A few weeks ago a friend asked if I could help with a project for his wife’s new salon and I jumped at the opportunity.  I had been looking for a project that would mean using the big new 100W laser since it was donated.  My friend sent over a design and I got to cutting.

This is by far my favorite laser we have.  The software is easy to use and the laser makes aligning the uncut piece in the laser bed a breeze.  This project was also a chance to show off some of the new things I am learning in Blender to make a nice rendering of the final product.

Often laser cut parts get attached at 90 degree angles, using finger joints, or screws and t-slots, but there may be times when you want to stack pieces of wood and have them aligned…

Pegs might be the answer!

Here’s a few photos of the pegs I’ve been experimenting with. For these pieces I don’t have a lot of room to have multiple pegs at opposing angles, but I can see where that might be useful. For these pieces the peg is really just for assembly alignment when gluing it all together.

You can DL the files here:  http://www.thingiverse.com/thing:454265 and get your pew-pew on!

CAD rendering of the parts

After much thought and a few prototypes I came up with a system that allows a laser to mount on a phone and that assembly to mount on a tripod, a handle, or a telescope.  The tube that holds the laser has adjustment screws to allow the laser to be aligned with the SkyMap on the phone.  It also has to slots that fit over standard gun sight rails.  On one side I have a phone/tablet bracket that has a gunsight rail and slides into the laser tube, and the other side can be used for a rail that mounts on a tripod or a handle.  Extra rails can be mounted on telescope tubes.  I haven’t yet designed a binocular mount, but will soon.

Parts printing on MegaMax

I printed the parts on MegaMax with Octave fluorescent red filament (that’s why the colors vary in the photos- the flash apparently excites the fluorescence in the picture with the handle).   All the parts fit VERY tightly together but I included screw holes for extra security.  The phone/tablet mounts on the bracket using velcro tape.  I think it may be better to print or buy a cheap case to fit the phone than screw it to the phone/tablet bracket.  I’ll be posting the design files to Thingiverse shortly.

Phone and laser mounted on handle

Phone and laser on a tripod

Check out this video of the laser cutter in the middle of cutting 10000 circles!  Note the mysterious logic employed by the laser cutter to determine the order of its cuts.

I imported a photo into GIMP, and desaturated it to produce a black and white image.  After bumping up the contrast and darkening it slightly to nearly saturate the darkest areas (and avoid any totally white areas), I brought it into Inkscape.  Inkscape can create halftones in a two step, manual process.  The first step is to draw an 8 pixel by 8 pixel circle in the upper left corner of the 1133×720 pixel image, and select Edit->Clone-> Create Tiled Clones.  To create a rectangular grid of halftone dots whose sizes are set by the color of the image below, use these settings:

From a quick test cut of a particularly dark area, I found that I needed to add an offset between each row and each column to account for the kerf of the laser.  I.e. the laser beam has a cutting width that is wider than that of the line, and so in the darkest areas of the photo the halftone dots overlapped, causing a large section of the paper to fully detach. That led me to make this test strip with 11 shades of grayscale, evenly spaced between pure black and white.  I laser cut this test strip with various offset distances between the rows and columns in order to arrive at the optimal 10% extra offset between adjacent rows and columns shown in the above settings. Note also that the smallest size circles may not even be exported from Inkscape due to their infinitesimal dimensions (i.e. if you export as a .pdf).  The minimum gap between circles with 42% speed and 100% power on an 1133 pixel wide image blown up to 24″ is 0.79 pixels, which is 0.017″.

Applying these same settings to the image created a 128 by 81 array of circles, for a grand total of 10368 vector objects.  In my first trial run last weekend, I found that sending this much data to our 60 Watt Universal Laser takes 5 minutes and results in a print error I noticed only after hitting start!  After 1.3 hours of vector cutting, I found that a few of the rows and columns were shifted a bit from their intended location.  It’s not clear whether this had to do with the print error, or if the paper moved slightly during the cutting process.

