Can clutch power increase over time?

[davee123]

I've heard of parts changing in high humidity-- but generally (as is my understanding) they become "squishy" in those circumstances, and slowly work their way apart on their own. It's not outside the realm of possibility, certainly, for parts to change over time with various environmental conditions... but it certainly is pretty rare!

I would guess that the worst-case conditions for elements changing would be to be stored in varying temperature and humidity-- where it frequently changes from hot to cold, and humid to not-humid. But even that shouldn't really be enough to do what you're describing. Clearly we need a plastics expert!

DaveE

[spacefan6901]

I think I had some bricks & plates from back in the early 1980's that had so much clucth, I used teeth on them!

Then I got older (and more fearful of damaging teeth) and used sewing pins and needles to force the tips into the cracks to be able to push them in enough to be able to pry them apart.

This did leave small marks on the edges where I forced the pin tips in.

(I wonder if my old stuff I recently got back from my grandmother's house after almost 20 years will all be suffering from this?)

[Phoxtane]

I've heard of similar issues when two transparent parts are put together. It's something about the different type of plastic used that actually causes them to start to bind together. Maybe I'm crazy, but my guess is that somehow Lego produced some parts with the wrong plastic, but the right color, and you just happened to get those parts.

That, or glue.

[LEGO Historian]

TLG used to have Germany's Chemical giant Bayer testing the LEGO colors and the clutch power of the ABS plastic (and their Cellulose Acetate before that). We all know how well TLG has gotten along with quality issues with mixing their own colors... makes you wonder about issues with clutch power?

[Front]

TLG used to have Germany's Chemical giant Bayer testing the LEGO colors and the clutch power of the ABS plastic .....

Is that a fact that a material supplier tested the clutch power ? A property dependant on both friction values of the two materials, and dependant on the geometrical properties of the parts.

I guess you are not making up history ?

Erland

Part Design

[vittorio]

Thanks for the replies! Here are some updates:

• I was able to pull the assembly apart by using the tip of a metal nail file to open up the tiny gaps, and then with a much thicker metal wedge to pry them apart. It still wasn't easy, though, and some of the bricks got dented as expected. But what surprised me was that the metal wedge easily scraped off a thin layer/strip of plastic from the bottom of a curved brick when I wedged it in.
  

• I started re-building my sets to check the condition of the other elements. There are some 1x2 dark tan bricks that now have little or zero clutch power! They're tight when stacked with each other and with other elements, but when connected to base plates they don't hold up. Again, I don't recall it being like this before.
  

This is baffling.

please contact (write to) consumer service at lego.com and tell them about the problem.

Tell them which set the pieces (part design no. 6091) are from, and what text is written inside them (e.g. 02-8).

Thanks for the tip, Erland. I have only three sets with this element but I can't tell which set these came from in particular. I did check the other curved bricks and the dark red ones noticeably have more clutch power than the rest.

Maybe I'm crazy, but my guess is that somehow Lego produced some parts with the wrong plastic, but the right color, and you just happened to get those parts.

I'm also starting to think that it's probably more of a production slip. Then again, why does it seem that nobody else has noticed it? And now I also have the inverse problem with the loose 1x2s. Aaah, I don't know.

[LEGO Historian]

Is that a fact that a material supplier tested the clutch power ? A property dependant on both friction values of the two materials, and dependant on the geometrical properties of the parts.

I guess you are not making up history ?

Erland

Part Design

No not making up history, but not exactly answering the original question either....

Bayer Corp. used to test the colors and "grip" of LEGO bricks... my Dutch collector friend MAXX has a large collection of Bayer bricks, and some have letters A, B, C, D on the studs (instead of "LEGO").... IIRC, "A" denotes the least clutch power brick, while "D" bricks have the most clutch power". Later Bayer changed this process by just keeping "LEGO" on the studs (although I don't know exactly how they determined the various clutch powers that way?).

Here's MAXX's site and some info....'

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=373938

Note: Chapter 49 of my LEGO DVD/download has an online link to Bayer bricks (thanks to MAXX and Arnoud Van Den Bos (another Dutch LEGO collector), but I've been so busy with other LEGO items, that I've yet to fully research that site...

[splatman]

Those 80's hard-to-press-together-and-hard-to-get-apart bricks may have been made in molds nearing the end of their service lives. My theory is, every time plastic is injected into a mold, the plastic "scrapes off" a few atoms/molecules from the mold surfaces, effectively changing the geometry of the mold, so each brick (and their studs) is an Angstrom or 2 longer, wider, and taller, and the inside likewise smaller, than the last one. After a few 100K molding cycles, the bricks are so much larger (and their insides smaller), that they squeak when pressed together. And hold together real well. Then someone at the factory says, "OK, these molds are a bit out-of-shape. Time for a swap-out.". They might then be used to make bricks for the Model Shops, where the extra clutch power may be little concern. Then the molds will get subbed in for gravel in their next batch of concrete.

[Front]

It's a normal property of ABS, that the friction level will increase during aging.