[MINDSTORMS] Big Robot v2

[Glaysche]

  On 4/30/2022 at 5:27 PM, Jim said:

Sweet! That's an awesome tip. I'm still learning the Studio ropes, so these tips are more than welcome. There are still some nuisances, but I am definitely starting to appreciate this program. I love to try out quick concepts by drawing them in a digital design environment to get an idea of how to fit everything. And the render option is awesome.

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I'm still pretty new at it myself.  My first experience with Studio was making the model of the 6 axis robotic arm.  I still very much prefer making things in real life first and just use Studio to document and share my creations.

 

  55 minutes ago, Jim said:

Wow, thanks for building this example. It's not that I don't want to go wider, but I am/was afraid that wider would make it more difficult to turn the wheels. Do you think it matters a lot, if there is a big difference between your setup and mine?

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Given the big turntables you are planning, I don't think any design (within reason) will be too hard to turn.

 

Another random idea I had was to have a single wheel per unit but drive it from the top.  This is a quick mock up.  I'm not sure if it can be properly braced or if the gearing would work out properly.

 

 

 

The idea is to attach 36t gears solidly to the wheel and drive it with a couple 12t bevel gears.  As much as possible, I try to have redundant gear trains in high stress applications to make things more solid.

[Jim]

I just made your first design with the bigger tires (rendering as we speak). I didn't realize that the wider tire is also bigger. The bigger tire does look better.

  On 4/30/2022 at 6:31 PM, Glaysche said:

Given the big turntables you are planning, I don't think any design (within reason) will be too hard to turn.

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I was thinking about driving the inner turntable and maybe add the our bigger outer turntable to carry the weight so to speak. This is something I need to test in real life.

  On 4/30/2022 at 6:31 PM, Glaysche said:

Another random idea I had was to have a single wheel per unit but drive it from the top.  This is a quick mock up.  I'm not sure if it can be properly braced or if the gearing would work out properly.

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That is a nice mockup. I was wondering if driving a single from one side would be feasible. I do think your design might work. It's a compact sleek design. I like it.

I do wonder which solution is better in terms of load on the axles. Your latest solution will result in the entire robot applying force on four simple axles, right? Not sure if that's the optimal solution.

The bigger tires do look better on the wider assembly!

[Jim]

A sidenote about Studio; I am not impressed by the performance. I am using a brand new Mac Book with M1 Pro chip and it is sometimes struggling with adding stuff or copying an assembly. I was hoping for a more fluent experience.

[Glaysche]

  On 4/30/2022 at 6:36 PM, Jim said:

I just made your first design with the bigger tires (rendering as we speak). I didn't realize that the wider tire is also bigger. The bigger tire does look better.

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I agree.  I only used them in my mockup because they were on top of the pile of parts... :)

 

  15 minutes ago, Jim said:

I do wonder which solution is better in terms of load on the axles. Your latest solution will result in the entire robot applying force on four simple axles, right? Not sure if that's the optimal solution.

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Yeah, I'm not sure.  If it were really well supported so the sides can't splay apart, it might work.  Maybe some triangles in the design holding the sides together.

I had one other random thought.  It seems like this is the perfect application for the new 3x19 frame:

 

[Jim]

Yeah I need to order a couple of those. Now that I am out of the reviewing business, I need to keep up with the new parts  

Since I like to go big and I do have the parts (well, almost) I do think I will try your initial design with the bigger tires.

[Jim]

  On 4/30/2022 at 6:57 PM, Glaysche said:

I agree.  I only used them in my mockup because they were on top of the pile of parts... :)

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So you accidentally had two of them laying around? Or did you get two BMW motorbikes?

[Glaysche]

  On 4/30/2022 at 8:19 PM, Jim said:

So you accidentally had two of them laying around? Or did you get two BMW motorbikes?

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I did actually buy two BMW sets for the parts.  I used the 4 shock absorbers on the last version of my robotic arm and I’m planning to use the wheels and tires on a different MOC.

[Jim]

Nice 👍🏼 

[Glaysche]

  On 4/25/2022 at 6:42 PM, Jim said:

And please post a WIP for your robotic arm. I always love to see robotic arms. And I am interested to take a look at driving the inner turntable. Are you using a worm wheel or a gear/gears? I reread your message and you mention 4x 12T gears. I would like to see a pic of your setup.

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I finally had time to write up all the changes I have done and post them in my robotic arm topic.  For those who haven't seen it, the topic is now a couple years old and I have been periodically updating it as I improve the robotic arm.

 

[Jim]

  On 5/3/2022 at 10:06 PM, Glaysche said:

I finally had time to write up all the changes I have done and post them in my robotic arm topic.  For those who haven't seen it, the topic is now a couple years old and I have been periodically updating it as I improve the robotic arm.

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Sweet, I will reply in the topic.

Today I received the big tires and they are so much cooler/better/robust. I will absolutely use these for my initial concept.

[Jim]

I have been looking at Big Red and I am trying to use that mechanism in my robot. Any thoughts on the feasibility of this solution (without the large outer rim turntable, or possibly with the outer turntable).

I should have used more contrasting color for the example, sorry.

[ninoguba]

  On 5/4/2022 at 6:44 PM, Jim said:

Any thoughts on the feasibility of this solution (without the large outer rim turntable, or possibly with the outer turntable).

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I have used this similar simple solution with my 6DoF Arm and it held up pretty fine.   I didn't use any "bearings" for the banana gears like it was done with the Big Red/Liebherr or others' robotic arms.   The banana racks in my MOC are primarily just where the arm glides over.   
 

I think if the weight is evenly distributed between your wheels, the simpler design should not be an issue.  Testing this with real physical model will give you the confirmation.

Edited May 4, 2022 by ninoguba

[Jim]

Great. Thanks for the info. Can’t wait to start building in real life, but that will definitely take another month or so.

I am contemplating going for the four wheel design, which will add another wheel to carry the weight. But I can easily switch between three and four when I am able to physically build the wheel assemblies.

[Jim]

Looks like the new Ferrari is providing some interesting new gears. Do you think this new solution is made to be stronger?

[mdemerchant]

  On 5/24/2022 at 1:32 PM, Jim said:

Looks like the new Ferrari is providing some interesting new gears. Do you think this new solution is made to be stronger?

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Looks like it, the teeth are much larger.  Also putting the extra 14 tooth one in seems to be just to help support the differential.  I am a bit puzzled as to why they put this in the Ferrari.  I assume they will appear in some future motorized set where it might be useful for them to be stronger.

[Jim]

  On 5/25/2022 at 12:31 AM, mdemerchant said:

Looks like it, the teeth are much larger.  Also putting the extra 14 tooth one in seems to be just to help support the differential.  I am a bit puzzled as to why they put this in the Ferrari.  I assume they will appear in some future motorized set where it might be useful for them to be stronger.

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I have spoken to Balasz about this and he said exactly the same thing. Maybe for the delayed crane?! I will be picking up some of these gears when they are available.

[Jim]

Since my LEGO room is operation again, I couldn't resist to start the physical build. The assembly is okay in terms of measurements etc, but those wheel hubs sure result in a lot of slack. Makes me wonder if it's too much. Maybe it's not that bad when the final robot has four of these assemblies, but I am not convinced using the hubs is the best solution.

[Jim]

So, the project is up-and-running again. I am trying out the Big Red setup. I found out that building digitally is great for concepts, but I already made a huge mistake. I connect both rings, so making a 360 turn wasn't even possible 

Great thing about the need for four wheel units, is you can build one and iterate to the second and to the third and to the fourth. Hopefully by the fourth one, the design will be more or less okay.