This instructable will cover my own experiments with laser kerf bent wood, also known as lattice hinges, and how I tried to create it parametrically to bend along a curved surface.

There's a lot of good information about lattice hinges here http://www.deferredprocrastination.co.uk/blog/cate... which explains the concept and actual physics behind it.

I'm no engineer, so all of what I've found is through trial and error.

## Step 1: Patterns

I tried a lot of different patterns to try to achieve different results, most of which were failed attempts at making a doubly curved surface. Some turned out to be more flexible than I expected. Some were much less than expected.

I'll explain each pattern in the following steps.

I've attached the files for the pattern samples in the photo above. If your browser tries to open the file and you get a blank page, try right clicking the link and choose "save link as". It seems people are having issues downloading the files.

## Step 2: Straight Lattice

This is the most common lattice hinge and the most reliable. Lattice hinges rely on torsion of the material to bend and it's easy to see in this photo. The radius of the bend depends on the length of the cuts, the distance between them and the thickness of the material.

## Step 3: Wave Lattice

This is one that turned out to be more flexible than expected. It was an attempt to bend in two directions, which it does not. It does however bend in one direction pretty well for such short spring members.

## Step 4: Cross Lattice

This is what I've found to be the most flexible pattern so far. In thinner materials, it's even able to bend on a diagonal. The last two photos are of a variation I tried that was not as successful, but showed potential in bending two directions.

## Step 5: Fillet Lattice

The idea behind this pattern was do distribute the stress of the torsion more evenly. Sharp corners tend to be breaking points when a material is under stress. Rounding the corners distributes that stress a little more evenly along the spring.

In the last image, I was experimenting with varying the density of the pattern to bend in a gradual curve.

## Step 6: Beehive Lattice

This is one that I was sure would be my answer to a doubly curved surface, but it turned out to be the least flexible of all. The answer is pretty clear, the spring members are very short.

## Step 7: Bastian Lattice

This pattern was inspired by Andreas Bastian's work on Mesostructured Materials http://www.andreasbastian.com/blog/3d-printed-meso... which is exactly what I've been trying to do with laser cutters.

It is not yet very flexible, but shows potential. The pattern in the photo is accidentally flipped and creates a rigid pattern that cracks in very satisfying directions. The pattern in the sample files is correct and less cracky.

## Step 8: Bending Along a Curve

I have come up with two ways to create curved bends. The first is manually warping a pattern with illustrator and photoshop. The second is parametrically generating the pattern on a surface.

First I'll cover the photoshop technique, then I'll get into the more complex parametric design with grasshopper.

## Step 9: Warping With Photoshop

Begin with the 2D outline of the surface you are wanting to bend. You get this by flattening or unrolling a developable surface (this can be done in most design software like Inventor etc.). For more information about developable surfaces you can read this http://en.wikipedia.org/wiki/Developable_surface . It is important to understand the concept when designing for fabrication with sheet materials.

With the outline in illustrator, copy and paste it into a new photoshop document. Choose to paste as a path. Next brush a stoke over the path so it's visible by clicking the solid ring at the bottom of the path menu.

Next copy and paste your cuts in the same way. Ideally you would measure the length of the surface and the radius of the bend to determine the number of springs in the pattern before you warp them. If you're like me, you take an educated guess and try it.

While you cut paths are selected, transform them by pressing ctrl+t. Then right click and select warp. You will have a grid with four points and their control points.

Warping will take some practice. It helps to have a good understand of how to work with bezier curves when using illustrator and photoshop. If you have a four pointed surface, match the warp points to the corners of the surface, then align the control points so that they are tangent to the edge they are following. I didn't do a very good job of this in the photos.

Once you are satisfied with your warp, hit enter to finish it. Now you can export your paths back into illustrator for laser cutting.

## Step 10: Parametric Kerf Bending

I have been using paneling tools for grasshopper to generate patterns on curved surfaces. The paneling tools "morph 2D" tool allows you to morph a 2D curve onto a 3D surface. It does this by dividing a surface by its UV domain to create a grid. Then it stretches a pattern into the frames created by the grid. In this case I am morphing it onto a flattened 2D surface, but it seems that the pattern doesn't change when it is flattened . I assume the surface domain is equal on the flattened surface (please correct me if I'm wrong). The pattern in the pictures is created by a grid with 1 division in the U direction and X number of divisions in the V direction. This process generally works well for simple ribbon-like surfaces, but is not an accurate way to generate the correct bend for every surface.

