MakerBot Industries

Viktors Nyckel (spare key for piggybank) by snrk

What does a MakerBot dad do when his kid loses the key to his piggy bank?  Design and print a new one!

During the winter, my son lost the key for his piggybank. I tried to print a new one this January out of ABS, but that didn’t work. Today, he nagged me for another try, and with a little downsizeing, and PLA in my new Stepstuder, the key actually forced the pigs security system. Big win!

Hurray for snrk, dad and MakerBot hero!

Replacement Key Fob

My mom came to visit on Monday night and left yesterday morning.  Monday evening she mentioned her car key was broken, I measured the broken parts, printed up two prototypes, and printed out a fully functional replacement the following morning.  Well, last night I received an e-mail from my dad:

What a fantastic job you did on your mom’s car keys. Wow! I hope you still have the measurements for that key saved because that car came with two keys and over the years both keys had plastic parts which were shattered. The one you repaired was the better one of the two. However if you can make another one of those cases for it, may be then you can repair the second key as well.

Measurements?  Where we’re going we won’t need measurements.

If you need one¹ just download the designs from Thingiverse, fire up your 3D printer, and crank out a few parts.

Posts in this series:

• MakerBot Hero:  Car Keys I
• MakerBot Hero:  Car Keys II
• MakerBot Hero:  Car Keys III
• MakerBot Hero:  Car Keys IV
• MakerBot Hero:  Car Keys Epilogue

1. Or, in the case of my parents, two or more. [↩]

MakerBot fixed key, front

And, here it is.  The fully 3D printed, fully functional replacement key fob housing.  It’s got all of the improvements discovered from the prior two revisions.  All of the parts fit snugly in the case, the case fits snugly together, and there is zero wobble between the key and the case.

MakerBot fixed key, back

One half has a 2mm lip and the other has a 2mm groove – the result is a case that required channel lock pliers to shut…  but isn’t coming apart any time soon.  All of the sides are at least 1.5mm – which is way thicker and sturdier than the original case.

No WAY is this case cracking after a simple drop.  From the EMPIRE STATE BUILDING.

This may just be my favorite 3D printer fix ever.

Posts in this series:

• MakerBot Hero:  Car Keys I
• MakerBot Hero:  Car Keys II
• MakerBot Hero:  Car Keys III
• MakerBot Hero:  Car Keys IV
• MakerBot Hero:  Car Keys Epilogue

First draft on the left, second draft on the right

I’d like to address some comments to the prior two posts.  The first post was essentially about identifying a problem that could be solved with a 3D printer.  In this case, it was the cracked plastic case for my mom’s car key fob.  The second post was about one method for measuring and documenting measurements in a meaningful way.  Basically I trace out the parts on a sheet of paper and draw in arrows indicating the dimensions.

@Mark wanted to know why I was breaking up the posts.

Well, originally I had intended to live-blog the process of identifying, measuring, designing, and printing the solution.  This was not to be for a variety of reasons.  Instead I opted to break what would be a very very long post into discrete sections. ¹²

@Alex Guichet wanted to know when you’d get to see the results and if this was just going to be a teaser.

I’ve broken the entire saga into four posts.  You’ll get to see the finished product at the end.  Promise.

Draft, the First

From the photo above you can see the first attempt on the left.  There were a number of deficiencies in this draft that I didn’t really think about until I was actually holding the part in hand.  In my zeal to measure the electronic-beeper-thingie and the metal key, I had completely forgotten to measure or design the less critical part that allows you to put the darn key on a keyring.  Next, the metal part that is the actual key is quite a bit thinner than the electronic-beeper-thingie.  As such, there needs to be a raised section that is only “key”-width rather than “beeper”-width.  In this first version you can see that there is no such raised section.  I also failed to include a hole for the small screw that holds the key in place and both sections together.  In this draft the two parts do not actually fit together, they are both just flat pieces that do not interconnect in any way.  I also noticed that I made the entire enclosure slightly too big vertically.  Just one more thing to tweak in the next version.

