STEP files into LDraw

[Dorota Sauer]

Hi Everyone! I guess simple convertion of .STEP file into .dat is not possible, so what I need is advise on what is the best way to translate it.

I have a model of a LEGO part made in CAD. It is an original base plate (no studs, only holes, designed for easier building of robots) so I didn't find a ready part in libraries. I wanted to make the plate available in LDraw for everyone to see it, play with it, maybe give feedback on its functionality. Maybe some of you already saw the project, and has an idea how to solve it: http://www.minutebot.com/minuteproducts/base/

If you know how I can do it, it would be a great help to me.

[Rolf Osterthun]

Hey,

I like the plates! Can you share a sample .STEP file? Or can I download one somewhere?

Rolf

[Tim Gould]

The best solution would be to write an auto-generator for plates of different sizes, using primitives. Basically you have corners, edges and interior parts so you could make any dimension using just three basic building blocks.

I'm sure Philo will have that written by tomorrow

Tim

[Steffen]

Hi,

I think that trying a STL->LDRAW conversion is overkill here.

It is by far easier to create that part from scratch manually, putting together some simple subfiles.
I've done this for your suggested "Technic Baseplate 21x30", please see the attachment of this post.

When subfiling a little more granular, one can easily compose other XxY dimensions.

Have fun!
Steffen

EDIT: oh, this was a cross-post with Tim :-)) maybe Philo will base his tooling on this first sketch :-))

EDIT 2: hmm, while looking at your kickstarter project for this, I don't really get it why you would need 11.000 $ to
do this thing: why don't you just buy some Technic bars, fixate them with some other technic bars,
then simply glue them together, then remove the fixation, and thus get a "Technic Baseplate"?
This would by far be cheaper, and you wouldn't have
the precision problems and so on. For 11.000 $, you can buy _a lot_ of Technic bars to glue together.

EDIT 3: ah, you want to manufacture other parts as well, and this fundraising is for the initial setup, right? hmm.....

[Steffen]

PS:
The world really needs more 3D printers :-) :-) :-)

PPS:
to be consistent with LDRAW nomenclatura, the part above probably needs to be named
"Technic Beam 21 x 30"
(cf. e.g. 32250.dat)
:-D

[Tim Gould]

Haha. You know I almost added "or Steffen" and only left it off as Philo is usually the first to do technic parts.

Tim

[Philippe Hurbain]

(OK, I'm a bit late...)
A tool to create highly repetitive parts like this one already exists: Tore Eriksson's LDraw Script Compiler... I think this is a perfect target for this tool!

[Dorota Sauer]

Thanks for all the input and comments!

@Steffen:

Cool! Thanks! There seem to be a problem with the scaling of the MinuteBot Base? Much too small! We had a look in the data but we're clueless on where the error is!?

@ Steffen EDIT 2: We like Airfix and we like LEGO - but never do both at the same time! Further, there are a couple of practical issues: Using a 1 x 15 studless beam, we need 42 of them! The width of one beam is not 8,00mm but 7,80mm so you need to do some very precise glue work (probably using a fixture). So: A lot of work (and hopefully with a durable glue).

@ Steffen EDIT 3: Yes. correct.

[Philippe Hurbain]

Cool! Thanks! There seem to be a problem with the scaling of the MinuteBot Base? Much too small! We had a look in the data but we're clueless on where the error is!?

Steffen's model has correct dimensions - but maybe we don't speak the same language? LDraw uses LDraw unit, with 1 LDU = 0.4mm.

[Dorota Sauer]

Thanks. The parts looks nice when loaded alone - but together with other parts something goes wrong... Here together with a 3x5 (which looks perfectly ok until we add the MinuteBot Base), see screendump...



We probably have to find and set a tickmark somewhere...?

[Steffen]

there's some things going wrong here.

First, you shouldn't be adding other parts into the baseplate itself.

Instead, you need to move my mpd file to e.g. your "models" folder.

Then create a new file, and insert that part there.
Then you can add more other parts.

What I see from your screenshot is that you've inserted more parts _into_ the *.mpd file,
this is not how you're supposed to be building with LDRAW.

Said that, I think that MLCad 3.40 may have a bug here.
What I see from your screenshot is that the added part gets scaled _up_ by MLCad...:
it has an option at "Settings/General/Change.../Document/Orientation of new object"
which says "same as previous". This seems to go mad here. MLCad seems to insert
the matrix of some line of the MPD as default here. Which of course will hurt badly for parts.
They're not intended to be scaled up, just rotated and offset.
Try if setting the option to "Default" heals the upscaling.

Nevertheless, you should be following my advice above: do not _insert_ other parts _into_ this part,
but instead create a *.ldr file (a "scene"), in which you insert the mpd _plus_ the other parts.

[Steffen]

I just tried to do this myself. MLCad seems to have a problem when you try to insert a mpd into a scene as a part.
Weird errors happen.

So here's an alternative solution:
the mpd file I posted is a multi-file container for 3 files.
I've extracted them from there for you here, just download them separately.

Then do this:

1. put "Technic Baseplate 21 x 30.dat" to your "models" folder.
2. put "side.dat" and "middle.dat" into a folder "s" which you create in "models".
3. start MLCad and choose "File/New". This will give you an empty scene.
4. insert the Technic Baseplate part into that scene by picking it from the part picker tree from "Models"
5. insert other parts at will
6. save the result into a *.ldr file inside the "models" folder

maybe also checkout
http://www.holly-wood.it/mlcad/basic1-en.html

[Dorota Sauer]

Thanks a lot for your help!

We just kicked off the MinuteBot Base Happy Design Week where AFOLs can show what they would use the Base Plate for!

Here is a cool example: