Monthly Archives: November 2011

Another CNC-made Random Tree

Posted by on November 30, 2011 2 comments

CNC cut random tree over doorI first made a “Random Tree” model a few weeks ago using Inkscape Render and Gcodetools extension.  Since then, my wife thought that a scaled-up version of the original would look nice on the wall above a doorway in our house.  Although I have a 7×12 router, my “tree” ended up about 7″ tall and 6″ wide.  It could have been slightly larger, but given the proportions, this was close to the limit of my machine.  The scaling was done in Inkscape, with the proportions locked.  Gcode was then generated in the same way as the first post.

After it was cut, I unfortunately had to cut it out more with a Leatherman tool as I didn’t cut deeply enough.  I set it to cut a depth of .256 inches, so either the material was oversize, I didn’t zero correctly, or somehow the router was loosing it’s position on the Z-axis.  I would guess it was a combination of the first two – since the shaft of my spindle can be compressed slightly, this could have also contributed.  This happened on my little random tree as well using a Dremel tool, so I may need to start cutting deeper on 1/4 inch MDF.

After cutting, the MDF Read more »

The Chemistry Behind Bleach T-Shirts

Posted by on November 30, 2011 2 comments

white king bleachThe most common bleaches in use today, such as the chlorine-based Clorox and Purex, are aqueous solutions containing 4-6% sodium hypochlorite (NaOCl).  They are formed by dissolving chlorine gas in sodium hydroxide according to the following reaction.

Cl2(g) + 2NaOH (aq) –> NaOCl + NaCl + H2O

The chromophore is the part of a molecule which is responsible for its color.  Examples of chromophores include C=C and C=O (Carbon to Carbon and Carbon to Oxygen) bonds.  The chromophore of a dye molecule causes it to absorb certain wavelengths of light and transmit or reflect other wavelengths of light.  An oxidizing bleach such as Clorox breaks chemical bonds in the chromophore so that it can no longer absorb light (a dark t-shirt is absorbing instead of reflecting most light, whereas a light area reflects more light).

When the objective is to bleach a dark object white, problems often arise.  Typically, the new color is orange, not white.  This has happened to me – one day, I was at work and spilled some bleach on my black shorts.  They ended up with orange spots all over them and I had to buy some new shorts.  It may be possible for one to bleach a black object white if he is patient and allows the chromophore-busting reaction to proceed for an extended period of time (considerably longer than 15 minutes; it may take up to one day as the process requires multiples bleach/rinse cycles).  Therefore, I would recommend trying the following procedure to dye a white tiger paw onto a dark-colored shirt (or check out this article to see how it was bleached in orange).

Procedure for bleaching a dark-colored shirt: Read more »

A Free Monitor Stand from Your Engineering Catalogs

Posted by on November 28, 2011 1 comment
computer monitors supported by books

The correct way to utilize 2 monitors

As an engineer, I receive many catalogs each year.  Some get outdated, and some I didn’t want to begin with.  At 6’4, and with some back issues, the standard monitor stand just didn’t cut it for me height-wise.  I was having to look down all the time, whereas it would seem the proper ergonomic position would be for the monitor to be level with your natural eyeline.  The solution I came up with was to use these unused catalogs as monitor stand.

After installing this “book monitor stand”, my back feels much better.  I’ve also been doing some different exercises at home so that probably helped too.  Interestingly enough, one of the Industrial Engineers that I work with is 6’7″ and has his monitor at the standard height.  Apparently looking down on your monitor isn’t a problem for everyone. *Edit: he has a normal stand on his non-notebook monitor.*

On a side note Read more »

New HDTV Antenna Installation in Attic

Posted by on November 26, 2011 1 comment

DB8 antenna new versionIf you’re going to cut cable like I have, one thing that is important is being able to receive broadcast TV signals (especially if you want to watch college football).  Although we should be able to get all the major networks in our area, only NBC would come in clearly with a small indoor antenna.  After installation of the DB8 antenna was completed in our attic, 20 digital signals were found by our receiver!  That’s without any aiming, which will be the next step.  Right now we get NBC flawlessly – CBS and Fox pretty well.  A huge improvement.

Assembling the DB8 antenna wasn’t particularly hard, but the included directions weren’t great.  One thing that is initially confusing is that the picture on the box uses the old DB8 model with coaxial cables connecting everything, where what you get is a “new” DB8 with a strip of metal connecting the two sets of antennas.  This picture from HDTVPrimer (which has a rather in-depth review of this particular antenna) shows the new DB8.  As you can see, there are no coaxial cables.

When assembling everything, pay close attention to the orientation of the parts and which way they are facing.  If you’re careful, everything should go together smoothly.  It’s probably a good idea not to tighten any of the included wingnuts too much until you have everything in place. Apparently this doesn’t always go as well as it should.  The warnings on the manual had this to say: Read more »

Zen Toolworks DC Spindle Motor First Impressions

Posted by on November 25, 2011 No comments

Zen toolworks spindle with mountAlthough this may not be a full review of this product, I recently received the official spindle/chuck and mounting bracket from Zen Toolworks.  I also got the power supply meant to be used with it, but this article won’t focus on that aspect, as I assume it will work as advertised.

My first impression upon unpacking the spindle was that it was quite a bit larger and heavier than it looks on ZTW’s site.  It’s about the same diameter as the Dremel 4000 that I recently burned out (per my carelessness).  I could have probably the same mount for both if there was a need, but with the exception of being an emergency back-up, I don’t see where there will be.  It appears to be a solid spindle, and with the included mounts, everything should fit nicely.

The ER11 chuck looks very solid compared to the Dremel’s stock collet and a bit better than the aftermarket 4486 chuck.  It really looks like something that would be at home in an actual machine shop with solid wrench flats on both the spindle and nut to keep Read more »