MakerBot Industries

Evolution of a replacement caster

Robert Bowbridge used his MakerBot print his new designs for a replacement caster for his dining room table.  One of the amazing things about having a 3D printer in your own home is that there’s no harm to trying a new crazy design or improvement.  There’s also no harm in trying out a rough draft and refining the designs as you go along. Robert offers two great tips for designing and working with a MakerBot:

1. Design a simple model, add the high-accuracy features, print, test for fit.  Once the important sections of the replacement part have been dialed in, begin playing with and improving the design.
2. If you’re using Google Sketchup, try the Rounded Corners plugin by Fredo6 to round or bevel edges.  You can do this manually in several ways, but they are time consuming.  Robert noted an issue with Sketchup not correctly handling intersections between “extruded” sections.

Google Sketchup is still my digital design program of choice for its gentle learning curve.  I’ve noticed the same issue with Sketchup, namely that it will allow objects and geometries to collide with one another without actually intersecting.  Basically, there’s no line between the colliding objects.  This can cause all kinds of design and printing problems.

If you have this problem too, here’s a work around:

1. Select those objects, lines, and surfaces you wish to have intersect.
2. Right click
3. Intersect -> Intersect Selected
4. Done!

(For more thoughts on designing with a 3D printer, I highly recommend Forrest Higgs’ recent blog post on the topic.)

Calling all NYC MakerBot operators! We’re building a bot farm and we need your help! Today (Thursday, September 2nd) at NYC Resistor (map) we are throwing a build party. The goal: assemble three MakerBots in four hours. Drinks and snacks will be provided.

A bot farm is a group of MakerBots available to a group of people ready to print whatever is wished. We would love to print more of the great things popping up on Thingiverse, but here at the bot cave our machines are mostly used for developing future hardware and software. To increase the awesome we need to increase the number of bot hours available for printing. We need more bots and we need your help building them.

Everyone is encouraged to attend. There will be three or more kits for assembly. Just let us know you came for the build party and we’ll get you started on a task. If you’re thinking about buying a Cupcake CNC, this is a great opportunity to experience the build process. Feel free to bring your own MakerBot and work along with us. Several MakerBot employees will be in attendance, building bots and ready to help. We’re looking  forward to seeing you there.

Location:
NYC Resistor, Floor 4
87 3rd Avenue,
4th Floor
Brooklyn, NY 11217

Time:
September 2nd
6 – 10 pm

colorbroken's Film Advance Crank

Colorbroken on Thingiverse just uploaded a 120 Film Advance Crank.  Replacement cranks and knobs are nothing new to Thingiverse.  Replacement cranks and knobs are probably the first repair people think of when looking at a MakerBot.  They’re easy to model, small enough to print without too many problems, and relatively easy to print.

What makes this particular knob special is how colorbroken designed it.  A typical knob design would include a thin cylinder sitting atop a flat… knobby bit.  Using Skeinforge, you would then set the desired fill ratio of plastic.  However, there are different benefits to different fill ratios. ¹  The problem with a heavy fill is that the part uses more plastic, takes longer to print, and is heavier – the upside being it will be a more sturdy part.  The problem with a low fill is the part is more sparse and potentially weaker² , but it prints much quicker and conserves plastic.

But what if you need one area of the part to print quickly and another area of the part to be extra sturdy?

Well, colorbroken thought of an interesting way around this problem.  By putting a hollow core inside the axle for the knob, the MakerBot printed a thick ring inside the axle.  The end result is the knob is whatever fill he specified, but the axle has a thick sturdy hard core running all the way through it providing additional strength and durability.  I love this design tip for its simplicity and effectiveness.

Thanks for the idea colorbroken!

1. Fill ratios aren’t rocket science.  I use 20% fill on all of parts unless I absolutely have to change that setting. [↩]
2. Although, I’ve printed amazingly sturdy parts using a fill as low as 10%.  It’s really a testament to the strength of ABS. [↩]