The Hell Ya Beller Fun with hot, pointy, sharp, and caustic stuff.


Scout: A printable tribot


Here's the first iteration of 'Scout'.  A simple printable frame for a robot based on two continuous rotation servos and an Arduino.

The idea was to limit the number of printable parts and 'vitamins' to the bare minimum and keep the total cost for the bot below $50.  I'll use this to teach the robotics merit badge in December.  Here's how the costs breaks down:



  • 2 Futaba S3003 servos or equivalent (modified for continuous rotation).   $4.50 each.  I found deals on ebay to buy sets of 4 for $16 with no shipping.
  • 1 arduino diecimila.  $20 - 25.  Also an ebay deal.  A nano may work better.  I'm still looking into this.
  • 3 o-rings for tires.  $3.00. Might be possible to replace these with rubber bands.
  • 9V battery
  • adapter
I still have to add some form of input.  This can be as simple as a bump switch (couple bucks)  or I may have enough budget for an ultrasound sensor.  Stay tuned.




I’m now, officially, “Hard To Live With”

The September 2011 issue of Popular Mechanics has their annual "Backyard Genius" feature.  This year, my Bad Idea Pinewood Derby Car made the cut.   Although I've been telling my wife for years that I'm a genius, she's still not buying it.  Now, at last, we have proof.  I'm sure that my days of emptying the trash, doing the dishes, and other un-genius tasks are behind me.


Test Cubes

The reports of the demise of the test cube are, perhaps, premature.  I've read people saying that new firmwares and versions of Skeinforge make test cubes unnecessary, but I'm not buying it just yet.  To be sure, one can get a lot closer to a usable print quickly, but there's still plenty of room to screw things up.


I don't know why I keep all the old junk.  Maybe to keep my humble.  Maybe I hope for a recycling option in the future.   Still, in a weird way, I like to see how far I've come and what I've learned from all this fail.


Fun with Mazes (part 1).

I stumbled across a very interesting project called Theseus which is a maze generator library.  It has some impressive algorithms for generating mazes of various sizes.  The focus, however, is to produce a graphic which means drawing the walls.   I thought it would be interesting to generate a maze to be routed out on a CNC router and that would mean I'd need lines that define the centerline of the passages where the router bit will travel.

The developer is a great guy and he offered to take a look at modifying Theseus to produce .dxf files!  In the meantime we started trading emails and discussing a 3d cube maze where the passages turn corners from face to face.  He got Theseus to produce such a maze (unfolded) like this.


I took the top section, worked it through HeeksCAD to produce something printable.

Here's the first attempt:

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Deathtrap joins the collection

I finally got some pictures of my son's derby car for his Bear den entry.

Deathtrap closed

Deathtrap open with dearly departed gummy skeleton

This year we built a casket on wheels.  Both parts of the lid are hinged and it carries a 'Gummy' skeleton as a rider. Obviously he had adult help on this design.  The main parts were cut out on the CNC router.  But you might be surprised how much he did himself:

  • Sanding (They say sanding builds character )
  • soldering the rails together with the torch (close supervision)
  • Staining and sealing
  • polishing axles.
  • Shaping, sanding, lubing wheels.
  • Testing weight.

The final assembly and alignment we worked on together.

Ross also enjoyed correcting adults who referred to this as a coffin.

It's fun to see the boys progress from doing very little as tigers to doing almost everything as Webelos.   Our shelves are really filling up with some cool cars and 'Deathtrap' joins a distinctive collection.

Pictures of the other cars after the jump.


Bad Idea

It's Pinewood Derby season again and I kinda enjoy making derby cars.  This year, my youngest son and I made an awesome car for his bear den division.  It came out great and I'll do a blog post on that one as soon as I get some good pictures.

We also have an 'open' class where the rules are a little more relaxed.  Last year's car was fast and I actually won but not because I was the fastest. I was really impressed by a c02 powered car that another dad had made.  He had trouble keeping it on the track, but it was REALLY fast.

This year, I decided to follow his lead but with more power.  I designed this motor to be printable on a 3d printer like a reprap or makerbot.  All the files have been released on Thingiverse.


HeeksCAD Article

My  friend Dan Falck and I wrote an article about HeeksCAD.  It got put in a magazine that looks like this:

They sell it at these places:


Two very handy fixes for HeeksCAD.

Dan Heeks made two fixes to HeeksCAD today that made my life a lot easier.

Sometimes you have a sketch that you want to extrude to multiple faces.  For example you have a sketch like this:

And you want a solid like this:

In order to extrude a solid, you need a face.  To get a face, you need a sketch.  That means the two inside lines have to be duplicated and three separate sketches have to be created, faced, extruded.  With simple parts this was a pain, but doable.  Complicated parts meant juggling dozens of sketches.

The fix allows you to select a group of elements from a sketch and create a face directly from them.  To use it, make sure you un-tick 'sketches' from the selection options.  Then select the elements that make up the face you want and right-click to 'convert sketch to face'

The other fix added today will be especially appreciated by anyone using HeeksCAD to design parts for 3D printing.  You can now select individual solids from your design and save them out to .STL files.

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HeeksCNC does additive printing…sort of .

Here's my first attempt at using HeeksCNC to generate g-code for my makerbot.  I wanted to print a part with a screen.  That should be a pretty easy part, but since skeinforge wants to slice a .stl,  it turns out hand coding it is easier.  Enter HeeksCNC.  I used the pocketing operation with a custom post-processor to do the work.  This is a very limited application, but it shows the promise of using HeeksCNC operations.



4:45pm Labor Day.  Chatting with my wife in the garden.  She uses these cattle panels to form an arch between a couple of the beds.  It works as a trellis and is very stable.  However, the 10' panels will reach from the left of one bed to the left of the other spanning the walk way and it's pretty easy to smack your head.  It would be nicer if the panels were longer to span higher and farther.

5:00  Nap time.  I start thinking about welding a couple panels together.  I think it would be nice if I could hook them together to experiment  with how much overlap is needed to get the length and flex right.

5:10  It occurs to me that I could print out a couple plastic clips.

5:15 Draw it in qcad.

5:20 Heekscad to convert it to a 3D object and export as an .stl

5:22 Skeinforge for slicing.

5:30 ReplicatorG for printing.

5:45 print in progress (warm up takes a bit)

6:00 First prototype printing is done.

6:10  Clean it up a bit.

6:15  Test fit.  It's too small.  I didn't account for the natural variability of the panels and the gap that is forced between by the nearby welds.

6:20  Stretch it a bit.

6:40 Second prototype done.

6:50pm Labor day.  Perfect fit.  The clip fits tight but has enough give to stretch into place.  The plastic is very strong.  I don't know how they would hold if I tried to bend the joined panels.  Maybe I'll print a few more and try it.  Good enough for today.

7:00  Blog about it.  In the end, it took longer to blog, edit pictures, and upload them then it did to make the part.

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