Tag Archives: diy

Laser upgrades

Back when we opened our workshop, one of our members went nuts and bought a $4000 laser engraver for the space. He very graciously offered to let us all use it if we treated it well and replaced the consumables.

With sporadically heavy use over a year and a half, the poor thing has seen a variety of conditions from pretty okay to painfully broken. We’ve run into many of the same problems seen by other folks who have also learned that there’s really no such thing as a cheap laser cutter.

Our cutter started life as a Jinan Artsign JSM3060U. Sadly it didn’t even survive shipping, and needed a fair amount of debugging and back-and-forth with the vendor just to get it going the first time. Over the course of the last 18 months it has had two new tubes, a new HV power supply, fresh optics, a gantry overhaul, two chillers, two pumps, and extensive rewiring. We even built it its very own room. One of our members started calling it the Laser of Theseus. At this point it’s more like a project than a tool… But having access to a laser cutter is so tremendously useful that it still seems worth all of the cash and attention.

If you go down the path of discount Chinese laser cutters, be prepared to learn this lesson: in the quest for rock-bottom prices, margins get razor-thin so every possible corner has been cut. This includes design decisions that make no apparent sense at all, until you realize that it probably shaved a few cents off of the BOM. Fasteners that have no washers. Tension screws that have no fasteners (or even loc-tite). Wiring that is hopelessly too small gauge (probably copied from a design intended for 220V supplies.) Exposed live wiring. Gantry components that appear to have been hand-filed out of scrap metal and bent into approximately the roughest shape that could still be called “close enough”. And on and on.

One very useful upgrade we recently made was to replace two of the optics holders with actual, professional kinematic mounts. Before the upgrade, we used the stock mounts. These appear to have been designed (and possibly manufactured??!?) by five-year-olds. Here, see for yourself:

Before: cheesy sheet metal mount

Loosen any one of the five rough screws, and the whole mount sags. That goop is loc-tite, which I added after a frustrating hour trying to align these things. It helped, a little. Maybe. Also, notice how the tiny mirror has a ridiculously large aluminum piece covering at least 1/8″ all the way around it? This is what cheap looks like.

We recently replaced two of the mounts with kinematic mirror mounts, mirror holders, and 1″ mirrors from Thorlabs.com. Here’s what they look like installed:

After: real optics mount and bigger mirror!

Alignment time went from over an hour to about ten minutes. The larger mirrors are easy to find, and the fine pitch thumb screws make adjustments trivial. The whole mount is under spring tension, so after you set the position it will not vibrate out of alignment. Little upgrades like this may not seem worth it first, but after the second or third time you find yourself fighting the twisted bits of aluminum scrap that came with your bargain laser, you will wonder why you didn’t install real mounts in the first place.

In short, if you buy a cheap laser expect to spend time and money keeping it eeking along. Having now repaired or redesigned just about every component of this beast I think that my next laser project will likely be a fresh build from the ground-up. At least then I’ll know exactly which corners I cut, and why…

Cell Phone Spectrometer

(or, A Guided Inquiry Approach to Teaching How to Think About Analytical Instrumentation.Wired has a great article about a scientist at the University of Illinois / Urbana-Champaign who published software and plans for turning a cell phone camera into a simple DIY spectrometer.

The camera simply takes a photo, and the resulting JPEG is analyzed by a Windows program. The software and source are available under Creative Commons on the project’s website.

“Science is basically about using your senses to see things – it’s just that we’ve got so much technology that now it’s all hidden,” Scheeline said. “The student gets the impression that a measurement is something that goes on inside a box and it’s completely inaccessible, not understandable – the purview of expert engineers.”

“In order to get across the idea, ‘I can do it, and I can see it, and I can understand it,’ they’ve got to build the instrument themselves,” he added.

This is a fantastic example of how to encourage people to learn by taking a complex idea and breaking it into simple (and fun!) to reproduce steps.