Category Archives: Things I Learned

Things I learned, usually the hard way, so you don’t have to!

Sometimes a good deal isn’t

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$3 utility knife and $1 utility knife

$3 utility knife and $1 utility knife

Several months ago I made an impulse buy at the local hardware store.  I picked up a utility knife that came with 6 blades for $1.  It was a good deal, if even for just the razors, and I couldn’t find my usual $3 knife.

Here they are, side by side.  My trusty Stanley utility knife on top.  This knife has a good heft, stores a few extra blades in its handle, and is slightly wider, making for a more comfortable grip.  The two sides also interlock as well as screw into one another.  Clicking the blade out another notch requires a small amount of force – just enough so you’ll never do it by accident – and so that it will stay in each notch as long as you don’t intentionally depress the button.

On the bottom is my no-name brand knife.  It’s lighter, slightly thinner, rattles with the extra blades inside, and the button to extend/retract the blade has a little bit of wobble and play to it.  Also, there’s no interlocking between the two halves.

What an extra $2 buys you

What an extra $2 buys you

I discovered that the seams between the two halves of the cheapie utility knife left a lot to be desired.  While using the knife I felt a sharp poke in my palm.  Turns out that some of the spare razor blades were poking through the incomplete seam.

So, if you’re headed to the hardware store, invest the extra $2 in the better knife.  :)

If I only knew then what I knew now

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I’m going to warn you right now, this post has nothing to do with RepRap or MakerBot.

Three years ago I was  unemployed with a big fat mortgage payment.  The year that followed my newfound unemployment was a roller coaster.  I took contract work for others, I had a few small clients of my own, taught myself how to program in PHP/MySQL, built my first website, tried to turn that website into a business, did some freelance programming, and generally did whatever I could do in order to make ends meet.  It was an exciting and scary time.  About a year after becoming unemployed I accepted an unsolicited job offer and have been there ever since.

I wish that I had read Tim Ferriss’ Four Hour Work Week and Guy Kawasaki’s Art of the Start back then.1  I just finished reading the FHWW for the first time and I’m glad I bought it.  Like Reality Check and The Art of the Start before it, these are books I’m positive I will be using as reference manuals.  It would have been sooo helpful to have Guy’s book around when I started my first website business.  I needn’t have learn so many lessons the hard way.

The same goes for the FHWW.  Tim’s book includes a lot of advice that would have been invaluable to me as an unemployed entrepreneur-by-circumstance2 .  Basically, when I had a surplus of time and deficit of money.  With a steady job I no longer have a deficit of money3 , but I do have a deficit of time.  Some days I will daydream about what I could accomplish if only I had a little more time in the day.  I won’t know until I try, but the Four Hour Work Week may just be my chance to find out.

Suffice it to say, I’ve read both books and will probably re-read both again soon.  If you’re unemployed or want to start a business4 , you should definitely pick up both of these books.

Okay, back to your regularly scheduled nonsense.  :)

  1. Guy’s new book Reality Check is an updated and expanded version of “The Art of the Start.” [↩]
  2. As opposed to an entrepreneur-by-choice [↩]
  3. And, by no means a surplus!  Haha! [↩]
  4. Perhaps a MakerBot or RepRap based business? [↩]

What’s the cost of printing with a MakerBot?

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I’ve wondered for a while about the cost of operating a MakerBot.  Let’s break it down and see what happens:

  • Plastic. According to some calculations on the MakerBot Operators group, the cost of MakerBot ABS is around $0.03 – $0.04 per cubic centimeter based upon a price of $70 for 5 pounds (or 2268 grams) of ABS, a density of 1.2 grams per cubic centimeter. 1  Using the current prices of $81.36 for a 5 pound coil after shipping, I calculate the price of ABS at $0.035 per cubic centimeter.  Since we’re talking about such large numbers, let’s just round on up to $0.04/cc.
  • Time. Skeinforge has been estimating about 85 minutes to print 19 cc of plastic.  This comes to about 4.5 minutes/cc.
  • Electricity. At at $0.20/kWh, a MakerBot probably draws around $0.03 per hour.

Thus,we may estimate the cost of operating a MakerBot in terms of consumption of goods and resources (excluding computer, human, and MakerBot time and wear and tear) as follows, where V is the volume of the extruded object in cubic centimeters or “cc”:

Supposing I wanted to recoup the entire cost of my MakerBot to date and spread it across the entire life of a single 5 pound roll of ABS. 2  Let’s round the cost of the MakerBot, all repairs, and all extra MakerBot related materials up to $1,500.00.  One 5 pound coil would have 1890 cc’s of plastic.  This would come to $0.794 per cc of plastic.  So, I would suggest the cost of buying a MakerBot and printing off an entire coil of plastic would probably end up costing you about $0.85 per cubic centimeter of plastic.

Resource cost of printing a 19cc totally MakerBottable 3x2x1 Rubik’s Cube is $0.80.

Actual pro rated cost of printing a 19cc totally MakerBottable 3x2x1 Rubik’s Cube is $16.15.

Absolute cheapest MakerBot usage I’ve seen anywhere at Metrix:Create for members printing from Thingiverse is $0.30/minute, which would print the totally MakerBottable 3x2x1 Rubik’s Cube for $25.65.

Cost = V * ($0.04/cc + $0.0025/cc)

  1. No one has yet quoted me a price on a pint of tears. [↩]
  2. Printing an entire coil would take about 142 hours. [↩]

New 3x2x1 Rubik’s cube design – totally printable!

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X-Ray view of the 3x2x1 puzzle cube

X-Ray view of the 3x2x1 puzzle cube

This is easily my most intricate digital design for the MakerBot yet.  It’s a 3x2x1 variation on the Rubik’s cube puzzle I had posted earlier.

