How to Make a Vacuum Former

First, a huge thank you to Airship Noir and their Maker Faire Kansas City 2016 project, “Make Your Own Vacuum Formed Steampunk Goggles.”  They were kind enough to post pictures and instructions about how they made an incredibly cheap, but effective, vacuum former.

Inspired by their project, I wanted to pay-it-forward and help others build their own vacuum former.  Here’s how I built mine:

  1. Parts

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    1. Home Depot “Bucket Head” ($23)
      1. I had no idea this thing existed until I saw Airship Noir’s post.  It’s basically a vacuum that clamps onto a bucket, turning it into a cheap low-power shop vac.  I believe “Bucket Head” is the Home Depot branding for this, but that you can find alternates under the title of “Power Head.”
    2. 5 Gallon Bucket ($5)
      1. I bought a Home Depot brand bucket for this exact task.  Although I have other 5 gallon buckets, it was worth the $5 to me to make sure I had something that would easily attach and detach from the vacuum top.
    3. 1/2″ wooden dowel, 4′ in length ($2)
      1. My own design uses 3D printed parts, a length of a 1/2″ wooden dowel, and a little hot glue.  However, you can substitute whatever you have on hand.  The Airship Noir vacuum former used wood shims, some nuts and bolts, and PVC pipe.
  2. Tools
    1. Chisel
    2. Drill and 1/8″ drill bit
    3. Hot glue gun / hot glue
    4. Ruler
    5. Pen / pencil
    6. Hacksaw
    7. Sharpie
    8. Masking tape
  3. 3D Print Parts

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    1. You can download all the 3D printable parts from Thingiverse.
    2. Print one vacuum cork.  This will just be placed into the vacuum where the hose would normally go.  This will cause the vacuum to suck air through the bottom of the bucket.
    3. Print two dowel caps.  These will go on either end of a short length of wooden dowel, to keep the “float” inside the vacuum from falling into the vacuum.
    4. Print three bucket attachments and three “toes.”  These will be used, with wooden dowels to elevate the bucket off the ground.
    5. Print the PDF of a 1″ grid on paper.  This is actually a 1/2″ grid, with bold lines forming the 1″ grid.  I searched for more information about optimal hole size and placement, but didn’t find anything dispositive.  I think as long as you get close, you’ll be fine.
  4. Cut Wooden Dowels
    1. Use the hacksaw to cut three pieces of wooden dowel to approximately 8″ each.  These will become the feet for the bucket.
    2. Cut a fourth piece of wooden dowel to approximately 6″.  This will be used to keep the vacuum float from falling into the vacuum, when the bucket is turned upside down.
  5. Prepare the Bucket

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    1. Turn the bucket upside down and, carefully, use a chisel to remove as much of the raised areas at the bottom of the bucket.  Working slowly and carefully, it took me about 30 minutes to move the rim at the bottom of the bucket and all the little raised areas.
  6. Add Feet to the Bucket

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    1. When the “Bucket Head” attachment is on the bucket, the top will be rounded.  However, we’re going to need to turn the entire thing upside down to use the bottom of the bucket as the surface of our vacuum former.  This means we’ll need to raise the vacuum top of the bucket off the ground so that it can stand flat – and so we can access the power switch.
    2. I designed the three bucket attachment parts so that they will slide snugly into the rim under the bucket.  The rim has approximately 24 little fins under the rim.  Place each of the three feet equally around the bucket – approximately 8 fins apart.  Mark the outline of the part on the bucket with a Sharpie, remove the part, add hot glue, and slide the part back into place.
    3. Add a little hot glue to the end of each of the three 8″ wooden dowels, then some hot glue to the inside of the “toes,” then slide the gluey end of the dowel into the feet.  You should end up with three short “drumsticks.”
    4. Don’t glue these into the attachments at the bucket sides.  The attachment and bucket feet parts were designed to be as minimally obtrusive to the function of the bucket as possible.  If placed properly, they shouldn’t interfere with the handle or bucket usage.  The newly formed feet can be placed into the holes in the bucket attachments when you’re ready to start vacuum forming – and placed back inside the bucket for easy storage.
  7. Drill Holes

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    1. Print the PDF of 1″ ruled grid paper from the Thingiverse page, courtesy of Kent State.  Center the paper on the bucket, then tape it down.
    2. Drill 1/8″ holes 1″ apart along the grid.
    3. A word about these holes.  The more holes you drill, the more holes you might have to cover up when making parts later.  However, the more holes you drill now, the bigger the parts you can make later.  It’s a little bit of a trade off.
    4. Once the holes are drilled, use the chisel to remove the burrs off the bottom of the bucket.  You don’t need to remove the burrs from the inside of the bucket, but I did to keep the inside of the bucket as clean and useful as possible.
  8. Raise the Float

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    1. Underneath the vacuum top there is a plastic cage surrounded by the filter, held in place by a big rubber band.  Remove the rubber band and filter and you’ll see a little plastic cup that is designed to act as a “float” inside the cage.  If you turn the vacuum upside down, the float will fall against the vacuum – and would prevent it from working.
    2. Holding the vacuum upright, insert the 6″ length of wooden dowel through the plastic cage and above the float, pushing it against the bottom of the cage.  Use the plastic dowel caps to hold the ends of the dowel in place so it won’t slip out or rattle.
  9. Completed bucket vacuum former!

    Completed bucket vacuum former!

    Put it All Together

    1. Place the Bucket Head on the bucket.  You may need to rotate the Bucket Head slightly to make sure you can insert the feet into the plastic parts glued to the sides of the bucket.
    2. Insert the feet into the holes in the bucket attachment parts.
    3. Invert the bucket and you’re done!

