With a lot of hard work from Ed H. and Steve P. our 4′ x 8′ CNC router has achieved a milestone, instead of the X axis sitting on the ground it has taken a leap up and is now mounted, ready for the Y and Z axis to be mounted to it along with the electronics and motion control.
Sometimes solving one problem creates a few new ones! As part of the Laser Cutter Room Reconfiguration, the exhaust system got an upgrade. A new, bigger, more powerful fan meant we needed a new way to control it. The previous system (Version 4.0) was a simple on/off switch. That just wasn’t going to cut it for this industrial grade blower. Tom G., Tony W., myself and others spent the holidays installing this new two-horsepower beast above the ceiling in the Craft Lab. Once it was hung from the roof joists with care, Tom got to work ducting it over to the Laser Cutter Room. Finally, when all the heavy lifting had been done and the motor drive had been wired up, all we needed was an enclosure for the switch.
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.
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.
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!
I made a few RTC / LCD clocks and disliked setting the time using an Epoch converter so I found a solution that uses 2 buttons to advance the Hours and Minutes. I substituted toggle switches for the buttons because I didn’t want to have to hold down the button while the Minutes were advancing, thus enabling me to move on to determining how long it is until Spring!.
Today was spent researching all the manipulations involved in getting a CT scan into printable form and I managed to get a print out of it. The process starts with DeVide where the dicom data from the CT scan is processed using a dual threshold, decimation filter, and stl writer. The stl file contains a lot of unwanted stuff, in this case, soft tissues inside my head that add triangles but won’t be seen in the print, so those are removed by applying ambient occlusion followed by selecting and deleting vertices by “quality” (which will be very low values for vertices on the interior of the object). This process invariably blows small holes in the desired surface, so you apply a “close holes” filter to fix that (which closed up the nostrils very nicely). Next you open the stl file in netfabb and rotate and clip unwanted external stuff and apply repairs as necessary. Finally, drag it into slicer and scale it. slice and print.
While investigating software to extract bone data from CT scans and turn it into 3D printable STL files, I played with a CT scan of my own head that was used to treatment plan orthodontics. I have been using DeVide to process the data and finding it is not only easy to use, but a lot of fun!
The animated gif was made by sweeping the lower threshold of a dual threshold module from -800 to 900 in steps of 100 with the upper threshold fixed at 1400. The effect is to strip away the lower density tissues leaving only dense bone at the end of the sweep. I saved the result of each run as a png file then converted to an animated gif using an on-line service.
I’ve really struggled with the Raspberry Pi Project. As I posted earlier, the Raspberry Pi kept killing the file system on the SD card. Pete traded me for a different Pi, which behaved much better, making the card last at least long enough to get the operating system and other software installed. Yet the Raspberry Pi continued to corrupt the file system if left running for longer periods. The latest time it totally killed the SD card; I couldn’t even reformat it on my computer.
If I include the Pi in the traveling mascot, I’m convinced it will not survive the inevitable rough treatment. The only other use I can think of for a Raspberry Pi in a travelling mascot is as a home base server for the mascot, publishing the travelogues. Yet it’s too unstable for even that task.
I still like the idea of a traveling mascot that can track it’s own travels, but I’m convinced that building it around a Raspberry Pi is not the proper foundation. I really like the little GPS unit that came in this kit, and will try to build a scaled down version of the traveling mascot with a USB interface to hook up with any computer for collecting data.
Thanks again Adafruit Industries, we really appreciate the kit, and we’ll continue to work with the parts on other projects. Like vultures, some other members have already picked off some pieces of the kit for their projects.
Feedback and constructive criticism can be great tools for planning and managing any sort of endeavor. Gauging the interests, concerns, and opinions of our group can help us make better decision on how to spend time and money as well as working with each other and the community. Last month we asked our members to take a survey and share their thoughts with us. Why do people come to Milwaukee Makerspace? What do they do here? What would they like to see more of? What can we do better? 44 members responded (or about 39% of the total group) and after spending some time slaving over spreadsheets, we published the results.
Two of the biggest questions we asked survey-takers were: 1) What do you come to Milwaukee Makerspace for? and 2) What is important to you? The following results can be found in our 19 page report, available for download here: http://wiki.milwaukeemakerspace.org/_media/2013_annual_mms_member_survey.pdf
As someone who has gone to GenCon quite a few years and knows several of the GMs of major events, I’ve started getting asked to make props… This year I have decided to expand my experiences in molding and casting in order to make one of the props. The prop requested was a “Bracer that looks like it is made of Amber – part of the shell of an insect”. Thankfully I was afforded quite a bit of creative leeway beyond that.
