Answers.Body: <blockquote>
  <p>What are the parts used for the [Hirolabo delta robot's] arms and circular base (labelled as parallel links and universal joints) ?</p>
  </blockquote>
  <p>Let's see another still from that video:</p>
  <p><a href="https://i.sstatic.net/DgacA.png" rel="noreferrer"><img src="https://i.sstatic.net/DgacA.png" alt="parts inventory" /></a></p>
  <p>There I see:</p>
  <ul>
  <li><a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=2736" rel="noreferrer">2736 Technic axle 1L with tow ball</a></li>
  <li><a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=32293" rel="noreferrer">32293 Technic, 1x9 link</a>, AKA &quot;Technic steering link 9L&quot;</li>
  <li><a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=4185" rel="noreferrer">4185 Technic wedge belt wheel</a></li>
  <li><a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=41678" rel="noreferrer">41678 Technic, axle and pin connector perpendicular double split</a></li>
  <li>2L pins</li>
  <li>4L axle</li>
  <li>Red ball</li>
  </ul>
  <blockquote>
  <p>I'd like to use Mindstorms 51515 [...]</p>
  </blockquote>
  <p>Well, I'm looking at the <a href="https://www.bricklink.com/catalogItemInv.asp?S=51515-1" rel="noreferrer">parts list for 51515</a> and am seeing no universal joints and only four towball axles. Seems like you'll need to replace each universal joint with two perpendicular joints.</p>
  <p>Working with a limited selection of parts is always challenging, but I think 51515 has everything you need. Try something like this for the actuator and the base of the parallelogram:</p>
  <p><a href="https://i.sstatic.net/JGkqr.png" rel="noreferrer"><img src="https://i.sstatic.net/JGkqr.png" alt="sketch, base" /></a></p>
  <p>The key is using <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=6536" rel="noreferrer">6536 Axle and Pin Connector Perpendicular</a> to provide the extra degree of freedom. It's gonna be worse than a universal joint or a ball-and-socket joint, but it's what you've got. Remember to use the <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=3673&amp;idColor=86" rel="noreferrer">low-friction gray pins</a> for the joints (instead of the <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=2780&amp;idColor=11" rel="noreferrer">high-friction black ones</a>).</p>
  <p>I've drawn only one arm, but the other one is symmetrical; and I haven't drawn the pins - add them as needed.</p>
  <p>The top part would also use two connector blocks, and perpendicular-axle-pin-connectors for the arms:</p>
  <p><a href="https://i.sstatic.net/HUYcf.png" rel="noreferrer"><img src="https://i.sstatic.net/HUYcf.png" alt="sketch, upper" /></a></p>
  <p>Since 51515 doesn't have any parts with an hexagonal pattern, or any other easy way of achieving a 120° angle, you'll have to rely on interconnecting the upper assemblies (with <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=6558&amp;C=7" rel="noreferrer">3L pins</a>):</p>
  <p><a href="https://i.sstatic.net/kS8OC.png" rel="noreferrer"><img src="https://i.sstatic.net/kS8OC.png" alt="sketch, 3" /></a></p>
  <p>That still looks flimsy, so consider reinforcing the assembly with more interconnections.</p>
  <p>You'll need to fiddle and test, but I think this design should provide you with a solid base to start tinkering with.</p>
  <p>Also note that the joints in this design are lacking a degree of freedom, and that this might apply excessive <strong>torsion</strong> to the beams used in the six arms. Experiment with adding an additional 6536 perpendicular-axle-pin-connector to each joint to provide that extra degree of freedom.</p>
  <hr />
  <p>Of course, you can always go shopping for more parts. In your case, you would only need twelve of <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=32474" rel="noreferrer">32474 ball joint</a> and <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=93571" rel="noreferrer">93571 ball joint socket</a>. You should be able to acquire those from the usual marketplaces (pick-a-brick, bricklink) for about 0.5$/0.5€ each pair, or about 6€/6$ the full set.</p>
  <p>Welcome to the rabbit hole of &quot;I just need to buy one more of that one piece&quot;.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-03-30T04:57:22.557Z
Answers.Text: "low-friction black pins for the joints (instead of the high-friction blue ones)" - are we talking about the same pins I'm thinking about, where the black have the extra friction ridges and the blues don't? <https://www.bricklink.com/v2/catalog/catalogitem.page?P=2780>
Answers.UserDisplayName: RSchulz
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-03-30T06:47:16.017Z
Answers.Text: My bad, I had in mind the 3L blue pins with friction and the 2L blue pin+axle with friction. The 2L pins without friction are the grey/bley ones.
Answers.UserDisplayName: IvanSanchez
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-03-30T12:11:47.743Z
Answers.Text: OMG this answer is amazing! Thank you so much for the detailed information: much appreciated !
Answers.UserDisplayName: George Profenza
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-03-30T04:37:48.363Z
Answers.LastActivityDate: 2022-03-30T06:53:30.503Z
Answers.LastEditDate: 2022-03-30T06:53:30.503Z
Answers.UserDisplayName: IvanSanchez
Body: <p>I'm fairly new to Lego Mindstorms and I'd like to assemble a pick and place mechanism.</p>
  <p>I was looking for existing delta robot designs and found a lot of good looking designs:</p>
  <ul>
  <li><a href="https://www.youtube.com/watch?v=TbXBTZhhlYs&amp;ab_channel=HiroLaboOECU" rel="noreferrer">https://www.youtube.com/watch?v=TbXBTZhhlYs&amp;ab_channel=HiroLaboOECU</a></li>
  <li><a href="https://www.youtube.com/watch?v=sGPw-bnQF-k" rel="noreferrer">https://www.youtube.com/watch?v=sGPw-bnQF-k</a></li>
  <li><a href="https://www.youtube.com/watch?v=OmMKpRE4X5w" rel="noreferrer">https://www.youtube.com/watch?v=OmMKpRE4X5w</a></li>
  <li><a href="https://www.youtube.com/watch?v=Bs1SoyfvZ4Y" rel="noreferrer">https://www.youtube.com/watch?v=Bs1SoyfvZ4Y</a></li>
  <li><a href="https://www.youtube.com/watch?v=rjV4PJEjDKg" rel="noreferrer">https://www.youtube.com/watch?v=rjV4PJEjDKg</a> (not a delta, but still a parallel robot)</li>
  </ul>
  <p>The majority are use Lego NXT. I'd like to use Mindstorms 51515 and hope it's a matter of swapping servos, maybe some minor part adjustments (due to difference in servo dimensions) and porting the code over.</p>
  <p>The HiroLabo delta robot looks the simplest to me (but I might be wrong, so please correct me). What are the parts used for the arms and circular base (labelled as parallel links and universal joints) ?</p>
  <p><a href="https://i.sstatic.net/fzkaA.png" rel="noreferrer"><img src="https://i.sstatic.net/fzkaA.png" alt="HiroLabo Delta Robot screenshot displaying parts" /></a></p>
  <p><a href="https://i.sstatic.net/BEWlo.png" rel="noreferrer"><img src="https://i.sstatic.net/BEWlo.png" alt="HiroLabo Delta Robot screenshot displaying parts" /></a></p>
  