I’ll do another post soon about how to actually use the device.  If you’ve read the Airship Noir post, you know the basic steps are to place things on the bottom of the bucket, heat a plastic plate with a toaster oven, and lower the heated plate over the things you want to mold while the vacuum is one.

Paper Circuits: The Adventure Begins

While I’m a big fan of paper and circuits, I’ve never really given paper circuits/circuitry a shot.  Unfortunately, I have no good excuse for this.  (Fair warning:  I’ve been collecting links and ideas on this topic for several weeks now, and even though I intend to break up the post into more manageable chunks, I have a feeling this is going to be a doozy)

1. TapeTricity

Years ago Chris Connors, a STEAM educator/maker and friend, had posted some photos and videos about something called, “TapeTricity” and helped hundreds of kids as young as 3 and 4 years old build their very first circuit at Maker Faire 2013.  TapeTricity is all about making electronics accessible to people by showing them how to make real circuits using cheap and common components while removing the need for specialized tools and materials.  This system of designing circuits made use of several very interesting innovations: aluminum HVAC tape and paperclips along the edges to form electrical contacts.

1. Aluminum HVAC Tape – Benefits and Limitations

Back in 2013 copper tape was reasonably common in artistic settings for use with soldering stain glass.  However, the copper tape wasn’t readily available with conductive adhesive and tended to be more expensive than the aluminum HVAC tape used in Chris’ projects.  While the prices of copper tape with conductive adhesive have fallen over the last few years and conductive inks/paints have become more common, pretty much nothing is going to beat aluminum HVAC tape for price per project.  However, HVAC tape is not without its limitations.  The adhesive is a decent insulator rather than a conductor, the tape only comes in strips about 2 inches wide and must be torn or cut to much thinner strips, and has a tendency to curl at torn edges, and aluminum tape does not take solder well.1 I expect that the non-insulation properties of the underside of the aluminum tape could actually be very useful in conjunction with copper tape – to essentially make for circuit board traces that can cross over one another.

2. Taped Edges – Contact Points

TapeTricity components

As you can see from some of the photos above, the edges of the cards had foil tape wrapped over some edges which were then connected to some of the components.  The result is that the edges of the paper essentially become functional I/O pins.  The nifty thing about this is that it could allow TapeTricity cards to be wired/rewired/networked together.

3. Paperclips – Alternatives to Alligator Clips

Another interesting feature of TapeTricity comes from the use of paperclips.  Paperclips are ubiquitous and cheap23 and, with a little bit of wire, become cheap DIY alligator clips replacements.  While individual alligator clips aren’t that expensive (let’s say around $0.25 each?), the cost of providing a number of them to a room full of students would quickly add up.

These TapeTricity cards allowed kids to color and draw on one side of an index card – then bring their designs to life with electronics on the back and through the card.

4. Lessons from TapeTricity

  • HVAC tape is a great choice for paper electronics with a few limitations.  The adhesive is an insulator which allows HVAC tape to be leveraged in bridges and there aren’t easy ways to solder to it.
  • Edge conductive pads from HVAC tape allow for cards to be powered or networked
  • Paperclips and wire are a great cheap DIY alternative to alligator clips

2. Evil Mad Scientist Labs and Paper Electronics

Evil Mad Scientist Labs is one of my all time favorite open source arts/electronics designers/manufacturers ever.  Not only do they enable other people to realize their plans for world domination, they’re pretty cool people.  I had the good fortune to be able to visit Evil Mad Scientist Labs (now celebrating their 10th birthday!) a few years ago.

1. One Sided Circuit Board – paper, conductive ink, and soldering

Mobius Circuit - 21

While there Windell Oskay and Lenore Edman gave me a tour and showed off their awesome single sided mobiüs circuit board.4

2. Electronic Origami – several methods for electrifying paper

toner - 15

More recently, while researching for this blog post I discovered their simpler, but perhaps more spectacular, origami balloon circuit.  EMSL posted several possible methods for electrifying paper.  Since the post explains each of these methods in detail, I’ll only list them:

  • Using dry mount adhesive to glue aluminum foil to paper
  • Using an iron to fuse aluminum foil to freezer paper
  • Using an iron to fuse aluminum foil to the toner on laser printed paper
  • Lessons on resistors and simple LED/battery combinations inspired by LED throwies

This circuit is beautiful and eerily reminiscent of a certain other cube.  If someone hasn’t made an origami LED paper circuitry companion cube, well, this is just a thing that needs to exist in the universe.

3. Edge-Lit Cards

EdgeLitCard - 31

Another particularly cool post from EMSL is their piece on edge lit holiday cards.  The electronics are essentially the same as a simple throwie or TapeTricity circuit, but the use of scored sheets of plastic allow incredibly interesting display possibilities.

4. Lessons from EMSL

In no particular order, here are some of the lessons I’ve learned from EMSL:

  • The conductive ink in the mobiüs circuit has enough resistance that the LED’s don’t really require actual resistors
  • Electronic paper projects need not be merely two-dimensional and adding a third dimension can be truly transformative
  • Scored or scratched plastic plus paper and carefully designed LED circuits can create amazing display possibilities

3. Paper Circuits / Paper Circuitry / Electronic Notebook

Just before Maker Faire 2016 I saw a tweet from Jeannine Huffman showing off her development of a paper circuitry robot panda which would cost about $5 per student.

I was astounded by what Jeannine was doing.  Where TapeTricity was a great way to introduce kids to electronics, making those same electronics smart by adding a microcontroller could make those same pages smart and interactive.  Moreover, a TapeTricity project could be “leveled” up by just wiring the aluminum contact pads to a microcontroller.

