Archive for category Science
Their offspring began emerging in early July, with our first picture on 3 July. I’ll leave the image file dates in place so you can reach your own conclusions:
We think a titmouse (a known predator) pecked some holes, including the upper hole on the middle tube, as they seemed to expose solid (and presumably inedible) chitin from the outside:
More holes appeared in a few days:
The irregular spacing along each tube suggests they don’t emerge in the reverse order of installation:
Three days later:
Two weeks after the first holes appeared:
No more holes have appeared since then, so it seems one young wasp emerges every few days.
This nest produced about a dozen wasps, with perhaps as many launch failures. We’ll (try to) remove it and examine the contents in a few months.
We expect they’ll start build nests all over the house in another month …
The MPCNC isn’t the most stable of CNC machine tools, given its large masses and 3D printed structure. My early plotting pen tests suggested speeds around 250 mm/min were appropriate:
Diamond drag engraving produces a thinner line and makes the wobbulations more obvious:
Another test showed similar results:
Slowing down definitely reduces the shakes:
Producing the best results takes quite a while:
Similar results on another test:
Those “mm/s” labels are typos; they should read “mm/min”. Plotting at -1.0 mm on scrap CDs and DVDs produces a downforce around 200 g.
Eyeballometrically, 100 mm/min seems fine, but 50 mm/min (I’d likely use 60 for a nice round 1 mm/s) eliminates all the shakes.
Smooth curves, like Guillloché patterns, can run much faster, because they don’t have abrupt direction changes. This 3-½ inch hard drive platter has text engraved at 100 mm/min and the pattern at 600 mm/min, both at -3.0 mm for 300 g of downforce:
A closer look at the text:
And some digits:
When I want to brand an engraved CD, this will suffice:
All in all, the MPCNC engraves much better than I expected!
The turkey hen who once had nine chicks, then seven, now has only two:
We haven’t seen the fox since it nailed the previous chick, but it may be responsible for taking a chick a day, every day, for a week.
We wonder if she misses the rest of her brood as much as we do …
Taken through two layers of 1950s window glass, zoomed all the way in, with a phone camera.
With an outmoded LM12UU linear bearing drag knife mount on hand, I threaded an M4 screw into each brass insert, lined it up on a hole in a homebrew (by a long-gone machinist, not me) steel bench block, and applied pressure with the drill press until the insert tore out:
The retina-burn orange ring is printed in PETG with my usual slicer settings: three perimeter threads, three top and bottom layers, and 15% 3D honeycomb infill. That combination is strong enough and stiff enough for essentially everything I do around here.
The insert on the left came out of its hole carrying its layer of epoxy: the epoxy-to-hole bond failed first. Despite that, punching it out required enough force to convince me it wasn’t going anywhere on its own.
The column of plastic around the insert standing up from the top fits into the central hole (hidden in the picture) in the bench block. Basically, the edge of the hole applied enough shear force to the plastic to break the infill before the epoxy tore free, with me applying enough grunt to the drill press quill handle to suggest I should get a real arbor press if I’m going to keep doing this.
The third insert maintained a similar grip, as seen from the left:
And the right:
The perimeter threads around the hole tore away from the infill, with the surface shearing as the plastic column punched through.
Bottom line: a dab of epoxy anchors an insert far better than the 3D printed structure around it can support!
Homeostasis is a thing:
Mary saw a fox trotting behind the garden, gripping a (dead) turkey chick in its jaws, with the hen in hot pursuit. The fox dropped the chick, circled the pine grove, picked up the chick, and departed stage right. The hen eventually led her remaining chicks into the yard, but gathered them underneath while watching for danger:
She settled down for a few minutes:
With the fox safely departed, she released the chicks:
Then they returned to foraging, with one chick trying out its wings:
Two days earlier, she led nine chicks through the yard; we think the fox picked off a chick a day. She lost two more during the next four days, suggesting they rapidly improve their ability to scamper out of harm’s way.
The left display is rotting out:
The center display seems undamaged:
The right display took a direct hit:
So the middle station refilled 3025 = 10460 – 7435 bottles, roughly eight bottles a day, every day, for a year. Seems like a lot of refilling, doesn’t it?
Unfortunately, I didn’t take pictures of the other watering hole last year, but here’s what it looks like now:
Now, it’s entirely possible I have the two stations reversed, in which case I have numbers for all three displays:
- Left = 242 = 4758 – 4516
- Center = 633 = 8068 – 7435
- Right = 800 = 9689 – 8889
Does a bottle or two a day, every day, for a year, seem more reasonable? Hard to say, so, with a bit of luck, we’ll have more data next year.