Best way to add a hole pattern to a round sheet metal part?

Tristan_Neumann

I am trying to create a sheet metal cylinder with drainage holes in the sides as shown in the attached screenshot. I created the cylinder as an extrusion of an arc that almost creates a complete circle. Then, in the flat pattern made a sketch with 2 circles and patterned it to fill the flat. Then I extruded that sketch. As you can see in the screenshot, this took over 37 seconds to compute. I'm sure there is a more efficient way to create this feature, I'd be grateful for some suggestions.

wayne_sauder

@Tristan_Neumann
 I don't see any screenshots or a link to your project. Either would better show us what you are trying to accomplish. 

SethF

Unfortunately, you're missing said screenshot

dirk_van_der_vaart

You mean something like this?

Tristan_Neumann

Tristan_Neumann

Yes, this looks like the same approach I took. I was just wondering if anyone had a less computationally intensive way to get the same result.

eric_pesty

The problem is that sheet metal doesn't allow "face patterns" so it's slow to create the pattern.

Creating a vertical "slice" of your part with just one row of holes (pattern in one direction only in the sketch) and patterning the part should be significantly faster but will require more features...

john_mcclary

I find adding holes to the original cylinder then create the sheet metal thicken off that face usually works much faster. It seems there is a lot more progressing going on every feature you add after sheetmetal 

S1mon

The approach that one takes may depend on if you need the holes to be true circles in the flat pattern (e.g. they're going to be punched with a round punch when flat), or if they want to be circular when viewed normal to the bent up shape (in which case they're not circles when flat). There's a third situation where the holes want to be perfectly round on the finished bent metal, and they would have to be CNCed to make them (see the "cheese grater" Mac case.).

john_mcclary

For my case, sorry ome of the holes end up being slightly oblong, but we're taking thousands of an inch. So it doesn't affect the end product. But it cut the regen time down significantly 

eric_pesty

john_mcclary said:

For my case, sorry ome of the holes end up being slightly oblong, but we're taking thousands of an inch. So it doesn't affect the end product. But it cut the regen time down significantly 

Did a quick try on the "slice" concept and helps a lot: I had 32 holes around the perimeter and 10 rows. That took about 35s as a sketch pattern in SM, vs just doing one row of 32 in the SM sketch and patterning the part 10 times, which took about 7s.
The holes are all perfectly round in the flat so can be dimensioned on a drawing (which could be annoying if they are slightly out of round).
I'm not sure why face patterns aren't allowed in sheet metal though, maybe it's a Parasolid limitation?

john_mcclary

Hard to say. When i try to dimension the slots on a cylinder it says 180 degrees, rather than the width of the slot, so i assume it is slightly off.

So i do a line to point dimension and it comes out good for the drawing, so i don't care. 

The fact it isn't absolutely perfect does bother me, but that is so mild i doubt you could manufacture it closer with our laser table... 

wayne_sauder

If the goal is to reduce regen time you could do the math (which I did not) and go this route. Just because you can. Personally I'd rather make the program do the math and deal with a little longer calculation time. 

Tristan_Neumann

Thank you for the feedback everyone. For my project I'd like the flat pattern to have true round holes, so I decided to go with my original approach. I just suppressed the feature until I was done with the design. It seems like patterns are just inherently slow, especially when working with sheet metal.

shawn_crocker

You can do one row of holes on the flat. Then you can do a circular face pattern on the active sheet metal model.

eric_pesty

shawn_crocker said:

You can do one row of holes on the flat. Then you can do a circular face pattern on the active sheet metal model.

That's the problem, face pattern doesn't work on active sheet metal parts so it has to be a "regular" pattern, which is slow to rebuild.