Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The top profile fits snugly into the battery mounting plate, with clearance on the sides for the latches:
UPP Battery Mount – trial fit
However, I had enough trouble measuring those recesses that I broke down and added a projection() view to the OpenSCAD code:
UPP Battery Mount – profile
Exporting that as an SVG image and importing it into LightBurn let me cut it out of chipboard:
UPP Battery Mount – laser cut profiles
Obviously, it took several iterations to fit the top profile to the baseplate, particularly after finding slightly different measurements at each block position. On the other paw, laser cutting the profiles proceeded much more quickly than 3D printing just a few millimeters of the block, so it was a net win.
One of the folding wood chairs that Came With The House™ had a loose arm that turned out to be due to a missing chunk of wood:
Wood chair arm – as found
The obvious lay of the grain shows why it failed like that, surely hastened by the crack below the screw.
So I cut a snippet of brass tubing that, mirabile dictu, fit both the hole and the M6 screw, mixed up some wood epoxy and buttered it up:
Wood chair arm – brass tube epoxy fill
The crack extended entirely through the arm and was more extensive that seemed reasonable to expect the epoxy to handle on its own:
Wood chair arm – splits
So I slobberedsoaked saturated the cracks with wood hardener and clamped them shut:
Wood chair arm – clamping
The hardener is intended to solidify rotted wood, but it makes a reasonable adhesive and, being much more liquid than ordinary wood glues, seemed like it would penetrate further into the cracks than anything else on hand. We shall see how this works out.
Rummaging in the Drawer o’ M6 Screws produced a better match to the brass tube than the original flat head screw:
Wood chair arm – repaired
It screws into a fancy tee nut in the upright chair rail, where a dot of thread locker should hold it forevermore.
I hit the exposed end with some sandpaper to smooth off the last of those smears and, after a few years, it’ll probably look like it grew there.
It seems all the drain boards under dish drainers are now intended for contemporary under-counter sinks without a rim, which is not the Old School drop-in sink we have in the kitchen. After considerable faffing about, I hacked a fix to make the drain board & drainer fit the sink:
Dish Drainer – sink lip cutout
The crude notch not only lowers the front edge by a few millimeters, it also encourages the lip to stay over the sink, rather than sliding back over the counter and slobbering water everywhere.
The drain board has stiffening ribs under the center section, cleverly arranged so they do not actually touch the counter. I measured the shape of the board near the ribs:
Dish Drainer – measuring center ribs
And then cut shapes to both support the board and rest on the counter:
Dish Drainer – center support
The board has a swale in the middle, directly over those ribs, requiring more tilt for proper drainage:
Dish Drainer – rear support
Getting all of that flying in formation required several iterations and we’re still not entirely satisfied, but at least the water flows into the sink and does not puddle in the drain board or on the counter.
Stipulated: wood is the wrong material for the job, hot melt glue is breathtakingly ugly, and you want no part of this.
The intended cuts are the dark lines, each with a poorly defined scorch 2 mm on its left. Knowing that the nozzle is about 4 mm, this suggests the beam is off-center enough to juuuust kiss the nozzle and splash the outer part of the beam away.
Having recently spot-checked the alignment and not seen any odd behavior on another platform-spanning project, this was puzzling. Given that the laser recently survived a move from one Basement Shop to another, with plenty of jostling while standing on end, I suppose I should have been more careful.
The biggest clue was seeing the shadow lines only near the front-right corner and noting they got worse farther into the corner. This seemed like the “fourth-corner” alignment problem described by St. Sadler some years ago and covered in a more succinct recent video.
AFAICT, the problem boils down to the difficulty of precisely aligning the beam at the longest distance it travels in the front-right corner. Careful adjustment of Mirror 1, after getting everything else lined up properly, seems to be solution.
The beam is slightly off-center at Mirror 1 and only a millimeter high on Mirror 2 at either end of the gantry travel along the Y axis.
The beam position at the laser head entry upstream of Mirror 3 shows the problem:
Beam Alignment – Initial M3 entry – 2024-05-31
The targets are left- and right-rear, left- and right-front, with varying pulse lengths obviously underpowering the last and most distant shot.
Looks like a classic fourth-corner problem!
Tweaking Mirror 1 by about 1/8 turn of the adjusting screw to angle the beam vertically upward eventually put the beam dead-center at Mirror 3:
Beam Alignment – M3 adjustments – 2024-05-31
The bottom two targets are double pulses at the left- & right-rear and ‑front, so the beam is now well-centered.