Once it was in my hand, I decided that the next version would allow a portion of one part to fit into a section of the other.  Just looking at the finished product was enough to help me realize all of these deficiencies – that’s why I didn’t even bother to clean the part up. 

Onwards and upwards!

Draft, the Second

From the photo above you can see the second attempt as the two parts on the right.  While these parts were much more suitable than the prior, there were still some issues to work out.  I included a section for the keyring, a hole for the screw to hold the key in place, a lip on one side and a bevel on the other so they would fit together, and I reduced the interior height by 2mm to reduce the extra room.  The parts fit together well – but came apart relatively easily.  I decided the next version would have an even larger lip.  It turns out that a reduction in 2mm was too much, since the electronic beeper just barely kept the parts from fitting properly.  Increase by 1mm.  I decided all of the buttons needed just a little more clearance on each side, so I gave them all 0.4mm more space.  I made created a recessed section for the screw head to disappear flush into the top section once installed.  Lastly, I also widened very slightly the two walls on either side of they key, since it was a very tight fit.

The benefits of drafting

Imagine you had to program by punch card.  Get one punch wrong and that card was toast.  Get one punch card wrong and your whole program was toast.  Sure, you could double, triple, and quadruple check your program by inspecting every punch and the order of every card…  But it’s not a very efficient use of time.  For modern programmers there is little penalty for just taking a chunk of code and firing it up.  The most common worst case scenario is an error code directing you to where the problem might exist.

Now, if software guys can try out a draft of code without any significant penalty, why not hardware guys? ³  I don’t need to get everything exactly right the first time – and I might even find a few improvements along the way.  With an investment of about 20 minutes of unattended printer time and $0.20 of plastic each I got to try out two interim designs – and improve my final design.

Up next:  The final results!

Posts in this series:

• MakerBot Hero:  Car Keys I
• MakerBot Hero:  Car Keys II
• MakerBot Hero:  Car Keys III
• MakerBot Hero:  Car Keys IV
• MakerBot Hero:  Car Keys Epilogue

1. Like Dave Durant long post. [↩]
2. Dave, I kid because I love! [↩]
3. And, for that matter, why not tinkerers, makers, hackers, repair people, and dads? [↩]

Tracing the key fob

The last post covered my decision to remake/repair my mother’s car key. Frankly, I’m surprised I haven’t been fired from this job for not having fixed this problem immediately. In my defense, from the moment I learned of this issue I dropped everything to begin working on it.

A critical step to printing a replacement part is measuring your existing parts to make sure the replacement components will fit well.  I find the easiest way to start doing this is to simply trace the existing parts on a white sheet of paper.  Once this has been completed, I flesh out the “sketch” a little and draw in all of the measurements.

Marking the dimensions of the key fob

Once the measurements have been taken down and associated with the relevant areas on the existing parts, I like to create a digital representation of these parts.  Doing so allows me to use those existing components as a basis for developing the replacement parts.  With printing tolerances, a little ooze, and some very minor Z axis wobble I find that 0.5mm – 1.0mm room on all sides is sufficient to develop parts that print and fit together nicely.

Next up:  A first draft

Posts in this series:

• MakerBot Hero:  Car Keys I
• MakerBot Hero:  Car Keys II
• MakerBot Hero:  Car Keys III
• MakerBot Hero:  Car Keys IV
• MakerBot Hero:  Car Keys Epilogue

Key fob, apart

My mom had been a public school teacher for all of her working life until she retired several years ago.  It was just before she retired that she bought herself a nice new car.  Yesterday she came to visit and she handed me her car keys to grab something from her trunk.  I was horrified at what I saw.  Her car keys, which have a built in electronic car lock/unlock remote, was wrapped in cheap packing tape.  On top of that, it was old packing tape.  So old that it had become stringy and oozey.