This version incorporates the prior improvements as well as designing a connector system inspired by R3bbeca‘s beco block connectors.

This has enabled a totally printable toy.  This just makes me happy. 1  The idea that I can crank out a set of these parts, clean them up a little, and just snap the toy together is just amazing.

TomZ‘s original 1x2x3 “friendlier” Rubik’s cube designs were also totally printable – but required a printed pin that was later glued in place.  I like the ideal of all printed parts – but strongly prefer a design that can later be disassembled easily.  And, as I mentioned above – the ability to hand assemble the toy is important to me.

I wasn’t able to recreate R3bbeca’s female connector designs2 so I made a simplified version that should suffice.

The simplified connection mechanism is essentially two plastic fingers that will (hopefully) pinch the barbell into place.  This was made by designing the outline of the gripping “fingers,” creating a horizontal cylindrical hole slightly larger than the intended end of the barbell, then creating a vertical cylindrical hole in the center for the barbell to be inserted through, then a bit of cleanup.

The biggest potential problem is that this design will require a carefully tuned ‘bot.  The center cube pieces have a lot of stuff packed in there – semi-circular slots for the semi-circular tabs, connectors for the barbell, and thin walls separating things.  With those thin walls and interior overhangs, this may be a difficult design to print.

I think Bender is up to the task, but we’ll see in a few hours.  :)  I can’t wait to print this!

For me, having a MakerBot is like waking up to Christmas every morning.

Oh, and before I forget, if you want one of these – leave a comment or send me an e-mail through the Contact page.  Make me an offer.

  1. Perhaps a little prematurely, since I haven’t actually printed this yet… [↩]
  2. I believe I’ve already sufficiently lamented my inability to understand women and their mysterious lady ways. [↩]

How do upgrade your extruder firmware

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Just as an FYI for anyone who’s having trouble upgrading your MakerBot Cupcake CNC plastruder firmware, the instructions built into ReplicatorG don’t tell you to unplug the TTL cable from the motherboard and plug it into the extruder board.

So, save yourself 5 minutes of frustration and googling for the answer…  and just plug the TTL cable into the extruder board.  :)

Things I learned while trying to unclog my extruder barrel

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I learned a lot this morning!  And now you don’t have to learn, as they say, the hard way.

  1. Never ever ever use tiles. I thought I was being very clever with the tile idea.  Apparently leftover kitchen tiles can shatter and fly apart when you heat them.  Who knew?
  2. Instead, use a big piece of metal to hold the barrel. I ended up using a piece of metal I had laying around to hold the extruder barrel and weight it down with a rock.  This worked perfectly.
  3. Don’t tilt your blow torch too much. Probably an elementary thing for most people.  My torch kept going out when I tilted it too far – probably a safety feature.  This meant I had to change the set up so that the barrel was somewhat elevated so I could keep the torch mostly vertical.
  4. Keep a friend handy. This was one of my few ideas/preconceptions that actually worked out.  Thankfully I didn’t need him to use the fire extinguisher or garden hose, but I very well could have.
  5. Don’t leave a nut on the extruder barrel. At the last minute I decided to screw a nut part way on the barrel.  I figured I could prop the extruder barrel up in the washer, heat it, and not discolor the nut or washer.  This didn’t work out because I needed to apply more heat to the barrel to get the clog out.

MakerBot extruder clog experiment

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DO NOT USE THIS extruder unclogger setup

DO NOT USE THIS extruder unclogger setup

UPDATE: DO NOT USE TILES!!!  THEY WILL SHATTER!  READ LATEST POST!

The bad news is this is my first clogged extruder.  The good news is I have all the spare parts to whip up a new extruder, no problem.  That means I can experiment with wild abandon!  My backup plan is to slice and dice the PTFE insulator into washers.

Having drilled out most of the plastic clog from the barrel, it’s mostly empty.  The PTFE is in pretty good shape with the threads intact, if a little worse for wear.  My plan to get the remaining plastic out of the nozzle is to put the nozzle/barrel assembly into the large washer upside down and prop it up on some ceramic tiles.

My hope is that by applying a heat source to the nozzle the plastic will just drip/fall out.  The suggestion for using a blow torch to clear out the barrel and nozzle comes from Rick Pollack / MakerGear.  Thanks again Rick!

By the way, wicked Google Sketchup skillz, no?

Things I learned while soldering opto-endstops

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The opto-endstops marked the very first parts I had to solder for this MakerBot.  Not having soldering anything more complicated than two wires together, this was an adventure and learning experience.  Here’s what I learned today:

  • The 3-pin connectors used for two of the opto-endstops (on the Y-axis stage) are in the Generation 3 MakerBot Electronics Kit (Mostly Assembled) with some of the other connector bits.  I was a little confused about this for a while.
  • It helps to lay out all the little bits in an organized fashion beforehand.
  • Keep a long thin rigid stick handy for bending delicate leads into the circuit board holes.
  • Although I read the RepRap electronics fabrication guide and found it helpful, I still felt a little lost.  I found the most effective way to solder the parts in was to:
    • Get the soldering iron good and hot
    • Put the leads through the holes
    • Bend the leads a little so that they stayed in place
    • Flipped the board over so the leads were sticking up
    • Touched the solder to where I wanted the joint
    • Gently stroked the solder with the soldering iron tip towards the joint
    • This process seemed to create a pretty good joint
  • You’re going to burn a finger at some point, accept it.1
  • This almost goes without saying, but go slowly.
  • Check and double check the orientation and placements.
  • I found it helpful to take a large sheet of aluminum foil and shape it into a tray.  This helped contain the parts I was working on and was a good way to catch the flying leads that I clipped off.
  1. I burned two. [↩]