Non-Existent Parts

[DrJB]

If we look closely at many of the technic connectors, these are made of only four possible 'elements':

1. Male pin (friction or smooth, does not matter)

2. Female pin

3. Male axle

4. Axle hole (old bushing)

Then, each of the available connectors (below) is essentially a combination of the above 4 sub-elements stacked next to one another, and with 3 relative orientations/rotations. With such 'basic' framework, What parts are 'missing' i.e., not in the current lego assortment? We have some recent connectors recently, but there are few still missing.

For example, all connectors shown below fall into such group made-up only of male/female pins and axles

Incidentally, all lift-arms (thick, not thin) are series of female pins and sometimes axle holes, all stacked next to one another.

Some connectors that do NOT fit in this scheme are those that have half-width beams and those at angles

Edited April 3, 2017 by DrJB

[agrof]

There is some more basic connection possibilities, a perfect example the flick missile , the bar end can be connected to the black pin's hole  (or even with axle holes), just like seen in 42043:

And we can use the studs as connectors with the rim of the pinholes - like the rear lights here:

Also we have the ball joints connection with many parts:

, and more.

 

I don't miss any further version, even combined with system / bionicle bricks, I think we have versatile possibilities.

Edited April 3, 2017 by agrof

[Erik Leppen]

What I miss most is short half beams with round holes at the ends and axleholes in between. The 3x0.5 beam with pin comes closest, and the cam, but it's a bit limited in that regard.

[DrJB]

@agrof I agree there are other types that I have omitted. My main focus was on the pin/axle type as most connectors are made up of those. Yes, we could add the spherical joints but those serve a very 'specialized' purpose. 

 

As for the connection of   with , the last time I tried in LDD it was NOT allowed. Yes, I know the Mercedes truck has many of those. In fact, while assembling that truck, it dawned to me that such truck has way too many of such part.

Edited April 3, 2017 by DrJB

[aeh5040]

This is a fascinating question! I would say there are more than a few combinations missing, some of which would be very useful.

Just restricting to a 1x1x2 piece containing two of your four connection types, I reckon there are 24 possibilities, leaving out symmetries and things that seem physically impossible, such as two parallel male pins. Of these, I believe 13 exist as parts. For a further 3 there is a part that is close, in the sense that it does achieve the correct placement, but sticks out further than 1x1x2.

I'll add pictures to the table tomorrow....

Key: Yes/No/Close

axial/axial

pm/pm Y 2780
pm/pf N
pm/am Y 43093
pm/af C 32054
pf/pf Y 62462
pf/am N
pf/af N
am/am Y 32062
am/af N
af/af Y 6538c

axial/transverse

pm/pf Y 15100
pm/af N
pf/pf N
pf/af N
am/pf Y 22961
am/af C 57585
af/pf Y 32013
af/af Y 32039

transverse/transverse parallel

pf/pf Y 43857
pf/af Y 60483
af/af Y 41677 x2

transverse/transverse skew

pf/pf C 44809
pf/af Y 6536
af/af N

Edited April 3, 2017 by aeh5040

[J_C]

Very interesting question. I thought about it a lot recently. I came to completely opposite conclusion.

To me, part of beauty of building LEGO is that there are "parts" not available. If anything that would be possible would be available, that would not increase the entertainment. It would take it away. 

Often I think during MOCing: "If only I had this in 0,5 thickness, if only this would be in 6 not only 5 and 7, if this would have pin/hole here, if only..." Often. But working my way around it, design the alternative, that is the essence and core of the fun for me. If I just had anything available, it would degrade the LEGOing in just "putting stuff together". Hardness and beauty of LEGO is limited sources. With limitlessness, fun would be...not gone...but much much smaller.

This philosophy of mine also applies to amount of parts available, bricklinging everything is "cheating" to me, making it work with what I have is my aspiration.

(Just my LEGO-philosophy).

 

[Didumos69]

6 minutes ago, J_C said:

Very interesting question. I thought about it a lot recently. I came to completely opposite conclusion.

To me, part of beauty of building LEGO is that there are "parts" not available. If anything that would be possible would be available, that would not increase the entertainment. It would take it away. 

