Wednesday, July 23, 2014

A 3d printer hot end. Everyone's favorite late night project.

Going on two years ago, I got a kit to build a hot end for my 3d printer. It's sat in my car since then. DrD kept pushing me to get my 3d printer going.. so step one, is make something hot.

The hot end I have is a Makergear V2 hot end.  Hopefully they'll read this, and take my recommendations to heart.  They're on the V3, but the issues I ran into, still stand.  (I think.)

At about 11pm last night, I spilled the contents of the bags out on shop rag and got to work.
Digging in, I started to build the actual hot end.  I expected that my kit would have cohearant start to finish instructions.  As it turns out, there are two separate sets, and a lot of "uh.. what's this?" bits in the baggies.  A chart identifying what the bits are would be useful.  For instance, the teflon tape comes wrapped on a little plastic spindle, that looks like a teflon tube.  Nothing about it said "this is the teflon for your hot end" so I ended up using my own teflon tape. 

As I was following the hot end instructions, I ran into a step that said "install your ceramic hot end."  And.. that was really about it.  No link to those instructions.  And no further detail.  Just suddenly a grey blob with wires showed up in the directions. 

It turns out, that the other baggie, with the brass threaded inserts was the ceramic heater kit.  I found the page on how to build that, and went about building my two heaters. 

Here's my wound heater.  What would be nice, is if they told you what the orientation of the core was.  As later on, when you're trying to attach the hookup wires, it starts to matter a little bit.  Also, the insulation on the nichrome wire, is wound on, so you can futz with it and unwind it.  The first few times I went at it, I tried a wire stripper.  ... don't use a wire stripper.

The next step is to protect, and insulate the leads.  Here's where things got a little wacky.  At these steps, knowing that you next move is to fold them back up onto the sides of the heater core, would be useful information.  Also, knowing they need to clear the teflon sleeve would have helped. 

The wiring setup, is on the next page, which doesn't have a well indicated link.  That means I didn't know there was a second page until I got there.  

At least it looks good.  Now they tell you to cure the core.  They don't hint that it will need a second curing until the next page.  Knowing there's a second cure coming, would have helped a bit.

I managed to get over those hurdles.   Here's what it's supposed to look like before the second curing.

Now that it's all encased in Cecobond, it's time to make sure it's all working.  6.0ohms... right on the money.  I then went an made the second ceramic heater core. 

I didn't take any shots of the rest of the mechanical hookup.  The two copper wires go to the thermistor.  The thermistor is held on with Kapton tape.  Oh, and it's now 2am.

 Next?  I need to get a x-y-z table set up so I can test this thing out.

Monday, February 17, 2014

3D printing. In no uncertian terms.

Today I was challenged to make a 3d printer that wouldnt' need to be re-leveled anytime it's moved. 

The Prusa designs lack a rigid base, so every time they're moved, the table needs to be re-leveled. 

Saturday, November 30, 2013

Doing some other things. Bike Time at PumpingStation:One

As it should be well known by now, I'm a fan of the whole hackerspace thing.  Recently I've signed up, and I'm helping maintain the Bike Time office hours at

So.. here's what we've done:

Fixing bicycle tubes:

Wrapping bar tape:

Installing a new crank and bottom bracket:

Saturday, November 9, 2013

Rewriting the screenplay for Ender's Game.

Recently, Ender's Game came out as a movie.  The movie felt like it completely missed the (unintended) feel of the book. Instead of being about kids who figured out the strings, and started to pull back, the movie was about the string pullers.

So for a good clean Saturday's entertainment, Chaosmonk and I sat down and tried to rewrite the movie.  This is what we came up with.  It needs another pass, to develop dialogue, and settings.  And then talk throughs, to verify running times.  

We think that this could have been "the right solution."

