Sunday, June 22, 2014

Entomological enclosure (aka "bug house")

I took my son fishing Saturday morning. We didn't catch anything, but Colton enjoyed looking for bugs around the pond. When we got back to the house it was time for his afternoon nap. After he was settled down I wandered out to the garage and made this:

It's just a piece of screen and some scrap lumber. I cut everything to size on the table saw then put the frame together using brad nails and glue. The screen is folded over at the edges and stapled. The door hinge is a piece of leather and the door is held shut by a neodymium magnet that attracts the screw holding on the door knob. A light coat of danish oil finished it off. The entire project only took about 30 minutes.

In the image below, you can see the magnet countersunk into the frame. I drilled the hole to be snug and coated the inside of it with super glue before pressing in the magnet. I've done this before on several projects. The metal holding the knob on actually ended up working great and was more than enough for the magnet to attract. Here are the magnets I used:

There is a little green praying mantis in there. As I was putting in the last staples and testing the door in my garage this bug jumped in. I saw it all happen and just stood there in stunned silence. There aren't words I know of for coincidences this crazy. I could have searched my yard for hours and not found a bug this cool to show my son and here he is jumping over my shoulder and into our little bug cage just as I finish it. Perfect.

Here's a video of the enclosure in action. When my son woke up we studied and talked about the bug for a while and then went outside to try and let him go.

Saturday, June 21, 2014

Converting videos for Roku with Linux

I bought a Roku 3 and I wanted to watch some video files on it. Unfortunately it only supports a few video formats. Maybe this is a good thing as long as it does them well. Conversions are pretty easy using ffmpeg or avconv. An Internet search didn't turn up many results on how to do this, so here's a script I made to make my life easier after I figured out which codec works best.

avconv -i "$1" -strict experimental -c:v libx264 "`echo $1 | sed s/\.[^\.]*$//`.mp4"

To use it, put this in a file called and chmod +x
Then use it like this:
./ video_to_convert.avi

It will create an .mp4 from any formats that your avconv install supports. The .mp4 can be placed on a usb thumb drive and plugged into the side of your Roku 3. Find and play it using the Roku Media Player (download for free from the Roku channel store). Here's what it looks like:

Sunday, June 8, 2014

Forge update - gas adaption

When I woke up this morning I didn't know I was going to be converting my coal forge to gas. While on a family trip to Home Depot, I snatched my son up and we split away from my wife and daughter. I did my typical run around to see if anything good was on sale, look at esoteric stuff, and maybe find inspiration for a new weekend garage project.

I was never enthusiastic about playing with flammable gasses, but another project (you'll see in a future post) had me learning how to use Acetylene and Oxygen cutting tools. Acetylene and Oxygen is a potent mix fraught with all kinds of danger. After learning about and circumventing all of the ways to kill myself with it, I'm simply amazed more people don't get hurt using it. By comparison propane seems tame, so when I ran across some refractory cement at Home Depot it didn't seem like too much of a bad idea to build that gas powered forge I've been planning for a few years. Earlier in the week Harbor Freight had a sale on propane torches and I picked one up for next to nothing.

This propane forge is nothing more than a fire-proof container with a hole in the side where you can drive in fire. The pressure of the propane leaving the nozzle sucks air in via the Venturi effect. Here's a cool video by Mathias Wandell about the Venturi effect. Some forges have active air (like a supercharger) driving air by fan, but it's not really necessary. Especially for a back yard forge. The container keeps the heat in allowing you to approach the 3000 or so degree burning temp of propane in air over a wider area.

I created the fire-proof container by cutting/bending some steel mesh to fit inside of a paint can and packing the mesh with the refractory cement. I just used a pair of rubber gloves to smash it all in there and smooth it. Here's a picture of the process.
I cut a hole in the side and then very carefully welded in a piece of square pipe large enough to hold the torch tip. Another set of pictures showing how that works:

The front view of the forge after the first burn:

I scavanged a piece of 1/2" angle iron from a bed frame were throwing out. I cut that up and welded it together to create the stand which the paint can sits on. I sized it so that it fits on top of my coal forge, effectively using my brake disc coal forge as a heavy stable stand. Here's a picture of the whole setup sans propane. I took these pictures after I had already put away the propane for the day.

Before this forge will be truly usable, I'll have to figure out how to narrow the front opening. I'll probably use fire bricks, but not sure yet. I'm out of time this weekend.