Trircle Bowls

是的，你没有看错：trircle!我将向您展示如何制作独特形状的碗on a bandsaw with a really simple jig. Using the technique you can make oval, triangular, rounded rectangle, and rounded five-sided bowls. As an added benefit, you get more than one bowl each time and they will perfectly nest to make a complete set. I’ll describe the technique by making atrircle碗套；那是具有圆形三角形的碗。

此处显示的实际形状的名称似乎不安。我喜欢这个名字“trircle”，这是三角形和圆圈的舌头组合。以下是图形设计和数学社区讨论的其他一些命名选项：Tri-oval，Trircle，Eggllipse，3个裂缝表皮choid，Trifocal Ellipse，3-ellipse

I will show a lot of pictures. Take a look at them, they are annotated throughout for additional information!

Bandsaw, miter saw, sander

Various small pieces of wood.

Before we go into the workshop, let’s model these bowls inFusion 360。

Use the attached Fusion 360 file (triangular bowl parametric.f3d) to follow along for thetrircle。I made the design parametric so you can change the shape and size of the bowl; and get the relevant measurements for making it in your shop.

如果您想直接去切割碗跳到步骤3，以从附带的PDF模板制作一个碗。

将Fusion 360文件加载在“设计工作区 - 实心”中，然后转到“修改”>“更改参数”。您应该在上面的第二张图中看到一个屏幕。

The shape of the bowl is determined by the radii of the two different arcs forming the sides.

You can change these two parameters: the large_arc and the small_arc

然后，碗的“直径” D由d = groun_arc + small_arc给出

If the values of the large_arc and the small_arc are close to each other the bowl shape approaches a circle. A good range for a pleasant looking trircle is for the small_arc to be somewhere between 10% and 50% of the large_arc. The example we are making below has the values of large_arc = 5.5 inches and small_arc = 1.7 inches, resulting in a 7.2 inches ‘diameter’ bowl - measured at the bottom. The top of course is larger because of the angled sides!

您可以在Fusion 360中更改大_arc和small_arc，并立即看到所得的碗形状。在“参数”窗口中，单击“大_arc”或“ small_arc”的“表达式”以更改其值。值以英寸为单位。下一步中的动画显示了一个trircle，对于Small_Arc参数，从0.4英寸到5.5英寸。

您可以更改的其他参数是：

(1) the angle of the sides of the bowls

(2) the height of the bowl sides

(3) the wall thickness of the sides

Keep the parameters at reasonable values otherwise the results become unpredictable or break the model.

The last parameter is calculated:

triangle_side =（大_arc -small_arc）

您将需要此测量来布置并切割自己的碗设计as described below. In our example triangle_side has a value of 3.8 inches (5.5" - 1.7" = 3.8").

Once you have a design that you like write down the values for triangle_side, angle, height, and thickness. You can also do a screen capture of your design and parameters in Fusion 360. Now it’s time to actually make the bowls.

如图所示，这是最简单的，看起来最好从六个部分粘上三层。每个片段的外部为6.5英寸，宽3.5英寸，两端都有30度斜切切割。附件是带有尺寸的布局的草图（三角碗部分）。六个部分组成一层环。将三个片段粘合在一起，然后将桌子直接修剪成锯子，以使其完美。制作三个戒指，并确保它们放平；可能需要一些策划/打磨。

Make a bottom board that is about 12 inches by 12 inches square. Mark an equilateral triangle with a side-length of triangle_side from step 2 in the center of this board, and drill 1/8" holes A, B, and C through the board at the triangle corners. It is important that the spacing of the three holes is准确和等距(e.g. 3.8 inches). The attached pdf file (triangular bowl sketch) will help in the layout.

现在，将层环粘在底板上，从下面的一个旋转每30度。这将重叠接缝以获得更牢固的纽带。确保可以访问三个三角形孔，以便以后插入枢轴引脚。将多余的角落从底部的板上剪裁。

您准备构建一个非常简单的切割夹具。乘以12英寸x 15英寸的MDF或胶合板板（实际尺寸不是很关键），并从一侧到另一侧，而不是对角线！如PDF图（夹具尺寸）所示，在中心线上标记孔位置A和B在距离边缘6英寸和9.8英寸。通过A和B的夹具板钻1/8英寸的孔。exactlytriangle_side inches (e.g. 3.8 inches) apart toexactlymatch the holes of the bowl blank from the previous step.