Without further ado:

Ender's Game "Done Right"

15 minutes - Ender's set-up, travel to Battle School
30 minutes - Ender is a soldier, Ender's classes
35 minutes - Ender as a commander
10 minutes - Ender and Valentine
25 minutes - Command School
5 minutes - Epilogue

Act I: Ender Is Introduced - 15 minutes

1.5 minutes - Montage of Bugger invasions, text introduction & set up of counterattack
1.5 minutes - Fleet authorizes Ender/Ender is born
5 minutes - Ender at school
2 minutes - Peter/Valentine/Ender is recruited/Peter mistreats Ender
5 minutes - Ender in shuttle

Act II: Ender at Battle School - 30 minutes

15 minutes - Battle School setup
Ender meets launch group - grabs two lockers
Ender finds game room - defeats older kids from Salamander - Bonzo & Rose de Nose in background watching
Free Play game - Ender defeats unbeatable choice
First day of classes - Bernard conflict
First time in Battle Room - battle mechanics - Ender is confused by zero G
Classes and development - ships heading for Bugger homeworld - acceleration of Ender's classes

15 minutes - Salamander and Rat armies
Bonzo is annoyed at Ender's youth/beating game vs. Salamander kids
Battles where Ender does not participate - frustration/boredom/learning - Ender at top of stats
Free practice with launch group and Petra
Ender learns from watching Salamander/enemy's gate is down
Ender gets notice of transfer right before final battle
Final Salamander battle - Ender saves Salamander from a loss by disobeying Bonzo in defiance

1st battle - Ender is ordered to attack blindly - takes out a huge portion of the enemy as they emerge - Rat wins
Free practice becomes bigger & includes other commanders
Other armies begin to use Ender's tactics - more battles - Ender drops in standings, then returns to top
Ender misses Valentine - writes a letter
Ender and friends are attacked in practice by Bonzo and thugs
Ender remains at top of list throughout battles
Ender is assigned a command

Act III: Dragon Army - 35 minutes
Bean leaves office as Ender goes to meet Graff to get army roster - finds out they are all early promotions/people held back
Ender meets army and goes to practice immediately - Ender is a hardass
Whole scene: Ender's first practice
Ender changes traditional tactics - new soldiers at front of bunk - 5 toons vs. 4 - gives toon leaders autonomy
  to start training on their own while Ender researches videos of battles
Ender starts battles daily - less warning - rules change
Ender assigns Bean command of special group
Ender gets burned out - starts to become more defiant/more withdrawn - tells army "no practice"
Ender gets attacked by Bonzo
Ender gets final battle orders - second battle right after killing Bonzo, vs. two armies
WHOLE SCENE: Conversation with Bean - Ender's toon leaders are all transferred
Ender is reassigned to Command School while Bean is present, skipping Pre-Command
Ender refuses to proceed

Act IV: Ender and Valentine - 10 minutes
Graff and Anderson discuss Ender's mental state & letter - reference to game - "behavior in game is erratic"
Ender is flown back to Earth
Scene on lake - Valentine reminds him what he is fighting for

ACT V: Command School - 25 minutes
Ender lands on asteroid - is explained that it is a Bugger captured base
Explanation of Bugger technology - ansible, zero G
Introduction to simulator - mechanics are similar to Battle Room - simulated team leaders
Ender gets successful at defeating computer battles/missions
Introduction to Mazer Rackham in Ender's room
Introduction to weapons & bugger philosophy - Dr. Device - buggers destroy tug that found Eros
Mazer starts "planning" Ender's battles - Ender meets up again with jeesh
Ender and jeesh start getting burned out again
Final battle - Ender tries same tactic as in last Battle School battle
Ender comes out - people are cheering, hugging, Ender and jeesh are baffled
Revelation of victory - Ender's dilemma

Act VI: Epilogue
You can't go home.
Colonisation plans, yes, you can take valentine.
Close of movie.. the tug firing into space
Credits roll - scenes of jeesh returning home - Ender stands at window of tug gazing back

Nano DLG Plans - A cheap fast and easy discus launch glider.

The people who run were generous to give away the plans for their tiny DLG.  The plans require you cut out the parts by hand.. and aren't very clean if you'd like to use a laser cutter to make the parts for you.

So I did this:

That drawing has hard lines for all the parts you could use a laser cutter, or cnc router to cut it out for you.  I have the full SVG posted at the end of the post.

When I say tiny, it's in the 50g range.  Happily, radios in that class are cheap enough to buy these days.

Here's their demo video:

So I've built a couple of them.  I don't have much experience with solid balsa building, so.. it's not going badly.  But I"d like to make a few more tries.. and sadly, that means making the plane again.. and again..  That's where the laser cutter comes in.  With the laser cutters I can make a kit of parts in 15-20 minutes, instead of two evenings of hard work.  I suspect I"ll be able to make one that weighs 45grams eventually.

