Category Archives: Design

Design tips for creating 3D digital models for printing on a MakerBot

DIY laser cutting

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Peter Jansen's reciprocating laser concept

Peter Jansen's reciprocating laser concept

Peter Jansen’s latest post about selective laser sintering (SLS) is nothing short of amazing.  Most of his posts on the RepRap Builders blog posts deal with his adventures and research into SLS fabrication – basically directing a laser over a bed of powder to fuse powder in successive layers into a 3D object.  Since the object is being created in a bed of powder and any new layer is supported by the powder above it, the powder print media becomes it’s own support material.

His latest post diverges from his adventures with SLS 3D printing and details his efforts at building a DIY laser cutter.  His idea is for a “reciprocating laser” which would change the focal length or the height of the laser above the material being cut.  Peter points out that commercial high power laser cutters essentially brute force burn through the entire depth of the material to be cut.  They’re so powerful that it doesn’t matter that the laser is out of focus and “cooler” at different depths.

He has demonstrated a proof of concept using much lower power laser to cut material by lowering a much lower power laser as it cuts material.  The downside is that the lower power laser requires a much longer time to burn through the material – having to hit the same area several times at different depths to cut all the way through.  His proof of concept setup was about the size of a CD/DVD drive – since CD/DVD drives, motors, and housing provided most of his building materials.  So far he’s been able to burn through most of two CD case backs – about 2mm together.  He’s hoping to push it to cut thicknesses up to 3.0mm to 4.5mm.

The incredibly small size of his setup means that it can only very small pieces of material.  However, this gave me two ideas:

  1. If the low power lasers are so cheap, why not install multiple lasers at different focal lengths?
  2. If the entire setup is that small, what about making the entire setup mobile? 1  Think hexapod CNC mill.  If a laser cutter wheeled or hexapod robot was as small as a CD drive, you could conceivably just take out a large sheet of acrylic or thin plywood, set the robot in the dead center, and let it go. 2
  1. This reminds me of one of my favorite sayings.  “If Mohammed won’t go to the mountain, the mountain must come to Mohammed.” [↩]
  2. The robot could stay oriented in any number of ways.  You could draw a grid on the material, the material could have a thin paper coating with LeapFrog style micro-dots that told the robot it’s location, you could project a grid onto the material with light or guide it with another laser like a laser guided missile. [↩]

Note to self, too

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The Mummy Box Set - and detail of box

1. The Mummy Box Set - and detail of box

One of my favorite movies is The Mummy, and the coolest prop in the movie is a hexagonal puzzle box. When I get a chance, I’d like to design this object too. Here are some photos and informative links I’ve found:

  1. The cover of the Mummy Box DVD Set.
  2. What appears to be a homebrew prop replica.
  3. What appears to be an actual movie prop.

Sure, it’s frivolous.  However, I like the design challenge inherent in replicating this prop, getting the pieces to fit, perhaps even getting it to spring/pop open.

Home brew prep replica

2. Home brew prep replica

Mummy Puzzle Box Stats
Measurement of height 6-7/18″
Measurement from front to back 3-3/4″
Measurement of width, all sides 2-3/4″
Measurement of width, corner to corner 2-3/4″
Measurement of height 1-1/2″
Measurement of width, from base 5″
Measurement of all links 1-1/4″
Color Antique Gold
Other design details Top shows Seti I’s Horus name (men-maat-re), flanked by Anubis on the left and a male figure on the right, separated by vertical lines. Sides are inscribed with haphazard hieroglyphs including “Son of Re” and “Amen-Re.”
Puzzle Box - full picture

3. Puzzle Box - full picture

Puzzle Box close up

3. Puzzle Box - close up

3. Puzzle Box - side view

3. Puzzle Box - side view

Sonic Screwdriver – first draft

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Sonic screwdriver, first draft

Sonic screwdriver, first draft

To the right is a first draft print of my latest designs for the sonic screwdriver.  It’s next to a USB cable for scale and perspective.  There are several things I need to fix:

  • It’s too small.  I was guesstimating the scale based upon the size of hand holding the sonic screwdriver in one of the photos I saw.
  • Too much warpage.  I need to build my heated build platform.  :)  I’ve got my SMT1 soldering Toolkit, now I just need a hotplate.
  • Better connectors.  The connectors I designed are adequate, but not that great.  They need to be much larger to ensure a proper grip between parts.
  • Fix a connector.  I have a hex connector on one piece and a 16-sided connector on another.  That’s not going to work.
  • Consider changing the fit.  Some parts have a 0.25mm clearance on all sides between the male and female connections.  Other parts have a 0.5mm clearance instead.  I tried both on different sections so I could test the fit.  The 0.25mm clearance on all sides is fine for some parts, but other parts could use a little more wiggle room.
  • Change the thickness.  My earlier draft was a whopping 0.5mm thick all around.  I printed these parts at varying thickness to test their durability, flexibility, conserve plastic, and maximize internal space for future electronics.  A 1mm thickness seems to be the most optimal mix.