Often I think during MOCing: "If only I had this in 0,5 thickness, if only this would be in 6 not only 5 and 7, if this would have pin/hole here, if only..." Often. But working my way around it, design the alternative, that is the essence and core of the fun for me. If I just had anything available, it would degrade the LEGOing in just "putting stuff together". Hardness and beauty of LEGO is limited sources. With limitlessness, fun would be...not gone...but much much smaller.

This philosophy of mine also applies to amount of parts available, bricklinging everything is "cheating" to me, making it work with what I have is my aspiration.

(Just my LEGO-philosophy).

I feel the same way. This is probably also why the pinhole with pin feels like cheating, even though I use it a lot. It seems to make things 'too easy'.

[Lasse D]

1 hour ago, DrJB said:

@agrof I agree there are other types that I have omitted. My main focus was on the pin/axle type as most connectors are made up of those. Yes, we could add the spherical joints but those serve a very 'specialized' purpose. 

 

As for the connection of   with , the last time I tried in LDD it was NOT allowed. Yes, I know the Mercedes truck has many of those. In fact, while assembling that truck, it dawned to me that such truck has way too many of such part.

I believe LDD is correct here since some older molds of the pin with friction didn't allow for the bar to be inserted inside - at least if I recall correctly.

[agrof]

7 minutes ago, Lasse D said:

I believe LDD is correct here since some older molds of the pin with friction didn't allow for the bar to be inserted inside - at least if I recall correctly.

Correct, the older ones have thicker wall, just like the 3L pins.

@DrJB Luckily the latest version of LDD allows it:

34 minutes ago, J_C said:

Hardness and beauty of LEGO is limited sources. With limitlessness, fun would be...not gone...but much much smaller.

Totally agree with this, and that's why I don't miss any part - but I am open for new ones, if they are not overspecified for one purpose only and open new possibilities.  

Perfect example for this: 

And the opposite: (at least I have never seen any other technical application, just cosmetical maybe)

[Blakbird]

Your observation is well known to LDraw part authors.  That's why they build up parts out of "primitives": subsections of parts that are repetitive.  Each of the four you mentioned is a primitive which can be used to build up a more complex part.

[agrof]

So, if we go really down to the basics in this way, there is 2 very basic geometry, on which the Technic system relies:

• a free rotating connection along a surface (pin and pinhole)
• an interlocking connection along a surface (axle and axle hole)

The grandiosity of the whole system is this core simplicity.

If there would be more options, the combinability of the different parts would be radically decreased (example: you can not push a ball joint into an axle hole), and also the permeability between the LEGO building systems couldn't be so efficient like today. I think now I understood the topic theme better , and from this perspective I don't miss anything.

Edited April 3, 2017 by agrof

[Aventador2004]

10 hours ago, agrof said:

There is some more basic connection possibilities, a perfect example the flick missile , the bar end can be connected to the black pin's hole  (or even with axle holes), just like seen in 42043:

 

And we can use the studs as connectors with the rim of the pinholes - like the rear lights here:

 

Also we have the ball joints connection with many parts:

 

 

I don't miss any further version, even combined with system / bionicle bricks, I think we have versatile possibilities.

the le mans car [42039] has this too.

[Didumos69]

1 hour ago, agrof said:

So, if we go really down to the basics in this way, there is 2 very basic geometry, on which the Technic system relies:

• a free rotating connection along a surface (pin and pinhole)
• an interlocking connection along a surface (axle and axle hole)

The grandiosity of the whole system is this core simplicity.

If there would be more options, the combinability of the different parts would be radically decreased (example: you can not push a ball joint into an axle hole), and also the permeability between the LEGO building systems couldn't be so efficient like today. I think now I understood the topic theme better , and from this perspective I don't miss anything.

You are talking about the connection primitives, where as the OP is about the primitives from which parts are build.

Either way, I don't think we can reduce Technic - not even the individual parts - to such a small set of primitives. One of the primitives I'm missing for instance is how the 4 primitives mentioned in the OP relate to eachother in a single part. For a 5L beam the relation of the individual holes is simple, but for a it's much harder to describe. We would need primitives for these relations too.

Edited April 3, 2017 by Didumos69

[DrJB]

9 hours ago, aeh5040 said:

This is a fascinating question! I would say there are more than a few combinations missing, some of which would be very useful.