Speaking of construction, here's the assembly video.
I'd recommend turning off the audio.  It's a little to jesus-y for me.

Here's that SVG file I promised.

And here's the link to the original plans, and website:

If you build one, e-mail me!  and them.

Tuesday, October 1, 2013

A DIY Led Light Bulb, Courtesy of and

Purple looks good on green, doesn't it?
I'm an avid listener to The Amp Hour and they interviewed the guy behind OSH Park.  @Laen was a heck of an interview, and made me want to try out his service.  But my circuit drawing skills are, well we'll say, lacking.

I also hang out on IRC, and one day, in #electronics, someone posted a link to this:  I needed it.  It was just to clever not to have a copy of my own.  A few minutes later, I had an OSH Park account, and had ordered copies of the board.  

The circuit is really simple, and easy to follow.  It's a bunch of leds, a bridge rectifier, a big cap, a couple of current limiting resistors, and a resistor to make sure the cap discharges.  I could guess at the design values... and had already decided on what I was going to use, but, I thought it might be a good idea to contact the designer.

The designer of the board, is a seemingly prolific electronic artist, who turns out some really neat LED projects.  His site is:  Aki was a big surprised when I contacted him, but was happy to help.  He sent me a copy of the schematic that he built the circuit from.

A few days later, this showed up at my door:

My friends and I were wondering if I would need to trim the board, turns out that the solid black line is a routed line.  Not a bad looking board?

As soon as I had the schematic from Aki, I went and ordered the right parts.  But I couldn't resist putting int he parts I had on hand.  
You don't really grasp how many solder joints are involved in a 48 led bulb until you need to start trimming the legs off.
I didn't ask Aki how he did the hookups for the light socket, I suppose I should have.  Here's what my bulb looked like after getting my contacts in place, and all the LEDs soldered in.  
And since I'm silly, I ordered most of the finishing parts from Chinese suppliers.. it was another week before I could finish the board.  Here's the final product:

Oh, and I did a little video of the project too:

Thursday, August 8, 2013

Wood structural information, for building cheaper, or building where spruce isn't available.

Stolen, blatently, from Autodidact on the HBA forums.  :

Note: s/w=(Modulus of Rupture)/(weight/ft3)

Sitka Spruce

Common Name(s): Sitka Spruce
Scientific Name: Picea sitchensis
Distribution: Northwestern North America
Tree Size: 160 ft (50 m) tall, 5 ft (1.5 m) trunk diameter
Average Dried Weight: 28 lbs/ft3 (455 kg/m3)
Specific Gravity (Basic, 12% MC): .36, .46
Janka Hardness: 510 lbf (2,270 N)
Modulus of Rupture: 10,150 lbf/in2 (70.0 MPa)
Elastic Modulus: 1,600,000 lbf/in2 (11.03 GPa)
Crushing Strength: 5,610 lbf/in2 (38.7 MPa)
Shrinkage: Radial: 4.3%, Tangential: 7.5%, Volumetric: 11.5%, T/R Ratio: 1.7

Douglas Fir


Common Name(s): Douglas-Fir
Scientific Name: Pseudotsuga menziesii
Distribution: Western North America
Tree Size: 200-250 ft (60-75 m) tall, 5-6 ft (1.5-2 m) trunk diameter
Average Dried Weight: 36 lbs/ft3 (570 kg/m3)
Specific Gravity (Basic, 12% MC): .45, .57
Janka Hardness: 620 lbf (2,760 N)
Modulus of Rupture: 12,500 lbf/in2 (86.2 MPa)
Elastic Modulus: 1,765,000 lbf/in2 (12.17 GPa)
Crushing Strength: 6,950 lbf/in2 (47.9 MPa)
Shrinkage: Radial: 4.5%, Tangential: 7.3%, Volumetric: 11.6%, T/R Ratio: 1.6

Alskan Yellow Cedar

Average Dried Weight: 31 lbs/ft3 (495 kg/m3)
Modulus of Rupture: 11,100 lbf/in2 (76.6 MPa)
Elastic Modulus: 1,420,000 lbf/in2 (9.79 GPa)
Crushing Strength: 6,310 lbf/in2 (43.5 MPa)

