When to block instance this repeat pattern grille?


see attached, Being uneasy on BlockInstances (I never have them behave as I want afterwards) , vanishing, colour denail, layet movement problems etc) but knowing they speed up saves, I am wondering when to block instance the wavy pattern that needs extruding downwards (Z) 3/4 inch, after its been trimmed to within 1/16 inch of the outer frame and ends closed.

Q1. Do I select one long wave, blockInstance it, array it, then extrude them all Z -3/4 inch, or should I extrude it as well, then block instance it, and in that case just block instance the extrusion ?

same question for the straight bars (blue).

the frame I shall not bother with, .

Q2. I also find with block instance I cant alter the colours of it afterwards, or change layer. I dislike being denied such that I normally am free to do. why is this ?

I end up having to remake the part as the items have escaped somewhere.

As such I am reluctant to even bother.

I did even wonder if one should take a single wave of a few inches long and block instance that then mirror and union them to get one long wave row made of several blocks. Then block instance that set of blocks.

Q3. Is that necessary, more like asking for trouble my gut feeling says !

grille.3dm (720.9 KB)


Hi Steve -

When to block instance this repeat pattern grille?

That’s something that only you can answer.

As you observed, there are issues with blocks that you need to be aware of and know how to deal with. At the upside, as you also noted, it can speed up certain things. When all this tips in favor of one or the other depends on several things, such as the overall workflow, your experience with features and bugs, and your hardware.

As a quick test, modelling this as individual surfaces without blocks saves to disk as a file that is 47 MB, and doing the same with blocks ends up being 2 MB - all other things being the same. Changing meshing settings, using nested blocks, etc. will change all results somewhat…

Grille - blocks or not.zip (14.5 MB)

Hi Wim,
I feel it needs it as its the start of a much bigger project. already its taking 30 secs to save as part of the project. and three meshes.
It was the option, and which is best practice :-

  1. BlockInstance one row of the wavy row curves, then array them, then extrude
  2. Extrude one wavy row, then BlockInstance it, then array it.

which is best practice or correct method ?


Hi Steve -

There is no correct method.
Theoretically, the smallest unique part that will be repeated a lot of times should be made into a block.

Hi, I could I suppose take a single wave element, that of a line and the curve and stub (short line) at each end, and its offset, close curves with a .125 inch line at each end, extrude then make that extrusion a block Instance, then mirror it, union it, and repeat that, obtain a row of waves then array the row, on Y axis, so the smallest part is used, not sure if unioning block instances together is ok to do ? Unions have to intersect in fact, these would abutt face so I would have to extend on the stub a bit.

Is unioning block instances ok ?

I then read that they cant be used for Booleans so that shoots down that one. Looks like a row can be a blockInstance after I trim the ends off first.