I’ve posted my sonic screwdriver designs to Thingiverse for people to tinker with and, hopefully, improve.  I would sincerely appreciate any help anyone can provide when it comes to designing the upper half of the sonic screwdriver – especially the moving parts.

  1. surface mount technology [↩]

Plastruder MK5, now with 85% less heartache!

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Of all the bits to get working on my MakerBot, the Plastruder MK4 was the most challenging.  There were so many ways for some critical component of the Plastruder to go wrong.  You could:

  • Cut the wrong length or resistance of nichrome wire
  • A small patch of nichrome fiberglass insulation is scratched off, creating a short
  • The nichrome is not wound close enough to the barrel, requiring extra power to heat
  • There’s too much space between the barrel and nozzle, creating a gap where plastic and build up and cause a blockage
  • Heat can travel up the barrel and plastic can ooze up the threads
  • Heat can travel up the barrel, plastic can pool and then cool causing a blockage, bulge the PTFE
  • The thermistor can burn out or short out
  • Heat can cause the thermistor or nichrome to become unsoldered or lose connectivity

From the description of the new Plastruder MK5, it sounds like the improved designs solve all of the above potential problems!

Update: Beak90 offered several other possibilities!

  • one could not heat it up enough and strip the PTFE threads.
  • one could heat it too much and cause the PTFE threads to fail.
  • one could put the thermistor in the wrong place and have it read the wrong temp.
  • one could wind the nichrome in 2 layers and have it not heat enough.
  • one could tighten the nut on the barrel too much and cause extra stress on the PTFE causing it too fail.
  • one could forget to say the required magical incantations before firing up the plastruder causing everything to fail.

And, one more I just thought of:

  • Fail to play Daft Punk

Plastruder MK5 plans released!

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The plans for the Plastruder MK6 look downright wicked

The plans for the Plastruder MK6 look downright wicked

MakerBot just released the photostream and wiki instructions for the Plastruder MK5. 1 This looks like a total overhaul of their original designs. 2

It is based on Charles Pax’s Paxtruder which has such a small form factor that it is possible to squeeze two extruder heads into one Makerbot.  The Paxtruder also uses a delrin plunger which is used to push the filament against the extruder pulley, rather than the previous idler wheel design.  I like the delrin plunger idea since it would be a lot easier to adjust tension and remove/insert filament.  The idler wheel held in by a large bolt and nut works… but is finicky and sometimes prone to fussiness.

Out are the big/small/weird and whimsical dinos in favor of lasercut acrylic “arches.”  There may be a benefit to the arches over the dinos, but I’m not sure what it would be.

The entire heater element and extruder head has been redesigned as well.  I don’t recall seeing any published designs which reference this new system.  We’ve all seen power resistors in use in RepRap/MakerBot projects – but they’ve usually been relegated to heated build platform designs.  Now a pair are being used as the full heating element in place of tempermental3 nichrome wire.  The problem with the old nichrome wire wrapped around the barrel system is that if you need to rebuild the heater, you’ve got to toss out the old nichrome since the insulation is going to get peeled off as soon as you pull it off the barrel.

The new MK5 system uses a PTFE sleeve to feed the filament down into the heater.  Interestingly, the PTFE sleeve is encased in a snug metal tube which should prevent any bulging problems.

My understanding of the instructions is that the MK5 is far less prone to failure than the previous MK4 model Plastruder.  I’ll grant the Plastruder is easily the most4  challenging component of the Makerbot to get working.

The instructions also hint at Generation 4 electronics.  Right now I’m rockin’ the Gen 3 which have served me quite well.  I wonder what the Gen 4 has in store?  One thing I have to really like about the electronics is that I know they’ll never really be obsolete. 5  If I wanted to upgrade to Gen 4, I can always print off a Mini-Mendel or Mendel, and swap in the new electronics.

However, if this new system is as resilient as the instructions describe, I’m on board.  I’m probably not going to have a good excuse to test out this new Plastruder design for a while since my Plastruder has been behaving itself since the last time I rebuilt my Plastruder and I just scored some spare MK4 parts. 6

  1. Photo courtesy of Johnson Cameraface [↩]
  2. A close tie for the photo was “Number 5 is alive!” a la Johnny 5 from Short Circuit.  I’m just too much of a Doctor Who fanboy to NOT use an “You will be upgraded” joke. [↩]
  3. Pun intended!!! [↩]
  4. Dang.  I’ve already used temperamental, finicky, and fussy…  Where’s my thesaurus?  Oh, that’s right – he’s out EATING Tony Buser’s Laser Dinosaur! [↩]
  5. Bite me Cybermen! [↩]
  6. Thanks again guys! [↩]

Lazzersaurus Rex, I choose you!

