Tutorials – [as] https://alexschreyer.net AEC CAD/BIM, SketchUp, Timber Engineering, Web Design and more... Fri, 22 Feb 2019 14:20:48 +0000 en-US hourly 1 https://wordpress.org/?v=5.1 https://i2.wp.com/alexschreyer.net/wp-content/uploads/2015/09/cropped-as-square.jpg?fit=32%2C32&ssl=1 Tutorials – [as] https://alexschreyer.net 32 32 6702894 Unwrapping and unfolding correctly in SketchUp https://alexschreyer.net/sketchup/unwrapping-unfolding-correctly-sketchup/ https://alexschreyer.net/sketchup/unwrapping-unfolding-correctly-sketchup/#comments Thu, 29 Jun 2017 14:43:59 +0000 https://alexschreyer.net/?p=6888 Whether you are working with paper or sheet metal, unfolding is a crucial step in the manufacturing process when you are starting off with a digital model in SketchUp. If you want to build something exactly as designed on-screen, then you will need to unfold complex shapes and lay them out flat for cutting. Of [...] Read more..

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Whether you are working with paper or sheet metal, unfolding is a crucial step in the manufacturing process when you are starting off with a digital model in SketchUp. If you want to build something exactly as designed on-screen, then you will need to unfold complex shapes and lay them out flat for cutting. Of course, my Unwrap and Flatten Faces Extension for SketchUp is the ideal tool for doing that in SketchUp. In many cases, it can automatically unwrap a surface (i.e. multiple faces) and produce something usable. Of course there are some caveats for that to work and I will be covering some of those here.

Face Orientation

SketchUp faces have a front and a back side (turn on “monochrome” face style in the View menu to see those orientations) where the front of a face is commonly colored white. The unfolding algorithm of my extension starts at one face and folds it along an edge to end up aligned with the next face at that edge (and then repeats from there).

This relies quite a bit on face orientation. As you can see in the image above, if all faces are aligned the same (as in the topmost model where all fronts point outwards), the three faces unwrap correctly. If neighboring faces have a different orientation, however, (as in the model in the lower half of the picture), then the unfolding process ends up placing faces on top of neighboring faces, which leads to an inaccurate result (SketchUp merges those overlapping faces in the process).

Best practice is therefore to always double-check that all faces that are to be unfolded together have their fronts oriented similarly. If a face needs to be reversed, then that can easily be done with the “reverse face” right-click tool. Do so before starting the unwrap tool.

Developable Surfaces

In general terms, only flat shapes and developable surfaces (e.g. a cylinder) can be cleanly unwrapped and flattened. This means that if your object has double-curvature (as is the case for the semi-sphere and the shell in the image above), then my extension can fail because it is likely impossible to find a result for the entire object. In some cases, (as for the sphere), this tool may be able to “peel” a surface, which may or may not be a useful result.

It is always possible to select only part of an object (e.g. the curved top of the cone shown above) and unwrap that separately from the rest (the circular base in that case). For a double-curved surface (the rightmost object), the best way to unfold will likely consist of taking a horizontal or vertical set of faces and unwrapping in “strips”. This process is illustrated in the images below as well.

Double-Curved Surfaces and Material Stretch

When double-curved surfaces are unwrapped in strips (as shown for the sphere section above that was unwrapped in seven sections), then there are several ways to work with those to get a final result (see image below).

If the material has no stretch capacity (as with sheet metal, for example), then the best way to cut and reassemble is shown in the right example below. If, however, the material can stretch (as with fabric), then an educated guess must be made (because the unwrapping algorithm cannot at this point take stretching into account). All faces could be placed with a slight overlap (shown on left) and the outlining shape can be cut out. This assumes stretch to be possible in the vertical direction but assumes no horizontal stretch. This could be compensated for by scaling the shape horizontally a bit.

Material Thickness

Thickness of the used material becomes an issue when two flattened and then cut pieces need to be joined. You can see this in the example above. If the material is of negligible thickness (much thinner than the overall material area) as is the case with paper, sheet metal, and the like, then flattened shapes can likely be reassembled just as they are cut (bottom example). When the material has some amount of thickness, however, as can be seen in the upper model in the image above, then mating edges must be treated (by tabbing, backcutting or chamfering) to allow for pieces to be reassembled as they were intended.

