The diner smacked his lips. "This #fillet steak is marvellous." He raised his voice. "Well done, in the kitchen!"

The chef stormed out. "Idiot! Boor! It was perfectly rare."

#MastoPrompt #MicroFiction

The #MastoPrompt for Monday 28 July 2025 is:

#fillet

The poem or story can include the prompt word or be about the prompt word.

@ me, if you like, or just include the #MastoPrompt tag (to allow people to follow or filter their feeds), or keep your work to yourself - all the options are good as long as you're writing.

If you're including an image please do include alt-text if you’re able to.

#Writing #SmallPoem #Poetry #Fiction #MicroFiction #SmallStories

The second step to improving the aerodynamics of the glider's external 'shark fin' antennae...add fillets to the mounting base.

This reduces interference drag.

After the low density filler cures (epoxy resin with glass microspheres mixed in), I'll sand things smooth. (The piece of wood is covered with transparent packing tape that was lightly waxed. The antennae should come off easily.)

This is a follow-on to:
https://universeodon.com/@KrajciTom/114836322219112991

#AvGeek #Aviation #ElectricAircraft #ExperimentalAviation #Homebuilt #Glider #DIY #Aerodynamics #Antenna #Fillet

#ModernIonicCapital sketch

The modern #IonicCapital with curved faces and radial symmetry is a drop-in replacement for the classic Ionic capital with flat faces.

Unlike the classic variant, which has a rectangular footprint, the modern variant has a footprint that fits in a square. In the classic variant, the volutes and scrolls project out so that they are visible from the top. In the modern variant, there are no scrolls, the volutes have a curved face, and they are completely nestled under the top.

The sketch omits the #fillet at the bottom because we added that to the column #shaft in https://pixelfed.social/p/Splines/791794072490907090.

So, we start at the bottom with an #astragal which is exactly the same size as in the classic variant.

Next up from the bottom is the #ovolo which is shorter than in the classic variant. It still has a #tectonicSurface on which #decorativeElements rest, and a #virtualSurface that envelops the decorative elements. In this case, I chose a minimalist design with no #eggsAndDarts. Instead, I use another plain ovolo as a substitute that is offset from the tectonic surface by 1 part (or 8 units, when µ = 144).

Above the ovolo is the #channel, which in this case is a round slab whose surface matches the neck of the column with a radius equal to 5/6 of µ (120 units).

Above the channel is the #abacus which has a curved face that is repeated on all four sides. There is an abacus with flat sides in the classic variant as well, but it is not visible from the front because it is hidden behind the #volute slab. In fact, the vertical #braidsAssembly in the classic variant is attached to the abacus.

Above the abacus is a #reed, and above that, another small Ovolo that tops the modern capital.

The curved volutes follow the blue circular arcs at the bottom of the sketch. The volutes are shaped like a wedge, as can be seen more clearly in the corner facing the front. The portion of the wedge between the outer rims has a concave surface.
Splines (@[email protected])

The bottom 1/3 of the #columnShaft for an #IonicColumn is a perfect cylinder. So the line below point B is a straight line. In https://pixelfed.social/p/Splines/791723063470910081, we blended the bottom end of the 60° arc and the top end of the long interpolated curve between points J and K. Now blend the bottom end of the interpolated curve and the top end of the straight line between points B and C to obtain the 3rd and final #NURBS segment for the #primaryProfileCurve of the shaft. Just like there's a #cavetto and #fillet near the #neck of the shaft, there is a fillet and cavetto near the foot of the shaft. However, there is a subtle difference between the two. The cavetto near the neck is tangential to the blended #NURBS curve that is not a straight line. The profile curve for the cavetto near the foot is tangential to a straight line. There is a special name for a cavetto that is tangential to a straight line or flat surface, like the two cavetto moldings in the #dado of the #pedestal. It's called a #conge. Another alternate name for the cavetto molding is #cove, which is evocative of "cave" because of its concave profile curve. Above the neck is a fillet 8 units tall and an #astragal 16 units tall that #Scarlata puts in braces in the column shaft section within his tables of #VignolaProportions, with a note saying they are not counted as part of the shaft but are accounted for as part of the #capital. I decided to include the top fillet as part of the shaft and keep the astragal with the capital. It does not change the design or alter the proportions in any way, but the inclusion of the fillet makes it more practical for #3DPrinting and #CNCMilling of the neck. This concludes the profile curve for the shaft with a height of 291 parts or 2328 units + 8 for fillet. The column shaft is tapered in the upper 2/3 due to #entasis whose purpose is to make optical corrections to the shape of the column which, without correction, appeared concave near the top.

