The CNC 3018-Pro uses cheap & readily available parts, so extending the Y axis went smoothly:
The 2040 side rails are now 450 mm long, as is the 8 mm leadscrew. I ordered 500 mm guide rods to forestall small length mismatches, then marked them to match the rails:
Cut them off slightly beyond the mark, face the raw ends to length, drill-and-tap for M5 screws, then put a pair of just-under-50-mm stubs in the bar stockpile. They ought to come in handy for something, right?
The original side rails & guide rods were 290 (not 300!) mm long, so the table gained another 160 mm of travel for a total of 340 mm; I suppose it’s now a CNC 3034-Pro. Seeing as how it’s the only one and I don’t want to kill my snicker SEO, let’s call it a CNC 3018-ProXL or a maybe 3018-Pro34. Whatever.
The embiggened 300×340 mm platform dates back to the original 1955 kitchen: genuine Formica over plywood. It sits atop the previous 300×180 mm table, now demoted to being a riser, and a sheet of closed-cell foam, with the same 50 mm long M6 screws holding everything to T-nuts in the 3018’s original aluminum platform.
And, yes, the identical Formica underneath the machine originally covered a freestanding kitchen cabinet; I knew I kept it around for some good reason. Kinda disorienting to see a piece of the pattern moving against the same background, though.
The GRBL setup now extends the Y-axis length (
$131=338) and puts the
G54 coordinate at the new middle, with the Z-axis origin kissing the ball-point pen on the new surface:
G10 L2 P1 X-145 Y-169 Z-24.6
While I was at it, I set the
G28 position at the far left side of the gantry, with the table sticking out to the front, and the Z axis at the top:
G28.1 X-298 Y-1 Z-1
Those are absolute machine coordinates, with Y and Z pulled off home by 1 mm. I set one of bCNC’s buttons to emit
G28 and park the tool carrier over there, out of the way.
With all that prepared, a full-size Tek Circuit Computer disk plots the way it should on a sheet of Letter-size paper:
I suspect the longer rods wouldn’t work quite so well for actual milling / machining any material tougher than, say, rigid foam blocks. For engraving and pen plotting, they’re all good.
Some measurements show this countertop isn’t quite as flat as the previous one, but a pair of tweaks got it within -0.15 / +0.1 mm:
Which I defined to be Good Enough™ for use with spring-loaded implements of cutting & drawing.
Your mileage will certainly vary.