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Showing posts with label headlight. Show all posts
Showing posts with label headlight. Show all posts

LEGO Techniques - Stud Height

At the end of the Reverse Engineering Challenge 4 I posted a picture on Flickr with a rather impassioned description. There had been some discussion as to what the height of studs are and whether or not they cause conflict in builds. The myth traveling around is that stud height is half of a plate, or, 1.6mm. As my picture shows, this is incorrect.

But there are times when it seems like the only explanation for stud height is that it MUST be 1.6mm.

Take for example the above picture. This little tablescrap attempts to show stud conflict. Notable is the top of the 1x2 technic brick with axle hole against the 1x2 technic brick with 2 pin holes. You would look at this and immediately think, "Duh, you just disproved your point. Studs are half a plate high, done."

Au contraire, my AFOL. Remember how I discussed the true dimensions of a LEGO brick? You would think at first blush that the white brick is 16mm across right? But it's not, it's 15.8mm. The height of the stud from the yellow brick would be the half plate difference from the white to black brick PLUS the tolerance factor of the white brick; 1.6mm + 0.1mm = 1.7mm. Some say the stud is 1.8mm but this shows it to be impossible. As for the logo? Negligible.

LEGO Techniques - Headlight Conflict

Finally getting back on track with the study on headlight bricks. A while ago I showed how headlight bricks are an odd construction. They maintain normal brick tolerance on 3 sides, but the fourth side actually reverses this and cancels out the tolerance on the opposite side. The effect is that of creating a true 2 plate high piece. But how does this affect SNOT construction?

Using my little tablescrap I've created two cases where the headlight brick creates error. The first is in the lower right corner under the yellow technic brick. You can see that the headlight brick is actually pushing against the sideways grey travis brick such that it doesn't want to rest easy. What's the deal?

First, a quiz: How wide is the yellow technic brick?

If you said 16.0mm, you're wrong. While it is that size nominally, the actual size is 15.8mm. Remember the 0.1mm tolerance on each side?

Using math, it's easy to see how the conflict can occur. The headlight brick is EXACTLY 6.4mm wide due to it's intended cohesion with a double high plate. The travis brick is exactly 9.6mm high. Added up, the total becomes 16.0mm which is obviously a little too much for our poor technic brick. You can certainly build up around such cases and get the bricks to be compliant but they will be stressed a little.

The second case is on the left where the headlight bricks interact with a blue and grey headlight brick. Using the same concept it should be easy to see what is happening. The red headlight brick atop the blue travis brick is in system... except for the stud face which is 0.2mm beyond. The width of the headlight/grey travis brick combo is again a true 16.0mm. The stuck out face of the headlight brick is pushing the grey travis brick (along with any connections) an extra 0.2mm further east. Therefore, even though the upside down headlight brick is attached to the blue travis brick, it's connection with the grey travis brick keeps it from pushing up against the brick.

Headlight brick, you are a wily one.

LEGO Techniques - Headlight Bricks

Excuse my summer burnout. I might be a bit sporadic over the next couple of months. That will just make you look forward to my posts all the more, right?  Riiight.

Headlight Bricks appear to have more nicknames than other pieces. Some call them headlight bricks after their original use, some call them Erling bricks. This is obvious since Wikipedia tells us that Erling is a Nordic male name, meaning "Heir of clanchief". OB-viously! But it really tells us more about the origin of the brick. It was nicknamed for the LEGO Designer Erling Dideriksen, who invented this element in 1979. And despite that, the model shop still calls it a washing machine brick, even though the Pick a Brick calls it an "Angular Brick 1x1". Angular? Like 90° maybe. What if we acronymize this name to HEWA (headlight/erling/washing machine/angular)?

Current study block, my piece de whatthehell...
Now that that's settled, let's look at the geometry of the brick. After the last Reverse Engineering Challenge, I got into a discussion with Sheo, another amazing builder and brick thinker. Whereas I had been looking at bricks with their nominal width of 8.0mm, he has been looking at them for their ACTUAL width of 7.8mm. All bricks have a 0.1mm tolerance on each side to reduce binding when placed next to each other. When bricks start getting used sideways, interesting results can happen.

The HEWA brick is often turned sideways and used for a SNOT approach. This means that the direction of tolerance is getting stuck into another dimension. Usually. This whole thing came about because I made a bold attempt to show that studs are NOT 1.6mm tall as is commonly thought. They're a mite taller and I don't mean because of the logo. Even hollow studs have collisions. Sometimes. But why not always?

Let's study the HEWA brick. Nominally it's 8.0mm across. Actually, it's 7.8mm across. At the base. For the brick portion, it's actually 6.4mm. You expected it to be 6.3mm? I did too. But the block is actually 6.4mm to allow it to be the exact same height as two plates. That was some forward thinking back in the good old days. So it has tolerance reductions in the upright position, and corrections in the prone position. Assuming the stud is truly 1.6mm tall, that would explain why the side stud sticks out a scoche. But it's not 1.6mm tall and we'll address that another time.

So what if we turn the brick sideways? The geometry is similar to another newer piece, 99207. I've drawn the studs to line up, but do they actually? We'll take a deeper look into the HEWA brick's relationship with other pieces in the next few installments of this blog series.