With the “first critical measurement” in the bag, my way forward was clear tonight. First thing, cut the Y-axis pieces to the correct length. Then, lay out all the measurements. By the way, the Y-table pieces have the most drill holes of any part of the machine; the main piece has 14 cross-dowel holes (and their attendant 1/4″ holes), plus 10 counterbored holes (which means 20 passes through the drill). That’s a lot of measuring and laying out and drill bit changes and &c.
Before I started cutting on the Y-axis, though, I had to get one piece of busywork out of the way. I measured, cut, and drilled the X-table rails, and got them installed on the X-table. The X-table is complete. w00t!
After I had prepared the X-table to receive the gantry, I went to work getting the gantry installed. First, I went to work on the gantry bottom (a relatively simple 6 cross dowels and 2 holes for the X-transmission nut). Once that was in place, I was able to attach the Y-gantry sides (which have been complete for a few days now, waiting for “critical measurement #1″), and suddenly, I had some moving parts! The U-shaped Y-axis was rolling along the X-table rails. I did a little dance of joy at this point.
I admit that I had some frustration getting the cross dowels to hook up with my drilled holes. I really do suck at hand drilling. But I eventually got them installed, and I got *lots* of practice doing cross doweling on the Y-table. But I am skipping ahead.
I then started in on the Y-table, first drilling the 1/4” holes that connect the two pieces (with the pieces clamped), then disconnecting the pieces, drilling the “second set” of cross dowel holes (I had pre-drilled one end of the piece previously), then going back through and counterboring all the 1/4″ holes. I tried to attach the Y-table pieces together, and after thrashing about trying to figure out which screws go where, I realized that I needed to counterbore more deeply. So 20 more counterbores to get them to the right depth. It went together pretty easily after that.
I decided to test-fit the Y-table with just a few 1/4″ holes connecting to the cross dowels. I had a lot of these to get through (10 in all to connect the Y-gantry sides to the Y-table), and I didn’t want to have to drill them all twice (or more). So I very (!) carefully drilled just one or two holes on each end of the Y-table, then installed them to check the fit. I think I finally got my hand drilling mojo. Out of the 10 holes, I only had to re-drill 2 of them. Very nice. That went together sort of rough, but I got it done and all of a sudden, I had a full Y-gantry rolling back and forth.
It was at this point (or a little earlier) that I realized that the X-table is narrower at one end than the other. The gantry gets really loose on the rails and looks like it’s going to fall off at one end, but is nice and tight at the other. After worrying and thrashing around this for awhile, I decided to shim one of the X-rails to make the gantry tight all they way down the X-axis. I will likely have to tweak this a bit. But I am learning how to solve problems with this rig. Building it all by hand really gets me a level of understanding about how it all works that would have taken a few years with a commercially-bought machine.
With the Y-table in place, I was just a hop, skip, and a jump from being able to make “critical measurement #2”, the Y-table width. All I needed to do was to cut the Y-table rails to size, and clamp parts C&D in place. Both operations went a lot faster the second time around, and I was able to easily get “critical measurement #2″, 10-1/16”. Strangely enough, this is the exact measurement from the plans. With all my “off by a 16th here” and “measure to the 8th” there, my Y-table is somehow exactly on-spec.
So I’m ready to cut out the Z-axis “table” and “gantry bottom” tomorrow. I even have the length already set up.
I may have the structure done tomorrow night. I’m really, really close with the “major” parts. I have to get the Z-axis assembled (which secretly consists of a Z-axis and a “router axis”), then cut the leadscrews to length, get the motor mounts cut out and installed, and I’m done!
Then it’s on to electronics and PC software setup. I found an ancient PC with a parallel port that’s running XP. If I get some time, I will start cleaning off the HDD and get Mach3, CamBam, and … erm… can’t remember what CAD program I was going to use… I should make sure Eagle is on there, too.
It feels like I’m in a progress cascade at the moment. With X- and Y-axes both up and running to some extent, the “pile of parts” is really starting to look like a CNC machine. It’s so cool!