A friend brought over some plastic to CNC mill about a week ago and we got talking about  CNC gantry routers and the currently in development DC Servo Drive.  Eventually as all things go, we talked ourselves into the idea of building from scratch of course, a CNC gantry router.  We quickly settled on 3/4 inch MDF as the primary material with bits of steel and aluminum in the mix for additional support where necessary.  

Our plan of attack is to start with the Z-axis and work outwards, CADing as we go.  The Z will have 20cm of travel and be running on un-supported 25mm round rail with recirculating ball trucks as seen above.  The 25mm linear bearings can be found online at VXB Bearings for about $12 each, precision ground rail can be had locally for about $4/lb.

Where possible and within travel, we’ll be utilizing my CNC milling machine to make precision interlocking parts.  We have most of the Z-axis in final design and figured it would be a good time to make some test cuts to get a better understanding of MDF.  As seen below, using 3/4 inch MDF, we milled one half of a closed bearing block with an insertion/location tab.  And then milled two location holes with one being an exact fit and the other allowing for 100 mills difference to test for tolerance, material expansion and fit. 

It was found that a 1:1 fit is best, the parts required just a minor amount of force to insert.  And a bit of glue will make for an extremely rigid construction.  We took some video of the milling process with a bit of commentary wrap up at the end:

More to come as the project progresses…