Pixelfed
#ModernIonicEntablature with #modillions and #dentils adapted for #arcadeIntercolumnation.

This image shows modillions across the top of the entablature, including modillions visible on the side wall. The dentils are below the modillions and are a bit shorter than in the classic variant.

As with dentils, a #modillion must be centered on a column axis. In the front, there are two modillions directly above the two columns and eight other modillions equally spaced between them. The number is always 10. So the spacing is different for an #arch with no #pedestals.

This image also shows a skinnier #keystone. Its thickness is half that of the one shown in https://pixelfed.social/p/Splines/804548474524642209 but all other measurements remain the same. There is never a modillion directly above the keystone.

The #cymaReversa and #fillet above the keystone have #profileCurves identical to those in the #capital but the top is a square that is only µ x µ units. The top slab is centered front to back on the face of the arch.

In this image, the modern entablature is shown with the classic capital, but it goes really well with the #modernIonicCapital. As I mentioned in https://pixelfed.social/p/Splines/791065657488081419, the classic variant of the column capital has parallel flat #volute slabs only visible from the front and back, but not from the sides. Because of its lack of radial symmetry, the capital does not look as satisfying when viewed from the side, especially in a #colonnade, as seen in https://pixelfed.social/p/Splines/803089629244302486.

The modern variant has curved volute faces on all four sides with pointed ends at all corners and optimized for use in a corner column, but not limited to that. The modern #IonicCapital is the last remaining piece in our systematic look at the complete #IonicOrder.

This concludes our look at the entablature, both classic and modern, and both for #simpleIntercolumniation, or #Architravato, and #arcadeIntercolumniation.
Splines (@[email protected])

#Arch with #Ionic #Entablature and #Keystone Detail The #dentils arrangement we saw in https://pixelfed.social/p/Splines/791013152244518907 goes well with the classic entablature #profile we saw in https://pixelfed.social/p/Splines/790888454384861893, and they both go well with #simpleIntercolumniation, also known as #architravato. However, with arches, the entablature profile has to be adjusted a bit so that the dentils arrangement is as shown here. The shape, size, and gap between individual dentils remains the same, but a crucial difference is that the dentils at the #outer corners touch each other. As I mentioned in https://pixelfed.social/p/Splines/803615973439041638, in #arcadeIntercolumniation, the entablature is repeated on the wall behind the half-column. It doesn't end at the columns and has two "outside" corners and one "inside" corner. While the dentils at the outer corners touch each other, there is a single dentil in the inside corner that is shared by both walls. A bedrock principle of dentils (like that with #flutes and with eggs in the #EggsAndDarts motif) is that when viewed directly from the front or the sides, a dentil must be centered on the column axis. It is this principle that forces us to adjust the profile of the entablature in arcade intercolumniation giving us the arrangement shown here. The image also shows the detail of the decoration in front of the #keystone. The most easily recognizable component of that is the large #volute, which is the exact same size as the ones on the #capital. The smaller volute is exactly half the size of the larger one. It is mirrored, rotated and put within a bounding rectangle whose height is exactly 2µ (288 units). The channels of both volutes are bridged with #sinusoids derived from half turn of #helix curves that have been flattened. This motif in the keystone, where volutes of different sizes are combined with sinusoids is very common. It will be seen in the #modillions of the #modernEntablature.

Pixelfed
#Arcade #Intercolumniation without #Pedestal

In https://pixelfed.social/p/Splines/803089629244302486, we saw #simpleIntercolumniation, also known as #Architravato.

Roman architects combined columns with walls thick enough to bury half of the column width inside the walls and added arches to them for better load distribution. An arcade (multiple arches) can be run in series along a single wall, or in parallel to form a walkway. They can also be combined in both series and parallel configurations, perhaps the most famous of which is the #Colosseum in Rome.

In the Colosseum, the outer walls follow an elliptical curve (even though it looks circular from the outside), and it has multiple tiers of arches in series. The interior has arches in concentric passageways in the lower tiers giving it a lattice-like design.

Because arches distribute the load from above, they allow for wider intercolumniation. The rules for #ArcadeIntercolumniation differ depending on whether the columns have pedestals or not.