1. Jeannine Huffman’s Notebook

I was fortunate enough to be able to catch up with Jeannine at Maker Faire Bay Area 2016 this year and we compared notebooks.  Here’s some pictures of her work:

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I regret that I didn’t take more pictures of Jeannine’s notebook, she’s been kind enough to post much of her designs on her website, her Twitter account, her Google Plus page, and in the 21st Century Notebooking Google Plus community.

2. Lessons from Jeannine Huffman

To just jot down some of the problem solving and ideas I noticed in the few moments when we compared notebooks:

  • Mixing off the shelf electronic components and circuit stickers with conductive ink, copper tape, and soldering
  • Incorporating electronic components, sensors, and microcontrollers with DIY sensors, switches, and other solutions
  • Melding a notebook and electronics – by sketching in, around, and through circuits to provide annotations and instructions
  • Finding a way to create a copper tape hinge that could survive repeated opening and closing of the notebook

4. 21st Century Notebooking

The ideas shared in the 21st Century Notebooking Google Plus community are just too numerous for me to do justice.  Since my blog posts are as much about me documenting my own discoveries as it is about sharing with you, gentle reader, perhaps you’ll forgive my jotting down just a few of the ideas found within a 30 second scan of this community:

  1. Paper electronics with mixed media arts crafts
  2. Paper electronics mixed with origami
  3. From +Jie Qi and @Chibitronics:
    1. Conductive fabric to create conductive hinges for use in circuits spanning more than one page in a notebook
    2. Light up paper helicopters
    3. Copper tape paper speakers
    4. UPDATE 10/26/2016: Jie Qi’s “paper-based electronics for creative expression” tutorials have some really great ideas for getting started with paper circuitry.  Frankly, this is to be expected from the lady who created Chibitronics and circuit stickers.  :)  These tutorials are great – and you can see exactly how she refined these ideas to become circuit stickers and the kind of skill building projects seen in Chibitronics books.  These tutorials include:
      1. basic circuits,
      2. paper battery holder,
      3. parallel circuits, soldering,
      4. making switches,
      5. blinking LED’s,
      6. pressure sensors,
      7. basic programming,
      8. fading program,
      9. blinking program,
      10. random program,
      11. sequence program,
      12. and a microphone program!

5. Project Daffodil (Update 10/26/2016)

Project Daffodil is the work of Sian Geraghty, Robert Foster, and Christine Ho as their graduate thesis project for the Masters in Multimedia Program at CSUEB.  Their project combines pop-up books, paper circuitry techniques, and 3D printing to provide an interesting introduction to electronics for kids.  When I saw them at Mini Maker Faire Rocklin on 10/5/2016 they had combined their work with an iPad app which could interact with some of their 3D printed models infused with conductive material.  They’ve been interviewed on the Make Magazine website and published a tutorial on building pop up paper crafts with electronics.

1. Lessons from 21st Century Notebooking, Circuit Stickers, and Project Daffodil

I think what I learned most out of these projects is that there’s a lot of ways to combine paper circuitry with other interesting and creative ideas like origami, paper crafts, greeting cards, pop up books, and 3D printing.

6. What’s Next???

Smart sketchbooks, electronic origami, and the ability to program anything.  With all these incredible designs, pieces of code, and ideas – where can we go next?

Well, I have a few ideas…

  1. When I googled “how to solder copper wire to aluminum foil” the top result was a YouTube video which suggested applying a thin layer of oil to the foil, using a soldering iron with solder to heat up the foil, with the oil supposedly preventing the aluminum from oxidizing, then the wire could be soldered to the foil. []
  2. Or free when you are at a Kinko’s []
  3. Perhaps the better phrase is “complimentary”? []
  4. I hope you will, once again, forgive me as I present these items in the order of my discovery, rather than chronological order? []

XY-Plotter Robot Kit v2.0 Unboxing

The crew over at Makeblock.cc were kind enough to send an XY-Plotter Robot Kit v2.0 my way for a review.  I’ll be assembling the the robot and posting pictures of the process soon, but for now I wanted to do an unboxing preview for you.

1. The Box

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The first step to any unboxing review must, necessarily, start with the box in which the product arrives.  The box arrived safe and sound from China and was well packaged for transport.  Most parts were wrapped in plastic, the electronics were in anti-static bags, and the boxes were nestled in thick foam padding.  The blue anodized aluminum beams were mostly not wrapped in anything.  There were no noticeable scratches on any of them.  I did find a few blue anodized aluminum burrs from the parts in the box.  Keep an eye out for them if you’re opening the package on carpet, as I did.

2. The Electronics

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Above are the pictures of electronics.  As mentioned earlier, each board arrived in its own little anti-static baggie.  The card with the QR code to the instructions and rubber feet were a nice touch.  At this point you’ll notice that the connector ports on all of the boards have colored coded stickers to assist with assembly.  Clockwise starting at the top left corner, the box includes the card with the QR code to the instructions, three Me RJ25 Adapters, two Me Steper Driver v1.0 boards, an Me Baseboard, and four sticky-backed rubber feet.

3. The Tools

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Clockwise starting at the top left corner, the box includes RJ25 cables, a USB micro cable, three timing belts, three micro switch buttons, three lasercut acrylic “LS” brackets for the micro switches, 11 tiny screws, one lasercut acrylic “servo bracket,” another RJ25 cable, a small Philips screwdriver, a 2.5mm hex screwdriver, a 7mm wrench, two 1.5mm hex wrenches, a Micro Servo, a lasercut acrylic “Baseboard,” and one Beam 0808 72/80 aluminum beam.