For cutting I am using a 1/4" wide bandsaw blade. Set your bandsaw table to 25 degrees (the angle from step 2 above, or whatever angle you designed for the side of the bowl - 10 to 30 degrees is good); and set the fence to about 2” from the blade. Make a single cut into the jig up to the center line. Clamp a stop block to the fence against the jig so that you can reliably repeat the cut to the centerline in the following steps.

视频动画显示了Trircle切割技术的工作原理。

Place the bowl blank on the jig so that you can insert two pins (8d nails work well) through holes A and B进入the holes in the jig. You are ready to cut the perimeter of the first bowl.

Turn on the band saw and run the jig against the fence up to the stop block/centerline. This will make a tangential cut into the bowl blank. Turn off the bandsaw. Clamp the jig to the band saw table so it won’t move or slide off, or hold it in place. Then remove the pin from hole A (closest to the blade), turn on the band saw, and slowly rotate the bowl blank clockwise to continue the cut. You pivot around point B. Stop when hole C lines up with the open hole in the jig, i.e. at 60 degree rotation. You completed the first large arc cut. Turn off the band saw.

Insert a pin through hole C into the jig, remove the pin in hole B, and make the next 60 degree cut until hole A lines up with the open hole in the jig. As you pivot around point C you make your first small arc cut.

Then repeat the same procedure making 60 degree large/small cuts until you made it all the way around. Turn off the band saw and unclamp the jig. Carefully back the jig out from the blade and discard the outer waste piece.

该技术通过削减公司工作nsecutive arcs at 60 degrees each. A large diameter arc is followed by a small diameter arc, large diameter arc, small diameter arc, etc. The transition from large to small to large is perfectly smooth.

同样，请在：https：//youtu.be/-f7vzgyhpi4上查看“切割trircle动画”

Move the fence to the left by about 1/2” (12 mm). This determines the wall thickness of the bowl. Then repeat the same procedure as above. When you are done you will have the first trircle shaped wall-ring. There is a tangential split (entry cut) at the start of the ring that you will have to glue back together. I have found that with careful cutting/glueing the split is nearly invisible in your final bowl.

Continue cutting wall-rings until you run out of wood towards the center, or until the blade gets too close to the pivot points and can't cut the small arc. The last picture above shows the bottom of the bowl blank where I was unable to cut the very small radius around the pivot.

The resulting bowls will nest nicely into each other. Depending on your glued-up blank and angle you may get from two to four nested bowls.

I prepared a different bowl blank that may be easier to make; but not as good looking. It is also a little more difficult to cut the wall-rings cleanly as the bandsaw blade tends to follow the long-grain. Pictures only!

将每个墙环中的拆分粘合在一起后，您需要将内部面部面部磨砂以使您的喜好光滑。在附加底部之前执行此操作。然后准备一些板，底部的1/4英寸至1/2英寸厚。将它们切得比碗底大一点。如图所示，将四个小垫片粘在碗外部周围的底部。当您将其粘在底部时，这将防止墙环滑动。小心地将墙环粘在底部，然后在一切干燥后修剪冲洗。打磨外部，并涂上您选择的食物安全饰面。

You don’t have to stop attrirclebowls. The same approach can be used for oval, rounded square/rectangle, five-sided pentagon shaped bowls, and even higher polynominal shapes.

Ovals: use four pivot points, and e.g. 38 degree and (180 - 38) = 142 degree arcs (angles vary with design)

trircle：使用此指示中所示的三个枢轴点和60度弧线

Rounded rectangle: use four pivot points and three different arcs

Pentagon: use five pivot points and 36 degree arcs

显示了Fusion 360模型效果图，但我应该提到我还没有在商店中制作这些效果。如果您确实可以与有指导的社区分享！如果有兴趣，我可以为这些设计共享我的参数融合360文件。

Of course you can also 3d print the bowls from the Fusion 360 mesh files! I’m showing one small trircle bowl, just for fun!

And the last picture is a ceramic bowl made with the help of a wooden trircle mold.