One of the things that delayed my work on the Mendel over the last week or so was that my trusty HP TC1100 tablet computer was out of action. This was caused by my preparations to get another project underway after the Reprap is finished.
This is a small CNC router called the DIYLILCNC. It is open source and the plans are freely available on their website. It has a cutting area of 12"x14"x2". I am going to build one to complement the Reprap since it will be great for cutting small parts out of flat stock. The DIYLILCNC is constructed mostly out of stressed hardboard, called Masonite in some places. A full 4x8 sheet is required but it is very inexpensive and the parts are simply bolted together, much like a Mendel. All in all it is a very elegant little design and has the advantage of being complete, tested, and well documented. The parts are designed to be laser cut but, like Repraps, the user community has already begun their own redesigns. Someone has posted a set of cut patterns optimised for a CNC router. Since my daughter's school has a large CNC router setup I plan on doing some horse trading for the cutting service. Perhaps I can do a presentation on the Mendel for the shop students.
Instead of designing their own electronics hardware the lilcnc team simply used one of the commercial 3 axis kits that are now available from a number of sources. They also use an easily acquired Dremel tool as the cutter. I ordered my motors, electronics and power supply as a kit from China. I have no idea what the quality will be like but the price was worth taking a chance on (about $200 including shipping). The three NEMA 23 motors are slightly less powerful than the ones called for in the DIYLILCNC plans but they should do the job.
As far as my tablet being out of action - I tried to load an application called EMC2. It is an open source CNC control application and is the one most commonly used if you can't afford the (very expensive) commercial alternatives. Unfortunately, when I loaded it up it somehow corrupted my Nvidea drivers and I was unable to even boot the machine. It took the better part of a week to get things going again. Since I use that machine to run the Mendel it really slowed down the work on the current project. Perhaps I should stick to one project at a time. In any case, I discovered while troubleshooting the problem that the folks at the EMC2 website do not recommend running it on tablets or laptops since it is a realtime control program and the older laptop technology usually can't keep up with the cutter and will start dropping instructions. Oh well, Live and Learn.