Background:
A friend who saw the 3-1/2 axis CNC joinery machine I'm building suggested that it might be a good idea to offer a 3-axis version of the machine in kit form. It would be identical to the joinery machine except that the z-axis could not be tilted.
The machine would use four 200 inch*ounce stepper motors producing 400 half-steps per revolution to drive 3/8"-12 TPI Acme lead screws - two motors on the x-axis and one on each of the y- and z-axis. This results in a linear step size of 1/4800" and (ignoring frictional losses) increases the "oomph" of the 200 oz*in steppers by a factor of
- Speed of movement will be limited by the speed of the controlling PC; but 5"/sec is probably not an unreasonable expectation for moderately slow machines.
The nominal work space (the actual range of movement will be larger) is 12" x 12" x 4" (x, y, z).
There are four main groups of parts involved: (1) The wooden structure, (2) The electricals (a controller box that plugs into a PC printer port and provides power to the steppers - and the four stepper motors), (3) the collection of hardware (bolts, washers, nuts, rails, bearings, etc.), and (4) software to convert drawing (DXF) files to CNC command files, and software that reads the command files and communicates with the controller box to produce stepper activity.
Installing the software is a matter of downloading and un-zipping the two packages. One of the packages requires registration and a $60 registration fee - and doing a fill-in-the-blanks configuration. I don't provide either package; but feel that the package which requires registration is a bargain.
Assembling the structure is quick and easy (15-30 minutes with an allen wrench).
Assembling the controller box is probably an all-day job for most people. It involves drilling, soldering, tapping holes, and a bit of screwdriver work.
Some of the hardware requires cutting, drilling, and tapping metal and plastic blanks. Most of these operations don't require what I think of as advanced skills; but I'm aware that there may be woodworkers with no metalworking experience at all. There is perhaps a day's work involved.
My questions:
- Would anyone be interested in such a small machine?
- Should I expect kit builders to assemble the controller or should I pre-assemble it and increase the price to include that labor - or should I offer this as an option?
- Should I expect kit builders to do the preparatory operations on the hardware, should I do that myself and build it into the kit price, or should I offer this as an option?
- Should I discard the kit idea altogether and just offer finished packages?
- Any other thoughts / suggestions?
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA