Successful CT scan processing into 3D printable file

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.

First successful ego print!

First successful ego print!

CT Scan Processing into 3D printable STL files

CT Scan with lower threshold swept

CT Scan with lower threshold swept

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.

Raspberry Pi Project Ended

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.

2013 Annual Member Survey Results!

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

2013survey-reasons

Picture 1 of 2

 

Molding & Casting a Prop Bracer

The mold and final cast part.

The mold and final cast part.

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:

UMR 12 oz.

Alumilite Dye 1 oz. Red

Alumilite Dye 1 oz. Yellow

Mold Putty – 15 2 lb. Lt. Blue

Amazing Clear Cast 2 gal. Kit Clear

Synthetic Clay

 

Other items I used:

PVC Pipe form

A form made out of a 3″ PVC pipe shaped to look like a human arm.

3” Diameter PVC Pipe – Approximately 18” long

3” Diameter Hose Clamp

Plaster Bandages

Vaseline

Disposable Mixing Containers

Stir Sticks

Steel Wire (to hold the mold together)

Syringe

Drinking Straw

 

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.

 

The form and original covered with mold putty.

The form and original covered with mold putty.

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.

 

The mold with half of the mother mold present.

The mold with half of the mother mold present.

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 raw bracer prop as removed from the mold.

The raw bracer prop as removed from the mold.

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.

Hackerspace Challenge 2013

Team Milwaukee Makerspace

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…

Staying Stocked Up

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
  • Propane
  • Soda
  • Duct Tape
  • Painter’s Tape

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

MegaMax 3D printer lives!

After a year’s work designing, building, scrapping, redesigning, building, and working through software and firmware issues, the MegaMax 3D printer is now functional.   It has some common 3D printing issues like printed objects peeling up off the glass printbed.   Tweaked settings in Slic3r, ABS “juice”, and Aquanet hairspray have all been tested with moderate success in attempts to improve adhesion to the printbed.  Finally, have_blue gave me  a block of foam out of the Stratasys printer to try out and it seems to work better than the other methods and doesn’t require heating the bed!  Further experiments to be conducted post-haste.

More info on this project can be found here: http://wiki.milwaukeemakerspace.org/projects/megamax_3d_printer

MegaMax printing on foam from Stratasys printer.

MegaMax printing on foam from Stratasys printer.

Custom Snow Globe

 

Well, I’ve been slaving away on creating a unique X-mas gift for my wife and two-year old daughter, and I think I got it right. They loved it!

I’m talking about a Custom Snow Globe!

A while back, I was working in the driveway on a styrofoam project. Of course, that white stryrofoam dust gets static-charged and STICKS TO EVERYTHING. I also found that the best tool for cutting it was my wife’s kitchen electric carving knife. When I headed inside to take a break and warm up, I was COVERED with styrofoam. My two-year-old girl looked up at me and squeeled “Daddy a Snowman!”.

Indeed I was. I imagined myself inside a snow-globe with styrofoam swirling around me like a snowstorm. But could I actually BUILD a snowglobe that would match my imagination?

I started looking at every snow globe I could find and set to work building one. I looked around and found a glass dome, used for light fixtures. I got two of them, and gave one to my brother-in-law, who is a clay artist, among other things, and commissioned him to make a caricature of me. Since he had one globe, and I had the other, he could make a figure that would fit inside the globe, and I could do the woodworking on the base, and insure that the globe fit that.

I headed to the local cabinet shop and talked to old high-school class-mate Steve about what wood to use for a base. He gave me a maple block, and I grabbed some scrap maple from the bin to practice cuts and routering on. At my Dad’s back-of-the-garage shop, I experimented with routing, until I could get it right, and routed a circle for the base of the glass globe, cut the wood base to length and cut a 45-degree bevel on the top edge, and routed a pocket in the bottom for the electronics.

I wanted to make a “singing” snow-globe, so I bought a singing greeting card at the Hallmark store, and then dissected it for parts. The electronics were then mounted on the bottom of the  wood base, along with a custom switch.

I headed to the Milwaukee Makerspace to use the laser-cutter.

Using the vector graphics program on the laser’s computer, I laid out an inscription for both the top and bottom of the snow globe base. I practiced on a piece of paper, and then when I actually focused the laser properly and had everything else figured out, I wood-burned the maple block, front and back.

I also used a solder station to add the momentary on switch to the greeting card electronics, so that the song would play whenever the globe was picked up to shake up the snow.

Next, was clear-coating the figure and the wood base. I used “Parks Super-Glaze”, a two-part epoxy clear coat used for bars, to completely seal and waterproof both the figure and the base, as well as to permanently attach the figure to the base.

Then, it was a matter to holding the globe upside down, filling it with water, filling the routed circular grove of the base with silicon glue, and flipping the figure and base, upside-down, into the dome of water. Once it was cured, the snow-globe can be flipped right-side-up, gift-wrapped, and put under the tree!

I’m glad to say that the project turned out just great! It was a bit of a stretch to my skill-set, so THANK YOU to the people who gave me a hand with it. Nothing quite like a project that runs the gamut from sculpture to wood-working, electronics, glass, water, laser-engraving, and more! But that’s how we grow… by stretching a little bit more every time!

Merry X-mas

From Ben the Snowman.