CNC Build, day 32 and 33 – I love it when a plan comes together

My task this weekend was pretty straightforward; get the legs trimmed down, get the lower frames installed, cut and install the spacers, and install the torsion box onto the completed base.

I must say that in light of this task list, I was successful in all respects. But I’m skipping ahead.

When I left the build, I had the upper frames installed on both base pieces. I had intentionally cut the legs a little too long, with the idea that this would give the torsion box a cradle of sorts. However, they were protruding too much and I realized that they would interfere with the operation of the gantry, so they had to be cut down. I set up a fence for the tablesaw and uninstalled and reinstalled the 8 legs one at a time. I rechecked them for plumb while I reinstalled them.

I also found four pieces of wood that were all the same length (I had cut them while I was making ribs for the torsion grid), and that were the correct length to use as spacers for the lower frame. I decided that I needed at least 17″ between the frames so that I could fit the monitor down there. This leaves about a foot below the lower frame.

By the end of the first evening, I had the legs cut and the lower frame installed on the first base unit.

I knew that I had help coming on Sunday, so I needed to hurry and get as far as I could on the base unit before Anthony arrived.

I cut the four legs to size, got them reinstalled, and got the lower frame done pretty quickly. The second time is a lot easier. With the two frames built, I just needed to cut the spacers. A quick measurement, and I set up the tablesaw for the cut. I needed to make one small adjustment after testing out the first one ( luckily I needed to trim off a bit extra ), and all four spacers got created pretty quickly.

I decided where the CNC machine is going to live, and moved stuff around in the shop to clear the spot for it. In particular, I had to move the gantry construction (which has been living on sawhorses since, what, September?, somewhere else to get it out of the way. I even had time to sweep up a bit before Anthony showed up.

A short aside, the assembly of the bearings on the Z axis table is proving to be tricky. The spacing needs to be pretty exact, especially for the bolts that have two bearings on them. I found the tap and die kit, but I may have to go buy new 3/8″ bolts for this, because I don’t know how that whole thing is going together with the lag bolts I have. Back to the show.

Once Anthony was onsite, we took a short detour to see if we could get the heater running in the shop ( we couldn’t ), which made good use of the incredibly sturdy base units that were lying around but were about to become permanently stuck under a CNC. With the bases in place, we put in the spacers, checked for square, and started to work on moving the torsion box.

We went forward with the plan to put the torsion box bottom in place, then install glue, then drop the torsion box on top. This worked pretty well, but we made a couple of missteps, and I’m not certain that the bottom is really attached all that well. Nothing a few well placed nails wouldn’t fix, but I didn’t install any ( and may or may not, given how stable the whole thing is ). It’s glued in place, and shimmed in a couple of places where the box top was warping in a different direction than the bottom. The glue is curing under the weight of the box itself, which I estimate at around 250#. Once I add the plywood shelf, a spoil board, a workpiece, and the Y gantry, I estimate the whole mess will probably weigh about 600#. Needless to say, it’s not going anywhere soon.

As a coup de grace, we got the X axis rails clamped into place, all ready to be drilled and bolted when I get around to that.

With the base and the torsion box moved off of the workbench, all of a sudden, there is a lot more space in the shop again! It really felt good to get the work tables broken down and to see all that space open up.

I feel like the last huge hurdle is behind me now. I still have a pretty big task of drilling the X rails, but with them clamped in place ( and of course I have all my clamps back now they’re not keeping the torsion box level ), even that task should be easier.

I need to get the Z table straightened out. I think that I am going to just go buy some new bolts. Maybe I will see if I need some for the X axis also, although I feel pretty confident that the tolerances won’t be as tight as they are on the Y axis.

Other than those two engineering challenges, though, I think that I am nearly into full on assembly mode. Soon I hope that my complaints will be about sprockets and chains and perhaps calibration and alignment.

Thank you, Anthony, for helping out today. This part was definitely a two man job.