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Archive for category Science

Monthly Science: Organ Pipe Mud Dauber Emergence

An industrious pair of Organ Pipe Mud Dauber Wasps assembled their nest last August:

Organ Pipe Mud Dauber Wasp Nest - side view
Organ Pipe Mud Dauber Wasp Nest – side view

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:

IMG_20190703_184657 - Organ Pipe Mud Dauber Nest - right
IMG_20190703_184657 – Organ Pipe Mud Dauber Nest – right

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:

IMG_20190703_184647 - Organ Pipe Mud Dauber Nest - left
IMG_20190703_184647 – Organ Pipe Mud Dauber Nest – left

More holes appeared in a few days:

IMG_20190709_172632 - Organ Pipe Mud Dauber Nest - right
IMG_20190709_172632 – Organ Pipe Mud Dauber Nest – right

The irregular spacing along each tube suggests they don’t emerge in the reverse order of installation:

IMG_20190709_172623 - Organ Pipe Mud Dauber Nest - left
IMG_20190709_172623 – Organ Pipe Mud Dauber Nest – left

Three days later:

IMG_20190712_181634 - Organ Pipe Mud Dauber Nest - right
IMG_20190712_181634 – Organ Pipe Mud Dauber Nest – right
IMG_20190712_181625 - Organ Pipe Mud Dauber Nest - left
IMG_20190712_181625 – Organ Pipe Mud Dauber Nest – left

Two weeks after the first holes appeared:

IMG_20190717_172908 - Organ Pipe Mud Dauber Nest - right
IMG_20190717_172908 – Organ Pipe Mud Dauber Nest – right
IMG_20190717_172922 - Organ Pipe Mud Dauber Nest - left
IMG_20190717_172922 – Organ Pipe Mud Dauber Nest – left

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 …

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MPCNC: Diamond Drag Engraving Speed Tests

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:

MPCNC - GCMC Text - 250 mm-min
MPCNC – GCMC Text – 250 mm-min

Diamond drag engraving produces a thinner line and makes the wobbulations more obvious:

MPCNC Engraving Speed Test A - 600-900 mm-min
MPCNC Engraving Speed Test A – 600-900 mm-min

Another test showed similar results:

MPCNC Engraving Speed Test B - 700-900 mm-min
MPCNC Engraving Speed Test B – 700-900 mm-min

Slowing down definitely reduces the shakes:

MPCNC Engraving Speed Test B - 100-300 mm-min
MPCNC Engraving Speed Test B – 100-300 mm-min

Producing the best results takes quite a while:

MPCNC Engraving Speed Test A - 50-200 mm-min
MPCNC Engraving Speed Test A – 50-200 mm-min

Similar results on another test:

MPCNC Engraving Speed Test C - 50-150 mm-min
MPCNC Engraving Speed Test C – 50-150 mm-min

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:

MPCNC Engraving - Guilloche drive platter test
MPCNC Engraving – Guilloche drive platter test

A closer look at the text:

MPCNC Engraving - hard drive platter - detail A
MPCNC Engraving – hard drive platter – detail A

And some digits:

MPCNC Engraving - hard drive platter - detail B
MPCNC Engraving – hard drive platter – detail B

When I want to brand an engraved CD, this will suffice:

MPCNC Engraving - CD attribution text
MPCNC Engraving – CD attribution text

All in all, the MPCNC engraves much better than I expected!

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Monthly Image: And Then There Were Two

The turkey hen who once had nine chicks, then seven, now has only two:

Turkey Hen with two chicks
Turkey Hen with two chicks

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.

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Threaded Brass Inserts: Test to Destruction

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:

Brass Insert Retention test - A B
Brass Insert Retention test – A B

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:

Brass Insert Retention test - C left
Brass Insert Retention test – C left

And the right:

Brass Insert Retention test - C right
Brass Insert Retention test – C 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!

,

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Monthly Science: Weight

Homeostasis is a thing:

Weight Chart 2019-06 - Ed
Weight Chart 2019-06 – Ed

On the other paw, the eyeballometric trend line since mid-April slopes at -1 lb/month and arrives at just over 150 lb in December, so progress continues apace.

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Monthly Image: Turkey Hen and Chicks

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:

Turkey hen with chicks - alert
Turkey hen with chicks – alert

She settled down for a few minutes:

Turkey hen with chicks - resting
Turkey hen with chicks – resting

With the fox safely departed, she released the chicks:

Turkey hen with chicks - emerging
Turkey hen with chicks – emerging

Then they returned to foraging, with one chick trying out its wings:

Turkey hen with chicks - dispersing
Turkey hen with chicks – dispersing

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.

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Monthly Science: Water Bottle Refill History

This year’s Northern Star Quilt Guild show in the O’Neill Center at WCSU gave me an opportunity to update last year’s data points, although not quite in the way I expected.

The overview:

Gym water bottle refill station B - overview
Gym water bottle refill station B – overview

The left display is rotting out:

Gym water bottle refill station B - left
Gym water bottle refill station B – left

The center display seems undamaged:

Gym water bottle refill station B - center
Gym water bottle refill station B – center

The right display took a direct hit:

Gym water bottle refill station B - right
Gym water bottle refill station B – right

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:

Overview:

Gym water bottle refill station A - overview
Gym water bottle refill station A – overview

Left:

Gym water bottle refill station A - left
Gym water bottle refill station A – left

Center:

Gym water bottle refill station A - center
Gym water bottle refill station A – center

Right:

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.

For science!

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