CNC Router Plans and Projects

The original computer used on the first servo drive trial table was a $25 hand-me-down that turned out to be a 1995 Cyrix 6x86 133MHz.

This was plenty fast for using TurboCNC as the controller. TurbocCNC can be operated on an ancient 486, so getting started in CNC does not mandate a new computer.

Mach2/3 requires at least Windows XP. An entry level 2004 Compaq w/ AMD Sempron with 256 MB SDRAM is still used here with Mach2, and it works fine.

This is mentioned because there once was concern about the processing power required, but now even new cheap computers are fast enough.

The electrical components of this shop's first servo, not stepper, system were initially screwed to a piece of scrap plywood. Right images.
(Stepper systems as used in the plans are available as packages and do not necessarily require the work shown here.)

The power supply is a toroid from Plitron® wired with a rectifier, capacitor and bleeder resistors.
There is more on the Power Supply page.

The break-out board such as it is, is simply a Centronics receptacle from a dead printer soldered to some terminal strips.
The Gecko 320 drives have to be reset after they fault.  A simple N.O. (normally open) push button switch serves this function well.

With the drives visible from the work-station, and the switches next to them, it is easy to keep an eye on their status and reset them as needed.

There are also STOP switches wired between the Gecko's err/reset terminal and the Gecko's negative encoder terminal.
When pushed, these switches connect the err/reset terminal to ground and fault/stop the drives and servos. The servos then freewheel, which can be handy for job setups. The cord that attached the computer to the drives was a standard printer cable with a Centronics connector at the printer end, and a DB25 connector at the computer end.

Note the DB25 printer cable pin order does not correlate 1 to 1 with Centronics. Pins 1 through 14 match but then they diverge for some reason. Only pins 1 through 17 are usually used, so there may be no need to connect anymore than these. It seems that the other connections from 18 to 25 vary among manufacturers, so be sure to check your own cables before soldering.

The Gecko 320 servo drives require 5vdc from the computer, which was taken directly off of one of the stray power supply leads. (Red is 5v, Yellow is 12v, on the ones I have dealt with anyway).

An in-line ½ amp fuse was soldered into the wire, and the wire was run with the printer cable to the the three Geckodrives.

People have mistakenly used wall wart transformers to supply this 5v for the Geckos; this is not the source Geckos require. It should come from the controlling computer.

The 5vdc can also be taken from the computer's game or USB port.

The components were initially but in panel boxes as shown on the right, but the space was too tight for the relays, so a computer case was used. Above image.

The relays, diodes and FETs all came from mouser.com. They ship in small quantities.

It is important to note that when shutting down the controlling software, the parallel port pin that controls the spindle's relay can change state and turn on the spindle.

This happened here, and was resolved by placing a manual master switch, as well as a master relay switch, between the 5v from the computer and the bank of relays.

An auxiliary set of Gecko control switches is at the keyboard and is shown with the trackball.

The controls are housed in a 4x4 handy box; these cost a buck, more or less, and are found at Lowes etc.

The LEDs indicate the condition of the Geckos.

The circuit for the indicator LEDs is in the documentation that comes with the Geckos, but the Geckodrive docs do not make it clear that the pos. and gnd. for these LEDs are off the encoder terminals, not the power supply. That tip could save some head scratching ;-)

The unit resting on the back of the monitor is a USB numeric keypad. This serves as an inexpensive pendant that controls each axis. It is in a sandwich bag to protect it from dust.

A wireless keypad was tried as a pendant. However, its lack of consistency made it unsafe for all but the most basic moves.
The wired keypad has received the most use since it is dependable.

The arrow keys, 4, 8, 6, and 2, move the X and Y axes. The Page Up and Page Down keys move the Z axis in Mach.