In order to improve the second version (shown at top), I chose to move away from the rectangular grid of halftone dots – recall that Kays and London teach that hexagonal close packing is for champions.  The reason to abandon the rectangular spacing is to improve the dynamic range (i.e. to make the blacks blacker).  For example, rectangular grids of circles pack at an “efficiency” of Pi/4, which is 79%, whereas hexagonal close packing results in a pi/6*sqrt(3) packing, or 91%.  That means that the darkest sections of the image will be darker, as more of the light colored “front” piece of paper can be cut away.  See the image below, and note that the hexagonal pattern does indeed appear darker.

It turns out that Inkscape doesn’t easily permit this.  I ended up spending an hour or two fiddling with the column and row offset settings using my 11 black/white tone test strip to find settings that gave the hexagonal offset with the closest, even hexagonal spacing between adjacent circles.  The following settings worked great for an 8 by 8 dot on the darkest square of the test strip:

I test cut this yesterday, sending ¼ of the data at a time to the laser to avoid printing errors. However, part way through the cutting, cut-out paper circles stuck to the long air assist nozzle of the laser head (ironically) hit a washer I was using to weigh down the paper to prevent movement while cutting. The paper shifted by about 1mm, which was enough to make some adjacent halftone dots overlap and cause others to have a visibly wider spacing.

In the process of cutting that photo, Shane happened by and mentioned that vector cutting 10368 objects may be just as fast as the typically-very-slow raster cutting time.  With three clicks, I turned off the vector outline of the halftone dots, and selected a fill color.  After test cutting a row, I found that he was right.  Check out the difference between raster  (100% speed, 100% power) and vector (42% speed, 100% power) in the darkest section of the image – the area with the closest spaced circles:

The vector halftone dots are perfectly circular, though the edges are a bit rough.  Some of them have a very small border and so are a bit fragile.  The raster halftone dots are not very circular, but the edges are very smooth and the boarders are slightly wider.  I chose to raster cut the 24″ x 18″ image, and found that the raster cutting time of 1.4 hours was nearly equal to the 1.3 hour vector cutting time.

Note that many programs can create halftones, though often the results will not be suitable for laser cutter use:

The next step is to laser cut this image into wood.  Also, Inkscape will let you draw any shape to create tiled clones from – so please do share photos of any halftone images you create with star shapes!

This map was inspired by a project made by my friend NJStacie a while back.  While she has both the infinite patience and the limitless awesome that allowed her to use an X-acto knife to cut out all the city blocks of Boston from an actual map, I used a laser cutter and software. To create images for my roadtrip coasters, I simply took screen captures of google maps, and processed them into vector files using GIMP and Inkscape.  There are so many extraneous details in google maps (lines for buildings, the text labeling street names, etc), that it was clear I needed an alternate approach for making this map.

Its easy to get a small google map without text labels, check out the url of this page.  My first approach to get more than 512×512 pixels was to use the Google Maps API, which is a toolset to imbed an interactive google map into webpages using Java.  The great thing about it is that the rendering style is completely configurable. Even better, there is a GUI to quickly configure your desired style, and automatically generate the JSON object to pass to the style property of the MapOptions on your webpage.  Instead of investing 10 or 15 minutes reading about how to integrate all these steps, I just created the style, and took a few .png screen captures.  I opened them as layers in GIMP and combined them to create the following grey and black image:

I saved it as a .png, and imported it into Inkscape, selecting Embed Upon Import. I created vector data from this raster image by first selecting Path -> Trace Bitmap, opening a dialog box with many choices.  I really only experimented with the top two import choices, Edge Detect and Brightness Cutoff.  I found that Edge Detect gives two outlines, one of the streets and one of the city blocks.  For this reason, Edge Detect seems to be the best choice to create the widest streets, and therefore the strongest paper cutout.  It required some cleanup though, so I selected Path -> Break Apart, adjusted the Fill and Stroke, and then just deleted all the street outlines (thereby widening the spaces between buildings, which is effectively the streets).  As some of the streets were to narrow to really form one continuous outline, they formed a lot of smaller street segments that I deleted in five or ten minutes of fast and furious clicking.  After all those steps, a vector version of the following image was produced:

I did a few test cuts to find a power/speed that cut all the way though some colorful, 98lb, 25″ by 19″ acid-free archival paper I picked up.  The goal is to use enough power to cut though, without using too much power, which widens the kerf (laser cut width), thereby undesirably narrowing the streets.  This ended up being 100% power, with 52% speed. Check out the laser cutter in this real-time (not sped up) video.  Note that one typical problem of having both air assist and super-power fume-removal suction while cutting is that the laser cut bits tend to flip over into the cutting path, potentially resulting in an incomplete cut.  That meant when the laser cutting was complete, I had to carefully punch out the 15 or 20 stubborn city blocks that weren’t completely cut though.