Tags: <part-identification><technic><mindstorms><robot-inventor>
Title: What's the easiest way to build a delta robot using LEGO Mindstorms 51515?
UserDisplayName: George Profenza
ThreadText: # What's the easiest way to build a delta robot using LEGO Mindstorms 51515?
  
  (Asked by: username_0 on 2022-03-30)
  
  I'm fairly new to Lego Mindstorms and I'd like to assemble a pick and place mechanism.
  
  I was looking for existing delta robot designs and found a lot of good looking designs:
  
  * <https://www.youtube.com/watch?v=TbXBTZhhlYs&ab_channel=HiroLaboOECU>
  * <https://www.youtube.com/watch?v=sGPw-bnQF-k>
  * <https://www.youtube.com/watch?v=OmMKpRE4X5w>
  * <https://www.youtube.com/watch?v=Bs1SoyfvZ4Y>
  * <https://www.youtube.com/watch?v=rjV4PJEjDKg> (not a delta, but still a parallel robot)
  
  The majority are use Lego NXT. I'd like to use Mindstorms 51515 and hope it's a matter of swapping servos, maybe some minor part adjustments (due to difference in servo dimensions) and porting the code over.
  
  The HiroLabo delta robot looks the simplest to me (but I might be wrong, so please correct me). What are the parts used for the arms and circular base (labelled as parallel links and universal joints) ?
  
  [![HiroLabo Delta Robot screenshot displaying parts](https://i.sstatic.net/fzkaA.png)](https://i.sstatic.net/fzkaA.png)
  
  [![HiroLabo Delta Robot screenshot displaying parts](https://i.sstatic.net/BEWlo.png)](https://i.sstatic.net/BEWlo.png)
  
  **Tags:** part-identification, technic, mindstorms, robot-inventor
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2022-03-30. Score: 11 | Accepted answer
  
  > What are the parts used for the [Hirolabo delta robot's] arms and circular base (labelled as parallel links and universal joints) ?
  
