Calculating N^2 as a series?

I am working on a problem from project Euler solving for Pythagorean triplets. I think it is supposed to be a simple coding problem solved brute force with two for loops. Something about the problem has my gut telling to try to solve the problem a little more elegantly.  To that end I was looking at trying to calculate N^2 as a series so I could break up the triplets into over common and different components to manipulate.

This is the first thing that jumped out at me – obvious pattern when I thought about N^2 having 2N as the first derivative and 2 as the second – but I did not see it right away. Might be useful.

Roughing out coil winder

So Ross suggested a CAM lock that was better than what I was originally thinking. If the ABS flexing is not problematic I think it will work. I am less happy with the spring loaded spool. I wanted it to help provide tension in the system – but I think it looks like overkill.

Hmmm, I think I am going to add the mount points and start building. Just build the carriage last after I have thought about it some more.

Making a Coil winder


So I need to make a bunch of custom wrapped magnets as part of building a batch of eletro-permanent magnetic actuators. So far all my prototypes have been hand wound – which is just about as fun and time consuming as it sounds. So I decided to make a CNC coil winder. I am making not buying one as the decent ones are crazy expensive.

I roughed out a model for the frame, motor mounts, and sled this weekend. Over the holiday I am going to finish the sled, the tensioner, and bobbin support. If the design looks a bit weird I also designed all the parts so that they would print on a 3D printer that did not have a support material.

I am using roller skate bearings, springs, and some nuts and bolts – but the ideas is to keep everything else printed. I will probably just throw together a UI to drive it that talks to a micro-controller board. Either an Arduino or a UC3L. I have not decided yet.




Stop laughing at yourself and act

This picture is more representative of how I have been feeling lately. I got a plan, I am fixing things, but I need to stop laughing long enough to act. Life is weird.

This picture is from a climbing trip a few years ago. I lead a single pitch climb as a quick warm-up for the day and Grant cleaned. Rather than rapping off there was a permanent ladder set up. Grant and I got down, and then realized both of us had through the other one had the rope.  This is especially funny as Grant and I had climbed together a lot and are normally in sync.

Once Jesse stopped laughing, and that took a while, he took pity on us and showed us the fast way to get the rope back. Jesse asked for my cordelette and grabbed a stick. He couldn’t quite snag the rope – so he showed us this really cool trick turning our gear picks into a sort of make shift grappling hook. Very cool.


So it was a bit weird – but I was in this guys office interviewing for a new position and saw this sweet thing on his desk. I totally had forgotten about how cool zoetropes were! Excellent thing for messing with my nephews head and sneaking in a little science lesson at the same time. I like this tiny design as well – going on the projects list.

Ok, what now?

This picture pretty much sums up how I have been feeling lately. “Huh, how did this happen and what am I going to do about it?”


That is me in the picture, but it is my friend Konrad’s cabin. I was helping him thin out some tree’s near a few years ago and the last one – well – it did not go as planned.

A test run for casting metal in the garage

In this modern age people have forgotten how to be truly horrifically bad hosts. I like to start by inviting new friends over to do something dangerous, then build on that momentum by spending the entire time out in the garage. Letting people actually come in the house sends the wrong message. Then to truly sell the experience I generally have them do some manual labor when they arrive. It is the bad host hat trick.

In this case Ian and Dave came over to test cast some belt buckles. We started by making a “sandbox” so we could cast in the garage. I live in Seattle and that means lots of rain. Rain does not mix well with molten metal.

I was surprised how well the sandbox ended up working. With the garage door open and an extraction fan ventilation was not a problem. The sand also gives a clear working area over which to keep anything hot, and minimizes the hazards of a spill. So all in all it looks like I will be able to cast in the winter time.

One nice thing about sand – it lets you wiggle items a bit to seat them. Even hot items. So you know they wont tip or move on you. Very useful.

And here is Ian’s first pour. More videos describing the process of casting to follow.


3D printing and support

So with 3D printing finally gaining main stream awareness I get a lot of requests to explain exactly what it is. People generally quickly get the slicking up a model into layers and building up the model a layer at a time. What tends to be harder to visualize is the use of support.

Support is used to support the print material during printing. It is then removed after printing is completed, enabling impossible looking parts to be printed. I think the best example is the artwork of Bathsheba (

What you see here are two pictures of the Metatron model, both with and without support. The support is the black material and it is dissolved away in a solvent tank. The white material the model is made from is just ABS plastic.

Some printers are built the model from a powder which is blown away once the model is done being printed – but most of the fused deposition modeling use this style of support.


All tapped out

When my dad retired he gave me a few tool boxes that had belonged to my grandfather. I ended up turning one of the new boxes into my “tap and die” box. For years you only ventured to open it at the peril of loosing ten minutes looking for the tap or die you were really after. A task that was typically 1-2 minutes of looking and another 8-9 minutes trying to jam everything back in the box.

I finally had enough after a spectacularly time consuming hunt for a tap lead me to buy one I already had but could not find. I mean it is a 2.5 square foot space! So I went and divided the tool box into tills. Here are the results.

When you open the tool box you have direct access to your basic smaller taps, guide blocks, a tooth brush, flash light and tapping compound.  There are normally a set of gloves in here as well. I made the top till extra deep so I could still throw a few small odds and ends in there if needed.

The entire top tray lifts out to reveal a inner tray – which contains two smaller tills. So that gives me 4 compartmented areas to store things. The top ones I use for taps, and the lower ones for dies. You can see the box pictured here with all the tills and trays out

The bottom of the box has a French fit set of tap and die handles. I keep a set of small tap handles in the top tray, underneath a lift out till, but the ones in the base of the box are for dies and huge sized taps.

Tap and die box - french fit base

I am still living with the design – but so far I love it. It has easily already saved me more time in finding the right tap or die than I spent making it.  I highly recommend taking the time needed to organize your tool chests. Sure you feel like an anal freak while you are doing it – but that feeling goes away and is replaced by little snippets of “wow I am glad I did this” every time you have to use a tool.