Create small holes on a curved surface

Hello all,

I have been trying to develop a mold tool for a manufacturing process. The tool needs to have 10’s of thousands of tiny holes on the surface around 0.3 mm diameter. Traditional CAD software’s are unable to handle this and the system usually crashes.

I need to to add the holes to the curved surfaces in a pattern.

Would like to know what is the best way to do it as I am completely new to rhino.

Not knowing anything about your hole pattern:

First draw your circle ( I assume your hole is a circle) in a parallel viewport such as front view and align it to where you want to place the hole. make sure the curve is closed. Make sure UseApparentIntersections= Yes

From here you can run the _Trim command and cut away the inside of the hole

In some cases it mIght be advantageous to run the _Project command before running _Trim

Use the _Divide command and divide one of your edges by the number of time you want to copy the hole.

From here try to use the _MoveHole command to copy your hole.

Other potentially helpful commands:

http://docs.mcneel.com/rhino/5/help/en-us/seealso/sak_holes.htm

Another option if your pattern can afford to be distorted a bit would be to use the _Squish and _SquishBack commands.

http://docs.mcneel.com/rhino/6mac/help/en-us/commands/squish.htm

It seems that another of Hussain’s major concerns is whether Rhino can even handle “tens of thousands” of hole trims. As someone who has never had to do anything like he proposes but is curious nontheless, I’d be interested too.

Here is 10K holes in a hemisphere (not organized well, but they are there). Splitting the hemisphere surface with the holes took a little while - maybe a minute or two here on this old machine.

I have not tried to create a wall thickness though.
Edit, I used OffsetSrf>Solid and it actually worked OK, I let it run in the background, so I have no idea how long it took. A few mesh or rendering artifacts though…

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You need to describe, in more detail, exactly what you want to do. Which surfaces are you wanting holes in exactly, just the top like a salt shaker, or the conic section as well? what type of pattern? Because the answer is YES Rhino can do it, that’s the easy part.

How is the mold tool being created? If a laser is cutting the holes you may only need to supply a vector file containing the holes, or drill points if being milled. That will save you the time if the model does not need to be rendered.

If you want to keep the holes on the surface exactly round, you need to orient a cutter normal to the surface and then boolean it if the model has thickness. Like the other replies, getting an idea of the type of pattern you require would help here.

If you want to keep hole size and the gap between holes even it can be a bit tricky on conical surfaces

Well you’d maybe use arraysrf or flowalongsrf to distribute the cutters around the mold, but there are about a million questions to answer here. How are the holes being made?

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Thank you for taking the time to reply.

@Evan1, the holes need be on the complete curved surface, this includes the conical portion and the dome section on top. The holes need to perpendicular to the point at which it is cutting into the the surface. The center to center distance needs to be around 0.6 mm from one hole to its neighboring hole in all directions.

@michaelkreft I am planning to 3D print this with 0.25 mm nozzle with 0.1mm layer height. The aim is to be able to design one off vaccum forming mold tools for single quantity orders.

@Helvetosaur your dome looks really cool ! , I tried something similar in solidworks and I had to leave my system to complete the computation overnight, I do not know how long it took.

Well, it was mainly to answer @AlW’s question if it is possible and see how long it would take. The main problem is how to distribute the holes nicely - I didn’t care about that, I simply used a hack by arraying 10K circles on the XY plane and then applying them to the sphere with ApplyUV. The distribution is awful and the holes are not round, but it creates 10K curves on the hemisphere surface in a fraction of a second. Then I just Split the surface with the curves, it ran for a minute or two (but my machine is 5+ years old). I then tried offsetting the result solid, that ran for somewhat longer maybe 3-4 minutes?

So the answer is 10K holes in a surface like that does not pose any sort of problem for Rhino. The trick is getting a nice distribution, I don’t know how to do that, but one of the Grasshopper guys might have a good formula. If you are 3D printing the object, they do not need to be 100% round either - just as long as they are close within the printer tolerance.

So are the holes are just there to get the vacuum distributed to the sheet to be formed?

Umm… this sounds awfully elaborate for the sake of one vacuum formed part. Usually you would just CNC a one-off mold from wood or MDF, and vacuum forming isn’t suitable for shapes that are beyond the ability of a router anyway. Also high volume vacuum molds made from metal don’t have “tens of thousands” of holes drilled in them.

This mold is used in a refractory manufacturing process and not for vacuum forming plastic over it,

The metal molds in our case do have holes, but they are large holes and very few on the surface and then the vacuum is distributed through the surface.

If I can create a simple workflow with rhino or blender , the cost to 3d print will not be much.

Well Rhino can do it there is no question, its how you go about it as @Helvetosaur said. To get it exactly as described you need to find a grasshopper guy to help you.

If it doesn’t have to be EXACT, then maybe there are some things you could try. All of them will take some effort and trial and error to get the holes in a way you are satisfied with.

You could unroll the conic section then place holes… again in a very vast amount of ways… and then ultimately apply them back to the surface.

You could also use the spiral command to represent a curve along the conic section. this will very easily let you distribute features along it, but again they wont be exactly as described, and will take some iterations to get it close to the way you want.

Just brainstorming here…

Thanks for your help, planning to learn a bit of grasshopper myself and try to solve this. I have also found a professional certified rhino modeler, who will do it for me at a cost $$.

I’m also a certified rhino user as well, and i know others that are as well… Not sure that means much.

I’m just… certifiable… :stuck_out_tongue_winking_eye:

image

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…mainly British…
meaning that mainly Brits acts this way? Can confirm. :rofl:

how hard do you think something like this would be ?

I have been at it for a while and I cant seem to get started…

It really depends on how accurate your pattern needs to be, or if its just simply number of holes, and even distribution. You also said you wanted 0.3mm diameter holes, spaced 0.6mm apart…not going to go over well.