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Tony Buser, my origami laser dinosaurs accept your challenge.

SyFy Movie: MakerBlock origami laser dinosaurs Vs Buser's Laser Dinsosaur

SyFy Movie: MakerBlock origami laser dinosaurs Vs Buser's Laser Dinsosaur

Oh.  Dang.  That did not appear to go well for Team Buser. 1  You probably didn’t realize the scale of those origami dinosaurs before issuing your challenge.  See, that’s a laser canon, not a laser pointer.

Also, sorry about your robot dinosaur.  I’ll print you a new one.  :) 2

  1. You see, I use EVIL origami paper. [↩]
  2. Friends again? [↩]

Sonic Screwdriver progress

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Printable screwdriver

Printable screwdriver

I just redesigned the printable screwdriver in order to make the parts fit together better and be more printable.

It should be easier to see how these parts go together.

Basically, you take the “mid-handle” at the far end of the build sheet, turn it upside right, clamp the two “lower handle” pieces on either side of it, and slide that bottom ring onto the lower handle.

I still need to redesign the upper handle, hollow out the mid-handle, and make sure there’s enough room inside for the GoodFET / electronic sonic screwdriver guts.

Now I’m wondering if it is also possible to make this a piece of MakerBot origami – and make it printable on one build sheet…

Real life sonic screwdriver

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This morning I received an e-mail from Bre out of the blue introducing me to Travis Goodspeed.  Apparently Travis has been working on building sonic screwdriver guts out of the GoodFET, a universal JTAG programmer, a “sonic screwdriver of hacking.”  Travis suggested a GoodFET could be programmed to act as a TV-B-Gone, light show, or any number of other things.  Given that his circuit board is about 3″ x 0.85″ x 0.2″1 , there shouldn’t be a problem finding space for it in the sonic screwdriver I’m in the middle of designing. 2

Freaking sweet.

So, here’s my real life sonic screwdriver wishlist:

  • Lights.  Red LED3 , white LED4 , green LED5 , and a UV LED6
  • An actual screwdriver bit or spot where you can attach a screwdriver bit.  It would just be cool to have a sonic screwdriver that could be used as a screwdriver.
  • A shakey Tic-Tac container style recharger.  Having a sonic screwdriver that doesn’t need batteries would be awesome.
  • A tiny speaker that played the sonic screwdriver sound.
  • A tiny magnet.  I remember watching Doctor Who back in the day, black and white old school episodes, where he used his sonic screwdriver to take screws out of things, bolts out of doors, etc in the worst stop motion animation the BBC could get away with.  Still, if this sonic screwdriver had a magnet, it could actually affect a physical change via magnetic force.
  • TV-B-Gone.  On the episode “Midnight” Doctor Who shuts off a bunch of TV’s using his sonic screwdriver.  This would be an INCREDIBLE feature!
  • Flash drive and/or mini-memory card reader.  Perhaps with the entire library from PortableApps.com installed.
  1. For those of you non-imperialists out there: 76.2mm x 21.59mm x 5.08mm [↩]
  2. TBuser, if you want to help, lemme know! [↩]
  3. For night vision.  Also, there are suggestions that a sonic screwdriver can have a “red setting.” [↩]
  4. As a flashlight. [↩]
  5. The 11th Doctor’s screwdriver has a green light. [↩]
  6. For making things fluoresce such as secret messages, blood stains, and monsters. [↩]

MakerBot Origami

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1. Or, “Design Constraints and Creativity”

Origami is another of my hobbies and it is all about design constraints. 1 The rules are simple2 – one square sheet of paper only manipulated by folding. 3  Yet, within these rules it is theorized that a sufficiently skilled artisan can design and fold any arbitrary figure.  I find folding origami to be at once cathartic and contemplative. 4

Pondering the design constraints within origami reminded me of one of my own recent designs – the 3x2x1 Rubik’s style puzzle cube.  Quite apart from the medium or subject matter, I really liked the idea of a single print job resulting in parts that could be immediately hand-assembled without tools to form a useful object.  Then I thought – if the design constraints are one of the things I like about this design, what else is possible within these same constraints?

Thus, I propose a new style of “MakerBot Origami”:  One MakerBot print5 , multiple components6 , no tools or hardware7 .

What’s the coolest most awesome thing you can design within these constraints?

Update:  Cyrozap – sory fore mispellnig yoru mane.

((I waffled on that title.))
  1. I waffled on that title. [↩]
  2. Modern origami rules, anyhow. [↩]
  3. Designing an origami model is not about figuring a way to cheat those rules – rather a way to work within them to achieve a desired goal. [↩]
  4. I recall one origami master referring to the folding of a particularly difficult and rewarding model as invigorating. [↩]
  5. Or, as Cryozap Cyrozap calls them, “production file.” [↩]
  6. Otherwise, people would be making whistles. [↩]
  7. Thus, no bottle openers [↩]