Setting the tool home point quickly

Home Block Top
(click for larger view)

Now that we can quickly and accurately mount and re-mount the sacrificial board to the milling table, let's turn our attention to the top side of the sacrificial table.  First, we need a method to quickly, accurately and repeatedly 'nail' the X=0 and Y=0 points, without having to "eyeball it".

To do this, I made an "L" shaped jig, with conductive brass edges that pins very snugly onto the top of the sacrificial board.  The conductive strips are wired into the X-home and Y-home inputs of my optical interface board (see earlier post on Option Isolation Board).

The idea is to set the zero point one time, good for etching and drilling both sides of the board without having to reset anything.

Home Block Bottom
(Click for larger view)

The alignment pins are 1/4" aluminum rod, epoxied into place and are on a 3.0 inch center-to-center.

The square brass bar is set into small dados so they are sticking out just a little bit proud of the wood surface. This ensures the tool will touch the bar before it touches any wood.

This block fits snugly into the holes drilled in the sacrificial table in the previous step.

Home Block mounted to
sacrificial board (click for lager image)