I also cut this design into a coaster, and made one with my old Massachusetts neighborhood too.  Naturally this was a lot of data on a small surface, but the results are pretty good despite the vector cutting time approaching that of the raster cutting time! I cut these at 100% power, 100% speed, like the other coasters.

After I completed all these steps, I learned about a way to access vector map data directly.  The Open Street Map site allows export of .svg vector data just by clicking the share button on the right side of the page!  Even better, one can zoom in to Milwaukee, and press the big green Export button on the upper left to export an .osm database of the visible section of the map.  This OpenStreetMap archive can be opened in Maperative! and a style can be applied to the rendered map.  Maperative has several styles built-in, and I simply edited the google maps-like style to omit all the buildings, and draw all roads, highways, on-ramps, etc in a black with no border.  Maperative can export .svg files, but I found the content of these files are a bit of a wreck.  For example, each different road type is a separate vector path, meaning that there are many separate paths in the file.  Ultimately I found I’d taken the wrong approach, as I should have rendered all the city blocks as black vector outlines, and omitted the roads – as that is what I really need to laser cut.  With a bit more work, using Maperative would likely be a quite quick path from map to laser cutter. However, I abandoned this approach as I’d already created a somewhat reasonable workflow.

As I don’t use OpenPaths, I used Google maps to plot the course of past road trips, and simply took screen captures.  I wanted to create vector images with hairline width (0.001″) lines so the laser cutter can make each coaster in 45 seconds instead of 20 minutes. There are many ways to generate vector data using these raster .png images. I chose to semi-manually edit out unnecessary parts of the images using GIMP, and then used Inkscape to extract vector data from the resulting simplified images.  If you’re new to these tools, just search for “Inkscape raster to vector” tutorial videos.  An alternate approach is to just import the raster image into Inkscape, and use the Bézier line tool to trace the important paths.  Yes it is manual, but this alternate method also only takes 5 minutes to complete.

The coasters are cut from 3/16″ 4″ x 24″ solid basswood using fairly standard settings of 100% power, with 100% speed for etching, and 3.5% speed for cutting.

I made quite a few coasters, and above is a photo of three of them. The coaster on top is a rail trip through Italy, the second is a 1000 km, 12 day (right hand) drive through Ireland, and the last is a much longer than 12 day road trip through the southwest – note the vertical and horizontal lines are the state borders of NV/NM/CO/UT.

A few days later, after polishing my vector editing skills in Inkscape, I made an improved version of the above three coasters.  I added circles to more clearly highlight each stop, and I etched the names of each stop on the reverse side of each coaster.  One group of raster to vector settings I used in Inkscape resulted in the creation of two sets of (closely spaced) hairlines for the outline of Italy, as shown in the coaster above.  I really liked how distinct the outline of Italy is relative to the path of the trip.  I chose to intentionally create two offset hairlines for the other country or border outlines, using Inkscape’s linked-offset path command.

Check out the new and improved design of the front, with dual country/border outlines and circles to denote the stops:

Check out the reverse sides of these coasters shown below, with names of each stop etched on them. Albuquerque.

The request went out on the message board. Pete P., Shane T., and I all expressed interest, but life got in the way and it soon became a matter of whomever got to it first would be the one to make it. I ended up devoting the better part of last weekend to this project (much more time than I anticipated) but I can honestly say I’m pretty happy with the result.

The goal was fairly straight-forward: make an enclosure for the switch Tom had already provided. It was a color-coded, 4-button, mechanical switch that had been wired to provide four settings: OFF, LOW, MEDIUM, and HIGH. The more laser cutters in use, the more air you’d need and the higher the setting you should choose. There’s four duct connections available for the three laser cutters we currently have.

