[EMS Discuss] Why are CNC Kits so Expensive?

[Rick Osgood]

I don't honestly know the answer but I would guess that maybe it has
something to do with the fact that these parts have to be machined with
really tight tolerances.  If they are off by even a little it can add slop
and make your CNC machine less accurate.  I would think that in order to
make parts with such tight specifications they might need more expensive
equipment and maybe a lot more careful calibration and maintenance.  I
could be totally wrong but it seems to fit.

Kassie has built a few 3d printers so I wonder if she would have discovered
the answer in any of her research.

Rick

On Mon, Jun 18, 2012 at 2:40 PM, Josh Marinacci <EMAIL HIDDEN>wrote:

>  I realize this is an extremely broad and open ended question, so please
> allow me to narrow it down a bit.
>
> A few weeks ago I came across a video of a tiny drawing robot. It can draw
> using a regular pen controls on the x and y axes with what appears to be a
> screw + stepper drive, plus a tiny servo to move the pen up and down. The
> builders think they can mass produce it for 80$ but their design is not
> ready yet, or for sale.  Inspired by this video I began to research drawing
> machines, which led to plotters, which led to general CNC machines.
>
> Now, a few weeks later I know far more about stepper motors and linear
> motion systems than I would like.  I still want to know why, however, they
> are so expensive?  Not the electronic parts but the mechanical ones.  Why
> is a linear slide so expensive? Why are steppers 30$ or more each.  Why is
> an ACME linear screw as much as several hundred dollars.  Why is a simple
> coupler over 10$?
>
> My real question is what are the market and manufacturing reason that
> these parts are so expensive, especially since the base technology hasn't
> changed in many years (also, why do all CNC drive kits require a Parallel
> Port?  USB is nearly 2 decades old now).
>
> Am I simply spoiled by software and moore's law where things become
> drastically cheaper every few years?
>
>
> Once I figure this out, I can go onto my next challenge: designing a <
> 100$ CNC plotter.
>
> Thanks.
> - J
>
> --
> Josh Marinacci
> joshondesign.com
>
>
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