In the past I have used Smooth-on products, but one of the members of the Makerspace mentioned they were a distributor for Alumilite, so I thought I would give them a try. This was my first experience with most of the Alumilite products.
I ordered the following supplies:
Other items I used:
3” Diameter PVC Pipe – Approximately 18” long
3” Diameter Hose Clamp
Disposable Mixing Containers
Steel Wire (to hold the mold together)
I wanted to make a “generic” bracer that would fit either arm, not a right or left arm bracer, so I didn’t want to do a life cast of my arm first – it would be too specific. Instead I picked up a piece of 3” pvc pipe, cut a section out of most of it (leaving a part connected) and then used a hose clamp to tighten the open end down. It turned into a really good stand-in for a human arm. The shape is close enough that it is recognizable, but is not left or right arm specific. (Note that the screws in the picture were added at a later stage)
Once I had the basic form for the arm, I used the synthetic clay to create the shape of the bracer. I was going for an organic look, so I wanted curves and no sharp edges. The biggest challenge I had was trying to smooth out the sculpt. I still need to figure out the right technique. Sadly, I forgot to take pictures of the sculpted bracer.
Once I had the sculpture complete, I added some screws around the edges as alignment points. I was careful to make sure the heads were close to the PVC so they would not get stuck in the molding material. Then I got to try my first new material – the Mold Putty. I really liked the idea of it – take two parts, hand-mix, then just push it onto the original. It essentially worked exactly that way. I thought the mixed consistency was almost perfect for my application. Unfortunately, the biggest difficulty is being sure not to trap air in it – particularly when placing a second mixed batch next to an already placed batch. I ended up with some imperfections in the final mold because of this. Would I use it again? Yes, but I think I may also try other approaches – either a box and pourable rubber, or brush-on rubber.
Given the way I wanted to cast the bracer – standing vertically – I wanted to make sure that I was able to hold the rubber mold to the arm form well. So, using the plaster bandages, I made a two-part “mother mold” for the rubber mold. First, I coated everything with Vaseline as a release agent, then I covered half of the arm piece with plaster bandaging, making sure the edges were particularly strong, and that the top edge, where I would be creating the second half of the mold, was also quite smooth. After the first half of the mother mold cured, I then coated the edge of the plaster with Vaseline to make sure the other half would not stick to the first half. Once I was done placing the Vaseline, I then coated the other half with plaster bandages.
Once all of the plaster dried, I used a sharpie and drew lines across the edges of the plaster. These lines are so that I could realign them easily after I took the mold apart to remove the original sculpt.
After I removed the original sculpt, I realized I forgot something major… A way to get the resin into the mold. Oops! After a bit of thought, I decided the easiest way to get the resin in would be to drill some holes through the PVC pipe and pour it in that way. Ideally, I would have designed pour holes and vent holes into the original design of the sculpt. Something to remember for the next one! In order to try to control the fluid a bit better, I used straws to extend the holes out. Bendy straws would have been good – I’m not sure how effective straight straws were.
Using the volume of clay from the original sculpt, I did a rough guess at how much resin would be needed to fill the mold (~12oz). I measured out 6oz of each of the two parts, added one drop of red and six drops of yellow to one of them, then mixed it. I used a syringe to suck up the mixed resin and transfer it into the mold. It worked quite well, although it was a bit disconcerting because of the number of bubbles that were exposed during the suction process. Thankfully, as soon as the resin reached normal pressure the bubbles disappeared.
The resin takes 24 hours to cure. 24 hours wondering if it turned out.
And after that full day of waiting, I de-molded it. Quite the pleasant surprise! I think it may have slightly too much red, so I’ll have to correct that for my next iteration. I’m still debating about sanding and buffing it in order to get it to be more glass-like.
Last year it was East vs. West, and this year it’s Milwaukee Makerspace vs. some unsuspecting challenger! That’s right, we’ve been chosen to take part in this year’s Hackerspace Challenge put on by Popular Mechanics and RadioShack!
During the month of July our team will be busy building, uh, something, and we may be a bit hush-hush about it until it’s done, but don’t worry, once completed you’ll see and hear all about it! :)
Oh, and this year’s theme is “Turn something old into something new” which you can imagine we’re going to have quite a bit of fun with…
The idea was simple: make something to help keep track of our supplies so we know when we’re running low on the essentials. After weeks of kicking the idea around and various rough doodles, this project finally took shape. Two days after the first cut on the laser cutter, it was complete.
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
- Duct Tape
- Painter’s Tape
A digital version may or may not be planned for future release.