There’s a saying: “Better is the enemy of done.” Truer words have never been spoken in a makerspace.

At first I wanted to build the enclosure out of acrylic. Then I remembered this awesome plastic bending technique that Tony W. and some others told me about. I found a video on the Tested website and got inspired. (If you don’t know about Tested, please go check it out. You’ll thank me later.) Unfortunately, my bends kept breaking and melting through, so after a few hours of tinkering I moved on.

Thankfully, we have a small cache of plastic and metal project enclosures on our our Hack Rack. I managed to find a clear plastic, vandal-proof thermostat guard. It looked workable.

I tried laser cutting it, but the moment I saw the plastic yellow and smoke, I knew there was probably some nasty, toxic stuff in it, so I moved to the CNC router. About an hour later I had my holes cut.

Then came the wiring. Up until this point I had been focused on the control box itself. Now I wanted to add a light!

No, two lights! Yeah!

One light to tell you when everything was off, and another that lit whenever the fan was in use. People could look at the lights from outside the room and instantly know if the fan had been left on. (It should be noted that the new fan, despite being twice as powerful than our last, is actually much quieter. Tom added a homemade muffler to the inlet of the blower and shrouded the whole contraption in 3″ fiberglass batt insulation. The best way to know if the fan is running is to open a slide gate damper and hear air being sucked in.)

OK, I totally got this.

Draw myself a ladder diagram and get out the wire connectors… Remember that I need to isolate the signals from each other so any button doesn’t call for 100% fan… A few more relays… Some testing… and done!

Wait a second… the motor drive doesn’t have a ground for the control signal.

Hmm.

Guess I can’t power it from the drive. I’ll just tie into the drive’s ground. Nope, that didn’t work.

I’ll read the motor drive manual. OK, it has a set of “run status” contacts I can monitor.
….and they’re putting out a steady 0.4 volts DC. That’s enough to light up a single LED! …except, no. It’s not lighting. Doesn’t seem to be any real current.

I’ll just use a transistor! That’s the whole point of a transistor!
….well nothing I tried worked.

I’ll build a voltage multiplier circuit!
….and this isn’t working either.

On Day 3 of this “little project” Ron B. made a comment about using a pressure switch of some kind.

Wait.

We have a Hack Rack full of junk and I know there’s this old bunch of gas furnace parts. It couldn’t be that easy…

Yeah. So, three days (and a few frustrating epiphanies) later, this all came together. Press the beige button, get some air. Press the other buttons, get some more air. Any time there’s suction, the red light comes on. The indicator light is powered by its own 24 volt DC wall pack. The pressure switch has both normally open (N.O.) and normally closed (N.C.) contacts so it would be totally feasible to add another light at some point. The controller could display “OFF” or “SAFE” or whatever as well as “ON” or “FAN IN USE” or whatever. The text is just a red piece of paper with words printed on it, then holes laser-cut out to fit. We can trade it out with different words or graphics if we ever feel the need. I was just glad to have it done, so I called it. Better is the enemy of done, indeed.

You can learn more about the evolution of our laser cutter venting system on our wiki!

Made from multiple layers of acrylic, cardboard, and wood, the “Milwaukee Makerspace Consumables Super Analog Status Board” is a clipboard-sized device with nine sliders installed in enclosed slots.  Sliding the tabs right displays more green to indicate “full” or “lots” and sliding left reveals the red acrylic below to indicate “empty” or “low.”  The user can carry the board around the Space with them as they check on supplies and when done, a large hole centered at the top allows the board to be hung up and displayed on a wall.

The hardware holding the whole thing together can be loosened and the layers disassembled.  The cardboard insert that the text resides on can be swapped out should we decide to change the list of items we want to keep tabs on.  The supplies being tracked currently include:

• Toilet Paper
• Paper Towels
• Hand Soap
• Welding Gases
• Welding Wire
• Propane
• Soda
• Duct Tape
• Painter’s Tape

A digital version may or may not be planned for future release.