Just restricting to a 1x1x2 piece containing two of your four connection types, I reckon there are 24 possibilities, leaving out symmetries and things that seem physically impossible, such as two parallel male pins. Of these, I believe 13 exist as parts. For a further 3 there is a part that is close, in the sense that it does achieve the correct placement, but sticks out further than 1x1x2.

I'll add pictures to the table tomorrow....

Key: Yes/No/Close

axial/axial

pm/pm Y 2780
pm/pf N
pm/am Y 43093

...

 

Thank you, that's exactly where I was going with this: Some sort of mathematical description with all possible combinations, then those 'impossible' can be removed (e.g. the 2 parallel pins as you mentioned). In fact, if we think of all such connectors and parts as occupying some space in a 3-dimensional matrix, then that matrix can be filled with any of such basic shapes, to yield a large numbers of options. Not sure at this stage how 'useful' those new parts/connectors would be, but still, it is worth the 'mental/mathematical' exercise.

In fact, even the most basic pins/axles can fit such framework, namely, all parts below are candidates

 

I mentioned in my original post that lately we've seen some new connectors. I was thinking of those below

 

In fact, a related question/observation can be made about the 'quintet' below, which all are 1×3 but aligned male/female pins/axles

There are 3 missing from the above set and they have either no usability or are impossible to connect. Can you guess what they are? 

 

 

Edited April 3, 2017 by DrJB

[DrJB]

10 hours ago, J_C said:

Very interesting question. I thought about it a lot recently. I came to completely opposite conclusion.

To me, part of beauty of building LEGO is that there are "parts" not available. If anything that would be possible would be available, that would not increase the entertainment. It would take it away. 

Often I think during MOCing: "If only I had this in 0,5 thickness, if only this would be in 6 not only 5 and 7, if this would have pin/hole here, if only..." Often. But working my way around it, design the alternative, that is the essence and core of the fun for me. If I just had anything available, it would degrade the LEGOing in just "putting stuff together". Hardness and beauty of LEGO is limited sources. With limitlessness, fun would be...not gone...but much much smaller.

This philosophy of mine also applies to amount of parts available, bricklinging everything is "cheating" to me, making it work with what I have is my aspiration.

(Just my LEGO-philosophy).

 

I fully understand why you would reach a different conclusion. Maybe I need to clarify the point of this discussion: I am not after 'suggesting' that new parts be made, not at all. In fact parts by themselves are totally useless ... they become useful once they are connected to other parts. In that context, if you need to connect two parts (via a third intermediate part) occupying two separate positions in 3 D space, then there are multiple ways of achieving this. And, here is where the current 'assortment' of parts seems sufficient. So, you're right, but again, this is more a mathematical exercise (for me), and maybe a way to convince ourselves that what we have is good enough.

With all this, there is one part  that I needed a while back and found no other way to use a substitute: the part shown below but with a 2M axle attached to it... I needed this to build Nico's 2CV car. He used the 3M axle with stud, but that could be better.

 

Edited April 3, 2017 by DrJB

[DrJB]

2 hours ago, Blakbird said:

Your observation is well known to LDraw part authors.  That's why they build up parts out of "primitives": subsections of parts that are repetitive.  Each of the four you mentioned is a primitive which can be used to build up a more complex part.

Exactly, good to know we're converging onto something already known/validated and put to good use. I bet this is how Lego build their prototypes as well, by adding well known 'modular' geometries.

1 hour ago, Didumos69 said:

You are talking about the connection primitives, where as the OP is about the primitives from which parts are build

Either way, I don't think we can reduce Technic - not even the individual parts - to such a small set of primitives. One of the primitives I'm missing for instance is how the 4 primitives mentioned in the OP relate to eachother in a single part. For a 5L beam the relation of the individual holes is simple, but for a it's much harder to describe. We need primitives for these relations too.

I think it's rather simple here (or I'm missing your point). That L shape is just 3 pin holes connected together. Care to clarify your point? 

If we first decide on how much space the part is to occupy, for example a 2×2×3, then there are a finite number of combinations of 'useful' and unique connectors that can be made to fit in that space, by simply adding pins and axles male/female. Though, most available parts fit in a max of 1×2×3 volumeat most. Yes, there are exceptions such as the frames and large connectors.

