Basic Electronics Class Update

Here are the slides from the class: BasicElectronics_1_20130320 . Note: We are preparing a follow up class that dives further into the subject. Please keep an eye out for the announcement.

Laser Cut Jewelry Box

A few weeks ago one of our members (Mike) picked up the RedSaid X700 Laser Engraver from ebay. Ordering and shipping of the engraver turned out to be a lot of trouble and very expensive.

Mike spent a few days soldering wires to the laser tube, aligning the mirrors and doing a few test cuts on various materials we had laying around the shop. Then he turned the machine loose for the rest of us to play with.

I decided that I wanted to make a gift for my daughter so I used SolidWorks to draw a Jewelry Box and then exported the files as DXF 2D Drawings. These were then imported into LaserMate which is software that came with the laser engraver.

I designed the Jewelry Box to use 1/4″ Material. It turns out that the Birch wood and Acrylic from Home Depot says 1/4″ (5.2mm) but if you do the math a 1/4″ is not 5.2mm. So that material we had laying around the shop was not going to work for me.

Luckily, another member of ours had left over scraps of 1/4″ Baltic Birch which he purchases locally from Woodcraft. I attempted cutting this wood but even at 100% Power, 2mm/s speed, and 4 passes I was unable to cut consistently all the way through the wood. Also, this wood is rather expensive. So I decided to look for other materials which I thought would cut easier but was still 1/4″ thick.

I learned about a place called Total Plastics, Inc. located on Pulaski Highway through Terry Kilby. I stopped by their showroom and the nice man behind the counter gave me a piece of 1.4″ Cast Acrylic which was painted red on one side. I cut test patterns on this acrylic and I was surprised to find that was not cutting much better than the Baltic Birch. After roughly 10 hours of cutting pass after pass I was eventually able to make a Jewelry Box from the Acrylic.

I have come to the conclusion that the laser cutter needs some tweaking. It seems that the top left corner cuts okay but as you move down and to the right of the cutting area the laser is not as powerful. My guess is that it has to do with the alignment of the mirrors but I have not looked into the problem yet.

After many hours of work I present to you my Jewelry Box.

New Class: Beginners Electronics Part 1

Chris Cockrum will be hosting another class. This time is for beginning electronics.

There is limited seating available so Please register if you wish to attend. Wed, March 20th.

Part 1. Ohm’s law and Watt’s law

This class will teach the basics of voltage, current, and power. A lab will be included that will demonstrate how to calculate the proper value of resistor to connect LEDs to power.

Parts and equipment may be borrowed from the hackerspace or you can purchase a multimeter (http://www.harborfreight.com/7-function-digital-multimeter-92020.html), a few LEDs, a few resistors, clip leads, and a 9V battery for $5. Alternatively, you can bring your own.

Basic Cryptography Course at Baltimore Hackerspace

Chris Cockrum of the Baltimore Hackerspace will be giving a course on Cryptography this Wednesday, February 20th at the Baltimore Hackerspace. He will be teaching the fundamentals of public and secret key cryptography including exercises on RSA, elliptic curve, and cryptanalysis using Sagemath (Python Based).

According to Meetup, the class is full but if you are interested in having another class, please let us know by leaving us a message on the meetup entry.