Cedar of Lebanon

Average Dried Weight: 32 lbs/ft3 (510 kg/m3)
Modulus of Rupture: 11,890 lbf/in2 (82.0 MPa)
Elastic Modulus: 1,465,000 lbf/in2 (10.10 GPa)
Crushing Strength: 6,090 lbf/in2 (42.0 MPa)

Port Orford Cedar

Average Dried Weight: 29 lbs/ft3 (465 kg/m3)
Modulus of Rupture: 12,290 lbf/in2 (84.8 MPa)
Elastic Modulus: 1,646,000 lbf/in2 (11.35 GPa)
Crushing Strength: 6,080 lbf/in2 (41.9 MPa)

Loblolly Pine

Average Dried Weight: 35 lbs/ft3 (570 kg/m3)
Modulus of Rupture: 12,800 lbf/in2 (88.3 MPa)
Elastic Modulus: 1,790,000 lbf/in2 (12.30 GPa)
Crushing Strength: 7,130 lbf/in2 (49.2 MPa)

Radiata Pine

Average Dried Weight: 32 lbs/ft3 (515 kg/m3)
Modulus of Rupture: 11,480 lbf/in2 (79.2 MPa)
Elastic Modulus: 1,458,000 lbf/in2 (10.06 GPa)
Crushing Strength: 6,030 lbf/in2 (41.6 MPa)

Scots Pine

Average Dried Weight: 34 lbs/ft3 (550 kg/m3)
Modulus of Rupture: 12,080 lbf/in2 (83.3 MPa)
Elastic Modulus: 1,461,000 lbf/in2 (10.08 GPa)
Crushing Strength: 6,020 lbf/in2 (41.5 MPa)

Shortleaf Pine

Average Dried Weight: 35 lbs/ft3 (570 kg/m3)
Modulus of Rupture: 13,100 lbf/in2 (90.3 MPa)
Elastic Modulus: 1,750,000 lbf/in2 (12.10 GPa)
Crushing Strength: 7,270 lbf/in2 (50.1 MPa)

Slash Pine

Average Dried Weight: 41 lbs/ft3 (650 kg/m3)
Modulus of Rupture: 16,300 lbf/in2 (112.4 MPa)
Elastic Modulus: 1,980,000 lbf/in2 (13.70 GPa)
Crushing Strength: 8,140 lbf/in2 (56.1 MPa)

California Red Fir

Average Dried Weight: 27 lbs/ft3 (435 kg/m3)
Modulus of Rupture: 10,370 lbf/in2 (71.5 MPa)
Elastic Modulus: 1,483,000 lbf/in2 (10.23 GPa)
Crushing Strength: 5,410 lbf/in2 (37.3 MPa)

Noble Fir

Average Dried Weight: 26 lbs/ft3 (415 kg/m3)
Modulus of Rupture: 10,790 lbf/in2 (74.4 MPa)
Elastic Modulus: 1,619,000 lbf/in2 (11.17 GPa)
Crushing Strength: 5,730 lbf/in2 (39.5 MPa)

Pacific Silver Fir

Average Dried Weight: 27 lbs/ft3 (435 kg/m3)
Modulus of Rupture: 10,240 lbf/in2 (70.6 MPa)
Elastic Modulus: 1,681,000 lbf/in2 (11.59 GPa)
Crushing Strength: 6,060 lbf/in2 (41.8 MPa)

White Fir

Average Dried Weight: 26 lbs/ft3 (415 kg/m3)
Modulus of Rupture: 9,700 lbf/in2 (66.9 MPa)
Elastic Modulus: 1,485,000 lbf/in2 (10.24 GPa)
Crushing Strength: 5,740 lbf/in2 (39.6 MPa)


Average Dried Weight: 29 lbs/ft3 (455 kg/m3)
Modulus of Rupture: 10,100 lbf/in2 (69.7 MPa)
Elastic Modulus: 1,580,000 lbf/in2 (10.90 GPa)
Crushing Strength: 5,540 lbf/in2 (38.2 MPa)

Western Hemlock

Average Dried Weight: 29 lbs/ft3 (465 kg/m3)
Modulus of Rupture: 11,300 lbf/in2 (77.9 MPa)
Elastic Modulus: 1,630,000 lbf/in2 (11.24 GPa)
Crushing Strength: 7,200 lbf/in2 (37.3 MPa)


