The difficulty with large turntables made of LEGO parts is making them strong enough and stiff enough to withstand the large loads and moments that get applied to them. I’ve made many turntables through the years and I’ve noticed a lot of them have suffered from wanting to pry apart under load.

A solution to this is to make a sandwich of roller bearings; basically a self-contained stack of rings separated by bearings. It’s difficult to put into words, so hopefully this diagram will help:

This is the design currently used in my latest crane. The model is meant to be a tower crane with a luffing boom, but it is also a test bed for some new ideas that I’ve had.

I built the turntable for this years ago. I intended to use it to make a hammerhead style tower crane, but decided later to turn it into a slightly different style with a luffing boom.

The turntable uses the same roller bearing ring as used on my 4×4 offroad crane.

I can’t believe it’s been over a year since I posted last. I’m a %#&#^$ blogger

One year and two Brick Fiestas later, I’m still around and still building! Speaking of Brick Fiesta, I was Co-Chair this year. The event took place last week. It was a great success, and I’m still really tired!

I built a new crane for the event:

click to visit my Flickr site

It’s very similar in function to previous cranes that I’ve made. However, this uses a brand new turntable design. It’s smaller than previous designs (ie Crane Project #1) and it works well. I also designed a boom with a triangular cross section made mostly of studless beams and parts.

More details to come later! Hope you are enjoying your summer!

I volunteered to do our LUG display this month at the Houston Galleria LEGO Store.

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It’s a display of trusses with a little info card. Thanks to Matt S. for the idea

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I used the same base as my last display, except that I changed out the lettering for different colors to match our state flag.

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I wasn’t sure about putting in a little info sign. I made one for the last display I did in February. But the folks at the store assured me that the kids visiting the store will stick around a bit longer and actually read it. Cool!

I’ve created a “scene” for our (TexLUG) February LUG (LEGO Users Group) Showcase.

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The LUG Showcase program is program offered by the LEGO retail stores, and each store has a small display case for this feature. LUGs are invited to display a creation and advertise their club. The change-out of displays happens about every month.

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This is my first time to do a display. This display will go into the case in the Houston Galleria LEGO store on February 5. It will be up until early March.

I started this in April 2010, worked on it for a short while, then stopped building.

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Around the new year, I started up again and made significant progress. The main engine is pretty much done, except for some minor things and some “greebling” to be done. I also ran out of a few parts and I’m waiting for a Bricklink order to come in.

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I just started on the tender this past weekend. I’m working out the details of the wheels and linkages between wheel groups.

To recap: the engine is a model of Union Pacific’s 844 (4-8-4). It uses four geared 9V motors (pre-Power Functions), one for each driver set. The drivers are XL BBB (Big Ben Bricks).

It will be controlled by a Power Functions receiver and battery pack. Those will be housed in the tender.

I’m hoping to get this finished in a few weeks.

Well, tree as in one tree, really There will be more to come.

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I took the time to put together a tree with loads of flex tube. There is a single, long piece down the shaft (trunk) of the tree (the “trunk” is made of 2×2 round, brown bricks). There are four leaf pieces captured between every 2×2 brick, but then each leaf piece has a second piece connected to form a branch. There is a very short piece of flex tube at every one of these junctions between leaf pieces.

The problem with trees like this has always been that the branch leaf pieces do not stay connected. Any handling or vibration tends to knock them loose. When you pull something like this out of storage, there’s usually several dozen leaf pieces in the bottom of the bin.

The flex tube seems to fix this issue. I’ve let my kids handle the tree, and not a single leaf piece has fallen off.

Formally known as “Project X”, I completed this model last weekend. Actually, I did not find the time to blog about it and properly tease viewers. Life got in the way.

However, the thing is done and I’ve put it in high gear and cranked out a proper webpage for it:
http://www.texbrick.com/model_pbridge

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And here is another project that I’ve blogged about before. I’ve made a proper webpage for it, including a lot of photos and a write-up:
http://www.texbrick.com/10ftbridge

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I’ve blogged about this project already, and I’ve finally gotten around to making a proper webpage for it on my site. Although at this point, the webpage isn’t finished yet

At any rate, I just wanted to announce it and get it out there:
http://www.texbrick.com/model_craneproj

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My webpage for the Memorial Hermann tower model is done:
www.texbrick.com/model_mhtwr/index.html

photo © D.Birkhead
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