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Showing posts from 2013

OpenSCAD linear extrude that interpolates between two shapes

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Full source code is available for this thing on thingiverse.

OpenSCAD has proven to be an easy to use and flexible tool, but at times I'm left scratching my head to figure out ways around its limitations. In this case I had two squares with rounded corners, their sizes and the corner radius for both squares are configurable. Now I wanted a square tube to join these two pieces together.

My hope was that I could get it close enough with some fancy parameters piped into the OpenSCAD linear_extrude function. It seemed possible since there are some pretty fancy parameters regarding rotations and twists. After checking out the documentation it didn't look like there was anything that would be close.
For this project I found a module by Felipe C. da S. Sanches to create squares with rounded corners. I'm sure there are many like it, but this was the first one I found and it worked as advertised.
So made a little module using this which wraps around a rectangle for one side, and an…

A week of 3D printing with the OrdBot Hadron

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It has been about a week since my OrdBot's first successful calibration print and it seems like a good time to write down some of my initial problems, experiences and solutions. However before I get into that a review of my 3D printer stack.

Hardware
OrdBot Hadron
3/8"-12 TPI ACME Z-Axis screws
1.8 degree Nema17 X/Y motors
1.8 degree Nema23 Z motors
Qu-bd MBE Extruder (with some modifications)

Electronics
AzteegX1 v1.0 (644P processor)
Lava heatbed, I have only used PLA at this point so this is still disconnected.

Software
Mac OSX
Marlin firmware
Slic3r v0.9.9
Pronterface (March 2012 release)
Repetier-host Mac (0.56, lower versionthan linux/windows releases for some reason)

Now for the problems encountered during the past week, approximately in the order which I ran into them.

Pololu A4988 - I have used these before on my ShapeOko CNC machine. They have been so reliable that I completely forgot how to set them up, as such I blew up 3 drivers while setting up the electronics. So b…

Building an OrdBot 3D Printer

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I've been a fan of MakerSlide ever since building my ShapeOko CNC Mill, and have been interested in 3D printing since first hearing about the RepRap project in 2007. So when I first saw the OrdBot, I knew that it would be the printer I build. It didn't hurt that I had 10 feet of extra MakerSlide and a whole bunch of the special bearings and eccentric spacers left over from my ShapeOko build.


One of my goals was to build all the custom parts myself, the blue and black pieces in the photo above. Cutting aluminum on my new CNC machine pushed it to the limit, but worked out in the end. One of the larger OrdBot pieces is the handle, here is a shot of the ShapeOko making short work of it:



There are a couple parts that I modified or upgraded during the build. Most notably the Z axis. After reading about bent Z-rods I decided to get some ACME rods, and I wanted to use some spare Nema-23 motors that I had on hand.

The NEMA-23 motors for the Z axis were easy, I slightly modified the sto…

ShapeOko CNC Mill

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April of 2012 I signed up for the first batch of ShapeOko kits from inventables.com. Unsure of how popular the kit would be, inventables had a kickstarter-style order of 150 (or so) kits. That number was reached handily and several more batches followed. Since then the ShapeOko has become a standard item in their store.

I've wanted a CNC mill for a long time, but could never justify the expense. Now there are products like the MakerSlide linear rail system that made it possible for low cost machines. The first round of kits were only $200 for the entire mechanical platform - add your electronics and a dremel tool and the machine can start cutting.
So thats what I did.


The stock kit plus motors after assembly:

One of the nice things about the ShapeOko is how hackable it is. For instance if you want to make the cutting area larger you can just replace the MakerSlide with longer rails. So I added longer rails, a second Y-axis motor, a torsion box to mount everything on, a bigger rout…

Projects Past: The 2009 Automatic Cat Feeder

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In 2009 I took a week off from work to build an Automatic Cat Feeder to ration food to the overweight household cat. This was a project built from need and it had a deadline because my girlfriend and I were heading out of town for Thanksgiving.

The requirements were simple: It needed to be easy to refill and dispense the correct amount of food twice daily. Early on I had an idea for a large rotating drum to dispense the food, it needed to be easily removable for refilling and heavy enough that it could sit on a motorized wheel and cause enough friction to be turned.

Figuring out a latch mechanism that dropped the correct quantity of food after one rotation was the first tricky part. I didn't want any electronics on the drum so it had to be completely mechanical. In the end I hot glued a small box to the outside of the drum which filled during rotation, when it started moving back towards the top a tab would be hit to fling a door open and drop the food out. A magnet held the door…

Projects Past: The 2007 DIY Projector

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I've had many projects over the years, the most involved by far has got to be my DIY projector.  It is also my first serious project. By the end of it I had vastly improved my knowledge of optics, electronics, woodworking, and even a little thermal dynamics.

Research started sometime mid 2007, the now defunct lumenlab forums had a whole community of people building DIY projectors. There is a lot of theory to learn, optics to figure out, components to buy, and bringing all the pieces together is no simple task.  For such a complexe machine, at the core it has some very simple principles: A point light source radiates light into a fresnel lens, which straightens the light through the LCD screen, then another fresnel lens angles the light into a special lens which can focus the light on a screen. Here is an image from engadget which demonstrates the light path:


The major problem with these sorts of projectors is that they tended to be very large. 1080p monitors at the time tended to …