Thus laser cutting can create extremely complex accurate shapes exactly the way you want them. And very cheaply. A simple rule of thumb is that laser cutting costs 10 cents per inch cut plus the cost of materials. When compared to sawing and machining, this is a real bargain.
Since laser cutting is limited to one dimension, there are a variety of strategies to add the third dimension to your work. These include, bending, rolling, machining and various fastening options such as welding or bolting your parts together. Another option is to make mating tabs and slots for your parts and simply snap your project together.
Looking at the CRKTknife design.
Here is a review of the finished product by Butaangas
Here are some of the design parameters that I considered when creating this knife. Firstly, any knife on today's market needs to be both locking and easily operable with one hand.
In addition to this I have added these criteria to the mix:
Ambidextrous operation. Able to be opened and closed with thick gloves. Easy to clean. Affordable. Absolute minimum of parts and fasteners. Uniqueness, Safety, Lots of Panache and unlike anything on the market.
Another primary desire was to make a very versatile every day carry knife with a focus on outdoor fun activities such as camping and boating. To this end there is a carabiner and bottle opener included.
I was inspired to create this knife after seeing Ed Halligan's KISS knife, and wanted to do the same ultra simple knife only with a side opening mechanism. One of the primary ways that the knife is so utterly simple is that the pivots are intrinsic with the blade and frame, and there are no fasteners between the blade and frame while at the same time firmly locking and easily operated.
Where does laser cutting come in? Well this knife may look simple, but getting all the parts to play nicely together required more iterations than almost any project I have worked on. This involved the fit and finish, the bending of the frame and generally getting the knife to "walk and talk" properly. Fortunately, almost every part was a candidate for laser cutting. Generally, I create a CAD drawing of the part and send it to my cutter along with the metal that I want the parts cut from. Shortly thereafter, beautiful bits of metal arrive in the mail ready to be formed, machined and assembled. Warning: If you make mistakes on your drawing, you will get those as well.
Shown are the Tribanda Knife which features ATS 34 Blade steel and titianium frame and clip, all laser cut parts, below it is a stone set in a laser cut part originally designed as a low torque cog. The second image is of a set of dies for the Multiwrapper a machine I developed for Strawjet. They are cut from 1/2" Aluminum plate.
Step 1: Planning What to Cut
As with most projects, a clear plan of what you want to end up with is always good. Unlike some media, laser cutting will not introduce interesting random anomalies such as you may get with splattered paint. You will get exactly what your drawing describes. Thus you want to do as much of your design work in the computer, as this will allow you to ultimately have the best outcome from your endeavor.
I am not going to attempt to address the whole computerized drawing arena, suffice it to say that there are programs all the way from free to those costing tens of thousands of dollars that you can choose from. Primarily, I recommend a program that is robust enough to create the shapes you want, and can translate into a DXF file, which is the normal machine language for the industry. Be prepared to work with your provider. Like formatting issues with printing, there are similar issues with getting the files to work. Also, put some visible dimensions on the drawing as scaling issues are very common.
What can the laser do. The parts that I am creating require a more powerful cutter than the Hurricane of contest fame. As such, first you need to match the material both type and thickness with the machine available. Lasers can cut very accurately and are primarily a beam directed at 90° to the plane of the workpiece. More sophisticated lasers can cut both angled cuts and 3 dimensional parts, but we won't consider that at this time. Lasers can cut various thicknesses depending on the material to be cut. The thicker the material, the more the kerf irregularity will be an issue. This is the tendency of the burned material to entrain adjacent material as it burns out of the cut. The thicker the metal the more jagged the lower edge of the cut becomes. Thus it is often preferable to laminate an appropriate number of thinner members rather than one thick part. This is especially true if you require very accurate parts. The first image is of a bicycle power take off designed to work with the Multiwrapper shown here in Malawi and here in development
Step 3: Secondary Operations
If you just want a flat sheet or parts that are complete as cut, your done. Alas most creative project require the third dimension, and this is where understanding the techniques for forming and combining laser cut parts can get quite interesting in enabling you to make your dream work a reality. It may make sense for example to print out your parts on paper, and cut them out to see what they do when formed or combined.
Forming: This can be anything from hitting your part with a hammer to creating precise dies to create an exact shape every time. Parts can be bent in more than one place and at any angle. Placing judicious holes and slots can cause a part to "want" to bend in a very specific place. Be careful that this does not weaken the part unintentionally.
Machining. Hopefully, you have designed your part to require a minimum of secondary operations, but milling drilling grinding and other stock removal technologies are all part of what can be done to refine your part to do what you want.
Fastening: My favorite is snap together parts. Not always possible, but tabs and slots are very easy to incorporate into your drawing and require no tools or skills to assemble.
Image one: The Annulus of the multiwrapper, this is a rolled laser cut plate held by two rings also laser cut from 3/4" steel plate, this was the most cost effective way to make this, I used the lathe as a welding jig to insure that the rings were concentric. Giant bobbins and finally some bending and secondary things happened to this one.
Step 4: The Sky Is the Limit: Otic Oasis
This is the work of Gregg Fleishman, who has taken the art of interlocking laser cut art to a level it is difficult to imagine.
He has made sculpture, furniture and even a car body all without fasteners or glue.
Disclaimer: Other than being deeply moved, I had nothing to do with creating this art, but I have ridden in the car depicted.
The Car, the Otic oasis, the view from same.
Step 5: Tools and Materials
The good news, you don't need a laser cutter to get started. There are many excellent shops all over the country willing to burn your parts into reality for a small fee.
You will need a way to create DXF files describing your part. A computer and cad program and the skill to draw are assumed if you want to proceed.
Materials: Lasers like to cut metal, wood, paper and plastic. Of these plastic is the only one with issues arising from the out-gassed toxic material. Better to check with a cutter if you plan on a plastic project.
Beyond this you may or may not need a variety of tools to finish the product.
Image: laminated laser cut tooling for bending titanium knife frames.
For cad drawings I use a mac running windows xp running turbocad.
All parts shown were cut by BBC Steel in Canby, Oregon, I can't recommend them highly enough.
Step 6: Turning Flat Cut Outs Into a Complex Complex Finished Part
Here is a great example of how to turn laser cut parts into a complex part quickly and economically.
The design problem I solved here was how to make the frame for my combination hand tool. This is achieved by using 3 basic shapes, multiplied to a ration of one ring, two formed side plates and four guide parts, combined with silver brazing to form a strong lightweight and striking part. Note that the dashed line forms a bending guide so that the metal forms more easily to where I wanted it to go, rather than the straight line that a bend normally follows. The first image shows the CAD profiles and how they are connected, 2 the finished tool. 3 An earlier version with out the bending dashes closed and 4 open.
Step 7: What Would I Do With a Laser Cutter?
What will I do with a laser when I get it? Give it away! Locally here in Ashland, OR, we have an incredible ScienceWorks museum for kids. I would like to donate the laser to the museum, both to help them with creating their exhibits and provide a program that kids could use to create their own designs in some kind of supervised program where succeeding is easy and fun. Things that come to my mind are: Jig saw puzzles, skeletons and flying gliders. All could be designed so that kids could vary some parameters while the parts still always fit together.
Hopefully this is just what I can think up. I am sure kids will have a million ideas.
Disclaimer: the head of exhibits is my friend.