Category: Machine Shop

Mechanical widgetry

Magnifying Desk Lamp Pivot Clamp Repair

The clamp holding the magnifying lamp (with a fluorescent ring light!) over the Basement Laboratory Desk finally fractured:

Magnifying Lamp Pivot – broken parts

Gorilla Tape held the broken parts together well enough to determine how it used to work:

Magnifying Lamp Pivot – hole sizing

The two parts used to be 11.2 mm thick, but it fit on a random chunk of half-inch aluminium plate so perfectly as to constitute a Good Omen:

Magnifying Lamp Pivot – stock layout

I decided the saw kerf would make up the difference, because, sheesh, we’re talking pot metal here.

Lay out the center, use a transfer punch the same diameter as the lamp pivot to get the proper spacing, give it a whack:

Magnifying Lamp Pivot – hole marking

The alert reader will note I came that close to drilling the hole through the wrong side of the angle.

And, yes, extrapolating the vertical edge downward suggests the large hole-to-be will intersect the small hole-in-being. This is deliberate: the clamp screw through the smaller hole fits into a recess around the lamp pivot shaft to keep it from sliding to-and-fro. I had to convince myself, but it really did work out OK.

Pay some attention to clamping it at right angles to the spindle so the big hole goes through more-or-less in the right direction:

Magnifying Lamp Pivot – drill press alignment

The masking tape serves as a depth reminder:

Magnifying Lamp Pivot – drilling

Set it up in a machinist’s clamp, bandsaw in twain, file the kerf reasonably flat, clamp the halves together, then bandsaw the clearance slot:

Magnifying Lamp Pivot – clearance slot

The clearance kerf wasn’t nearly as on-center as I wanted, which doesn’t really matter, but I filed a bit more diligently on the shallow side while clearing up the slot:

Magnifying Lamp Pivot – clearance filing

Introducing the new parts to Mr Disk Sander roundified them enough to pass inspection. These angular bits obviously require a bit more attention to detail:

Magnifying Lamp Pivot – parts

The lamp originally had a fancy knob on the screw which never worked particularly well, so I replaced it with a nylon locking nut to maintain a reasonable amount of pressure:

Magnifying Lamp Pivot – installed

The far end of the screw has a square shaft fitting into a square hole in the lamp arm, making it easy to torque the nut enough to make the pivot grip the shaft properly; if I ever find my Belleville washer stash again, I’ll add one. I should cut the screw off, too, but that’s definitely in the nature of fine tuning.

A pleasant morning of Quality Shop Time!

The obligatory doodle with dimensions, some of which turned out to be completely incorrect:

Magnifying Lamp Pivot – dimension doodles

2018-10-03
Monthly Science: Cheese Slicer Epoxy vs. Water, Continuing

The epoxy coating on our cheap aluminum (?) cheese slicer continues to corrode (clicky for more dots):

Cheese slicer – epoxy failure – front

The back side:

Cheese slicer – epoxy failure – rear

The epoxy coating remains intact, although I expect it’ll break through as the corrosion products swell underneath.

For whatever it’s worth, I applied the epoxy almost exactly one year ago.

2018-10-01
Garden Hose Y-Valve Autopsy

One of the handles snapped off a Y valve at the garden and I finally got around to an autopsy:

Garden Y Valve – cross sectioned

That’s using a 24 tpi bandsaw blade, which doesn’t cut nearly as smoothly as a fancy diamond saw, but seems good enough for the purpose. Most of the ripply shading on the cut plane comes from specular reflections; it’s pot metal all the way through and cuts to a high shine.

A closeup shows more detail around the (now hemispheric) ball valve:

Garden Y Valve – thread detail

You can see faint straight lines just inside the hose threads, which gives a hint of what’s to come.

Pry out the sectioned ball and dislodge the O-ring from the now-obvious insert:

Garden Y Valve – O-rings

Gently squish the threads in the bench vise to pop out the insert:

Garden Y Valve – plug removed

If lives depended on it, one could dismantle and repair the valve without recourse to a bandsaw, but …

2018-09-26
MPCNC: Re-Relocated Probe Camera

Although the camera doesn’t hit anything, it seemed entirely too exposed out in front:

MPCNC – relocated camera – front view

So I moved it to the back, where I can’t see it and maybe won’t clobber it:

MPCNC Re-Relocated USB Camera

The camera sensor is now almost exactly aligned with the XY axes, so the goofy rotation is gone and the offsets look better:

bCNC – Rear-mount Camera Probe Config

The size of the “10 mm” inner circle at the crosshair depends on the target distance, so it’ll be smaller for surfaces clamped onto and thus rising above the table. Depending on how much that matters, I can tweak the camera focus and scale factor to make the answer come out right.

