Create a strainer

francois_lionet

Hello all,

My name is Francois, I have been using OnShape since a couple of days now, and I really enjoy it.
Yet, I am a bit stuck for a project of mine...

I would like to create a strainer, that is a thin half-sphere with regular holes in it.
I know how to create the half-sphere, but I do not know how to make it with a hole "pattern", holes at the tangent of the sphere all around the surface.
Can someone explain this to me ?

Thank you very much in advance,

François

pete_yodis

I think you mean like this... right?

pete_yodis

@francois_lionet

Your solution may be best handled by patterning bodies that are then used to cut your strainer sheet.  If you could provide the model as a public share, and then post the URL here, I'm sure there would be lots of interest in helping you.  This forum and community is a wonderful place for that.  If you want to keep the model private, then you can reach out to individuals you trust to help you.  Another way is for us to guess what you want, model a method, then post it here.  I threw out the patterned bodies as my first knee jerk reaction guess.  I envision a series of revolved bodies at staggered diameters radiating outward.  Each body is orthogonal or normal to the sheet at that radius.  Then all the staggered diameters are patterned.  Then, the bodies are used to cut away..

pete_yodis

I think you mean like this... right?

andrew_troup

I would do it as described by@pete_yodis

peter_hall

I would like to see this designed @pete_yodis not sure how you are proposing to achieve it.

pete_yodis

@peter_hall I'll see what I can whip up later tonight if I have some time... Off to dinner with the kids and wife   (that's for you @andrew_troup)

andrew_troup

francois_lionet : do you want the boundaries of your holes cylindrical (as they would be, approximately, if punched through sheet metal) or conical (as they might be if injection moulded, or 3D printed)?

And when you say "regular", do you mean that each hole is equidistant from all the other nearest neighbour holes? If not, how do you want to arrange them?

francois_lionet

Hello all,

Thank you for your answers and help. This looks like a great community, and I am happy to be here !

The model I would like to create is just as pete_yodis showed.
Andrew : I would rather have the holes cylindrical, but it is not really an important point as long as they are holes. "Equidistant" : just like on pete's image. Let me add images too (why didn't I do it at first place ?)
As you can see : as long as there are holes (basically I want air to flow through), it is OK. I think the important thing I would like to learn how to create is "how to wrap a thick surface with holes around a semi-sphere"...

andrew_troup

francois_lionet
Something like this? 



Model is public, at 
https://cad.onshape.com/documents/9c70cd8b50b64b4db0593678/w/e6a3caff96d640718ac60f49/e/dd6640658575426b860a47c3

pete_yodis

Nicely done @andrew_troup!  @francois_lionetAnother fabulous thing about the community is that it's global.  Answers from the users are often provided while you are sleeping.

Narayan_K

Go through this if it helps.




https://cad.onshape.com/documents/5f490d3945544e82b66d74ea/w/caa2e55b748040a9a7278747/e/2988af030b984a26976c3b0e

viru

@Narayan_K , Nice work.

pete_yodis

Fantastic @Narayan_K !

peter_hall

Thanks, made private copies in order to see the workings (only by requesting to edit each stage can you see the workings, this you cannot do on a public view) followed the workings and agree nice work @Narayan_K

andrew_troup

nice work indeed, @Narayan_K

I wondered if face pattern would work and you showed it to be a simpler approach
I also liked this construction



although it occurred to me it could be done more simply (the two shorter lines could be omitted by using the symmetric constraint)
your method makes it obvious which entities participate in the geometric relationships, and to me clarity trumps simplicity.

andrew_troup

I was interested to notice that "Face Pattern" was working even though the faces being patterned were subtly different.
In some respects, "face patterns" are not as resilient to change as some other features (as mentioned just now by @lougallo
in this post https://forum.onshape.com/discussion/comment/12820/#Comment_12820

Yet even after I tweaked @Narayan_K 's nice model to exaggerate the difference, to their credit,  the patterns still worked just fine.