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.

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.

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.

A Clockwork…Room Divider

A 6 foot tall, clockwork gear inpired, tri-fold room divider

Hopefully, we can use this as a backdrop for events like the Art Jamboree.

I’ve been toying with the idea of room dividers for a while now. I don’t exactly have use for one, but I think they look neat and it’s basically a blank canvas. Drawing inspiration from my Clockwork Boxes, I decided that a gear motif would best suit the makerspace, thus giving me a new use for the piece: as a backdrop at events we participate in such as Art Jamboree and the various Maker Faires.

A picture of myself, Jason, and Matt, standing around the room divider

There are 3 of us in this photo. Really.

The actual screens were cut out with a large-scale CNC router, while the frame was ripped from 2×4′s, with a dado groove down the center for the screen to slip into. Thanks, Jason H.!!

Assembly went well, although there were a few hiccups.  The drill bit wasn’t long enough, so some minor splitting occurred at a couple of spots. The frame was slightly warped and so needed to be clamped and glued before being screwed together.

After allowing the paint to dry overnight, myself, Matt W., and Jason H. assembled this thing just prior to heading to the Art Jamboree at the Hilton in Milwaukee.

EDIT: I’ve just entered this into the Furniture Contest that Instructables is running. Click the link. Vote. Be thanked. :)

Digi-Comp Making

Digi-Comp II
Photo by Windell Oskay

I love a good blog post! And I really love a good blog post about the process of making things! From selecting the proper wood, to cutting, laser-etching, assembling, and packaging, this blog post has it all. I’m taking about The Making of the Digi-Comp II, First Edition from our friends at Evil Mad Scientist Laboratories.

There’s a great/amusing comment on the post:

When’s the official air date on “How It’s Made”? :D

It’s funny because it is a long and detailed post about the process of making something (disclaimer: I’m a fan of shows like How It’s Made) but I don’t think a maker version of How It’s Made is a bad idea! Hmmm, maybe that’s what the MAKE TV show is going to be.

Snow-Globe Video

Just a minor update here from my recent Snow-Globe blog entry ( http://milwaukeemakerspace.org/2012/12/custom-snow-globe/ )

I made two VIDEOS about the snow-globe. The first is just a brief video showing the finished project. The second video is a longer “How-To” which includes some video, but is mostly a photo slide-show of all the steps I took to create the project.

For an in-depth step-by-step of how I built the project, check out the info I posted on Instructables. http://www.instructables.com/id/Custom-Singing-Snow-Globe/

-Ben

Halloween Skull Project

I want to open my first blog post with a statement that continues to impress me: Milwaukee Makerspace is a wonderful place! I mostly show up for the free meetings.  MMS provides an excellent environment to be social, to learn (happens every time I go!), to teach (when I can!), and to get the creative juices flowing.

I had recently started working with Arduino (after a failed run at Microchip’s PIC series of microcontrollers), and was making progress quickly.  I learned how to read infrared remote control codes, how to use an infrared motion sensor, and how to control servos. What I did not have, was a sense of direction as to where to go with all of this!

After listening to the Bay View Neighborhood Associate pitch their idea of MMS helping with the Pumpkin Pavilion, and listening to Royce Pipkins describe his idea of animatronic pumpkins singing along to a song, I was struck with my own idea: an animatronic skull.

Thus, it was born!

http://vimeo.com/55121596 <- Link to the video

I’ll post more details in a following post about how I built this guy. :)

Many thanks to Royce, Tom G., and Ed C. for their help on this project!

Ho Ho Lights

My Husband and I wanted to put up some kind of Christmas decorations in our apartment windows over looking the city. After talking about it for a while, I decided to make lighted letters saying, “HO HO HO” …but since we only have two pairs of windows, it would have to just be, “HO HO”.

In the wee hours on Black Friday, we got the materials: 4 sheets of wood, 4 boxes of 100 count LED lights, and extension cords. After sketching out the design…

…and cutting out the letters…

…it was time to drill the 400 holes and hot glue all the lights in place.

It only took a weekend to make and hang these and I think the end result is well worth it.

MAHRER CHRERSTMAHS

MegaMax Lives!

The video shows the last few layers of the calibration cube “printing” at 414% speed (according to my LCD display).

The Bucketworks 3D printing meet-up on 8/12 paid off big-time!  Gary Kramlich helped me debug a problem that was preventing me from flashing the firmware on the controller board for the MegaMax 3D printer.  After a few tweaks I was able to get it moving.

Red Lotus Build [Time Lapse Video]

This is a time lapse video of “Red Lotus” the Power Wheels race car that Milwaukee Makerspace built for the 2012 Power Racing Series. Tom Gr. did almost all the work (with some help!) His original plan was to do the whole build in one weekend… It took a little longer, but not much.

We’re looking forward to the 2013 season and have already started planning. I’m going to say this right now: Sector67 and i3Detroit, we’re coming for you!