21
DescriptionOld logo - 3mm stud recess - corner-pip
From1958
To1959
This generation is among the most complex generations to figure out. It's the last generation whithout mold identification numbers. At the end of the fifties, LEGO had scaled up their production, so that muliple molds were being used in paralell. This makes identifiying the various molds extremely hard. The process of identifying the molds is based on testing out a lot of different hypothesises regarding mold-specific properties. The result is with high certainty not correct, but without a lot more samples to work with, a best guess of how many molds that were used - and how the mold members were arranged.
The different 2x4-molds were identified in the same order as they are named - starting with the most obvious differensiators.
| Molds | Identifying feature | Secondary feature | Notes |
|---|---|---|---|
| 21a + 21b | "pend"-position (colors) | Mold pos. number layout | Mold pos. number on left side of tubes. |
| 21c | Tube-shape | NA | Tubes have sharp edges. |
| 21d | Pip | NA | Bricks have double pips (top + bottom). |
| 21e + 21f | Tube-shape | Colors | Base of tubes are wider edge around them. |
| 21g + 21h | Pat-pend-font | Colors | Normal font on both "Pat" and "pend". |
| 21i + 21j | Pat-pend-font | Colors | Bold font on both "Pat" and "pend". |
| 21k | Pat-pend-font | NA | Bold font on "pend" |
| 21l | Pat-pend-font | NA | Bold font on "Pat" |
Bold font can be identified by using magnifying glass. The open line in the letters "e" and "a" will be "closed" (connected to the rest of of the letter) for the samples I've identified as bold, while being "open" (space between the open line and the rest of the letter) for samples with normal font.
The different 2x3-molds were identified in the same order as they are named - starting with the most obvious differensiators. Compared to the 2x4-molds the process of identifying the different 2x3-molds was a bit more straight forward.
| Molds | Identifying feature | Secondary feature | Notes |
|---|---|---|---|
| 21m + @21n | Pip | Tube edge | Pip right, rounded tube edge. Colors used to differentiate between 21m and @m21n. |
| 21o | Pip | Tube edge | Pip left, rounded tube edge. Inside equal to 21p. |
| 21p | Pip | Tube edge | Pip left, sharp tube edge. Inside equal to 21o. |
| 21q + 21r | Pip | Tube edge | Pip right, sharp tube edge. No clear identifier between 21q and 21r. |
The 2x2-molds share some of the same identifying properties as with the 2x4-molds, but because of the square-shaped nature also adds new complexy with different logo orientations. Some identified molds have as few as two samples, so there is potentially a much larger complexity here that more available samples will reveal.
| Molds | Identifying feature | Secondary feature | Notes |
|---|---|---|---|
| 21s | Mold pos. number layout | NA | Mold pos. number on left side of tubes. |
| 21t | Pip | - | Pip top/bottom, rounded tube edge. |
| 21u | Pip | Logo alignment | Pip left/right, logo horizontally aligned. |
| 21v | Pip | Logo alignment | Pip left/right, logo vertically aligned. All members except pos 5 has sharp tube edge. |
| 21w | Pip | Logo alignment | Bottom identical to 21v, but with top part rotated 90 deg. (logo alignment + pip). Only identified one sample (pos. 18). |
The 1x2-molds come in two different sub-categories. There are molds with stud-logo along the brick length, and other molds with the stud-logo across. Within both categories there are mold evolutions across generations - with the same mold being modified from having large stud recesses to having small stud recesses.
| Molds | Identifying feature | Secondary feature | Notes |
|---|---|---|---|
| 21af | Stud logo | No evolution | Stud logo along. |
| 21ag | Stud logo | No evolution | Stud logo along. 21af rotated. |
| 21ah | Stud logo | Evolution | Stud logo along. Evolved into 23t. |
| 21ai | Stud logo | No evolution | Stud logo across. |
| 21aj | Stud logo | Evolution | Stud logo across. Evolvedinto 23v. |
See 23 for a note regarding missing mold members for the 48-member molds.
Two molds are identified for each of the two brick types, differentiated by double pips on either the left or the right side.