Pattern grooves on cylindrical surfaces

[shrekuntu]

In cadquery, is it possible to do grooved patterns on cylinders. Typically, these are pattern grooves in rubber lagging on conveyor pulleys, like attached pic shows. These patterns can be diamond, herringbone, chevron

[Adam Urbanczyk]

You could try: 2xsketch + 2xtwistExtrude + union to get the final shape.

[Adam Urbanczyk]

Here is some code if it helps:

import cadquery as cq

r = 20

s1 = cq.Sketch().circle(r).edges().distribute(20).rect(1,2).clean()
s2 = cq.Sketch().circle(r,mode='c',tag='c').edges(tag='c').distribute(20).rect(1,2).clean()

w = cq.Workplane()

w1 = w.placeSketch(s1).twistExtrude(2*r, 90)
w2 = w.placeSketch(s2).twistExtrude(2*r, -90)

res = w1.union(w2, clean=True, tol=1e-2)

show_object(res)

[Roger Maitland]

Is this the type of thing you are looking for?

r = 10

c = 2 * pi * r

d = 4 * (c / 10) / 3

pattern_wires = (

cq.Workplane("XY")

.hexArray(d, 10, 5, center=(True, False))

.polygon(6, 0.8 * d)

.wires()

.vals()

)

mapped_wires = [w.mapToCylinder(r) for w in pattern_wires]

mapped_faces = [cq.Face.makeNSidedSurface(w.Edges(), []) for w in mapped_wires]

pos_pattern = cq.Compound.makeCompound(

[f.thicken(f.flipNormal() * 1) for f in mapped_faces]

)

pos_patterned_cylinder = cyl.fuse(pos_pattern, glue=True)

if "show_object" in locals():

show_object(pattern_wires, name="pattern_wires")

show_object(pos_patterned_cylinder, name="pos_patterned_cylinder")

which results in:

The pattern is arbitrary, as long as you can draw it, it should be mappable. This code took 2.13s to run on my old laptop. As the pattern is a Compound object it could be cut from the cylinder as well (which takes a few seconds longer).

I still have more work to do to integrate it with the workplane class but I'd appreciate any feedback you have.

Cheers,

Roger

P.S. I'm actually working on writing text on a cylinder to label parts in one of my projects and this just kind of fell out.

On Sat, Dec 4, 2021 at 10:43 AM shrekuntu <shre...@gmail.com> wrote:

In cadquery, is it possible to do grooved patterns on cylinders. Typically, these are pattern grooves in rubber lagging on conveyor pulleys, like attached pic shows. These patterns can be diamond, herringbone, chevron

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[shrekuntu]

Hey Adam and Roger. Thank you both very much for your generous help, I appreciate it.

I tried both of your solutions but coudn't run either due to an error.

In Adam's code I get AttributeError: module 'cadquery' has no attribute 'Sketch'. I tried to run the skecth example from the cq docs, same error. It must be something wrong with my setup then, eh?

With Roger's code I get AttributeError: 'Workplane' object has no attribute 'hexArray'

I'm running this in cq-editor

One observation in Roger's code. Would it be possible to have partial hexes at the edge of the cylinders, this code only fits whole hex and leaves a gap where it can't fit the whole hex, is patrial hex with cut-off possible?

Thanks again to both of you.