Besides the arch itself, which is part of the wall, the figure shows some new architectural elements.

The narrow part of the wall immediately behind a column is known as a #pier. The visible face of a pier between a column and the opening under the arch is known as #alette. The base of the pier has a molding, the flat part of which has the same height as the column base (µ) while the rest follows the #fillet and #cavetto or #conge of the #shaft.

As we move up the pier, there is a horizontal molding known as #impost just below where the arc of the arch starts. The impost wraps around on the sides of the pier.

Around the arc is a circular molding known as #archivolt, the bottom portion of which has a #fascia that is aligned with the face of the wall.

The wall itself extends all the way to the top of the #entablature. It is worth noting that the entablature is repeated on the wall. It doesn't end at the columns and has two "outside" corners and one "inside" corner.
Splines (@[email protected])

Side View of a #Peripteral (#Sexastyle) #Colonnade with #IonicColumns arranged in #Eustyle #intercolumniation. In my previous post at https://pixelfed.social/p/Splines/803076419096100108, I mentioned that the consensus sweet spot for inter-column spacing was 2.25 diameters (4.5µ) between column shafts at the bottom (6.5µ axis-to-axis), except for the two middle columns where the spacing was 3 column diameters (8µ from axis-to-axis). This variable intercolumniation is only for #colonnades in the front and back. The spacing between columns on the sides is uniform as shown in the image here. Something worth noting in this image is the number of columns on each side. In a peripteral (sexastyle) building, there are 6 columns in the front (and back) with 5 intercolumniations between them. On the sides, it is an error to double the number of columns on the sides. Instead, the number of intercolumniations is doubled — in this case from 5 to 10, giving us 11 columns. So, the number of columns is always even in the front, and always odd on the sides (one less than twice the number of columns in the front). On the topic of even and odd, also note that the number of steps leading up to the base of the colonnade is always odd. #Vitruvious suggested keeping the rise between 9" - 12" and the run twice that, or between 18" - 24". Note that these measurements are in physical units — a marked departure from the abstract µ = 144 units we have been using all along. The rules for intercolumniation presented so far are known as #simpleIntercolumniation. When the Romans introduced #arches and combined them with #halfColumns to produce #arcades, the rules were adapted for the new design. Because the arches distributed the load from the beams above, it allowed for wider intercolumniation. With the addition of #pedestals, the gap was made even wider still, and the look of the complete edifice is just majestic! With half-columns and arches, we will see some new architectural elements.

Pixelfed
#IonicColumn #Flutes

This diagram shows the 2D geometry of an #Ionic #flute. The larger blue circle shows the flute outline near the #base of the #column. The smaller blue circle shows the flute outline near the #neck of the #shaft. Both subtend a 12° angle at the center of the column.

Like an egg in the #EggsAndDarts motif, a flute must be centered on the column axis when viewed directly from the front, back, or the sides. This is why the 12° are split into 6° on either side of the X axis. The center of the larger circle is µ = 144 units from the origin on the X axis. The center of the smaller circle is 5/6 of µ, or 120 units from the origin.

In https://pixelfed.social/p/Splines/799340150182400358, I mentioned working at sub-micron precision, and you might wonder where that came from when we have been using abstract units like µ without specifying any physical units. My apologies for not making it clear that I had assumed 1 unit was equal to 1 mm. If that assumption holds, then µ = 144 mm gives a total order height of 4104 mm, that is 13.46 ft. At smaller scales, the precision is even higher than 1/10 of a micron.

With that said, here the radius of the larger circle is 15.0728 units and that of the smaller circle is 12.5606 units, with sub-micron precision if 1 unit = 1 mm.

Refer to https://pixelfed.social/p/Splines/791399680747885646 and place the center of the smaller circle exactly at point J on the neck line. Later we will draw a sphere at the same location with the same radius.

If you want a flat bottom for flutes, place the center of the larger circle at exactly 28 units (12 for the #fillet and 16 for the #cavetto or #conge) above point A in that figure. If you want a round bottom, then further move the larger circle up by the size of its radius.

