Things like the router mount, the work surface, dust collection, and Estop and Home Switches. Topics that aren't covered anywhere else. 

The Router Mount
I was originally planning on buying a mount for the Bosch Colt trim router that I bought for this project. There are at least two sources, Probotix sell a a mount for the V90 and MCPI also sells a mount. However a friend posted .dxf drawings for one on the Fireball CNC yahoo group site, based on reading the BritishIdeas Blog. (Scroll down to the Rigid 2400 entry).  I thought I'd try my hand at making my own first.

Here the outer edges of the raw blank have already been machined away and I'm cutting the mounting hole for the router. Note the screw that's holding down the center part of the circle to keep it from coming loose at the end of the cut.
This is the back of the mount. The part that you bolt to the Z axis plate. The pocket has already been cut and the outer edges are being trimmed off.
Here is the mount glued together. You can see it with the router installed in the assembly section. Consider this as version 1. Based on some postings on the fireball cnc forum and my limited experience using the router I'm going to have to add a dust collection fixture to the mount.

See the entry below on Dust Collection for a
revised version of this mount!
(1) I had to cut two pieces for the part of the mount that holds the Colt. I'm cutting the first one in the picture above. Note the machining order. I trimmed the outside first, then I cut the circular part free and cut the slot between the 'jaws' of the mount. Those were two separate gcode files. I made the mistake of  reversing the cutting order when I cut the second piece. The circle & slot gcode was already loaded so I figured why not. I must have been tired. Really tired. The effect of cutting the circle is to remove the anchor from the left end of the piece of stock. There's nothing holding it down when you go to do the trim cut. That's 3/4 inch MDF and it's amazing how much it can flex!
(2) Glue the two jaws together before you cut the back of the mount. That way you can make sure that they fit into the slot you are cutting in the back piece

The Work Surface
CNC routers wind up with lots of work surfaces stacked one on top of the other. At the bottom of the heap is the nice sturdy, stable, heavy duty one that you really don't want to cut into. On top of it are a variety of work holding fixtures and sacrificial surfaces that allow you to cut all the way thru the work piece without damaging the real work surface underneath.
This accumulation of surfaces is a double edged sword. The closer you can bring your work piece to the bottom of the router the better. Closer means there will be less flexing and better accuracy. But eating up too much space means the size of the workpiece will be restricted.

Folks have used lots of material for their work surfaces. MDF is typical but I've seen aluminum plate, 80/20 extrusions and corian among the choices folks have made. I decided on MDF as the low cost option, figuring I could upgrade later on if it proved to be inadequate. Two posts, from the fireballcnc forum, prompted my choices of the worksurface design. Table Flatness convinced me that I should use two layers of MDF. T-Nuts is a good explanation of how to use them and convinced me that they would be a better alternative than insert nuts. Based on those two posts, I decided on a work surface using two sheets of 1/2" MDF.

I came up with three options for mounting the work surface.

1 - The conventional mounting

2 - Using an angle bracket to save working height

3 - Recessed bottom layer with extended top
The conventional mount would cost 1 inch of working height. The Angle bracket mount would save that height at the expense of additional parts and a more complicated alignment for the top. Recessing the bottom layer saves 1/2 inch with no added expense. Extending the top over the base rail shields the rail from some of the dust and debris generated by the router. I used the third option

The router was used to 'drill' the bolt holes in the top.

And then a V bit was used to countersink the bolt heads

The recessed layer was then drilled and spot faced

And the Tee Nuts were installed

The finished work surface.
The mounting holes around the edges were also countersunk
Right: The work surface overhangs the bearings to protect
them from debris
So, It turns out that it's a really Bad Idea to have the work surface overhang table. While it can protect the bearings from dust, It also makes it impossible to get a wrench in if you have to adjust the carriage. I wound up removing the top and cutting off the overhang.

To the right you can see the modified work surface with a wrench in place for carriage adjustments.

Dust Collection
The first thing I used my new router mount for was to cut the holes in the work surface for the tee nuts. Dust and chips from the MDF got everywhere even though I was holding a vacuum intake hose right next to the router bit. I remembered a post in the Fireball CNC forum "Dust Revisited". The downdraft from the router cooling air was blowing the dust away before the vacuum could suck it up. Using the idea's there I re-designed the Bosch Colt mount (above) and added a combination exhaust deflector and dust collector/vacuum boot.

This is the Business end of the Colt Router.
Because of the uneven profile, there's no convenient place to mount a downdraft deflector
I modified the original Bosch Colt mount by attaching a combination downdraft deflector and vacuum intake to the original mount. Not shown are four pieces of threaded rod that hold the assembly together (see below). The spacers are 7/8 inch, designed to leave enough space to fit a finger into the mount to engage the spindle lock when changing bits. The bottom is sealed with a thin sheet. I was going to use some plastic but didn't have any so I cut a piece of printed circuit board laminate that I had handy.

You can look at a 3D PDF model of the mount.
You can download .dwg and .dxf files for the version 2 mount.

The Colt is a tight fit into the hole in the dust catcher.

This pix was taken during my first test cut. notice the tornado of dust flying up into the intake. Yes some was left behind on the work surface but at least it stayed put. It was mostly in the slot that was being cut and was easy enough to vacuum up when the cut was over.

eStop and Home Switches
I went on-line to find a source for an inexpensive eStop switch. Experience with my Sherline 2000 mill has shown me that I'm not fast enough going to use my keyboard to stop the mill when there's a problem. When I found a source for the eStop switch I also found a supplier for home/limit switches so I bought some to use on this router as well. Figuring out how to mount them was a little bit of a challenge. It's important that the switch not be damaged by overtravel. Sometimes it's convenient to be able to move the carriage beyond the switch without having to remove the switches.

For the home switch and eStop switch wiring I used stereo audio cables with RCA phono plugs. These mate with the connectors I used on the electronics enclosure. They are cheap, and the stereo pair is easy to separate into single cables. I put terminal lugs on the ends of the cables I used on the limit switches with shrink insulation on the bare ground wire since it's close to the other switch contact.
Make sure you label the ends of the limit switch cables.

The Home switches were easier to mount than I had originally expected.  I made a small mounting plate out of 1/8 inch thick paneling and them bolted the plate in place using the same type of carriage bolts that are used througout the router build. This worked easily for the X-axis. In order to use the same mounting technique for the Y-axis I made 1 inch spacer blocks to position the switches correctly. You can download .dwg and .dxf files for the switch mounting plate. The switches are Micro Switch V3L-1101 series. A .pdf data sheet is included with the mounting plate drawings.

I have since moved this switch to the underside of the beam
Where it's more out of the way.

The eStop switch is mounted on a standard switch cover plate and then installed in a standard outlet box. There are a wide variety of switches on the market. This one, purchased on eBay, appears to be chinese in manufacture see the Jiangyin Changjiang Electronic Appliance Co. web site. The only markings I could find were LA23/203/209B. It mounts in a 22.5mm hole and the mushroom top is 38mm in diameter. A really nice switch for the price! The cover plate drawing is included with the micro switch mounting files above.

I used the same kind of  audio cable with RCA phono
plugs as with the limit switches
Holes were drilled in the sides of the outlet box for
The cover plate is oversized and hides
the nail mounting flanges on the ends of the box.

Home Alignment