Wednesday, July 16, 2014

Worms flying away

Some weeks ago people noticed that the sets that use the new worm gear started shipping with the old one, and their online instructions were changed to match. These are the affected sets:

42023 Construction Crew
42026 Black Champion Racer
42027 Desert Racer

You can see below an example of the change in the online instructions, for the 42023. On the left is a version not available any longer from the LEGO site, and on the right is the current version.

Some days ago an explanation came from the CEE Team:

The element has been pulled back since it didn't fully live up to the expectations.
Durability is not as the LEGO Technic team would like it to be, it can get overloaded/overworked too easily for their liking

This could explain why the 42028 Bulldozer uses an old worm where a new one would be expected: it probably was a change late in the production process, but early enough to occur before the set entered the market. I can see the reason for the pull back, as the worm’s driving axle can’t fully go through it, there’s the possibility of torsion forces breaking the new element apart in case of a stalled gear.

Still, the new worm has at least one big advantage over the old one: as it measures exactly 3 modules long (instead of the old one’s almost 2 modules), it produces a lot less backlash. Therefore I hope we will still get a renovated version of this new worm (like we did with the large linear actuators), and that this isn’t the last we see of it... but for the moment this is still known only in Billund.


Erik Leppen said...

Good we see an explanation. But too bad to see the part go before I could get hold of it. I liked the new worm because the actual worm part - the part that prohibits beams from passing by - is smaller.

But the torsion problem is a valid one and I'm not sure it can be resolved without sacrificing its versatility in some way.

If I had any say in it, I'd like to see a 1L worm that is simply half of the old worm (but without the "almost" in "almost 2L long" of the old worm). Especially when combined with 8t gears this would be a great part.

Fernando Correia said...

After seeing this stress test from a 3D printed u-joint, I wonder how is it not possible to produce the aforementioned worm gear in ABS and resistant?... :P

efferman said...

the new worm is not solid enough, but the universal joints without changes for some decades?

Fernando Correia said...

These are much robuster!... ;D

In fact the explanations we get from such decisions are always very comprehensive. See what we got for the V1/V2 IR receivers.
Did you understood it?... I didn't!
We even get V2 with trains. I'll wait to see if this continue to be shipped with LEGO RC Trains.

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