Nobody would quibble if you used a radius of 15 units instead of 15.0728 units, but it would make it easier to switch from flat to round bottom or vice-versa by simply moving the circle up or down 15 units.
Splines (@[email protected])

#Braids #3StrandBraids #MulticoloredBraids To preserve the ability to print different strands in different colors when #3DPrinting, we must keep them separate. When #CNCMilling a block of wood or other material, we don't need to keep the strands separate. To accommodate both kinds of output, I suggest that you keep the strands separate until the very end, and perform a #booleanUnion at the last possible stage after making a copy of the separate strands. The topmost part of the diagram shows what the strands look like after a boolean union. Much of the internal structure is absorbed in the channel block, and overlapping parts of individual strands are eliminated. The magenta curve from https://pixelfed.social/p/Splines/798252244743520392 is also shown here. Note that the location of the red cutting planes has changed slightly — Instead of 40 units from the origin, the first cutting plane is located at 39 because I ran into another limit that we must avoid. Also, we need two blocks 120 units and 32 units long (not 24 units as was erroneously mentioned earlier). Turns out that cutting the strands at 32 units from the first cut puts us at 71 units from origin, and we run into another limit that destroys the #airtight properties of the cut solids. To get around that, we place the second cutting plane at 72 from origin to get a block 33 units long. The last cutting plane is at 159 units from origin, and when used with the first cutting plane it gives us a block 120 units long. The lower portion of the diagram shows individual strands cut using the cutting planes as described above. Depending on precision, you might or might not see a #nonmanifoldEdge on the second strand when cutting a length of 33 units. With precision set to 1/10 micron, which is ~100 times finer than current high-end #3DPrinters, I got a non-manifold edge. Sometimes the fix is easy — Just #explode the solid, and rejoin the tiny surface fragments. Experiment with different precision settings.

Pixelfed
In https://pixelfed.social/p/Splines/792511464365923534 we created the outer spiral for the #IonicVolute. We will now create the inner spiral. Remember that we're temporarily using a 3x scale.

Recall from https://pixelfed.social/p/Splines/792124787573855518 that the vertical gap between the maxima for the 2nd turn of the spiral and that of the first turn shown by points G and H, respectively, is exactly 4 parts or 32 units when µ = 144. With a 3x scale, it is still 4 parts, but each part is 24 units, so gap is 96 units now. Of these 4 parts, 1 part (now 24 units) is the #fillet that gets progressively narrower as it follows the spiral, and 3 parts (now 72 units) form the #channelGroove.

The volute extends 3/4 parts or 18 units now (6 units in the original) to the left of the point of horizontal tangency of the outer spiral. This is the amount needed to accommodate the ribbon and 3-strand #braid on the flat vertical wall on the sides of the #capital as shown earlier in the same post by points F and H.

Now focus on the square where we have the 12 numbered vertices. At present scale, the square is 1 part or 24 units wide. Now inset each concentric square by 1 unit on each side, effectively dividing the gap between the original squares in a 1:3 ratio — same as the fillet height to groove size ratio.

Move to new point 1 in the square and sweep arc 1 of the inner spiral using a radius of 181 units so that the vertical gap between the top of original arc 1 and new arc one is exactly 1 part (24 units at present scale), and the vertical gap between the start of new arc 1 and the old arc 5 is exactly 3 parts or 72 units.

Continue with inner arc 2 from where inner arc 1 ended, using new point 2 as the center. Finish drawing the entire inner spiral exactly as described earlier for the outer spiral. This time you don't need arc zero or the outer circle unless you are contemplating a #medallion.

All that's left now is to complete the #eye of the volute, which I show next.
Splines (@[email protected])

Refer to https://pixelfed.social/p/Splines/792499765146596723 for Step 1 in #IonicVolute construction. Remember that we are temporarily scaling up by 3x. Connect points 4 and 5 and extend it to a length approximately 144 units. Connect points 8 and 9 and extend to approximately 72 units. These are #transitionRays that we use to transition from one turn of the spiral to the next. The volute is constructed in discrete steps using 13 arcs numbered zero to 12 in the figure. The arcs are centered on numbered vertices of the 3 concentric squares we made in the previous post. The center for arc 1 is point 1, for arc 2 it is point 2, and so on. Point 4 is special — I call it #groundZero. It is the center for Arc Zero as well as the circle that encloses the volute. Neither the circle, nor arc zero are used in the volute, but a portion of arc zero is used in constructing the #scroll surface. You can throw away the outer circle or use it to create a #medallion around the volute in other unrelated designs. With 3x measurements, start arc 0 at ground zero, or point 4 with radius 228 and stop after 90° clockwise sweep. Start arc 1 where previous arc ended using point 1 as center and sweep clockwise 90°. Start and end arcs 2 and 3 similarly using points 2 and 3 as their centers. For arc 4, continue sweeping past 90° until it meets the first transition ray. For the 2nd turn of the spiral, start at point 5 with a radius equal to the distance between point 5 and point 13. The angles for arc 4 and arc 5 are #supplementary — They total 180°. So arc 5 ends on a horizontal axis. Continue with 90° arcs centered at points 6 and 7. For arc 8, continue sweeping past 90° until it meets the second transition ray. For the final turn of the spiral, start at point 9 with a radius equal to the distance between point 9 and point 14. The angles for arc 8 and arc 9 are #supplementary — They total 180°. So arc 9 ends on a horizontal axis. Continue with 90° arcs centered at points 10, 11, and 12.

