This post is a continuation from last month’s laser cutting basics. If you’re totally new to the topic, start by reading that post first. This post will cover joinery, some advanced techniques, online resources and an overview of machines.
To me, the most fun thing about laser cutting is being able to make something that I couldn’t make by hand without spending many hours in a wood shop. Finger joints take a long time to set up and cut on a table saw but can be cut by a laser in minutes and made to fit just right. But there are also limitations to the medium---you can only cut on the XY axis, so sometimes you need to get creative when making 3D objects. Once you dive in and start searching though, you'll see what sort of things people have made, and you’ll be amazed by what’s possible. So what are some ways to make multi-dimensional objects using flat planes?
Layering If you need to create any kind of offset or step, or just increase the thickness of your current material, the easiest way to do that is by gluing two layers on top of each other. You can also create all sorts of visual effects by layering pieces of different shapes. It’s basically an entire art form. But just remember you should only glue surface to surface, not edge to edge or edge to surface, because those joints will be very weak! (Photo via @asbcustomdesigns on Instagram)
Finger joints (AKA box joints), mortise and tenon joints, and slotting joints are the most commonly used with laser cut structures, because they’re very simple and sturdy.
Slotted joints are pretty self explanatory. They can be used to create game components that slot into a base or build skeletal structures such as this cardboard rocket (photo via Ponoko).
This dice tower I made uses finger joints in the main structure and mortise and tenon joints for the interior shelves that the dice roll down. Each of the little squares you see on the side is the end of a tenon. In a way, they are very similar to finger joints only instead of slotting together on a corner they go into little holes. You can also create horizontal slots rather than square holes, but make sure they still have a shoulder so that the piece has a stopper and doesn't just slide through.
A note about kerf
When you cut wood with a laser beam, it burns away part of the material, but since it’s cutting in the center of the line you made, your final piece will actually end up slightly smaller than the measurement in your vector file. Therefore, joints will usually end up a little loose unless you compensate for the kerf. For example, if you’re making a slot for a tenon and your material thickness is 3mm, you might want to actually make your slot 2.9mm to compensate for the extra space the laser will burn away. In the case of finger joints, you’ll want to make the spaces a little narrower than the fingers for a snug fit.
Kerf varies by machine, (usually somewhere between 0.08 and 0.15 mm) so for your first sample you’ll need to approximate, and then nail down the exact dimensions from there. Tenths of a millimeter do make a difference, and you’ll really want to find the sweet spot because anything too tight or too loose is no fun to assemble.
This is not something I have personally played around with much, but people have come up with some ingenious ways to create laser cut hinges. The easiest thing is to just make a hole and stick something in there like a machine screw (seen in my laser dice tower) or a dowel with stoppers on the ends. You can also just make a simple hole and slot a piece in there, as was done in this simple but effective box. (photo via Andrew Bosta)
This box has a neat snap closure like a buckle. This is handy but be careful about making those too thin as they can snap off. You can also create a loop instead, and use that to lock it up. (Photo source unknown)
This concept kind of blew my mind when I first encountered it. There are many ways to cut slots or shapes into wood that releases the tension of the material and allows it to bend. This technique can be used to make “living hinges” for boxes and book covers, as well as intricate textile-like surfaces. This box is made out of one flat piece!(Photo via Thingiverse)
How crazy is this thing? (Photo via Instructables)
Online tools and resources
There are definitely more resources if you Google around, but these are my go-tos.
Makercase is a tool that generates box plans with finger joints. You can customize dimensions and make plain, polygonal, or even curved edge boxes. This is a great place to start.
This gear generator is a fantastic way to make mechanisms. It allows you to customize gear setups and even animates their movement for you. Look at this adorable mini trash can! (Photo via UncommonGoods)
Thingiverse has an online community of makers who generously upload their plans for a huge variety of project types. If you're not well-versed with vectors and making plans for 3D objects, this is an excellent resource. After all, it definitely can get complicated! Thingiverse also has 3D models you can download for 3D printers.
Search around on Pinterest or Instagram for laser cut projects. This won't help you make anything but you will find tons of inspiration.
Home laser cutting machines
I’ve been wanting to get a machine for myself for a long time now, but owning one comes with its own challenges, as laser cutters require space, proper ventilation, and maintenance. Do some research and consider all of these factors (where will I put this thing?!) before you go rushing to buy your own.
There are many different types of machines out there and this is a quick overview of what's available. Remember that the higher the wattage, the more powerful the laser is. Weak lasers can basically only be used for engraving. As you go up, some are powerful enough to cut but may need several passes on thicker material, while more powerful laser cutters can cut through almost everything, but industrial ones sometimes have trouble with maintaining small details. Most lasers are set up on a computer the way a printer is---you “print” your file to the laser using a program like AutoCAD or Illustrator and adjust settings such as power and speed in the printer dialogue. Others (like the Glowforge, see below) have their own system for sending information to the printer.
Engravers - if you don’t actually want to do any cutting and just want to make things look nice, you can get a relatively unobtrusive engraver for $150-$300 (but for many of us makers these are pretty useless.)
Orion Motor Tech is a Chinese brand that makes laser cutters in a wide variety of sizes and power levels. These can range anywhere from around $400 to thousands of dollars, and are considered pretty affordable when compared to American made machines such as from Epilog Laser (which are great quality but are priced in the thousands). The downside of not being local means very limited support, and these machines often require a higher technical knowledge (or a lot of research) to maintain. They're not particularly beginner-friendly and I believe they only run with PCs.
Glowforge created something special with its user-friendly home laser cutting systems, but it comes at a cost, ranging from $2500-$6000. The lower end model has decent cutting ability but is relatively slow. If cost is a bigger factor than speed, then that option may be enough, but if you’re doing a lot of cutting then one of the other models may be worth the investment. The nice thing about Glowforge is that it comes with its own interface, which has a lot of useful features like auto-focus, presets for different materials, as well as a camera inside the cutting space which allows you to place your images exactly where you want them on the material. It's certainly pricy compared to the Chinese models but on the other hand the ease of use can save you a lot of time in the long run.
Cubiio currently has their 2nd product on Kickstarter (the campaign ends in a week), which could be an intriguing purchase for those who want to save space and money while have the benefits of user-friendliness. The power is low compared to the Glowforge, so cutting is going to be even slower, but at half the cost and half the space (a Glowforge is about 2’x3’, whereas Cubiio 2's cutting area is limited to a letter sized paper), it may be worth it if you’re going to work on small projects and use it for prototyping rather than mass production. It can be controlled through a web app or tablet and seems to be very beginner-friendly with a good number of useful features. It’s hard to say if the convenience justifies the $1300 investment when you consider the power level (I want speed, damnit!) but it all depends on your level of use.
Do you have any advice or interesting laser cut projects to share?