Before I dive too deeply into the machine design, I would like to have a word or two on the motors and drivers.
I got these motors out of a trash container from a large German company, which may be a bit unfair to use in this ultra low cost application, since these are Swiss made motors and quite expensive:
Escap stepper http://www.electromate.com/db_suppor...edy_Line48.pdf
Once I have the machine running, I’ll measure the actual loads and will downgrade the motors likely to a 400 oz*inch holding torque.
For all more interested in the motor physics may read this:
Stepper info http://services.eng.uts.edu.au/cempe...s_ch10_ppt.pdf
I searched quite a bit on driver boards and was close to develop my own board until I found this one:
HY-TB4DV-M driver board. Vendor calls for professional designed board. I’m more interested in the optical isolation of the 5V signals to and from my computer
“50 Full closed-type optical isolation to protect the user's computer and equipment
60 Professional design, two-stage signal processing, super anti-jamming”
The board has no common ground and the mounting holes have nothing to do with ground either. If the board is a copy clone from China and the original board designer reads my thread, than I do apologize for my critical words.
All I can say, it worked well for me in the past and I haven’t blown up a board yet either.
You may buy this board from China or from me, tested, for a little more money.
More commonly used in the market are break down boards with parallel port or USB connection and driver boards, one for each motor. Advantage, you can hook up more powerful driver and motors, USB is certainly also a big plus, but it is more money than the single driver board, you can buy in 3 and 4 axis version.
Also, motors could operate at a higher voltage of 48 VDC with better torque, but the driver board calls for 36 VDC max (which I haven’t tested yet) and I do most of my applications with 24 VDC.
Although there is open source CNC software on the market, I settled with Mach 3 software, which can be used free with limited G-code. ArtSoft USA - Home of Mach3 and LazyCam
It is $175 for a license and I find it a well spent investment.
There are many free add-ons in this software like letter engraving in almost any font, but most importantly, I can configure the port and pins of the printer port, that it works for the driver board of my choice.
I’m using a 4 motor configuration in all my designs, operating the longer Y-axis in master slave configuration, or for CNC hot wire cutting all 4 axis operate separately in 2 y-axis and 2 z-axis set up.