Pixelfed
Classic #IonicCapital #Tectonic Surfaces Plan

We already made the 8 unit tall #fillet at the bottom of the #capital a part of the #shaft in https://pixelfed.social/p/Splines/791794072490907090. So, excluding that, the remainder of the capital is 14 parts or 112 units tall, for the bottom half of which we use the #revolve operation (like the #columnBase and #columnShaft), and for the top half we use the #extrude operation (like the #pedestal, #entablature, and #plinth).

Starting at the bottom, we have an #astragal that is 2 parts or 16 units tall and has the same profile as a #reed and #torus, falling in between the two in terms of size. The arc AD is shown in gray because it is an invisible #virtualSurface that envelops the decorations like #eggsAndDarts on the #ovolo. This is the measurement that is given in #Scarlata's #PracticalArchitecture, but it makes no mention of the #decorative and #tectonic surfaces. Arc BC with a radius of 4 parts or 32 units is the tectonic surface on which the Ovolo decorations rest. Such decorations have a variable or uneven surface which may not exceed 1 part or 8 units.

Points E and F mark the horizontal tangent or maxima of the second spiral and the first (outermost) spiral, respectively. The gap between them is exactly 4 parts or 32 units. GH is the profile for the vertical side surface on which part of the #ribbon and #braid lie flat, protruding exactly 6 units to coincide with the invisible virtual flat surface through EF.

The #cymaReversa is 2 parts or 16 units tall and 1.5 parts or 12 units wide. It starts 4 units to the right of F and stops 4 units short of the top fillet, which is one part or 8 units tall and 20 parts or 160 units from the #columnAxis.

Of the 4 parts or 32 units between G and H, the lower 3 parts or 24 units are part of the #voluteChannel groove and the top 1 part or 8 units is a fillet that follows the curve of the #volute and progressively gets narrower until it converges with the #eye of the volute.
Splines (@[email protected])

The bottom 1/3 of the #columnShaft for an #IonicColumn is a perfect cylinder. So the line below point B is a straight line. In https://pixelfed.social/p/Splines/791723063470910081, we blended the bottom end of the 60° arc and the top end of the long interpolated curve between points J and K. Now blend the bottom end of the interpolated curve and the top end of the straight line between points B and C to obtain the 3rd and final #NURBS segment for the #primaryProfileCurve of the shaft. Just like there's a #cavetto and #fillet near the #neck of the shaft, there is a fillet and cavetto near the foot of the shaft. However, there is a subtle difference between the two. The cavetto near the neck is tangential to the blended #NURBS curve that is not a straight line. The profile curve for the cavetto near the foot is tangential to a straight line. There is a special name for a cavetto that is tangential to a straight line or flat surface, like the two cavetto moldings in the #dado of the #pedestal. It's called a #conge. Another alternate name for the cavetto molding is #cove, which is evocative of "cave" because of its concave profile curve. Above the neck is a fillet 8 units tall and an #astragal 16 units tall that #Scarlata puts in braces in the column shaft section within his tables of #VignolaProportions, with a note saying they are not counted as part of the shaft but are accounted for as part of the #capital. I decided to include the top fillet as part of the shaft and keep the astragal with the capital. It does not change the design or alter the proportions in any way, but the inclusion of the fillet makes it more practical for #3DPrinting and #CNCMilling of the neck. This concludes the profile curve for the shaft with a height of 291 parts or 2328 units + 8 for fillet. The column shaft is tapered in the upper 2/3 due to #entasis whose purpose is to make optical corrections to the shape of the column which, without correction, appeared concave near the top.

Pixelfed