A quick cross-check shows the beam remains centered on Mirror 2 at the front- and rear-end of the gantry travel, Mirror 3 is still OK, and the beam comes out of the center of the nozzle aperture:
Beam Alignment – M2 M3 exit final – 2024-05-31
Subsequent cutting proceeded perfectly all over the platform, so I think the alignment is now as good as it gets or, perhaps, as good as it needs to be.
Being in need of small bins to sort cutoffs / scrap material from the laser and now having an essentially unlimited supply of corrugated cardboard at hand, this made some sense:
Laser scrap bins – cutting
The cardboard is 3.8 mm thick and laid with the ribs parallel to the X axis to make all the parts stiff in the right direction. I rearranged the parts to fit the space available and work around the butterfly finger hole over on the right.
Rather than gluing all those fingers into their holes, I ran a hot melt glue bead around the bottom perimeter and up the four corners, which seems to do the trick. The fingers parallel to the X axis tend to be fragile, as only one or two corrugated ribs run along their length, but the overall box is surprisingly rigid after gluing.
They’re nominally stackable and the pattern includes stiffeners glued across the leg openings so they don’t slide off the box below, but it’s obvious these boxes will always have too much stuff to allow stacking.
I made a longer box for plywood scraps and may need a couple more for other stuff yet to be unpacked, but you get the general idea.
The WordPress AI Assistant reminds me to remind you of the safety measures appropriate for using hot melt glue: consider yourself warned.
I’ve been using what’s now called a Multi balans chair since shortly after it came out in the 80s, during which time the plastic feet have worn flat:
Balans chair foot – foot wear
By now, the wood bases ride on the floor, which is a Bad Thing I should have fixed long ago:
Balans chair foot – wood wear
The newer Multi chairs have rolling endcaps, but AFAICT that’s not a retrofittable thing.
The feet have no obvious way to get them out, but after I saw how thin the plastic had become on one foot, some experimental carving solved the problem:
Balans chair foot – OEM foot removal
A large bolt threaded into the crude hole provided enough griptivity to yank the feet out:
Balans chair foot – removed feet
With measurements in hand, I picked up a quartet of furniture leveling feet with M10 stems and tee nuts that exactly fit into the recesses:
Balans chair foot – tee nut fit
I generally buy from sellers who include measurements in their descriptions, although I no longer believe any unit-measurement prices. Most of the time the sizes come out close enough to reality for my simple needs.
The stems were, of course, too long, but that’s easy to fix:
Balans chair foot – cutting stem
The saw does yank the stem down at the last moment, but cutting slow & steady thins the steel and reduces the drama to manageable proportions. Fitting a scrap of wood exactly under the screw would be a much better technique; be it so moved.
With the chair set to the mid-angle position I normally use, the feet meet the floor almost perfectly:
Balans chair foot – straight foot contact
At the steepest angle, things get skewed:
Balans chair foot – angled foot contact
Applying my nearly perfect hindsight, I got a set of swiveling feet and found an appropriate scrap of wood:
Balans chair foot – swivel foot cutting
Zero drama!
Which looks exactly like it should with the chair at the steepest angle:
Balans chair foot – swivel foot contact
The chair now sports two pairs of feet:
Straight feet on the rear
Swivel feet on the front
Now, to see how they survive on a chair, rather than motionless furniture.
If you have any idea why the WordPress AI image generator would come up with this, let me know:
Balans chair foot – WP AI image
That’s not hallucination, it’s just plain irrelevant.
While setting up the small table I conjured from scrap, I discovered one of the folding legs no longer had a latch to keep it from folding. Whether it never had one or the latch got lost along the way, there’s no time like the present:
Table leg latch – installed
The bolt I put there in place of the joint rivet precludes a smaller latch along the lines of the simple steel loop on the other leg, so I figured I may as well go large and, with that much surface area, plywood will work just as well as steel for my simple needs.
When those set, I glued & clamped them together in situ, then wrapped the whole mess with what’s basically high-strength friction tape to encourage it to not come too far apart under the inevitable stress when the leg tries to fold with a pile of stuff on the table.
We’ll see how long this survives; if past experience is any guide, it’ll be a while.
The WordPress AI image generator has a shaky grasp of both human anatomy and the blog topic:
Woodwork design by Escher. What is that interesting tool? So many arms, all with nightmare fuel anatomy!
The Smell of Molten Projects in the Morning 