Muỗng/cây cạo THC parametric ergonomic

Made by request: This is a spoon/scraper combo, intended to aid in the collection of THC crystals from a cannabis harvest. Two versions are included, short and long. The long one is 245 mm long, which should fit on most build plates.

Features:

• ergonomic handle, comfortable to hold
• a spoon on one end
• a scraper on the other end
• scraper is sharpened on three edges
• top of the scraper is recessed to serve as a scoop

Basically I made this as a reason to figure out the 3D problem of making a square spoon with a round bowl, which I had been wanting to do for a while but never had a practical use until now. The spoon profile is known as a "squircle", a hybrid between a square and a circle controlled by a squareness parameter ranging between 0 (circle) and 1 (square).

Everything is parametric in the thcspoon.scad file, if you want to change anything:

• Spoon length, width, depth, and squareness
• Handle width, height, and length
• Scraper width, length, and thickness

Printing

Print any way you want.

• I recommend adaptive layer height.
• This doesn't need supports; all negative slopes are printer-friendly.
• You may need a helper disc ("mouse ear") touching the spoon end to hold it down, because this is a long thin part that may warp as it prints if you don't have good adhesion. It worked for me without a mouse ear, however.

Post-printing

You may want to apply a primer and light sanding to the scraper sides and the spoon bowl to prevent small crystals from getting trapped in the layer lines.

How I designed this

The spoon is what intrigued me about this design, and the reason I agreed to do it. The requester had made a simple drawing showing a square spoon even though that wasn't intended, but it got me thinking about how I'd make a square spoon with a round bowl.

I started with the formula for a squircle, which includes a squareness parameter that controls the shape of the spoon rim. When squareness=0 the rim is circular (or elliptical if the width and length are different). When squareness=1 the rim is rectangular with sharp corners. In this model it's set to 0.7, which is a well-rounded rectangle.

To make the bowl, I started with the vertices from a geodesic hemsphere made with my octsphere.scad library, to make an upside-down spoon bowl. At the base of the hemisphere, I calculated the squircle radius for every vertex angle, moved the vertices into a squircle position. Then for all the higher vertices, I interpolated the squareness parameter such that it becomes zero at the height of the hemisphere, and moved each vertex to a new radial position based on the squircle at the vertex's height. Finally I shifted all the vertices down to the heights of a spherical cap much larger in diameter than the original hemisphere, to remove the vertical sides of the squircle-distorted hemisphere.

Once I had that shape, I could generate it again with a smaller radius and use that to cut a hollow into the first shape.

The handle transitioning to the scraper consists of a series of similar polygons that vary in width and height according to Bezier curves, and the polygons are stitched together to create a shape that can be rendered as a polyhedron().

Category: Hand Tools