  Let's see another still from that video:
  
  [![parts inventory](https://i.sstatic.net/DgacA.png)](https://i.sstatic.net/DgacA.png)
  
  There I see:
  
  * [2736 Technic axle 1L with tow ball](https://www.bricklink.com/v2/catalog/catalogitem.page?P=2736)
  * [32293 Technic, 1x9 link](https://www.bricklink.com/v2/catalog/catalogitem.page?P=32293), AKA "Technic steering link 9L"
  * [4185 Technic wedge belt wheel](https://www.bricklink.com/v2/catalog/catalogitem.page?P=4185)
  * [41678 Technic, axle and pin connector perpendicular double split](https://www.bricklink.com/v2/catalog/catalogitem.page?P=41678)
  * 2L pins
  * 4L axle
  * Red ball
  
  > I'd like to use Mindstorms 51515 [...]
  
  Well, I'm looking at the [parts list for 51515](https://www.bricklink.com/catalogItemInv.asp?S=51515-1) and am seeing no universal joints and only four towball axles. Seems like you'll need to replace each universal joint with two perpendicular joints.
  
  Working with a limited selection of parts is always challenging, but I think 51515 has everything you need. Try something like this for the actuator and the base of the parallelogram:
  
  [![sketch, base](https://i.sstatic.net/JGkqr.png)](https://i.sstatic.net/JGkqr.png)
  
  The key is using [6536 Axle and Pin Connector Perpendicular](https://www.bricklink.com/v2/catalog/catalogitem.page?P=6536) to provide the extra degree of freedom. It's gonna be worse than a universal joint or a ball-and-socket joint, but it's what you've got. Remember to use the [low-friction gray pins](https://www.bricklink.com/v2/catalog/catalogitem.page?P=3673&idColor=86) for the joints (instead of the [high-friction black ones](https://www.bricklink.com/v2/catalog/catalogitem.page?P=2780&idColor=11)).
  
  I've drawn only one arm, but the other one is symmetrical; and I haven't drawn the pins - add them as needed.
  
  The top part would also use two connector blocks, and perpendicular-axle-pin-connectors for the arms:
  
  [![sketch, upper](https://i.sstatic.net/HUYcf.png)](https://i.sstatic.net/HUYcf.png)
  
  Since 51515 doesn't have any parts with an hexagonal pattern, or any other easy way of achieving a 120° angle, you'll have to rely on interconnecting the upper assemblies (with [3L pins](https://www.bricklink.com/v2/catalog/catalogitem.page?P=6558&C=7)):
  
  [![sketch, 3](https://i.sstatic.net/kS8OC.png)](https://i.sstatic.net/kS8OC.png)
  
  That still looks flimsy, so consider reinforcing the assembly with more interconnections.
  
  You'll need to fiddle and test, but I think this design should provide you with a solid base to start tinkering with.
  
  Also note that the joints in this design are lacking a degree of freedom, and that this might apply excessive **torsion** to the beams used in the six arms. Experiment with adding an additional 6536 perpendicular-axle-pin-connector to each joint to provide that extra degree of freedom.
  
  ---
  
  Of course, you can always go shopping for more parts. In your case, you would only need twelve of [32474 ball joint](https://www.bricklink.com/v2/catalog/catalogitem.page?P=32474) and [93571 ball joint socket](https://www.bricklink.com/v2/catalog/catalogitem.page?P=93571). You should be able to acquire those from the usual marketplaces (pick-a-brick, bricklink) for about 0.5$/0.5€ each pair, or about 6€/6$ the full set.
  
  Welcome to the rabbit hole of "I just need to buy one more of that one piece".
  
  > **Comments:**
  > **username_2**: "low-friction black pins for the joints (instead of the high-friction blue ones)" - are we talking about the same pins I'm thinking about, where the black have the extra friction ridges and the blues don't? <https://www.bricklink.com/v2/catalog/catalogitem.page?P=2780>  
  > **username_1**: My bad, I had in mind the 3L blue pins with friction and the 2L blue pin+axle with friction. The 2L pins without friction are the grey/bley ones.  
  > **username_0**: OMG this answer is amazing! Thank you so much for the detailed information: much appreciated !  
  
  ---
  
  