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Messages - KRRRL

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Completed Projects / Re: Bicyle generator
« on: January 24, 2013, 11:38:09 pm »
Let there be bicycle light!

It did not even take that much pedaling to power the LEDs.  In fact, we burned out the diodes.

So Robbie sacrificed a "wall wart" ... pull 2 sturdier diodes from the transformer (the 2 black components at the top):

He removed the burnt diodes; and soldered the pillaged, stronger diodes into the LED board.

The fix worked, we tested it with a bicycle. 

Completed Projects / Re: Bicyle generator
« on: January 24, 2013, 04:12:37 am »
Elliot's simple fix did not work, the coupling still slipped off the rods, and the bike would not generate electric power.

Thus David remilled the coupling, so that it would fit more snugly on the bicycle side:

Then he reseated the coupling, pushing it more deeply into the rod on the bicycle side (later he would also have to shave down the 4 wood blocks, which surrounded the coupling for added strength):

The bicycle could certainly light a few super bright blue LEDs, even if it could not power anything else.  So David made a circuit board to house 4 bright blue LEDs:

They used this circuit (not that I understand):

The reverse side, with huge capacitors:

Unfortunately the coupling slipped yet again.  We then pleaded with David to drill the aluminum rod, and press a screw all the way through both the rod and the coupling, making it impossible to slip:

We tested the bicycle generator with an electric drill, and the lights lit up, so brightly that it hurt my eyes:

However the screw spun out like a bullet. Hopefully with a longer screw and nut, all will be fixed, and a bicyclist can light up those LEDs brightly as easily as riding uphill.  We will have to test that this Saturday.

Completed Projects / Bicyle generator
« on: January 12, 2013, 09:06:33 pm »
We decided to make a bicycle generator, if only to power a light bulb, for fun in the off-the-grid spirit.

First Krrrl bought a used stationary bicycle stand at BICAS:

Kyle donated his electric generator, which he built by hand:

The idea was to attach the generator to the bike stand:

Vince took apart the stationary bike stand:

And made measurements:

And then milled a coupling to attach the generator to the bike stand:

The piece was similar to a cylinder Vince had milled earlier:

Then he made wooden mounts to strengthen the connection:

The final product:

Elliot tested the bicycle generator, producing up to 12 volts:

However, after a while the generator rod slipped and came loose from the coupling.  The 2 opposing set screws did not bite strongly enough into the rod.  Therefore Elliot filed two sections of the rod flat, on opposing sides, so that the set screws had more surface area to grab onto:

Unfortunately, when we tested the bicycle generator again, the coupling came loose from the other rod (the stationary bicycle rod).  So Elliot repeated the fix, filing two opposing sections of that rod flat.

Completed Projects / Re: Burr Puzzle
« on: December 23, 2012, 12:00:42 am »
Inspired by David, Amir made a different Burr puzzle.

The cut pieces, which have to be sanded before they will fit together:

Completed Projects / Chocolate molds
« on: December 22, 2012, 11:40:53 pm »
Eli and I made a silicone rubber chocolate mold, from a Xerocraft logo made on the 3D printer. 

We used the quick setting Equinox 35, from Smooth On. 

Mix the white putty, with an equal amount of purple putty -- by volume -- to make a molding putty:

The molding putty sets up in one minute, after it is mixed by hand:

Pressing the molding putty onto the 3D print positive:

After 7 minutes, the piece can be demolded:

We then cooked the mold in the oven for 2 hours at 175 degrees, and then 1 more hour at 210 degrees, to fully cure the mold, as directed by the instructions that came with the product.  The Internet instructions are slightly different, to make the mold food safe.

Later, at the Sculpture Resource Center, Ernie melted and "tempered" the chocolate before pouring it into the silicone mold.  He heated the chocolate in the microwave for only 20 seconds at a time, so that it would not burn.  After heating, he stirred the chocolate.  Then he heated it again, and stirred again, repeating until the chocolate was melted.

Once the chocolate was melted,  Ernie worked it with a spatula on a plate -- distributing the heat, or "tempering" the chocolate -- before pouring it into the mold.


The dark spots are where pieces of chocolate broke off.  Maybe I demolded it too soon:

The inspiration was to convert a plastic 3D print into a different material -- which does not have to be chocolate -- and do so quickly and easily.  Maybe we should be 3D printing cookie cutters too.

Completed Projects / Burr Puzzle
« on: December 19, 2012, 06:58:33 pm »
David made 3 Burr puzzles out of wood in two hours, because they make good Christmas presents.

He started from an Instructable, and went through IBM, before selecting this particular puzzle.  Then he made them on a table saw, by eye.

Completed Projects / Portable 3D printer
« on: December 17, 2012, 11:37:00 pm »
The Printbot Jr kit has arrived.

These are the instructions on how to put it together -- (single page of instructions).  Or one can watch the video instructions.

Then there are instructions on how to use it, with the software Prontoface and Slic3r.  Can we use a portable netbook to run this software?

The Printbot Jr is a portable 3D printer that folds up.  In the future the company plans upgrades -- "A battery pack and LCD (sold separately) will allow truly wireless printing."  However, I wanted to use it in February, during the Tucson Sculpture Festival 2013, and could not wait for those upgrades.  Maybe later in the year, one will be able to print from one's iPhone (after scanning his/her face with the iPhone).

This portable printer is limited -- it has a small build platform, and only prints with PLA media.  However, that should be fine for making small, quick prints.  In public, no one would really want to wait more than 15 minutes for a print anyhow; so small is good.

