It's picture time. This is the top of the old cnc, or what's left of it.
That's a 12" scale in the upper LH corner for size reference.
Here's the belly of the beast.
Both the horseshoe shaped top and the base are 1 piece metal castings. I took them apart to make getting this off my workbench a little less clumsy. I'm pretty sure the base is aluminum, but as heavy as the top section is it could be Zamak. Then again, there IS a lot of steel bolted to the top. That orangish blob in the center is the 2 piece carriage for the Bosch 1Hp router. It was machined using the original convoluted belt drive system that could only handle a DOC of about 0.010" at MAYBE a 10"/minute feedrate. I remember it seemed like it took about a thousand passes.
OK, this is the new toy, it's sitting on its' base but nothing is bolted down yet.
The Sherline is visible sitting in the corner, that corner is where the old cnc sat for at least 15 years.
This next shot shows dumb luck in action.
In the background you see one of the new X axis 12mm rails with its' bearing blocks, just in front of it is the existing 10mm rail that's 450mm long and only supported by an M5 bolt at each end. The new 12mm rails are bolted to a solid aluminum extrusion that will be bolted to the base by a pair of M5 bolts every 100mm. The rails will be shimmed as required to make sure they stay flat. In the foreground is the 1/4" x 2" aluminum bar that the bearings will be bolted to. As you can see, that bar JUST fits under the work table. Like I said, this is dumb luck in action - not prior planning. Right in front of that is one of the 2040 extrusions that are the major support of the machine, and the just hang off 2 M5 bolts at each end. There's about a 4.5mm gap between the extrusion and the surface. It's no wonder that people complain about the lack of rigidity in these things, there's just so many places built into them where things can flex. I intend to make spacers and bolt through the 2040 extrusion and the spacer into my 30mm base.
This is the spindle, in all its'
glory whatever.
This assembly is 60mm at it's widest, and it uses every mm of the existing rails to get its' 300mm of spindle travel. The problem is that the new bearing blocks are 40mm long, and there's 2 per rail for stability. That's 80mm, and if you figure in a generous clearance Clarence - you're up to 85mm. So any way you slice it, with the existing gantry set-up I'm going to lose 25mm of work area. For now, I can live with a 4027 instead of a 4030. Especially when you consider that my old cnc was a 3020. You can also see that they didn't use any more plastic in those moldings than they absolutely had to, it's not just the rails that flex.
This shows where the new Y axis rails will sit in relation to the existing rails. The camera really messes with things, the old 10mm rails look bigger than the new 12mm rails, but it just ain't so - I checked to be sure.
I just got the 2040 extrusions to replace the existing 2020's. If I did the arithmetic right, I should have about a 15-16mm between the new extrusions when they're installed. I intend to make solid spacer blocks to fit between the 2040 extrusions and effectively turn them into a truss. At that point, the weak link in the gantry will probably be the 15mm phenolic side plates. If that's the case, I can try bolting on a stiffening rib, or just making some new side plates out of my 30mm stock.
The major renson I went with an ESP32 based controller is that the MKS DLC32 has the horsepower, and the programming, to function as a stand-alone controller if desired - no drip feed from GRBL required. Just load your g-code onto a thumbdrive, plug that into the controller, and run the file.
That's enough yapping for today, I have to go make myself some supper.
Don
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