Precision

With the start of school, I won't be able to do as much with my CNC, but I'll still be able to do less time consuming projects on the weekend. This labor day weekend I decided to redo the walls of the gantry so the router didn't stick so far forward.

Yesterday I attempted to cut out the new sides but failed all three times I tried. The first one looked fine but when I cut out a second, I noticed they didn't line up. The back of the second one was missing about a 1/8 on an inch. I tried a third time (and failed) before realizing that the wood I thought was 12 inches wide — the width of the gantry sides— was actually 11 and 7/8 inches. I would not be able to get identical sides without perfect alignment of the cutting material. I decided to stop there and get some wider planks of wood the next day.

Today, my dad and I went to Home Depot and got 4'x8'x3/4" piece of fairly nice plywood. We also picked up a wet/dry vacuum that attached to a bucket (used for the dust collection). The plywood was cut into 16 inch wide planks, which is wide enough for the gantry sides.

A little tweaking to the CAD drawing (to fix the upper corners; I forgot to readjust the diameter of the bearing mount but I don't use it anyways) and several dusty minutes later, the two new sides were cut out. They were a 1/8" short but I expected that. The entire gantry bends back as the router plunges into the wood and the cutting forces push and pull the bit off center. It's relatively accurate for now, but I'll definitely need to tighten up the y-axis or rebuild the lower axis to use supported bearings.

Old CAD drawing

New drawing.

It was fairly easy to disassemble the gantry and drill the holes into the new sides because we could use the old sides as templates. We did have a little confusion when we forgot which pipe mounting block went where but with a little trial and error and looking at pictures we got all of them in the right place.

Old.

New.

Vacuum is pretty good for the price; just need a way to mount it and to add a dust boot.

Now the gantry looks a lot cleaner and cooler. I tightened up the y-axis and added super glue to the thread to keep them from stripping. Tomorrow I'll cut out the back of the gantry as the old one doesn't line up anymore.