[EMS Discuss] Why are CNC Kits so Expensive?

[Bob Miller]

On Wed, Jun 20, 2012 at 2:50 PM, Josh Marinacci <EMAIL HIDDEN> wrote:

> Why does the Parallel Port latency matter?  I would think that the computer
> would download the instructions into some sort of board inside the CNC
> machine which does the actual drawing.  It seems like 1k of RAM would be
> enough to have a decent buffer of a few instructions.

Hi, Josh.

If you have a dedicated processor driving the motors, then latency at
the host does not matter.
I believe that most parallel port designs are using the PC to drive
the motors directly, so sub-
millisecond timing is necessary.

> Another question:  belt and pulley vs threaded rod? What's the better way to
> create linear motion?

I'll look forward to learning that, too.  I believe Kassie's RepRap
uses belts for the X and
Y axes and threaded rod for Z.

-- 
Bob Miller                              K<bob>
                                        EMAIL HIDDEN