In Which Jarrett Builds

I prefer to do most of my laser-cutting purely in 2D. The open-source vector software Inkscape totally rocks my socks off, and I can design things about three times faster using that than anything else.

When a design gets a little complicated, though, or it’s hard to see how everything fits together, it’s sometimes easier to model everything in 3D right from the start. So I built a linear actuator with SolidWorks.

If you can’t see, it’s a DC motor that rotates a threaded rod, with that slider piece in the middle holding a captive nut and a rod. You drive the motor, the rod goes in (or out).

This was just a proof-of-concept to see how it all fit together. I wasn’t really happy with:

• The amount of material it used up
• The physical size
• Way too much friction in the system
• Possible strength issues in the rod
• No way to read or track the rod position.

Solution: Mark II.

• Replace the DC motor with a stepper
• Triangular chassis for less material usage and size
• #10 threaded rod instead of 1/4″, also for size
• Add some bearings
• Triple up the actuator rod.

It’s very slow, but that’s simply a matter of choosing different motors and is acceptable for now.

The bearings I had on hand are standard axial bearings; totally not suited to radial loads. That’s something I’ll have to come back to. I saw a method of laser-cutting the races to make custom thrust bearings recently, I’ll have to see if that’s appropriate for this application.

Terrible picture, will be replaced

Laser-etching is a modern process that effectively carves a 1-bit image onto a material. A lot of very cool images can be made with it, given enough artistic talent. I’m not one of them.
Fortunately, all that heavy lifting has been done for me by artists far more talented than me. In the 16th century (and on), making and selling prints was popular with European artists.

That means that there’s a wealth of royalty-free images out there that lend themselves excellently to laser-etching, simply by googling the term “woodcut.”

Here are a couple things I’ve been doing in the background while designing something else.