I asked what happened only to be told that while at her school she had dropped her keys which immediately cracked at the point where the metal key met the plastic housing for the electronic guts.  The school maintenance worker had kindly offered to fix it up the only way he could – with public school¹ packing tape.

This conversation ensured:

• MakerBlock: “How long has it been like this?”
• MakerBlock’s mom: “Oh, a looong time.”
• MakerBlock: “How long?”
• MakerBlock’s mom: “About two years.”
• MakerBlock: “Two years?!  Mom, you do know I have a machine in the other room capable of just making you a new plastic housing for your keys, right?”²
• MakerBlock’s mom: “Oh, that never occurred to me.”
• MakerBlock: “This is just unacceptable!  You can’t live like this.  I’m making you a new one.”

With the careful application of a utility knife to remove the packing tape and precision screwdrivers to take out the one lone screw, the key fob revealed its secrets, as depicted above.

Next:  Designing the replacement

Posts in this series:

• MakerBot Hero:  Car Keys I
• MakerBot Hero:  Car Keys II
• MakerBot Hero:  Car Keys III
• MakerBot Hero:  Car Keys IV
• MakerBot Hero:  Car Keys Epilogue

1. Read: cheap [↩]
2. 3D printers has essentially been all I can talk about, or write about for that matter, since hearing about them for the first time in April of 2008. [↩]

Naked pull-less cord

I had a wildly productive Saturday morning this last weekend. ¹  I tore through my honey-do list as if it were made of paper. ²  For those of you unfamiliar with the concept, a honey-do list is a list of things your spouse gives you to fix, take care of, or generally address.

The way our list works is that my wife can add anything she wants to the list and I can ignore it all week long.  Come the weekend, I put forward a good faith effort to resolve as many of the things on the list as I can.  There’s no need to knock them all out, just make a dent.  My wife likes this system because she knows whatever she puts on the list will be taken care of one day.  I like this system because I know there’s a finite number of things, and I can do whichever ones I want whenever I want.  We both like this system because we can see the progress being made on things that need to be done around the house.

One of the things added to my list last week was to get a new pull for our kitchen mini-blinds.  The cheap plastic pull had broken or come off at some point and my wife wanted a new one.  The only requirements were that it “just work” and not be ugly.  No problemo.

I designed a simple cylinder with a hole in the top and knocked it out in clear PLA in 6 minutes flat.  For those of you who don’t print in PLA, it tends to hold its heat and stay malleable longer.  This is a mixed blessing.  On the one hand, the cylinder walls were so thin that they weren’t fully cooled before the next layer was put down, making the next layer up squish the lower layer slightly.  (This can be mitigated with any number of Skeinforge tricks such as the Cool or Orbit settings or using Multiply to create more than one instance at a time.)  The result was a slightly twisty, sculpture-esque tower.  Although the gloppiness of the molten PLA obscured the hole at the top of the cylinder, the part was still so hot that I easily widened the hole with a pair of pliers before it had a chance to cool.  This made for a very easy installation. ³

Printed PLA pull

I was fine with using this as a proof of concept, to make sure I had the basic design down, but my wife liked the twisty nature of the pull and that’s what we have on our kitchen mini-blinds right now.  One of the coolest things about this fix is that I was able to design and fabricate a fix faster than you could yank a part off a shelf, all without leaving my house.⁴

Bonus real conversation:

MakerBlock: Wow, honey.  You were totally right to insist I purchase a MakerBot last year!

Mrs. MakerBlock: <eye roll and grin>  Yes, I’m very glad I insisted you purchase a MakerBot.

1. At least, wildly productive for me. [↩]
2. Which, in fact, it is. [↩]
3. Step one: Untie knot in mini-blind cord.  Step two: Thread new mini-blind pull onto cord.  Step three: Tie knot in mini-blind cord. [↩]
4. A MakerBot might not necessarily be the best fix every home repair.  However, it is the best way to get me to start working on a home repair.     [↩]