The setup at the home position looked like this from a different perspective:

MPCNC – Rear-mounted USB Camera

No operational change, just a cleanup.

2018-09-25
Bathroom Drawer Knob: Whoopsie!

I managed to snag a cargo pocket on the under-sink drawer knob in the Black Bathroom:

Bathroom knob – bent screw

Did a job on the pocket, too, although after Mary was done with it, you’d never know.

With that much of a bend in the screw, the knob left a nasty divot in the drawer front requiring a layer of wood-filled epoxy:

Bathroom knob – filled divot

I sanded it more-or-less flush with the surface, taking great pains to not scuff the surrounding paint. A similar layer fills the corresponding divot under the screw head inside the front.

Despite appearances, only about 1/8 inch of the epoxy peeked around the knob, so I painted it black with a Sharpie, ran the knob onto the screw, and declared victory:

Bathroom knob – restored

I’ll (try to) (remember to) stand further back from the knob …

2018-09-23
Miniblind Roller Repair

The rod along the left side of our miniblinds turns a shaft spanning the length of the housing which pulls-and-releases three pairs of cords tilting the blades, with one roller for each pair. The cords loop over, pass under, and are secured to a tab on the roller with metal ferrules, thusly:

Miniblind roller – intact

One day, the middle section of all the blades on one miniblind stopped tilting, prompting this discovery:

Miniblind roller – broken tab

The correct solution is, of course, to replace the entire miniblind, but our 1955 window frames don’t match up well with contemporary miniblind hardware and I was unwilling to reinvent that particular wheel for this occasion.

So I laid the cords in place, put the broken tab atop them, and held the mess together with a strip of the obligatory Kapton tape:

Miniblind roller – repositioned tab

Easing some epoxy under the tab and soaking the cords atop the tape held everything together in approximately the original layout:

Miniblind roller – epoxy backfill

Two days after I reinstalled the miniblind, a second roller broke and was restored by a similar treatment. While I had the thing ~~on the bench~~ clamped in the bench vise, I preemptively slobbered epoxy on the intact roller in the hope of reinforcing it.

So far, so good!

2018-09-19

Fireball Island Figures

A cousin asked if my 3D printer could replace some figures gone missing from their old Fireball Island game board, a classic apparently coming out in a new & improved version.

Fortunately, solid models exist on Thingiverse:

Fireball Island figure - Thingiverse 536867 — Fireball Island figure – Thingiverse 536867

Unfortunately, the left arm requires support, which Slic3r supplies with great exuberance:

Fireball Island figure - Slic3r support — Fireball Island figure – Slic3r support

The vast tower on the figure’s right side (our left) seemed completely unnecessary, not to mention I have no enthusiasm for the peril inherent in chopping away so much plastic, so I replaced it with a simple in-model pillar:

The pillar leans from an adhesion-enhancing lily pad and ends one layer below the left hand, with all dimensions and angles chosen on the fly to make the answer come out right.

Works like a champ:

Fireball Island Figures - orange - on platform — Fireball Island Figures – orange – on platform

The dark band down the middle comes from the Pixel’s shutter.

They emerged with some PETG hair, the removal of which I left as an end-user experience.

I mailed a small box containing figures printed in my (limited!) palette of four colors, some spares Just In Case™, and a few QC rejects showing the necessity of lily pads.

Game on!

The OpenSCAD source code as a GitHub Gist:

	// Adding support under Fireball Island figure arm

	import("/mnt/bulkdata/Project Files/Thing-O-Matic/Fireball Island/Fireball Island figure – 100k.stl", convexity=5);

	translate([6.5,-4.0,0]) {
	intersection(){
	translate([-10/2,-10/2,0])
	cube([10,10,11.6],center=false);
	rotate([0,-5.0,0])
	rotate(180/6)
	cylinder(d=4.0,h=30,$fn=6,center=true);
	}

	translate([8/4,0,0])
	rotate(180/6)
	cylinder(d=8,h=0.2,$fn=6);
	}

view raw Figure Support Mods.scad hosted with ❤ by GitHub

2018-09-11

Category: Machine Shop

Magnifying Desk Lamp Pivot Clamp Repair

Monthly Science: Cheese Slicer Epoxy vs. Water, Continuing

Garden Hose Y-Valve Autopsy

MPCNC: Re-Relocated Probe Camera

Bathroom Drawer Knob: Whoopsie!

Miniblind Roller Repair

Fireball Island Figures