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


Launcing a new project – My OpenROV build

Anyone who knows me knows that I totally dig submarines and sub movies.  Whether it's a great one like Crimson Tide or a total pooch like Down Periscope, I gotta watch it.  Submarines are the ultimate toy and the closest thing to real spaceships we're likely to see for a long time.  When I first stumbled across the OpenROV project, I was hooked at once

Obviously an ROV isn't the same as a submarine, but it offers many of the same benefits and even a few advantages -- like the ability to actually see while remaining well above crush depth.  In the past, ROVs have been expensive so the design and testing cycle is long and they're reserved for high-value missions.

The OpenROV project is very young and they're still getting their legs under them but it has some really cool things going for it.  It's designed to be inexpensive, flexible, and require few specialized tools.  The physical structure is almost all laser-cut acrylic.  The bottom side electronics are meant to be open hardware like a Beagle board or Raspberry Pi.    That means the ROV can be cheap enough that innovations and improvements can be tried out quickly even if they risk the ROV.   It doesn't have anywhere near the depth capability of a 'real' ROV but at theoretical depth of 100 meters it could reach most of the continental shelf.  That's a lot of room to play.   My goals are a bit more conservative.  A 5 acre pond in my Missouri back yard that I'm certain is, like McElligot's Pool, connected to the deep ocean.  There's no telling what I'll find down there.

OpenROV recently started a Github repo to host hardware design files and software.  They seem to be working in Autodesk Inventor which is, unfortunately, a closed format.  A friend converted the files to both STEP and IGES for me and I was easily able to import them into FreeCAD.  From there I was able to assemble it in the computer to produce this:


I've forked the OpenROV repo and added my converted files and FreeCAD file.  FreeCAD doesn't support any bending of solids which is necessary to model the outside shell.  The friend who converted the files made both a folded and unfolded version of the shell for me.

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Sliptonic has a (frickin) laser!

Well, not quite....yet.

I found an old Universal Laser Systems model 25A for sale at a surplus auction.  It looked to be in good shape and went cheap.  After I got it home and cleaned up, I found that I couldn't get the laser head to fire.  I called in some expert assistance from Columbia Gadget Works, but no luck was to be had.  I've since learned that RF laser tubes have a life expectancy of about 10 years before they need to be re-gassed.  Re-gassing this one is prohibitively expensive and would *only* get it back to 25W.  Instead, I'm looking at replacing the RF laser with a chinese glass tube.  This should take it to 40W.

Either way, this looks to be a fun project.  Here's a picture.



2011-11-15 10.49.19


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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