Answers.Body: <p>The holes are necessary so that regular system bricks can fit on the Duplo bricks. The ratio is 2:1 in both dimensions, so you need four 2x4 system bricks to cover one 2x4 Duplo brick. This is an intended feature of the Duplo bricks and was decades ago even advertised in catalogues.</p>
  <p>Regarding the baseplates: Some people claim that TLC does not want people to use the comparably cheap and large Duplo baseplates for their large Lego system diorama designs which would be possible if the studs were hollow...</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-08-28T18:14:01.577Z
Answers.LastActivityDate: 2020-08-28T18:14:01.577Z
Answers.UserDisplayName: Jonathan Schott
Answers.Body: <p>Plastic molds are designed to have an even thickness wherever possible (I think it helps with cooling), so a having a hole in the stud made sense to keep the brick's walls consistently thin. The hole could have been placed on the underside of the brick, but putting it on top had the obvious advantage of being compatibile with standard bricks.</p>
  <p>Interestingly, DUPLO baseplates have their holes on the underside rather than the top. I believe this is because baseplates are vacuum formed instead of injection molded.</p>
  <p><a href="https://i.sstatic.net/kV4tV.jpg" rel="noreferrer"><img src="https://i.sstatic.net/kV4tV.jpg" alt="DUPLO baseplate" /></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-06-28T15:27:04.217Z
Answers.Text: Baseplates, at least for regular sized LEGO bricks, are made using vacuum forming/moulding: "Vacuum molds work like this: a sheet of plastic is placed inside a molding machine, and two radiant heaters pass above and below the sheet, heating it until it is soft. The sheet is then subjected to vacuum, i.e. it is “sucked” down into the mold and forms the familiar LEGO studs."
Answers.UserDisplayName: Alex
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-06-28T19:13:47.473Z
Answers.Text: @Alex Thanks I'll amend my answer.
Answers.UserDisplayName: Pubby
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-06-28T13:24:25.840Z
Answers.LastActivityDate: 2020-06-28T19:13:34.617Z
Answers.LastEditDate: 2020-06-28T19:13:34.617Z
Answers.UserDisplayName: Pubby
Body: <p>For some reason, all the Duplo bricks that exist out there have holes in their studs. I haven't seen a Duplo brick that <em>doesn't</em> have holes in the studs, and I doubt such thing even exists.</p>
  <p>System bricks can actually connect to Duplo bricks with these holes, but is that the <em>only</em> reason for the holes? Is there is a Duplo brick that <em>doesn't</em> have holes in its studs (if yes then please point it out in the comments or in your answer)?</p>
  <p>What are the other reasons for Duplo bricks to have holes in their studs, if any?</p>
  
Tags: <compatibility><duplo>
Title: Why are there always holes in Duplo bricks?
UserDisplayName: mindstormsboi
ThreadText: # Why are there always holes in Duplo bricks?
  
  (Asked by: username_0 on 2020-06-27)
  
  For some reason, all the Duplo bricks that exist out there have holes in their studs. I haven't seen a Duplo brick that *doesn't* have holes in the studs, and I doubt such thing even exists.
  
  System bricks can actually connect to Duplo bricks with these holes, but is that the *only* reason for the holes? Is there is a Duplo brick that *doesn't* have holes in its studs (if yes then please point it out in the comments or in your answer)?
  
  What are the other reasons for Duplo bricks to have holes in their studs, if any?
  
  **Tags:** compatibility, duplo
  
  
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  ## 2 answers
  
  ### Answer by username_2 on 2020-06-28. Score: 14 | Accepted answer
  
  Plastic molds are designed to have an even thickness wherever possible (I think it helps with cooling), so a having a hole in the stud made sense to keep the brick's walls consistently thin. The hole could have been placed on the underside of the brick, but putting it on top had the obvious advantage of being compatibile with standard bricks.
  
  Interestingly, DUPLO baseplates have their holes on the underside rather than the top. I believe this is because baseplates are vacuum formed instead of injection molded.
  
  [![DUPLO baseplate](https://i.sstatic.net/kV4tV.jpg)](https://i.sstatic.net/kV4tV.jpg)
  
  > **Comments:**
  > **username_3**: Baseplates, at least for regular sized LEGO bricks, are made using vacuum forming/moulding: "Vacuum molds work like this: a sheet of plastic is placed inside a molding machine, and two radiant heaters pass above and below the sheet, heating it until it is soft. The sheet is then subjected to vacuum, i.e. it is “sucked” down into the mold and forms the familiar LEGO studs."  
  > **username_2**: @username_3 Thanks I'll amend my answer.  
  
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  ### Answer by username_1 on 2020-08-28. Score: 3
  
  The holes are necessary so that regular system bricks can fit on the Duplo bricks. The ratio is 2:1 in both dimensions, so you need four 2x4 system bricks to cover one 2x4 Duplo brick. This is an intended feature of the Duplo bricks and was decades ago even advertised in catalogues.
  
  Regarding the baseplates: Some people claim that TLC does not want people to use the comparably cheap and large Duplo baseplates for their large Lego system diorama designs which would be possible if the studs were hollow...
  
  
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