 

[Didumos69]

12 minutes ago, DrJB said:

I think it's rather simple here (or I'm missing your point). That L shape is just 3 pin holes connected together. Care to clarify your point?

What I meant was that we need a way to express how the primitive elements are ligned up in an individual part. But the matrix you mentioned a few posts back does exactly that.

 

Edited April 3, 2017 by Didumos69

[agrof]

4 hours ago, Didumos69 said:

You are talking about the connection primitives, where as the OP is about the primitives from which parts are build.

Either way, I don't think we can reduce Technic - not even the individual parts - to such a small set of primitives. 

Eeeeeer, I think it is the same. Almost all technic parts - but the basic ones for sure - are variations of the connection primitives. A beam is a bunch of pinholes. An axle is a bunch of 1L axles. And all technic parts contains connection primitives, that is the key of a building system.

EDIT: I made a second thought, I got it now. You are looking for combinations of the core elements, which are not produced yet, and if could be described by a mathematical rule, correct? Example: axle with axle hole - like the pin with pinhole?

Sorry for confusion.

Edited April 3, 2017 by agrof
Took time to read and think

[DrJB]

5 hours ago, agrof said:

EDIT: I made a second thought, I got it now. You are looking for combinations of the core elements, which are not produced yet, and if could be described by a mathematical rule, correct? Example: axle with axle hole - like the pin with pinhole?

Yes, what parts are NOT available, and do we really need them?

Of course, the 'mathematical' description ensures we do not miss any combination.

[aeh5040]

Here we go.  Green exists, red doesn't.  (Like I said, I'm only considering 1x1x2 here).

17 hours ago, aeh5040 said:

axial/axial

pm/pm Y 2780
pm/pf N
pm/am Y 43093
pm/af C 32054
pf/pf Y 62462
pf/am N
pf/af N
am/am Y 32062
am/af N
af/af Y 6538c

axial/transverse

pm/pf Y 15100
pm/af N
pf/pf N
pf/af N
am/pf Y 22961
am/af C 57585
af/pf Y 32013
af/af Y 32039

transverse/transverse parallel

pf/pf Y 43857
pf/af Y 60483
af/af Y 41677 x2

transverse/transverse skew

pf/pf C 44809
pf/af Y 6536
af/af N

 

By the way, I sometimes find it rather amazing that this part can exist:

If you think about the two things that it joins in situ: an axle just abutting a pin hole without going in to it, it is amazing that there is enough space between them to make a connection, let alone a strong one in ABS, and, moreover, while keeping the bush part within the usual bush profile (so that a 24t gear two holes away does not foul it).

Another related topic: a few years ago Lego Education had a "parts pack" advertised for which the picture on the website contained a version of this part:, except with axle holes for the two horizontal holes!!  I eventually ordered it, and was disappointed to find I just got the part above.   I guess they planned such a part but decided to make that one instead.

Edited April 4, 2017 by aeh5040

[aeh5040]

I'm really enjoying all the abstract geometry discussion recently.  Keep it coming!

[agrof]

Thanks for the visualisation @aeh5040.

I have the feeling, in these 3D printer beaten days all the variations were and are tested by LEGO, the selection of which comes into production appends on experimental practical use. My thoughts:

• In the first row the missing ones are odd for me, meaning, what would be the advantage to have am/pf compared to the axle pin (more material, thus needs an extra stud place in build), or the am/af compared to a longer axle? This might be a reason why we don't see them.
• Some of those even cover the same functionality in practice - for example in the complete second row I can think only usable the am/af 90° with interlocking connections in 2 directions while saving 1 stud space. The others don't offer any extra compared to the actual variations (pins and connectors combo): 1 interlocking with 1 rotating connections or 2 rotating connections, which possibilities are already there.
• In the last row maybe the af/af 90° could be useful, the af/pf 90° covers pretty much the pf/pf 90° (on the very left) with different pins.

6 hours ago, aeh5040 said:

 

This is indeed entertaining to dig in depth. 

[julesvincent]

@aeh5040 send this pic to TLG to show them what they have to develop ;) Great visualization! Thanks

[1gor]

@julesvincent I agree with you completely.

Edited April 5, 2017 by I_Igor

[agrof]

@I_Igor I think your list fits better to this topic:

Although it is close to this one, here is the topic more specialized down to the genetics, so to say.