Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Tag: Improvements
Making the world a better place, one piece at a time
Trimming some poster frame edges brought this useful tool out of hiding. It’s an ordinary Stanley 20-331 flush-cut flexible-blade pull saw that I’d used while installing laminate flooring in the kitchen & laundry room some years ago; it cuts the bottom of moulding like nothing else.
Anyhow, what’s of interest here is the simple cardboard sheath I made to keep those delicate little teeth from getting bashed up in the tool drawer.
Saw and sheath
Here’s a closer end view. It’s nothing more than two large sheets of thin cardboard (think cereal box or maybe consumer electronics box) separated by two narrow sheets. The blade’s thinner than any practical cardboard you’ll find, so just do it. It’s held together with yellow wood glue, because that’s what I had nearby when I built it.
Saw sheath end view
The note written on the sheath reminds both my shop assistant and me which way the cutting happens. Sometimes, we need all the help we can get.
For what it’s worth, the new Stanley 20-331 listing shows a similar saw blade with a Fat Max handle. This is the older version, from back when thin was in.
I’m putting together an Atom 510 box to replace the ancient Dell currently acting as the Sherline CNC controller, with the intent of seeing whether a rather anemic low-power CPU with two cores will work as well. The system board has room for one PCI card and I figured I’d install a second parallel printer while I had the hood up.
But then I realized that the only LPT cards in my stash had tall brackets that wouldn’t fit in the new mini-ITX case.
Well, it turns out that the LPT card itself would fit in the box, so all I had to do was reshape the bracket:
A bit of filing on the bottom knocked off a millimeter and put a tidy taper on the tab
A brief session with Mr Hammer bent the top flange over, so as to meet the case mounting flange
A somewhat surprised tin snips removed the excess length
A cylindrical file chewed out a somewhat generous screw clearance notch
Finished LPT bracket
And then it’s just a matter of screwing things together.
LPT Bracket – outsideLPT Bracket – top
I’ll admit the clearance from the top mounting screw to the flange is terrifyingly cozy, but I’m not averse to applying force majeure to either an unsuspecting LPT connector or the case itself…
The top view omits the screwdown clamp that secures the card to the case so you can see where the screw notch goes.
After slightly over half a century, the rubber bumpers on the doorstops around the house have stiffened up and, occasionally, one falls off.
Although I suppose I should just buy a new doorstop, molding a dab of silicone snot around the end of the nice brass post takes only a few minutes (plus an overnight cure). If what they tell us about silicone adhesives is true, this one is good until the sun goes dark…
So, as I wondered there, it turns out that the tablet cursor can fall into the crack between my landscape left monitor and portrait right monitor, with the distressing result that the X server jams with the pointer jittering between the two displays. Worse, the keyboard isn’t active, so I can’t switch to a console screen and shoot X in the head.
I’m guessing this is a picket-fence error, where Something Bad Happens when the cursor hits the maximum possible value: X=16704, in this case.
The solution seems to be telling the Wacom driver that the tablet is just slightly wider than it really is, so that the X value can’t ever reach the maximum. Having done this before, the line is already in my xorg.conf, just waiting to be un-commented:
I suppose I should have known better: the bottom of that heatsink wasn’t anywhere near flat. I think it mated directly with the top of the CPU through thermal grease, not a compliant pad.
Curved copper heatsink surface
The obvious solution is to flycut the thing, which is where the Sherline’s limited Y-axis travel and teeny table put a cramp on your style. Normally, you’d put the length of the heatsink parallel to the X axis so the flycutter would clear on both ends, but there’s no obvious (read: quick and easy) way to clamp the thing that way.
So I mounted it parallel to the Y axis, which meant I couldn’t get the flycutter completely off the near end. The first pass at Z=-0.1 mm, however, showed that not only was the surface curved, but it wasn’t parallel to the top of the fins (which were flat on the tooling plate). I suppose I should have expected that.
This cut is has Z=-0.1 mm referred to the front end. It completely missed the other end:
First flycut pass
I flipped the heatsink around, measured the front-to-back tilt (about 0.16 mm), stuck a couple of brass shims under the front, and the second pass at Z=-0.05 mm from the new low point did the trick. Copper is nasty stuff and I did these cuts dry: the chips visible near the front are stuck firmly to the surface.
Final flycut pass
I scrubbed both the heatsink and the spreader plate on some fine sandpaper atop the sacrificial side of my surface plate until they were all good. I can see the remaining flycutter marks, but I can’t feel them, and the plates slap solidly together with a pffff of escaping air:
Flattened heatsink and spreader
A dab of heatsink compound should work wonders; the maximum dissipation will be under 20 W, roughly comparable to that old K6 CPU, but now the heatsink will be contacting the entire hot surface.
Most office desk chairs are crap. Spend a couple of hours in a typical office chair and you wonder if it had been designed by aliens who, perhaps, read the specs for human beings, but never actually met a person in the flesh.
Conversely, you can drive for a couple of hours and get out of the car feeling at least OK. (Well, if you buy a decent car, that is. Last rental car I drove had terrible seats.)
So, a couple of decades ago, I went to a junkyard and picked up a nice seat from a fancy wreck for about $50, built a plywood base with six casters from Home Depot, put a 1-foot-diameter Lazy Susan bearing between the two, and bolted everything together. The seat even had power adjustments, so (just for fun) I tucked a battery underneath.
After a while, I stripped off the seat belt doodads… and, of course, you really don’t need power adjustments after the first week.
Worked like a champ for about a decade, but even a high-end seat cushion eventually goes flat. So I swapped in a front seat salvaged from one of our cars (a Toyota Camry wagon, from back before minivans ruled the road) and that lasted another decade. It finally went flat and I swapped in the other front seat.
The 2×6-inch upright boards have slopes and cutouts that match the peculiar shape of the seat frame, with holes drilled in the wood for the metric machine bolts, and that’s a good enough anchorage for an office environment.
Chair base
The Lazy Susan bearing is between the top plywood layer and the square corner sticking out to the front. That layer bolts to the bottom sheet, providing enough clearance for the various heads and whatnot.
You really need six casters on a fairly large base, because the chair is immensely heavy (it was, after all, designed to not fall apart during a full-on collision) and rather top-and-back-heavy without you in place.
Considerations:
Get the seat close to the right height, as the adjustment range isn’t all that wide
Put your center of gravity in the middle of the base. Fortunately, the seat has plenty of forward-aft adjustment
Get the seat base pretty much horizontal
A closer look at the front:
Front detail
The back isn’t a lot different:
Back detail
Maybe I just have a weird butt or don’t spend enough money on office chairs.
The Smell of Molten Projects in the Morning 