Tabs

If you need to create overlaps at edges for glue or weld tabs, then the easy way is of course to simply overcut the flattened shape (while marking the original shape outline). For more control of tab size, one option is to use the tab tool in the Flattery extension that places tabs manually on single edges. An easier approach, however, is the Offset Contours tool in the Tools on Surface extension. As you can see in the image above, all edges can be offset in one go and a defined offset amount (1/2″ in my case) can be entered.

Further Reading

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Dryer fix made easy with 3D printing https://alexschreyer.net/sketchup/dryer-fix-made-easy-3d-printing/ https://alexschreyer.net/sketchup/dryer-fix-made-easy-3d-printing/#comments Mon, 20 Feb 2017 23:10:46 +0000 https://alexschreyer.net/?p=6861 As you can see in the image below, our dryer had a broken knob. It was just a small plastic part but without it, starting the machine became a bit of a hassle. To fix this, I could have gone to a site like Sears PartsDirect or similar, looked up the dryer’s model number, find the [...] Read more..

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As you can see in the image below, our dryer had a broken knob. It was just a small plastic part but without it, starting the machine became a bit of a hassle. To fix this, I could have gone to a site like Sears PartsDirect or similar, looked up the dryer’s model number, find the part, wait a few days and then get the original replacement part. I chose to go another route… I 3D-printed it myself!

Hard to start this thing without a functioning knob

Because this was such a simple part, it was very easy to model a replacement knob quickly in SketchUp. All I needed were the dimensions for the overall knob size and the small switch stem.

As you can see, the stem had a flat bottom that grips nicely into a void in the knob. Also, I was not too eager to replicate the original knob design (although that wouldn’t have been too hard). The knob just needed to fit and function as intended. So I went with a simple design that consisted of a disk and a box shape.

I might upload a video of the 3D modeling in another post, but I essentially used exact dimension entry and the tape measure tool for the main geometry and then the PushPull tool to form all the shapes (pull the grip up and then push the void in). The resulting shapes had quite sharp edges, so I also used Fredo’s Round Corner extension to round the top edges a bit. I then turned on the x-ray face style to be able to look into the object, which allowed me to find some stray lines that prevented this object from being 3D printable. After a few minutes, this was what I got and then exported to STL format using the SketchUp STL extension (click image to navigate):

Fortunate for us here at UMass, we have the MakerBot Innovation Center in the WEB DuBois library. A quick email and a trip to the library provided me with two versions of the knob in just a few hours (and for cheaper than ordering a replacement part):

Picking up the finished part at the library

So, did it fit? As you can see in the following image, it did (admittedly after some manual cleanup). Not too bad a solution!

Good as new!

I do have some tips and tricks in case you want to do something similar, too:

  • I didn’t use calipers to measure the exact stem dimensions. As a result, I didn’t get the dimensions correct. The fit was quite tight and I needed to ream the knob out a bit. Use calipers if you have them! Sparkfun has some cheap ones for sale.
  • This knob relies quite a bit on the strength of the perimeter of the internal void (to turn the switch stem, which has a bit of resistance). Therefore it is a good idea to increase the number of shells (the outside layers) during 3D printing from the default two to something like four.
  • I could also have used the SolidInspector or SolidSolver extensions to check and clean the model up for 3D printing. In this case, I didn’t need to do that because of its simplicity.

More

Interested in 3D printing with SketchUp? Want to learn more techniques and other ways to 3D print or otherwise make things with SketchUp? Check out my book Architectural Design with SketchUp, 2nd Edition.

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Support Hillary with a Website Bumper Sticker https://alexschreyer.net/web-programming/support-hillary-website-bumper-sticker/ https://alexschreyer.net/web-programming/support-hillary-website-bumper-sticker/#respond Thu, 03 Nov 2016 11:04:51 +0000 http://alexschreyer.net/?p=6258 You have put a yard sign up, you have plastered your car with cool bumper stickers, you may even have bought the woman card. Now what? Well, if you have a blog or website then you should be able to show your support there, too. Introducing: The website bumper sticker! As my friends already know, [...] Read more..

