Apparently I am on a roll of more questions than not today.

In the following drawing, there is a pattern (partial?) of 2.7 mm holes. The word in German pointed at them according to google translates as Division or Partition. Take that with several grains of salt potentially. The drawing title translates as "Cover Plate". The note in the bottom right supposedly translates as "Sandblast before processing"

enter image description here

What does the Division/Partition 4.25 mean?

I was originally thinking hole separation 4.25 mm. I am also thinking this is a partial pattern meant to illustrate what is happening on the surface of the disk. Though I was not sure as none of the 2.7 holes are shown in the section.

I was going to make a rectangular array of 2 off set rows of holes and super impose them over the plate then just delete the holes that get to close to the edge.

Or is this a case where you leave it as solid and make a material note that the metal is perforated with 2.7 dia holes at 4.25 offsets?

What is the best approach to model the holes in this part?

  • 2
    $\begingroup$ It's strange. I'm inclined to agree with your assessment. I note that the pattern of horizontally aligned holes breaks on the right hand side. It could be poor drafting. There was a war on. $\endgroup$
    – Transistor
    Nov 8, 2021 at 23:02
  • $\begingroup$ I am just looking to learn how to do mechanical drafting in my down time as opposed to the structural bridge drafting that I am used to. I am just trying to recreate the parts, not the war! $\endgroup$
    – Forward Ed
    Nov 8, 2021 at 23:05
  • $\begingroup$ I understand. I've been reading your other questions. $\endgroup$
    – Transistor
    Nov 8, 2021 at 23:06
  • $\begingroup$ @Transistor well it was either that or potentially find a cure for other people's insomnia with all the questions. I do try and research stuff before I ask, and I also try to apply my general understanding. But not being my field, my interpretations could be way off! $\endgroup$
    – Forward Ed
    Nov 8, 2021 at 23:09
  • 2
    $\begingroup$ This is a Zinner "showerhead" injector plate. The pattern was a simple hexagonal pattern. 4.25 looks like a good center to center distance for 2.5 mm holes. Later plates had all kinds of fancy arrangements. They tested thousands of different injector designs. $\endgroup$
    – Phil Sweet
    Nov 9, 2021 at 0:48


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