Average Dried Weight: 42 lbs/ft3 (670 kg/m3)
Modulus of Rupture: 15,930 lbf/in2 (109.9 MPa)
Elastic Modulus: 1,746,000 lbf/in2 (12.04 GPa)
Crushing Strength: 8,750 lbf/in2 (60.4 MPa)

Black Spruce

Average Dried Weight: 28 lbs/ft3 (450 kg/m3)
Modulus of Rupture: 10,100 lbf/in2 (69.7 MPa)
Elastic Modulus: 1,523,000 lbf/in2 (10.50 GPa)
Crushing Strength: 5,410 lbf/in2 (37.3 MPa)

Red Spruce

Average Dried Weight: 27 lbs/ft3 (435 kg/m3)
Modulus of Rupture: 9,580 lbf/in2 (66.0 MPa)
Elastic Modulus: 1,560,000 lbf/in2 (10.76 GPa)
Crushing Strength: 4,870 lbf/in2 (33.6 MPa)


Average Dried Weight: 49 lbs/ft3 (785 kg/m3)
Modulus of Rupture: 18,460 lbf/in2 (127.3 MPa)
Elastic Modulus: 2,147,000 lbf/in2 (14.81 GPa)
Crushing Strength: 9,070 lbf/in2 (62.5 MPa)

Black Walnut

Average Dried Weight: 41 lbs/ft3 (655 kg/m3)
Modulus of Rupture: 14,600 lbf/in2 (100.7 MPa)
Elastic Modulus: 1,680,000 lbf/in2 (11.59 GPa)
Crushing Strength: 7,580 lbf/in2 (52.3 MPa)

English walnut

Average Dried Weight: 41 lbs/ft3 (655 kg/m3)
Modulus of Rupture: 16,160 lbf/in2 (111.5 MPa)
Elastic Modulus: 1,568,000 lbf/in2 (10.81 GPa)
Crushing Strength: 7,280 lbf/in2 (50.2 MPa)

Cucumber tree (Cucumber Magnolia)

Average Dried Weight: 33 lbs/ft3 (530 kg/m3)
Modulus of Rupture: 12,300 lbf/in2 (84.8 MPa)
Elastic Modulus: 1,820,000 lbf/in2 (12.55 GPa)
Crushing Strength: 6,310 lbf/in2 (43.5 MPa)


Average Dried Weight: 33 lbs/ft3 (520 kg/m3)
Modulus of Rupture: 11,670 lbf/in2 (80.5 MPa)
Elastic Modulus: 1,676,000 lbf/in2 (11.56 GPa)
Crushing Strength: 5,820 lbf/in2 (40.1 MPa)


Average Dried Weight: 50 lbs/ft3 (795 kg/m3)
Modulus of Rupture: 17,900 lbf/in2 (123.5 MPa)
Elastic Modulus: 2,285,000 lbf/in2 (15.76 GPa)
Crushing Strength: 9,550 lbf/in2 (65.9 MPa)

Turkey Oak

Average Dried Weight: 45 lbs/ft3 (720 kg/m3)
Modulus of Rupture: 16,570 lbf/in2 (114.3 MPa)
Elastic Modulus: 1,568,000 lbf/in2 (10.81 GPa)
Crushing Strength: 8,170 lbf/in2 (56.4 MPa)

Wild Cherry

Average Dried Weight: 39 lbs/ft3 (620 kg/m3)
Modulus of Rupture: 14,980 lbf/in2 (103.3 MPa)
Elastic Modulus: 1,529,000 lbf/in2 (10.55 GPa)
Crushing Strength: 7,250 lbf/in2 (50.0 MPa)

Direct substitues for Spruce:

Port Orford Cedar s/w=423.8

Noble Fir s/w=415

Pacific Silver Fir s/w=379.3

Western Hemlock s/w=389.7

Almost direct substitutes for Sitka Spruce:

Poplar (comes very close, oddly enough) s/w=348.3

Black Spruce (almost, just slightly inferior) s/w=360.7

Direct substitues for Douglas Fir:

Loblolly Pine s/w=365.7

Shortleaf Pine s/w=374.3