How do you use CAD tools?

[Erik Leppen]

I was just wondering, how do you all use CAD tools? Do you use them? And if so, what do you do in them, and what do you do without ("by hand")?

Some examples:

You can design everything up to the last brick in CAD and then literally rebuild your virtual model in real life

You can plan the gear trains, and do the rest with real parts

You can plan the frame and do the rest with real prats

You can design small modules and use real parts to find out how to connect them

You can have several design phases where you design in CAD, then build and then use your findings to enhance the CAD and rebuild, etc. until you are content.

So, my question is, during which parts of the total process from an idea inside your head to a real-life model, do you use CAD tools to help you out? And how does that actually help making your models better?

PS I'm not talking about creating instructions, I'm just talking about creating the MOCs themselves.

[Sariel]

I have once used MLCad to design outer shell of a cab of my Scania truck model. The result: http://www.brickshelf.com/gallery/Sariel/ScaniaRacingTruck/dsc05612.png

But it only happened once, primarily because I was going to order red pieces for this model and I wanted to quickly figure out what to order, plus honestly it started as just a rough sketch, I did not intend to design the entire cabin with all the details. At some point things just got out of hand ;)

Now that I think of it, I sometimes use MLCad to see how some piece that I don't have and I'm about to order fits other pieces.

[Alasdair Ryan]

I don't really use cad for my mocs,i have started to make two things recently but this gets boring after so long.I really just use cad now for institutions and to help people on here.

[basbase]

For my current project I first made a quick prototype with real bricks, so I could see if the general idea would work. I then started to build it in MLCad. This allows me to try out a lot of different combinations of parts without having to take apart the entire model. I now almost have the entire model finished in MLCad, all essential parts seem to fit in. Before I'll finish the design I should first build the frame to see if it works. If it doesn't, I won't have to bother about the bodywork any more .

So CAD really helps me to figure out which parts to use and where to place them. But to test if forces are handled the right way, it is necessary to build with real bricks.

[AndyC]

I'll use LDD to mock up bits of idea sometimes, mostly because it's often more convenient than getting all the bricks out. It's not so great for Technic ideas though, but LDraw based tools I find too slow and cumbersome to be practical. Also it's sometimes nicer to just get a few parts in your hands and just fiddle around and see where it takes you.

[Jurgen Krooshoop]

MLCad and LPub4 are the Lego Cad-programs I use. But I only use them after completing a MOC in real bricks. I use these programs to make instructions.

[Splat]

I primarily use MLCad and LDView, but in different ways at different times:

• If I'm at work (where I don't have my Lego), and just need to work out if a few pieces will fit together, I will open MLCad to find out, but often I won't even bother saving the file.
  
• If I want to preserve an idea (of a gearbox, etc), but not tie up all of my bricks by keeping the model built all the time, I'll recreate the model in MLCad for future reference.
  
• If I need to order parts to build a MOC, I'll make it in MLCad first so that I get all the part quantities correct, and refer back to the MLCad file once the parts have arrived to build the model.
  

When using MLCad, I usually have an idea of what I want to do - I usually don't 'fiddle around' in MLCad like I do with real bricks.

I find that building a drive train in MLCad can help me work out how all the mechanics (axles, gears, etc) fit together, without having to build a frame around it to support it and make it strong. Similarly, I can move big chunks of the model around without having to rebuild the frame all the time. I can then open the file in SR3D and use the animation mode to see some simple movements. Once the mechanics are sorted, I'll design the frame and shell, which is a combination of MLCad and real life bricks.

When building Technic models in MLCad where bricks aren't always at 90 degree angles, I usually create a sub-model for each new angle. This results in lots of sub-models, but I find that easier to work with as you can then move the bricks around and still have things like up properly.

For the latest MOC that I'm working on, I found a 3D Studio file on the internet of a real life model, and was able to open it in AutoCAD, export the co-ordinates, and create an MLCad file that had all the line work in it to use as a reference. Now I am building the exoskeleton in MLCad to match the line work, then I will build a supporting frame and add the mechanics to fit inside it; so I'm sort of working from the outside in, but the shell will have the exact same proportions as the original 3D Studio file. I hope everything fits, otherwise I'll just have to scale up the model in AutoCAD, and start over.

I'm still not too familiar with the characteristics of the PF motors, so I'll usually have to mock something up in real life to make sure I don't have too much friction or not enough torque in my drive trains to avoid stalling the motors. I never know where the best place to put a 24T clutch gear is! Building in real life also helps to work out if the motor cables will be long enough, and how to route them so that they fit nicely.

MLCad is also good for working out how the shell will fit, as you can have multiple pieces floating in mid air to get it looking right, and then put supports in afterwards. You can do this in real life too, but you just need a lot of hands to hold everything in place

For something simple like a System model where you build from the ground up I can build it all in MLCad first, then in real life. But for Technic where there are weird geometries and angles, I'll go back and forward between MLCad and real life until things are working properly.