4. The Hardware

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There are a lot of hardware parts in the main cardboard box:

  1. Shafts
    1. 2x D shafts, 4 x 56mm
    2. 1x linear motion shaft, D4 x 80mm
    3. 1x threaded shaft, 4 x 39mm
  2. Flexible coupling, 4 x 4mm
  3. 6x timing pulleys 18T
  4. 8x flange bearing, 4 x 8 x 3mm
  5. 43x M4 nuts
  6. 25x plastic ring, 4 x 7 x 2mm
  7. 6x cutable linkage 3, anodized blue aluminum
  8. 6x linear motion slide unit, 8mm
  9. Beams
    1. 4x Beam 0824 48
    2. 1x Beam 0824 80
    3. 4x Beam 0824 96
    4. 2x Beam 0824 112
  10. 2x 42BYG Stepper Motor Bracket
  11. 2x bracket, 3 x 3
  12. 4x plate, 3 x 6
  13. 5x bracket, U1
  14. 3x belt connector
  15. 1x Beam 0828 16
  16. 1x 42BYG Stepper Motor
  17. 12V DC power adapter
  18. 1x 42BYG Stepper Motor
  19. 31x socket cap screw, M4 x 14
  20. 28x headless set screw, M3 x 5
  21. 28x socket cap screw, M4 x 16
  22. 6x plastic rivets R4100
  23. 18x plastic rivets R4060
  24. 10x shaft collar, 4mm
  25. 18x socket cap screw, M4 x 30
  26. 12x socket cap screw, M4 x 22
  27. 30x plastic zip ties and 5x rubber bands
  28. 36x socket cap screw, M4 x 8
  29. 3x cross recessed pan head screw, M2×10 and 3x M2 nuts
  30. 10x countersunk screw, M3x8

The last picture in the set depicts all the really long pieces of the robot – the linear shafts and beams.  In order, from top to bottom, they are:

  1. 2x Beam 2424-504
  2. 2x Beam 0824 496
  3. 4x linear motion shaft, D8 x 496mm
  4.  1x linear motion shaft, D4 x 512mm
XY-Plotter Robot Kit v2.0 Review
  1. XY-Plotter Robot Kit v2.0 Unboxing

Disclaimer:  This robot kit was provided by Makeblock.cc for the purposes of unboxing and review.  They have asked that I provide my honest assessment of this kit.

Printable Prosthetics: Brainstorming

An illustrative hand

An illustrative hand

My overall designs for a printable parametric hand are still far from done.  And, yet, I’ve come a long long way since jumping headfirst into the realm of open source prosthetics a little more than 30 days ago.12

Forgive the digression, dear reader, before I return you to considerations of prosthetics. After visiting the Asian Art Museum today with the family, I am feeling particularly inspired to discuss dualities.3 I find I am an often-inspired person. This is a very charitable way to describe myself by what would otherwise colloquially and clinically be considered ADHD. When I am inspired by a new topic, I tend to jump right into it – reading voraciously and trying to learn as much about it as I can. When this happens, I also tend to set aside whatever thing I was most recently working on. This means that recently I’ve done little work on drawing robots (big and small) and a multitude of other small projects that would otherwise be just amazing. However, such inspirations/distractions are not only external to a project – but can also be very much internal to a project. Consider, for instance, feature creep – the adding of ever more features to a project, usually at a faster rate than which features are resolved and refined. In order to combat this aspect of my nature, the wanting to add more and better features, I have developed a coping mechanism. To prevent myself from falling down the rabbit hole of features and improvements, I jot them down someplace – either in a blog post4 , in an email to myself, or in a notebook.5 I find that once I’ve externalized and memorialized an idea, I can continue working on a project unfettered and undistracted these other ideas.

To this end, and in the spirit of open source ideals, I will jot down some ideas while I have them:

