faces.

Now all that’s left is to make the opposite half and slightly
cleanup. Choose the entire geometry by triple clicking on it
with the Choose software. Triple click on will get the entire hooked up
geometry. Then use Transfer/Copy to make a duplicate of the choice.
Transfer that replicate over within the appropriate course. Then proper click on
on the nonetheless chosen copy and use the Flip Alongside command to
create a mirrored copy of the unique geometry. On this case
you’d use Flip Alongside>Pink Course. I’ve keyboard
shortcuts arrange for the Flip Alongside instructions which makes it
very fast and straightforward to do that.

Then use the Transfer software to convey the brand new half over to the
authentic half. Once you seize the copy with the Transfer software, seize
at a nook that can correspond to a nook on the
vacation spot. This can make it simpler to precisely place the
copy.

All that’s left is slightly cleanup. Erase the seam strains
across the half. For those who’ve moved the 2 halves collectively
accurately, the faces ought to stay. After these seam strains are
gone, shut the element and the choose it. Test in Entity
Information to see that it’s stable. To ensure that a element to be
acceptable for 3D printing, it have to be a stable.

The straightforward necessities for a gaggle or element to be
thought of stable in SketchUp are these. The group/element
mush not have something in its wrapper however edges and faces. So
nested parts is not going to be thought of stable. And each edge
have to be shared by precisely two faces. If there’s a gap, the
edges across the gap will solely certain one face. If there are
inner faces, the sides shall be shared by three or extra faces
and tails extending out from endpoints will certain no faces. A
third requirement is that each one again faces be on the within of
the form. 

Solids are extraordinarily vital for 3D printing however I discover it
worthwhile to ensure all parts are stable in my fashions
even when they aren’t going to be 3D printed as a result of solids are
usually a lot simpler to work with as I mannequin. It’s additionally an indication
of unpolluted, correct and environment friendly modeling.

Dave

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