[EMS Discuss] Why are CNC Kits so Expensive?

Josh Marinacci EMAIL HIDDEN
Mon Jun 18 14:40:18 PDT 2012

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.

- J

Josh Marinacci

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