  • How large and how small are prosthetic designs typically scaled?
    • I wanted to have a range of sizes for which my designs were optimized.  My guess would be no smaller than 85% and not much more than 160% of the size of the existing  Cyborg Beast.  Jorge Zuniga was, again, patient enough to discuss this with me.  His estimate of a range would be between about 105 – 150%.
  • What is the diameter of the Chicago Screws typically used in the creation of a Cyborg Beast?
    • From the retailer’s website, it appears the “barrel” diameter is 0.2 inches, or 5.08mm.  I’ll need to make some adjustments to holes for the Chicago Screws in the designs.
  • How important is hyperextension of these fingers?
    • The designs of the Cyborg Beast include fingers that can bend “backwards” very slightly.  Each finger joint includes a “stop” at the back of the joint.  While certainly useful, I question their necessity.  I previously designed a connection system for printable snap-fit parts ((For use in an equally noble project)) that connect very tightly and/or bend with a user specified degree of movement.  The point with me mentioning these parts is that the “stop” used at the back of each knuckle and joint in the Cyborg Beast may not be necessary at all.
  • How necessary are metal Chicago Screws to strength and durability of the hand and fingers?  
    • Before you laugh, consider this question – what is the weakest point of any given finger which uses a metal Chicago Screw when having to deal with lateral forces?  I would postulate the weakest points would be those thin plastic parts surrounding the Chicago Screws themselves.  Thus, even though the hand incorporates metal pins, I have to wonder just how much strength they are providing to the overall device.  It would be easy to conceive of a plastic prosthetic hand that was so small that there wasn’t a lot of plastic around each metal screw6.  In such a case, the weakest points would be plastic surrounding the metal parts.  Extending this conjecture, of what use are metal fasteners to a design that is primarily plastic?  The best guess I can offer is that they allow reliable and smooth operation.
  • Work on proportional fingers
    • In designing the fingers, I worked to be able to make them customizable in several different ways.  The user may specify whether the fingers have the “star grip” pads, whether the finger should be slightly shorter or longer, and scale the finger up or down – without distortion to the hardware and cord channels.
    • I need to add at least three additional options to these parametric designs.  The designs should include the option to add “mouse ears” and easily removable support structures.  Additionally, the design should also allow the user to change the diameter of the finger.  I did implement this, somewhat, in part of the design.  Without implementation throughout the entire design, these partial attempts aren’t helpful.
    • In creating the fingers shown above, I adjusted their lengths to conform to the measurements of my own hand.7 Next time, I think I would also measure finger diameters.
    • I think I should create a way to prevent finger parts from being mixed up accidentally while printing.  A possible solution is to include “mouse ears” with each finger – but embed an identifying mark in each mouse ear to label the parts.
  • Ideas on making a better parametric palm
    • The palm should be redesigned so that the fingers, at the appropriate lengths, would fit into it.  I designed the fingers quite a while since working on the palm.  I haven’t had a chance to ensure the parts would mesh well without adjustment to the scale.
    • On an entirely different note, I have an idea to redesign the entire palm.  By carefully placing deformed spheres, I was able to design a palm.  Using a similar process, I subtracted out a void for the user’s hand.  The result is a palm with an uneven thickness throughout.  Uniform thickness isn’t necessarily an interesting or useful goal.  That said, it could lead to a reduction in unnecessary plastic.  If I were to redesign the palm, I could design the internal area first8 – and then use the “Minkowski” function to create a uniformly thick shell around the internal form.  The bottom would have to be sliced off and the original internal area would need to be subtracted from it.
  • Ideas on making a more realistic hand
    • My designs so far are based primarily on the Cyborg Beast, with some minor changes.  The “Flexy-Handappears to be very organic and realistic.  It also features flexible printed connections between each finger segment.  Additionally, each finger is comprised of three segments – rather than two like the Cyborg Beast.  Interestingly, since the flexible connections between segments allows the hand to return to an “open” position, the hand only requires five tension cords – rather than five tension cords and five elastic cords.  The fingers appear to not have any “stops” behind each joint.  I have to wonder how having three segments to each finger impacts the function.  Does it allow the hand to better grip things?  Does it make the hand less sturdy?
  • Masculine/Feminine hands
    • One well-intentioned comment to my latest designs is that they are “pretty.”9 While I accept the compliment with the spirit in which it was given, it immediately made me wonder – is the hand I designed “feminine?”  Then it occurred to me that with more design effort, I could make “feminine” and “masculine” version of these hands.  I think the primary differences would be two-fold – thinner fingers and a less “hefty” palm for a more feminine version and a thicker and perhaps more “blocky” palm for a more masculine hand.
  • New developments
    • There have been a number of interesting and new developments and experiments of late.10 In no particular order, these ideas are:
  • Discussions with a 7-year-old
    • A few days ago my daughter and I were jotting down some ideas in my sketchbook.  As we did so, she saw some of the notes from the e-NABLE meeting on 3/21/2014 – including several sketches.  We discussed the problem – affordable, customized, and comfortable prosthetics.  We talked about amniotic band syndrome, how fibrous amniotic bands affect fetuses, and the different ways in which these bands can cause11 deformities to single fingers, whole hands, and a range of changes in between.  I explained how Mr. Jose Delgado Jr. had a $42,000.00 myoelectric prosthetic, the problems he has with that prosthetic, how and why he prefers his $50.00 printed replacement, and how for the price of his one prosthetic people could make 840 more prosthetics.12 She asked, “Why can’t someone use a stump to operate a hand?” I replied that this was exactly how these prosthetics worked – and I drew a few simplified sketches of the Cyborg Beast.  Her next question was, “Why can’t it move side to side?”  I said that Mr. David Ogreman had designed such a prosthetic.
  1. My first concrete step was going to an e-NABLE meeting in San Francisco on 3/21/2014. []
  2. The above picture is slightly misleading.  I haven’t confirmed that the fingers I’ve designed will properly fit into the palm that I’ve designed – or that the thumb would work at all.  Thus, the picture is partially a parlor trick and partially an indication of where I hope to take this design. []
  3. Many of the gods and goddesses in Eastern religions embody dual natures – creation/destruction, life/death, etc []
  4. In one of my several different blogs. Besides, what could be more ADHD than having 3+ blogs?!? []
  5. You may not find this as amusing as I do – but I probably have about four different sketch/notebooks. []
  6. Say, only 1mm []
  7. From pinky finger to thumb, the non-scientific measurements from knuckle to finger/thumb tip were 77mm, 102mm, 106mm, 92mm, and 72mm []
  8. Using the deformed spheres and hull trick []
  9. Thanks Erik! []
  10. I don’t even know why I’m saying “of late” when I’ve really only been involved a little over 30 days.  I guess becuase these developments are new to me? []
  11. Please forgive my lack of a more politically correct term.  If you’ve got a better or more sensitive phrase, please let me know as I will gladly adopt it []
  12. She wanted to know if he could get a refund! []

Printable Prosthetics: A Mock Hand

More progress on a fully parametric prosthetic design

More progress on a fully parametric prosthetic design

Here you can see the fingers placed appropriately with the palm. I’ve used the same “finger” designs to add a thumb.