The photos above are proof of concepts used for my instructable the Bloom Lamp and another lamp that is still a work in progress.

The next step will be to algorithmically calculate the density of the pattern based on the curvature of the surface and direction of the bend. One idea would be to find the points with the most curvature on the surface and use those points as grid attractors.

If you have ideas, please pick up where I've left off and remember to share it with the rest of us.

Enjoy your curvy wood!

<p>this is great</p>
<p>Hi Momsen,</p><p>I hope that Files work!</p><p>Please post a request.</p><p>Regards</p>
<p>Thanks so much!</p>
<p>@Aaron, could you please edit this instructable to add the SVG files along with your original proprietary files at step 1? I lost time in converting them into SVG before I realised someone already did that.</p>
<p>otimo gostei</p>
<p>Can I use this on my creation?</p>
<p>thank you</p>
<p>Hi Aaron</p><p>With the Straight Lattice, was there any reason that the distance between the edge and the cut only ever appears to be about half the distance between the ends of the cut lines.</p><p>The lines seem to be about 0.62 inches long with gaps of 0.2 inches ; except at the sides where you only use half the spacing (about 0.1 inches)</p><p>Did you try using 0.2 inch gaps at the edges ? but found that half the distance was better ?</p>
<p>Hi Aaron,</p><p><br>I saw on your blog searches you do on knitting hinges, and I was quite interested in including them in my doctoral thesis, but I got some questions about the geometry:<br>1. What is the origin of the geometry of kerf pieces of wood?<br>2. As cutting geometry was chosen compared to the movement/set of hinge piece of wood?<br>3. The movement/set of hinge piece of wood was achieved as desired?<br>3.1 If so, the movement / set of hinge is equal to the desired?<br>3.2 What is the criterion of control used in the two-dimensional geometric model construction to set the kerf on the laser machine?<br>4. What is the model of kerfing machine laser used for these pieces of wood?<br>5. What are the software used for the design and for cutting?<br><br>These questions serve to feed my research on my PhD in &quot;The flexibility of essentially rigid materials from the parametric design and digital fabrication.&quot;<br><br>I thank you immensely availability and help.<br><br>Regards,</p>
<p>Thank you! The file is just what I needed to easily print / cut the example files for my students. Easy to do! Kids are excited to use the concepts in future projects. </p>
A pupil of mine used one of your patterns to make a bit different birdhouse. Thanks for sharing!
<p>Nice.. she has more gaps which will make for beautiful shadows</p>
<p>Aaron, thanks for the inspiration. I tried this on metal with some gaps to help me shape it into a pavilion model.</p>
<p>Hi Aaron,</p><p>I used to laser as a hobby and really enjoyed it. Now it is a full time job and I still enjoy it but sadly my time for experimenting is greatly diminished. Your post here is very inspiring and thank you so much for sharing. You have a new follower.</p><p>Doug</p>
<p>Hi Aaron and everybody, </p><p>I was researching the same thing, and I have found a pattern that is super flexible in both directions and it is possible to achieve double curvature surfaces.</p><p>I wanted to share it with you since you've done such a nice research.</p><p>visit to download dxf file</p><p><a href="http://lab.kofaktor.hr/en/portfolio/super-flexible-laser-cut-playwood/" rel="nofollow">http://lab.kofaktor.hr/en/portfolio/super-flexible...</a></p>
<p>The link did not work for me. Can you repost, please?</p><p>Thank you!</p>
<p>Try this:</p><p>http://lab.kofaktor.hr/en/portfolio/super-flexible-laser-cut-plywood/</p>
<p>This is great! Thanks for sharing!</p>
<p>Dear creator, </p><p>Do you mind if I use these designs for educational purposes at school for Design and Technology</p><p>Thanks heaps</p><p>Matt</p>
<p>Thanks Aaron for sharing your experiments. Very cool stuff indeed. I thought everyone might get a kick out of seeing what a Chinese designer, Zhoujie Zhang, is doing with laser cut sheet metal, forming tessellated furniture and household decor objects: http://www.zhangzhoujie.com </p>
<p>Great job! I have some stupid questions. Do you know of any video tutorial where it is explained how to make lattice hinges in illustrator? or is there any other software that this task easier?</p>
