Technicopedia Hiatus and New Features

[Blakbird]

I just thought I would write a quick message to update the current status of Technicopedia. I am going to be moving to a new house in the Spring, so I have started the process of taking apart all my LEGO for the move. This process takes many months with a collection the size of mine. The effect of this will be that I won't have any models available to document more model years for Technicopedia until after the move is complete. However, 1995 is well under way and I should have that complete beforehand. Those will be the last models I disassemble.

I decided that I didn't just want the site to sit idle for all that time though, so I am working on some other things that I can incorporate into the existing site to improve it without access to the physical models.

The first thing will be the LDraw model repository. I had originally planned to have a master repository where I have copies of LDraw files for every model in one place, but now I'm thinking of just having a link to the file for each model on that model's page. For example, the page for set 850 will have a picture of the LDraw model and a link to it for download. This will allow closer inspection of every model virtually for those who don't have access to the real thing.

Since I've been doing so many renders lately, I'm also adding at least one high resolution render of each model.

The next thing is just a general improvement. I've become much more competent at LDraw in the time I've been working on the project, so I'll be going back to some of the original pages and improving the quality of the computer images.

Finally is my most ambitious idea. During Brickcon this year, I attended (and helped lecture) a class concerning the basics of how gears and mechanisms work. This was one of the most well attended classes at Brickcon, and this reveals that there are a lot of people out there who just want a basic tutorial on gears, mechanisms, linkages, and the like. Many of these people are not Technic builders per se, but could still benefit from the knowledge for adding features to their System models. Even for Technic builders, not everyone may have the technical background to know exactly how or why certain things work. For this reason, I am developing a "Technical Fundamentals" page to describe some of these things. Then, when I talk about something like a differential in the text, I'll be able to link to a "how stuff works" type page describing the concept for those interested. Here are some animations I've done so far to help make things easy to understand:

• Spur gears (parallel axes)
  
  
• Bevel gears (non-parallel axes)
  
  
• Differential gear (animated both driven and locked)
  
  
• Rotor (Helicopter rotor swashplate) this one was a little tricky
  
  
• Ackerman Steering (it took an entire day to derive all the correct equations of motion to allow this to animate automatically; it was the most fun I've had with math in a while!)
  
  

Here are some other things which I have planned but I haven't completed yet:

• 4 bar linkages
  
• worm gears (screws)
  
• rack and pinion
  
• driving rings
  
• LEGO reciprocating engines (old and new style)
  
• Trailing arm suspension
  
• Double Wishbone suspension
  
• U-joints
  

Some of these involve springs changing lengths, so I'm hoping the rumored new version of LD4DStudio will make this type of animation possible.

Please let me know what you think of this idea and if you have any other ideas for concepts that should be covered in this kind of section. And thanks to everyone for your continued interest in Technicopedia!

[Paul B Technic]

To me this sounds like a really good idea, good luck with it. :)

Paul

[Jetro]

That is a great idea and a brilliant addition to your technicopedia.

As for suggestions,

- I am quite comfortable with gears, but linkages are still very much a trial and error subject, especially the more complex ones.

- For absolute beginners some hints as to gear placement would be great (a good number are shown in the Tora no Maki book, but many others are missing).

- Additionally you might explain how to decide where to put a white clutch gear.

- You may also want to link to some external sources (unless you create your own) like Sariels gear ratio calculator and Philos motor speed comparison charts.

[Brickthus]

That's a good idea. It would encourage a few more people to get into mechanisms.

Jetro's mention of linkages reminds me - I had thought of doing a pictorial survey of "How to add an offset to a rotating shaft", which would show:

- Differential with worm on the crown gear.

- Epicyclic gearbox with worm on the planet carrier.

- 16-tooth gears in a tilting frame.

- Walschaert's valve gear.

- Stephenson Link Motion.

- maybe others, such as Gresley's conjugated valve gear or Capriotti valve gear.

- maybe even a custom solution of mine.

Some of these are geared and others using levers and sliders.

I doubt I could get them moving like yours though!

I have time to think about it till Brickshelf takes uploads again.

The white clutch gear placement is something many of us do by instinct with experience.

It's not like we calculate torque or anything!

Mark

[steele]

Being a train fan, I'd love to see some Lego valve gear. I barely understand how they work in real life, much less how to build a set in Lego.

[Burf2000]

Hi Blakbird. Sounds like your sites going to get even better, One of my favourite lego sites already and now its going to have quiet a bit more use. Well done mate! What about adding motor speeds with internals, (so why you this motor over that one) and pneumatics?

[Jetro]

The white clutch gear placement is something many of us do by instinct with experience.

It's not like we calculate torque or anything!

Mark

But you have that instinct because you know what you are doing. A newbie wouldn't know where to start and why to place the torque gear one way or the other.

[Burf2000]

I agree with Jetro as I dont do much with the clutch and more info on it would be very useful

[Brickthus]

I agree with Jetro as I dont do much with the clutch and more info on it would be very useful

Given that it might end up as a good discussion in its own right, I've started a new thread about using clutch gears.

Being a train fan, I'd love to see some Lego valve gear. I barely understand how they work in real life, much less how to build a set in Lego.

When building steam engines I consider how easy it is to do the rods, since I like to make them work.

Some engines have no visible rods, like Toby the Tram Engine.

The easiest ones have coupling rods outside and piston rods and valve gear inside (so I don't have to do it!)

- Thomas, Stepney and Duck are all like this.

More engines have coupling rods and piston rods outside and valve gear inside (so I don't have to do valve gear!)

- A Hall class engine (5972 Olton Hall for the Hogwarts Express)

- Many of these engines use Stephenson Link Motion for the internal valve gear.

Plenty of engines have external valve gear and I don't like to stint on having it move realistically.

- Class 9F closeup, LMS Garratt closeup (both Walschaert's)

- External valve gear is mostly Walschaert's valve gear, though a few have Stephenson Link Motion or Capriotti valve gear, which is harder to do in LEGO in that location.

The principle of Walschaert's valve gear is to take a multiple of the double differential (reverse for a trigonometric function) of the piston position and add a multiple of the differential of the piston position (90 degrees offset for a trigonometric function) to set the valve command for the piston. It solves a differential equation mechanically. WAKE UP if you fell asleep at the thought of a differential equation The proportion of the differential can be varied between + and -x% by the expansion link, whose position is set by the reversing gear in the cab.

Stephenson Link Motion does it a bit differently, using two equal and opposite angular offsets (both of them differential derivatives of the piston position). The proportion between the two is varied with an expansion link.

Maybe that's made it even less clear in theory than in real life!

For a practical (pneumatic) steam engine, made from two of these mechanisms, I found it easier to use gears instead of an expansion link because there's less play in the system. More pics of the steam engine as soon as Brickshelf is taking uploads again!

Mark

[Shompis]

solid axle vs independent suspension. A bit info on that would be nice.