Project 3 - XYZ Bench-top Router/Mill

Project 2 got me thinking... how am I going to cut the shapes?  I can design cool looking robot legs, but if I can't make them easily, why bother... enter Project 3.  I have been looking at a number of Blogs which discuss rapid prototyping machines and CNC routers and realized that the complexity of the machines and cost is relatively low.  I could probably build the XYZ stage for under $100, and buy the electronics for another $250.  With this tool, I could create any simple or complex shape I can model.

Take a look at the below sites for more building information.

Build Your CNC  a great step by step instructional site, who also sell everything you might need

OnShoulders a great blog which the writer has built his own rapid prototyping machine

HobbyCNC supplier of inexpensive driver electronics and kits

Probotix another supplier of inexpensive driver electronics and kits

After looking at the DIY as well as the turn-key versions, I started to design my own.  The first image uses the rollers shown at Build Your CNC (Rollers).  I was planning on building my own from replacement roller blade bearings, which are about $20 for 16.  In order to do a three axis machine, you would need 8 per axis.

XYZ router with roller bearings

This version has its drawbacks, mainly cost of bearings, and the volume each slide occupies.  In order to get the most out of any sliding system, the opposing bearings should be far apart as possible.  This reduces the amount of angular misalignment.  I found that the ball bearings on angle took up a lot of space.  Also, depending how big you want the bed size to be, there may be a lot of deflection between the bearing, which will add to the inaccuracy.

After looking around in Ace Hardware for a while, I found round bar stock and brass bushings.  This will allow me to design the router using the same methods as the professional machines, without the high cost of the linear bearings.  I will be loosing a bit of accuracy (compared to proper linear bearings) and gaining higher friction, but it should work pretty well.

XYZ router with brass busings

Once I have completed the design and built the first prototype, I will make it 'Open Source'.  Although I would like to sell the plans, legally I can not.  The version of Pro-E I have is only for student use, i.e. not for profit.  Bad for me, Good for you. But maybe I'll add a donate button for all you generous folks out there...

Keep an eye out for a new 'Designs' page.