How is your background with mechanics? It's actually pretty simple to build the mechanical systems -- to do it well is slightly harder.
Go to your kitchen. Pull out a drawer...slowly. That's your X axis. Seriously!
The cabinet itself is staying still. Between it and the drawer will usually be 2 glides, one on either side. The drawer moves in and out, and only in 1 plane. The motive force is your hand pulling it out...in the middle. Notice, now, that there is probably some "wiggle" present in the drawer, from side to side. In a machine tool we want to get rid of that wiggle.
Building something comparable in the shop, is just as easy. You start with a platform onto which you place your moving parts. This could be anything, including bed rails -- but it needs to be strong and absolutely flat. On top of this, you build a platform. Rollers, often called linear bearings, allow that platform to roll back and forth, just like the drawer in your kitchen. Since it's built with more precision than your kitchen drawer, there's no wiggling from side to side, during the rolling.
Now, you have a single axis. If you attach a drive screw to this, probably in the middle, you have the fundamental basis for a CNC machine. You need only build 3 of them...X, Y, and Z...and stack them on top of each other, to have the mechanical part of your router finished.
Now that you have a better understanding of what's going on, mechanically, take a look around this site. It contains an amazing depth of knowledge, and the members are among the most helpful I've ever had the good fortune to come across.
This is a picture from this site (don't remember the name...sorry!) that shows the sliding platform and stationary base. This one slides on what appear to be plastic bushings...simpler yet. It looks to be a good design, overall.
-- Chuck Knight |