<p>Hi,</p><p>Unfortunately there are no good examples for kerf bending with illustrator. You can look for more tutorials on using the &quot;warp&quot; tool in illustrator to get started experimenting. </p>
<p>Has anyone found out if one pattern works better than the others for doing a one direction bend of 180+ degrees? I don't have full access to a laser cutter so I would like to try to narrow the parts I have to buy. I was thinking of using it to make the spine of a memory book. Thanks!</p>
<p>Hi,</p><p>Unfortunately there's no easy answer without experimentation. It all depends on your material, its thickness and the density of the pattern. This article has links to more info on the actual engineering of this process http://www.core77.com/posts/36481/Adventures-in-Laser-Kerf-Bending</p>
<p>Hi Aaron, I am Yue, a new AiR just joined pier 9 this month. I saw your study of the bend wood sample material on the showcase shelf. the patterns are very cool. Gabe showed me this instructable today and I thought that I can use the bend wood to cover curved gaps. it turns out great. thanks for knowledge and sharing!</p>
<p>Hi Yue!</p><p>Glad it worked for you!</p>
<p>Those are great samples</p>
<p>I cannot download the .dxf file, i get a webpage with a lot of text, what do i do wrong?</p>
<p>Try right click and &quot;save link as&quot;, or the mac equivalent (sorry I'm mac illiterate).</p>
<p>Hello Aaron, Unfortunately I am also unable to save the .dxf, save link as.... does force me to save the file as html... please help!</p>
<p>Hi! Really nice work, really love how much you can use it for and how nice it looks. May I ask what scale you have been making it? What should be the distance between two lines? And how trick can the plywood be? Making a case for my boyfriends moduler synthesizer.</p>
<p>That looks awesome, shame I don't have a laser cutter!</p>
<p>Getting my head around the laser cutter. The kerf bending stuff is kinda amazing. I had some trouble with the curve math. How do you measure the curves so that the tabs line up correctly? Should I be measuring the inside edges?</p>
That looks great! Yes the length of the inner radius should match.
<p>Love the study of kerf bending patterns. I ended up using the cross lattice for a round box I'm making and it worked great. It opens up so many possibilities for working with wood and a laser cut. Thanks!</p>
<p>Great resources. Looking to make a 3mm plywood bookcover with this for a uni project. Any input on what pattern you'd recommend</p>
<p>could this be done on a cnc machine?</p>
<p>A laser cutter technically is a cnc machine, but I guess you mean a cnc router? It can, especially makes sense for thicker material (we bent 10mm plywood easily). The limitations of the cnc router are actually an advantage here, because it's impossible to create sharp 90&deg; angles.</p><p>Just keep in mind to adjust the distances accordingly, because the router takes away more material than the laser. It ends up being stiffer in the end, so it's more for bend-once-then-glue connections that won't move much.</p>
<p>I'm working on laser cutting a flexible ramp. Which one would you recommend to use where it'll create a relatively smooth surface? The ramp is a parabolic piece-wise function with the latticed section being the actual surface the ball is travelling on. #1 with some space filling cyanoacrylate or epoxy?</p>
I am not sure if it helps. I had tried for double bending sometime ago. These are out of thin PVC sheets. These could be useful for wood also if you try with different dimensions.
<p>amazing work! wonder if i can test it for some fashion project. can i use it? =)</p>
Nice! I wonder what would happen if it was scaled way down and cut from wood.
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<p>Hi, great work! Which material thickness of wood have you already tried?</p>
<p>Hi good afternoon, i say hi from mexico, recently i discovered your page i really like it, just a question i can not download the file, where in this page i can do it? thank you</p>
<p>Really well done, my adjacent possible has been expanded.</p>
<p>Thanks!</p>
<p>Thank you sooo much! I do appreciatte your generosity by sharing .</p>
<p>Thank you!</p>
<p>AWESOME! I am going to test this tomorrow!!!!!!!!!</p>