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2016-11-03_10-22-43

You have put a yard sign up, you have plastered your car with cool bumper stickers, you may even have bought the woman card. Now what? Well, if you have a blog or website then you should be able to show your support there, too. Introducing: The website bumper sticker!

As my friends already know, I am strongly supporting Hillary Clinton for president of the USA! Especially with such a dangerous buffoon on the other side. As a sign of my support, you should be able to see (at least until the election) an “I’m With Her” logo in the top-right corner of this site. Click it and support her, too!

How can I use this, too?

If you would like to use this website bumper sticker for your blog, website etc., copy the code embedded below. Just add it to the html code for your site’s footer (e.g. footer.php in WordPress just before the closing BODY tag) or to any individual page you like (just paste it into the raw HTML) and it should show up automatically.

Of course, I am asking everyone to share this. The code snippet and image are completely free to use by anyone.

P.S.: If you are using Google’s Adsense, don’t forget to adjust its settings to your liking, too.

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Upgrading our Bath Fan Light – for Under $25 https://alexschreyer.net/design/5639/ https://alexschreyer.net/design/5639/#respond Sat, 28 Nov 2015 14:00:41 +0000 http://alexschreyer.net/?p=5639 Our bathroom fan light was driving me crazy for a while now. No matter how much wattage I would put into it, the plastic cover only allowed for a very dim light to come out. And the arrangement of the bulb in the fixture together with the housing forced most light to emit downward and to [...] Read more..

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Light upgrade detail
Light upgrade detail

Our bathroom fan light was driving me crazy for a while now. No matter how much wattage I would put into it, the plastic cover only allowed for a very dim light to come out. And the arrangement of the bulb in the fixture together with the housing forced most light to emit downward and to the left. Time for a light upgrade!

To fix these issues, I was thinking about adding a cool looking panel from 3form about 2″ under the light which would be offset by metal standoffs. Unfortunately, even the 3form remainder cutoffs are quite expensive. So I tried a different approach.

As you can see in the gallery below, I did find some standoffs. My 3/4″ x 2″ standoffs are from Signworld and cost me $11 for a set of four. While there are also stainless steel ones available out there, these look great and are well adjustable. For the panel, I went with two sheets of clear acrylic from Home Depot for under $5 each. To get a frosted effect, I decided to put vellum paper between the sheets – at least for now. Having two sheets there I will be able to experiment with all kinds of interlayers, though. I might try some grasses at some point, for example.

So there you have it: A cost-efficient upgrade that looks quite sleek and elegant. The room is now much brighter and the fixture even creates some interesting shadows on the ceiling.

If you try this for yourself, make sure there is enough overlap so that you can’t see the innards of the fixture from the side. Also, use a cool light like an LED or a CFL or the panel might warp (but you were using those anyways, right?).

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What’s New in SketchUp 2014? Better Ruby, for Example! https://alexschreyer.net/sketchup/whats-new-in-sketchup-2014-better-ruby-for-example/ https://alexschreyer.net/sketchup/whats-new-in-sketchup-2014-better-ruby-for-example/#comments Fri, 28 Feb 2014 16:02:21 +0000 http://www.alexschreyer.net/?p=5180 By now you most probably have heard that SketchUp 2014 has been released. There are quite a few great new-feature overviews and reviews out there and I’ll suggest you look at the ones linked at the end of this post to get up to speed. For now, I just wanted to show you why the [...] Read more..

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Flickr photos in SketchUp

By now you most probably have heard that SketchUp 2014 has been released. There are quite a few great new-feature overviews and reviews out there and I’ll suggest you look at the ones linked at the end of this post to get up to speed. For now, I just wanted to show you why the Ruby update in SketchUp 2014 is pretty amazing. Look at this image: What is so interesting about the image above? Well – those are images that were loaded from Flickr directly into SketchUp using the now included “net/http” library. Since SU 2014 not only updated Ruby to 2.0 but also included all of the standard libraries, stuff like this is now possible. You can integrate Net functionality much more and create all kinds of interesting mash-ups. To replicate what I did above, copy the following code snippet and either paste it into the Ruby Console (it now accepts multiline Ruby!) or into my Ruby Code Editor. Here’s also an interactive version on Sketchfab:

Code Snippet

SketchUp 2014 Links

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