For right now, this is just to demonstrate the progress so far.  Theoretically, the only thing left to do is crank out an appropriate gauntlet to bring the entire design together.  In reality, there’s still a fair amount of work to do.  The design for the prosthetic palms was… not elegant.  Also, I want to create a separate (but very similar) design for the thumb.1 It is possible that if I improved the finger designs, I might be able to get away without designing a separate thumb.

In the meantime, I think it looks good and would probably be functional as-is.

Onwards and upwards!

  1. I feel like the thumb should be stubbier, so I’ll go back and adjust the designs accordingly. []

Printable Parametric Prosthetics: Design Features

Parametric fingers - different lengths, same scale, with no distortion to hardware

Parametric fingers – different lengths, same scale, with no distortion to hardware

I’m not ashamed to admit it – I’m proud of these parametric designs like few of my other designs.  I’ve worked to make this design as customizable and organic as possible.  The two modules that define each finger can be customized in two important ways – they can be lengthened1 as well as scaled up or down – without any distortion or change in the size of the holes for the hardware, elastic cords, or tension cords.

Parametric fingers - with grippy bits

Parametric fingers – with grippy bits

Being able to lengthen2 the finger segments is important because it allows the user to create fingers of different lengths, as normal fingers are of different lengths, all without having to actually scale the fingers to different sizes and without causing a change in each finger’s diameter.

As I’ve discussed in earlier posts, being able to scale the parts up and down without distortion to the hardware holes is important because it allows users to use standard hardware throughout different designs.

For now, it’s back to work on the parametric palm to ensure a proper fit with these parts.

  1. Or shortened []
  2. Or shorten []

Printable Parametric Prosthetics and OpenSCAD: Parametric Optimization

Picking parametric fingers

Picking parametric fingers

This post is intended as a set of “guidelines” to creating a parametric design in OpenSCAD.

Last Sunday afternoon was spent working out a parametric design for printable prosthetic fingers.  Using the OpenSCAD function “hull” it’s relatively easy to crank out a nifty organic appearing design.  Admittedly, you have to have a working knowledge the basic union/difference/intersection function first.  However, once you do it’s really quite easy.

The feature of the design I’m most proud of is the “nail” part of the finger tip.  I designed the “nail” by using the OpenSCAD function “intersection()” on two cylinders.  The little “nubs”1 consist of a small cube, rotated so a corner is pointed straight up combined, with an identically situated cube rotated slightly.

When I’m designing something to be parametric, I usually don’t really start out designing it that way.  I first strive to create a form in OpenSCAD that resembles closely the thing I wish to design.  Then, I poke through the design code looking for those elements that are related to the design aspects I’m interested in changing based on parameters.  Once located, I replace those parts of the design code with variables that can be specified when the module is called.  I realize this is kind of a “high level” description of my design process for parametric things, but it’s still the best description.

Since last Sunday I’ve really done a lot with the design.  Some simplifying and a lot of improvements.  In the next post I’ll go over these features.  I’m really excited to show these off.  :)

  1. Meant to give the finger grip and texture []

Printable Prosthetics Fingers and OpenSCAD Design Tips

Solid finger tip for Cyborg Beast

Solid finger tip for Cyborg Beast

Above is my first attempt at designing a “solid” finger for the Cyborg Beast DIY printable prosthetic in OpenSCAD.1 The reason this is a “solid” finger is that I haven’t subtracted out any material to allow this partial finger to connect with anything else.

The problem with scaling (up or down) any design that requires fasteners and hardware is that when you do, the holes for the hardware are similarly scaled.  This leads to more post-printing work drilling holes to widen them or to find larger fasteners that won’t rattle around in too-large holes.

Thus, if the hardware consists of 3mm screws, the holes for the hardware should be 3mm no matter how much the parts are scaled up or down.  To make matters more interesting, not all holes in the model should be excepted from scaling.  The above finger tip has a plastic end that is supposed to fit into a mid-finger piece – and those parts should be scaled up or down according to the size of the overall hand.  Thus, some voids should be scaled2 and others not at all.3

I’m rather happy with how this finger has turned out so far.  It has most of what I understand to be the essential features of the Cyborg Beast fingertips, including little nubs along the finger pad to allow for gripping.  I intend to make this an option, in case a user would rather use something like Plasti-Dip to make grippy finger pads, rather than relying on printed plastic bumps.

However, converting a decent design into a parametric design requires a little more work.  The way I go about designing a parametric model is to first design one instance of the thing, in this case the finger tip.  My next step is to poke through the OpenSCAD code to locate those aspects parts that contribute to the models’ essential features – length of the finger tip, for instance.  Once I’ve found these bits, I then try to modify them so that I can insert different variables and arrive at sane variations on the model.

Wish me luck!4

  1. If this is your first time tuning in, check out the prior posts in this series using the links at the bottom of this post []
  2. Where parts meet []
  3. Such as holes for hardware []
  4. See, this is a post about finger tips and design tips!  Oh, man, I crack myself up! []

Printable Prosthetics R&D Q&A FAQ: Part The Third – The Answering

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Tuesday afternoon I had the good fortune to talk to Professor Jorge Zuniga of Creighton University regarding his insights on printable prosthetics, measurements of uneffected/effected hands, and various important design considerations.  Getting to talk to him really helped crystallize my understanding of the various measurements and the way in which the parts of the printable prosthetic1