After the Tucson Sculpture Festival, the Printbot Jr might be a good toy to take outside of the hackerspace, to show people what we do at Xerocraft.

Completed Projects / Re: 25 XC figurines painted
« on: December 08, 2012, 08:50:02 pm »
...haven't I seen these sculptures before?

For what it's worth, stale beer may slow down the setting of plaster (as does cold water).  Bull urine does the same job; at least that was what the guy at the sculpture store told me once, and they sold the synthetic equivalent.   I do not know if the additives will make the plaster softer.

I know nothing, but cannot help commenting anyhow.  It seems like you might want to add the sand after you sprinkled the plaster in the water.  And I wonder if you couldn't paint a thin layer of plaster on the object first, to prevent bubbles, and then sink the whole object in plaster.  They do this when making rubber molds.

Again, I know nothing.

Completed Projects / Video graffiti
« on: November 28, 2012, 03:17:26 am »
Since I can project without having to "plug in," I can now spew video graffiti anywhere!

Basically I connected a small LED projector to a gel battery.  I then packed them and a DC adaptor into a discarded Tucson Public Schools box, with an iPhone cord.

12 Volt, 9 Amp gel battery:

90 Watt, universal car DC adaptor -- Input 11-15V, 12A; Output 15-24V, 6A(max):

LG HS201 LED projector, 19V, 4.74A:

HDMI and other input connections:

This projector lasts over an hour on one charge.  It is an LED projector, so there are no bulbs to burn out and change.  Nevertheless, it puts out 200 ANSI-Lumens, which is fairly bright.  While this model is discontinued, LG does sell other projectors.

Perhaps I can power this projector by bicycle, instead of with batteries.  In San Francisco there are concerts now powered by the audience pedaling.

Of course, the Graffiti Research Lab has been laser tagging buildings for years.  But how about recent video graffiti variations, like water light graffiti, and SweatShoppe in Europe.


Completed Projects / Re: High Power UV LED Flashlight for Hunting Scoprions
« on: November 20, 2012, 06:00:10 pm »
I wonder how well that UV LED Flashlight would light up our 3D prints.  Josh printed out the Xerocraft logo in glow-in-the-dark PLA, but it glowed dimly.  When I took that print up to Heatsync hackerspace in Mesa, Nate iluminated it with a small UV flashlight, and it glowed good:

Then Nate suggested that the glow-in-the-dark PLA might act as light pipe, which I could use to make another translucent concrete sculpture.  Even if that media did not act as light pipe, I might embed pieces of the glow-in-the-dark PLA in the translucent concrete mix that I imported from Mexico, to make another sculpture.  Then I might use a powerful UV flashlight to reveal both visible and  hidden patterns in the concrete sculpture.

Completed Projects / Re: Augmented Reality
« on: November 04, 2012, 02:05:46 am »
Yes, Connor did.  I rewrote the post with more information.

Project resources and information / Free 3D software
« on: November 01, 2012, 02:49:13 am »
The TinyUrl link to this list is --

(* indicates that I haven't tried it yet)

3D Tin
online software




3D CAD design software

3D scanning and other 3D software from Autodesk


123D Design

software to view and manipulate 3D objects


SVG exporter * (Google Sketchup plugin)
for exporting 3D files to be cut on a board in a 2D laser cutter

Smooth Teddy
3D drawing software by Takeo Igrashi

Rhonda 3D*
3D drawing software

3D drawing program

3D modeling software

Art of Illusion*
3D modeling software

Vue Pioneer*
3D landscape making software

topological mesh modeling

mathmatical models

Scherk-Collins Sculpture Generator

free 3D sculpture program from Zbrush

for viewing 3D files

netfabb Cloud
corrects the errors in STL files
before they are printed on a 3D printer

software for looking at how a file will 3D print

free 3D scanning software for the Kinect

free 3D scanning software for the Kinect

multi-user 3D application server

3D scanning from photographs


Augmented reality app

Augmented reality app

app for viewing 3D files

Completed Projects / Re: Augmented Reality
« on: November 01, 2012, 01:50:43 am »
After Connor 3D scanned the skull float, I pushed it into Augmented Reality.

Connor took several pictures of our giant skull, in the round, and uploaded them to 123D Catch, to make a 3D object file:

After downloading the 3D scan, he created the digital object on the Ultimaker 3D printer:

Leon holds the tiny printed skull, in front of the giant skull which he made happen:

I made Xerocraft business cards -- with a QR code that links to the augmented reality image, and the Augment app "marker."  Anyone with a smart phone and this business card, should be able to quickly download the app and view our skull in augmented reality.

The files necessary to print such business cards are attached to this forum entry -- front (Xerocraft_info__U-0113-01_P) and back (Marker__U-0113-01_P).  Use Avery Avery 5871  for laser (which Kinkos uses), or 8871 for ink jet.

Completed Projects / Augmented Reality
« on: October 31, 2012, 01:59:36 am »
I discovered how to display my drawings in augmented reality, with the Augment app.

James Stewart converted one of my drawings into a digital sculpture  (note the red Augment button in the last link, to go directly to the object from the blog) --  top view (Krrrl_002):

An older digital sculpture (Krrrl_001), which I could not  view with the Andar app, works with the Augment app:

Seeing double:

Any object we scan in 123D Catch, or 3D print, could also be viewed in augmented reality.

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