This week I designed and sent off requests for new laser cut cases — one wood sheet from Ponoko, and an acrylic sheet from Pololu.
Material: One surprise for me — I made a slightly bigger case, and adding on 1″ to each dimension roughly doubles the material. For instance, take a 4″ square, that’s 16 square inches of material. A 5″ square is 25 inches of material. This can get out of hand pretty quickly!
Speed: On the recommendation of a friend, I browsed onto Pololu.com, which offers custom laser cutting services. Pololu doesn’t have plywood or bamboo in stock, but they do have 1/4″ acrylic and promise a 3 day turnaround time vs Ponoko’s 11-15 day turn time. Of course, I pay extra for the speed but for prototyping it’s well worth it. I placed my Pololu order on Thursday afternoon and it shipped Friday!
Prototyping: Designing laser cut cases sure can be a pain in the butt. I spent all day on July 4th simply designing a bigger OpenPCR case with bolted edges rather than teethed edges. My workflow goes from the overall design in Google Sketchup, adding features like teeth, bolt holes, nodes, and radii. Then importing that into Illustrator, adding additional teeth, and the submitting it to be cut.
This is fine if you’re putting together a one-off design, but for prototyping, changing, and updating designs I certainly could use some better tools. A good friend of mine has the same issues. If you have any suggestions or experience in converting Sketchup designs to Illustrator for Ponoko/laser cutting, let us know!
Hi Tito,
You can’t beat parametric 3D modelers for doing mechanical design work. However, I’ve found that getting from one of those programs to laser cutting files can be tricky. I’m a hobbyist, and for the price (under $200), Alibre Design is a really good starting point. I do all of my modeling and assemblies there. It’s sort of the mechanical engineer’s equivalent of a software engineer’s compiler. You can mate your 3D parts together, and then rotate it around to ensure that there aren’t any interferences.
What I’ve done so far to get from Alibre to parts off of the Epilog laser is this:
1. design parts in Alibre
2. create engineering drawing in Alibre, then export to DXF
3. import the DXF to Inkscape
4. export from Inkscape as EMF
5. import DXF into CorelDraw and resize so that the dimensions are correct.
It’s a lot of steps, but totally works. I’m building a box with teeth, a la MakerBot, for a simple lab device and I’ll blog about it on my website when the time comes. Email me if you have any questions or need me to try stuff!
Thanks for the comments, Dave. My good friend Mac Cowell recommended Alibre as well, so I’ve signed up for a demo. I’ll let you know how it goes!
Tito
Oops, didn’t realize Alibre was PC only.
Hmmm
Tito
Hi Tito,
Just noticed your comment about delivery time for Ponoko vs. Pololu. Keep in mind that Ponoko is located here in Oakland, and you can pick up piece in person. It’s possible that if you ask them very nicely, you may be able to arrange a same-day turnaround time, providing you’re willing to drive back and forth across the Bay to pick it up yourself.
Something to keep in mind for the future, in case you’re ever stuck for a prototype part to meet a deadline…
Thanks for the tip, Patrik!
Tito
Dave, thanks for the Alibre lasercutting workflow. I have put a lot of hours into learning alibre to design a laser-cut robotic microscope chassis and I’m off to a local laser cutter tomorrow to test the prototype. You workflow will be really useful I think. I’ll be back later to let you know how it works out.
p.s. I still don’t totally think in terms of constraint-based drawing… seems to weird not to be able to drag every vertex or object around. Heh.