The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Tag: Repairs

If it used to work, it can work again

Solar-Flattening Fiskars Cutting Mats

Fiskars cutting mats must lie flat on the table to be of any use, but they’re remarkably sensitive to warping due to localized temperature variations; a hot cup of tea can wreak a remarkable amount of damage. Suggestions from the InterWebs generally involve a clothes iron, temperature tweaks, overnight cooling, and unpredictable results.

Given that the mats are large polypropylene sheets, I figured applying moderate heat to the entire mat while it’s compressed between two flat plates would work better:

Fiskars cutting mat – solar flattening

That’s one of Mary’s 36×24 mats atop an MDF sheet (with pictures of wood laminated to both sides), under a 7/32 inch = 5.6 mm sheet of non-tempered glass, with a maple shelf supporting the last two inches of the unwarped edge, all sitting on the driveway in full sun.

The first attempt started too late in the afternoon for good heating and, after a few hours, had only slightly reduced the warp. Laying it out the next morning got the mat up to about 110 °F = 43 °C around noon and the warp was completely gone by evening.

I don’t trust the IR thermometer’s temperature measurements on glass, but the surrounding MDF and driveway were plenty hot.

The next sunny day flattened the warp out of 24×18 inch mat on my desk, so success wasn’t a fluke.

We noticed that the larger mat is now uniformly smaller by about 3/16 inch along the 36 inch width and 1/4 inch over the 24 inch height. It was a tag sale find with unknown provenance and, due to the warp, Mary had been using her other large mat for layout, so we don’t know if this one arrived a little short or if my technique both flattened and shrank it.

The smaller mat seems unaffected by its similar treatment, so your mileage may vary.

In any event, a flat mat is much more useful than a warped mat, so we’ll call the operation a success.

2023-09-19
Craptastic Kitchen Scale: Shattered

So it turns out the surface of the craptastic kitchen scale really was tempered glass:

Kitchen scale – shattered glass

That’s after an inadvertent drop edgewise onto the concrete patio.

Stipulated: given what I’ve already done to / for the thing, the usual warranties do not apply.

The frame around the NP-BX1 lithium batteries held the glass fragments together surprisingly well:

Kitchen scale – shattered glass – detail

Of course, harvesting the good stuff resulted in a pile of fragments, but the carcass cleaned up nicely and, after grafting a temporary top made from scrap acrylic it still worked:

Kitchen scale – temporary surface

I expected to just cut a slab of 6 mm acrylic to match the original 5 mm glass, but for reasons probably related to dielectric constants, the touch controls do not work through that much acrylic. In fact, they don’t work through anything other than the 1.5 mm acrylic shown above, which seems a bit too flimsy for normal use.

The original glass had a design screened on the back surface and covered with paint, which I can certainly mimic, but right now I’m unsure how much effort to put into the thing.

2023-09-14
Tour Easy Broken Spoke

A rear spoke snapped on Mary’s Tour Easy while we were at the far end of a ride. Unlike most broken spokes, the flanged end that I couldn’t maneuver the stub out of the hub and deploy the FiberFix, so we rode home slowly while avoiding as much rough pavement as feasible.

Once in the shop, pulling the sprocket and extracting the stub posed no problem:

Tour Easy broken spoke

Install the new spoke, crank to 23 on the Park Spoke Tension Meter to match the rest of the wheel, check the truing, and it’s all good.

At some point in the last two decades of riding, it seem the chain fell off the high side and gouged the spokes around the hub:

Tour Easy broken spoke – damage

If another spoke snaps in the near future, I’ll replace the lot of them, but until then, well, there’s riding to be done …

2023-09-08
Onion Maggot Fly Sticky Trap Repair
One of the sticky traps absorbed a mighty blow during the season and its ski-pole mount snapped off. Rather then rebuild the whole thing, I decided to just epoxy the pieces together and stick a reinforcing plate on the bottom.

I added a pair of screw holes to the OpenSCAD model and produced a projection of the bottom layer:
```
if (Layout == "Projection") {
    projection(cut=true) {
        Attachment();
        Cap();
    }
}
```
Which looked like this:

Sticky Sheet Cage – projection

Cutting that shape from an adhesive sheet looks the same:

Onion Maggot Fly Trap – adhesive sheet

The somewhat raggedy large hole seems to come from OpenSCAD’s somewhat low-res SVG outline conversion.

Fill the broken part with epoxy:

Onion Maggot Fly Trap – epoxy ready

Clamp it together on a plate to keep the bottom aligned:

Onion Maggot Fly Trap – clamping

Cut an acrylic baseplate:

Onion Maggot Fly Trap – acrylic cut

Apply adhesive sheet to acrylic, stick it on the bottom of the cage, add a pair of stainless steel screws, and declare victory:

Onion Maggot Fly Trap – bottom view

We’ll see how long that lasts out in the garden next year …
2023-08-30
Zenni Optical Glasses: Metalbending

The new batch of glasses I just received makes me take back any nice things I previously implied about Zenni Optical’s nose pad alignment:

Zenni eyeglass pads – as received

Zenni does have a guide to reshaping the frames, but it does not include aligning the pads parallel to your nose, which definitely goes better with wire-bending pliers in hand.

They should look more like this when you’re done:

Zenni eyeglass pads – aligned

I suppose this is a consequence of being able to get two eyeglasses + two sunglasses in three different frame styles and two different prescriptions, each with progressive lenses and antireflective coating, for about $350 delivered halfway around the planet.

Makes owning a set of metal-forming pliers look downright economical.

A few years ago, Mary paid more than that for a single pair of badly fitted glasses from a local outlet. Those days are over.

2023-08-28
DMM Probe: QC Fail

Clearing off the Electronics Bench unearthed the probes for my fancy Siglent SDM-3045 bench meter, which had been producing erratic readings. I isolated the problem to the red probe, which had an irregularly variable resistance ranging upward from a few ohms.

The probe being a non-repairable thing, I used the lathe to cut it apart and eventually found the problem:

Failed Siglent DMM probe

The probe tip on the right originally had no solder on it at all (*), with the curved part of the soldered wire fragment resting around it. The plastic pieces originally molded around the tip and wire applied enough force to hold them together, but the wire fragment fell out as I dismantled the probe.

Apparently the assembler didn’t get enough heat on the wire-to-tip joint to melt the solder on the probe tip, but the plastic shell got it past whatever QC might have happened between assembly and the shipping department.

A few years back, I refurbished all my failing alligator clips (using the Siglent meter and its test probes!) and no longer believe increasing my spend for such things will increase their quality. I’d love to be proven wrong, but the evidence is definitely stacking up the other way.

(*) I tried soldering the pin just to see if it was solderable: yes, it was.

2023-08-16
Worm Bin Valve Transplant

For reasons not relevant here, I have a spare water heater drain valve with a thread matching the drain valve for the Can-o-Worms bin:

Can-o-worms drain valve vs. water heater valve

It lacks the flange required to seal the O-ring against the outside of the bin, but I can fix that:

Can-o-worms – sleeved valve

It’s a chunk of PVC pipe faced to the proper length, bored to fit the valve body, then gooped in place with acrylic caulk.

Snug the nut inside the bin and it’s all good:

Can-o-worms – new valve installed

The original valve depended on having a smooth plug turning inside the outer shell, but years of grit scarred the interface enough to produce a slow drip. It also had the annoying mis-feature of aiming the opening inward, between the bin legs, where a jug didn’t quite fit.

The water heater valve depends on compressing a smaller O-ring against a seat inside the body, which may tend to clog with crud. We added a mesh filter to hold back the worst of the gunk, so this is in the nature of an experiment using free hardware.

2023-08-15