  1. Design Ideals
    1. One of the design ideals of the Cyborg Beast prosthetic is to fashion a device that strives for symmetry with the unaffected hand.  Thus, all of the necessary measurements are taken from the unaffected extremity.  This serves two purposes.  First, it allows for the prosthetic to be similar in scale to the unaffected hand.  Secondly, the unaffected extremity tends to be, in most cases2 , slightly larger than the affected extremity.  The size difference may be due to the unaffected extremity being used more, and thus having more muscle mass, or due to the loss of muscle tone and muscle atrophy in the affected extremity.  Either way, a prosthetic designed using the measurements from the unaffected extremity should generally fit the affected extremity.  Since this particular prosthetic design uses velcro straps to fasten to the affected forearm, a prosthetic that is slightly too large can easily be adjusted to fit well by tightening the straps.
    2. Another design ideal is to create a core prosthetic design which works for the vast majority of persons.
  2. Critical Printable Components
    1. A rough sketch of the various parts of the Cyborg Beast prosthetic appear above as “Figure 2.”
    2. Palm.  This is the part that fits over the hand.
    3. Gauntlet.  This is the part that fits over the forearm, between the wrist and elbow.
    4. Four fingers, each comprised of two pieces.  The above simplified sketch only shows the fingers as a single piece.  Do not let my sophisticated drawings fool you.
    5. One thumb, comprised of two pieces.  Like the fingers, the thumb is comprised of two plastic pieces.
  3. Critical Measurements
    1. These measurements refer to the lines labeled in “Figure 1.”  All measurements relate to the unaffected extremity.
    2. F5.  This is the length of the forearm, from the interior of the elbow to the wrist.  While this could be measured along the side of the forearm, it very likely doesn’t matter.
    3. F2 (measured at 1/2 F5).  At a location along the forearm, half way long F5, the width of the forearm.
    4. H1.  This is the distance across the knuckles, from the pinky to the forefinger.
      1. When I lay my own hand flat on a table top, I perceive that an imaginary line drawn through my pinky and forefinger knuckles would end up being not exactly perpendicular to an imaginary line drawn from my elbow to my wrist.  More on this below.
      2. All of that is another way to say that I suspect H1 is not perpendicular to F5.
    5. W.  This is the width of the wrist.  Rather than being strictly measured from either side of the wrist, this measurement appears to best made using the endpoints of the H2 and H3 lines closest to the wrist.
    6. H2 and H3.  H2 is the length from the wrist to the pinky knuckle and H3 is the length from the wrist to the forefinger knuckle.
    7. All other measurements indicated might possibly be useful for refining the design, but they are primarily important for the Creighton University research study purposes.
  4. How Each Critical Measurement Informs Design
    1. F5.  Gauntlet length is not longer than 1/2 F5 and not shorter than 1/4 F5.
    2. F2.  Gauntlet forearm width is F2.
    3. W.  Gauntlet wrist width is W.  Theoretically, if the prosthetic’s palm is scaled up to accommodate the wrist width (W), the affected hand  should fit under and inside the prosthetic palm.
    4. H3 can be used to inform the relative lengths of the fingers to match the overall length of the unaffected hand.   This isn’t strictly required for a functional prosthetic.  As designed, the Cyborg Beast appears to use fingers of equal length.  However, the fingers could be scaled up or down along with the rest of the prosthetic hand.  Alternatively, and as will be discussed below, its possible that the fingers could be designed to be of different lengths.  Prosthetics for young children should contemplate fingers based upon slightly larger, 1-2cm, measurements.  The reason being that they quickly outgrow existing parts.
  5. Functional Design Considerations
    1. Thickness of parts is 3mm – 5mm, 20% fill.
    2. The wrist hinges should line up as exactly as possible with where the user’s wrist bends.  Additionally, the wrist hinge should be perpendicular to the line of the forearm/gauntlet.
    3. There should be about 1 – 2 mm of space between the hinge part on the palm and the hinge part on the gauntlet.  This allows a washer to be inserted for more fluid movement.
    4. Eliminate square corners when possible, as sharp edges can contribute to possbile injury.
  6. Cosmetic Design Considerations
    1. Using the unaffected hand for measurements also allows us to seek symmetry between the hands.
  7. Advanced Considerations
    1. Degree tilt to H1.  As mentioned above, it seems like the “H1” line is not perfectly perpendicular to an imaginary line drawn from my elbow to my wrist.  An educated guesstimate would be that there is a 9 degree tilt to this line.  While existing Cyborg Beast designs do not include this knuckle “tilt,” including this feature in future designs may allow the prosthetic to appear and function more naturally.  However, I don’t know if there’s any real ergonomic benefit to using incorporating this knuckle tilt.
    2. Different knuckle positions for fingers.  The Cyborg Beast has a knuckle “block” that positions the attachment points for all fingers in a straight line.  The reason for this is simple – it’s a lot easier to put one long screw through the entire knuckle block to secure and strengthen all four fingers at once.  At a recent e-NABLE meeting I had the chance to inspect a 3D printed prosthetic which used different knuckle positions for each finger.  Rather than all of the knuckles in a straight line, this model featured each knuckle at a different, and more natural seeming, position.  While this can appear more natural, I’m not sure there’s an ergonomic or aesthetic benefit.
    3. Different finger lengths.  Fingers are different lengths.  The Cyborg Beast, with all fingers having the same relative knuckle positions and same finger sizes, has a more mechanical look than might otherwise be possible.  I don’t know if there’s an ergonomic benefit to using different finger lengths, but this is certainly something to explore.

Based on the above, I think I’m ready to dive back into the OpenSCAD code and work out a parametric gauntlet, fingers, and thumb.  Stay tuned!

