A few months ago I was sold a bag of Technic parts and although I've been in the LEGO scene for about 5 years now, I wasn't able to tell immediately that I had a bunch of fake parts intentionally made to deceive me! I've since learnt that knowing the LEGO System Bricks did not prepare me with the skills of being able to identify Technic Parts. I was delighted to see that Steve Tan put this guide together to help distinguish the difference between LEGO and Non-LEGO parts. [Updated: 26 Jan 2020]
Here is Steve's research reproduced in it's entirety:
Fake Lego vs Real Lego (Updated 05 May 2019)
LEGO Technic common parts How to tell the difference by checking and comparing the parts in detail I recently had the chance to compare a batch of fake Lego with real Lego. Comparison is done only for Lego Technic pieces, as that is what I have. Conclusions were drawn based on my own limited understanding, and also the pieces which I have, with much help from Sariel’s Lego Technic book.
I have a little bit of knowledge about plastic injection molding, and will use some terminology to explain the differences.
Gating – Where the mold (hot runner or normal runner) separates from the part.
Cavity – The part of the injection molding tooling that is fixed to the machine.
Core – The other part of the injection molding tooling that matches the cavity.
Slider – Another part of the tooling that moves in a different direction from the core and cavity, to make undercut features.
Parting line – A visible line where the core/cavity/slider of the tooling separates. Well designed and well maintained molds produce a very minimal parting line.
Flashes – Excess material caused by incomplete/mismatch of the tooling parts.
There will probably be some mistakes, but do let me know so that we can all learn.
This is not a comprehensive guide, and there will be other ways that fake Lego can differ from the real Lego.
Update: We've discovered from a number of readers that older parts do have numbers, so simply by seeing a number on an Axel pin does not mean that it's a fake. We have updated this article at the end with more photos and details.
Fake Lego vs Real Lego: Summary
For most of the Lego Technic parts, it is possible to differentiate fake from real Lego, as there is usually the Lego logo molded on the real parts.
Some differences (low quality fakes) are very obvious, while others (higher quality fakes) require more scrutiny before the differences can be seen.
Axles pose the most difficulty as some real Lego axles do not have the Lego logo molded on them.
For some parts, only during a comparison, the differences can be seen. On its own, the fake Lego parts will not appear fake, unless you know the real Lego part very well.
Note that all these comparisons are based on my own observations, using the parts that I have. I’m sure there are other differences on other fake Lego parts, as there are many different sources of fake Lego parts from different molds.
The reason I made this comparison guide is to help genuine Lego fans, to ensure that they get genuine Lego parts when buying from second-hand sources. It is definitely not to promote any fake Lego.
Axel Pin Update:
In January 2020, a reader Erwin Eling sent us this update:
The picture of the pen I just send is from one of these sets. These sets have been bought in two different stores in two different countries. Both were sealed. Both have been assembled once and have never been taken apart. In one set I found this number 16. The first one I took out. The pin I took from the second set had also a number 2 on it.
Let me also explain how I got to this conclusion. I own a Bricklink shop. A customer ordered these pins. After receiving them he pointed out that we sent ten fakes. But the parts we shipped were coming from several lots from different sellers, so it was kind of strange that all the pins he received were fake ones.
But still, not impossible because we didn't know the history of these parts. So I went on the big all-knowing internet and found your blog. But besides this information not much reference material was available. Also not on Peeron.
Then I decided to see in which sets the black pins had been sold to see if I had bought any of these sets. Luckily I found 3806 (Gigamesh G60) and 3809 (Technojaw T55). These sets have multiple of these pins. I bought one of these sets in Emmen, Netherlands, factory sealed somewhere in 2005. I bought the second one, also factory sealed and also in 2005 in Nordhorn or Neuenhaus in Germany. Now, these sets I do know the history off. I assembled them myself and know that they have never been mixed up with other parts. I also know that the were fun for a short while but then became a bit boring after which I put both of them in a storage container where they stayed for several years until I unpacked them a year ago and put them on a shelve in our new house with my LEGO attic. Therefore I know for sure that these pins were originally packed with this set.
We've also had a reader pointed out in our comments (below) that the guide we published is useful for new LEGO parts (and not necessarily reflect older parts), and we all know LEGO changes manufacturing process all the time, so don't take anything 100%, but more of a guidance. We're fortunate that Erwin has some of the older sets and able to validate and share this information in detail. So we'd like to thank both Erwin Eling and hoklywood for sharing their experiences towards making us more aware of how to help us better be aware parts and accuracy.