  1. I’m basing my own designs off of his Cyborg Beast designs []
  2. Let’s just choose the large and arbitrary percentage of 95% []

Printable Prosthetics R&D Q&A FAQ: Part 2 – The Wondering

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In order for me to design an OpenSCAD parametric model that can be adjusted to work for more people, I need to get a better handle on the necessary measurements and how they effect the final design.  Below is my understanding of the necessary measurements and how those measurements necessitate changes in the final prosthetic.

  1. What are the design ideals, besides functionality?
    1. While answering a different question, Marc Petrykowski suggests, “My goal as the designer and printer is to make the hand as near perfect as the other hand so it feels the same to the body and brain, thus they will respond with the effected hand like it was their real non effected hand. Also as stated above, the degrees of flexion and extension and the size/length of the fingers are all incorporated into the final design before the printing the hand.”
    2. Thus, all other things being equal, he tries to craft a hand that is as similar as possible to the non-effected hand.
  2. What are the main parts of the Cyborg Beast?
    1. I’ve drawn a picture with the main features of the Cyborg Beast printable prosthetic.  There are really just a few parts – the palm, the “gauntlet,” fingers, and thumb.  The gauntlet fits over and is secured to the forearm and is connected to the palm by two hinges.  The palm goes over the user’s effected hand and is connected to the fingers and thumb.
  3. What are the necessary measurements?
    1. Marc Petrykowski has provided a set of photos to demonstrate the various measurements.  They appear to all be in millimeters.  Please forgive my layman’s description of these various measurements.  Measurements are taken of the effected and non-effected sides so that a prosthetic can be made that will fit the effected side, but have similar characteristics to the non-effected side.
    2. Flexion angle.  This would be the maximum angle of movement from holding your hand out and then bending the hand at the wrist towards the inside of the wrist.  An example is pictured above as “Figure 1.”
    3. Extension angle.  This would be the maximum angle of movement from holding your hand out and then bending the hand at the wrist away from the inside of the wrist.  An example is pictured above as “Figure 2.”
    4. Knuckle width.  This is the width of the hand at the knuckles.  In Figure 3, you’ll see this as “H1” and “h1.”
    5. Wrist width.  This is the width of the hand at the wrist.  In Figure 3, you’ll see this as “W” and “w.”
    6. Hand measurements.  I’ve identified these as “H1 – H3” and “h1 – h4” in Figure 3 above.
    7. Forearm width measurements.  I’ve identified these as “F1 – F3” and “f1 – f4” in Figure 3 above.
  4. How does each measurement inform the design?
    1. Again, this is merely my guess, impression, or understanding of how each measurement results in a design change.  For the purposes of these diagrams, I’ve assigned each measurement a letter or letter/number combination.  When applicable, I’ve differentiated between the effected (lower case) and non-effected (upper case) hands.
    2. Hand Measurements (Figure 1,blue and green)
      1. Knuckle width, non-effected hand, “H1”.  This is necessary to creating a prosthetic of the size that will match the non-effected hand.
      2. Knuckle width, effected hand, “h1”.  This is necessary to creating a prosthetic of the size that will fit the effected hand inside the palm.
      3. Wrist to pinky knuckle, “H2” and “h2,” the purpose of which is to ensure a prosthetic that will fit the effected hand inside the palm.
      4. Wrist to middle finger tip, “H3” is the overall length of the uneffected hand.  The purpose of this is to create a prosthetic of roughly the same size as the uneffected hand.
      5. Wrist to index finger knuckle, “h3” is for making sure the prosthetic palm will fit around the effected hand.
      6. Wrist to middle3 finger, “h4” is for making sure the effected hand will fit inside the prosthetic palm.
    3. Wrist Measurements (Figure 1, orange)
      1. Wrist width, “W” for the non-effected hand and “w” for the effected hand.  The purpose of the effected hand measurement is to ensure a good fit between the prosthetic palm and the effected hand and the purpose of the non-effected hand measurement is to allow the prosthetic palm to match the non-effected hand more closely.
    4. Forearm Measurements (Figures 1, purple and red)
      1. Various measurements from “F1” (and “f1) just below the wrist to “F4” (and “f4”) which is the width of the elbow. As best as I can tell, these measurements are to ensure a good fit of the “gauntlet” on the effected forearm.
      2. Elbow to wrist, “F5” on the uneffected arm and “f5” on the effected arm.  I’m not sure what the purpose of this measurement is, but perhaps it is to ensure the effected arm with prosthetic is roughly the same length as the unaffected arm.
    5. Angle Measurements (Figures 2, 3)
      1. Somehow the flexion and extension are incorporated into the design.  I do not know how these settings inform the design.
  5. How accurate do these measurements need to be?
    1. Within 1mm, rounded up would be best.  Thanks to Peregrine Hawthrone and David Orgeman for the input.
  6. Questions begetting questions
    1. If you’ve ever made one of these prosthetics, please let me know if there’s anything I’ve gotten wrong.
    2. It appears the measurements effect the design as follows:
      1. Measurements “h1, h2, h3, h4 and w” dictate the size of the palm.  The ratio of the increase/decrease is then applied to all the finger bits.  The measurement “H3” is used to adjust the size of the palm and fingers on the effected arm.
      2. Measurements “f1, f2, and w” dictate the size of the gauntlet.
      3. The additional measurements on the corresponding uneffected arm could be used to make the prosthetic over the effected arm appear more like the uneffected arm.
      4. I’m guessing the other unused measurements (“f3, f4, f5”) are used as part of the Creighton University research study, to measure the physical changes in the extremities before, during, and after use of these prosthetics.
    3. How does the flexion and extension change the design?
    4. Have you printed the Cyborg Beast designs I’ve uploaded?  What are your thoughts?

Thanks for reading and helping!  Comments appreciated!