32004b - Need advice.

[Damien Roux]

As stated on the tracker, I'm reworking this part (which according to Philo seems to have a lot of problems).

Problem is I do not own the part, but I've made assumptions and created it with a CAD software. With stl2dat, I've made a ldraw file.

Can some of you have a look and tell me what do you think of the pin-holes and axe-hole positions and dimensions (especially in the Z direction).
Then, if you compare with the tyre that goes with it (32003), the two parts don't seem to have the same diameters. Which one do you think is the correct one?


I know the part is very heavy and doesn't have any primitive but this is just a temporary file to first see if the geometry is correct.


Last question: if I rework the part from scratch: do I need to keep the name of the first author and put mine only in the file history?

[Philippe Hurbain]

Hi Damien,

Sorry for the late answer...

With stl2dat, I've made a ldraw file.

Great work!

Can some of you have a look and tell me what do you think of the pin-holes and axe-hole positions and dimensions (especially in the Z direction).

No, it's no good: try to put a Technic pin in one of the pegholes, you'll see that the hole is too long, and the peghole entry is too narrow for the pin collar.
Now I am not sure at all on the Z position of the peghole Same thing for the tire: I have no reference here.

Last question: if I rework the part from scratch: do I need to keep the name of the first author and put mine only in the file history?"

Yes, even in that case you must keep original author of the part...

[Damien Roux]

Thanks a lot for your reply.


So new version:

I've corrected the pinholes diameters. Now a pin can fit (there is one within the file).

Then, to know what could be the Z position: do you think that this part should be "clippable" on a 1x16 technic brick for example? If yes, I can move all the pins to fulfill this condition.

Another thing that can help: do you think I should use only 0 digit values for the Z position.
As an example: something like "from 0 to 16", and not like "from 0.5 to 16.5".

[Travis Cobbs]

Never mind. (I said something, then re-read your original post and decided what I said didn't make sense.)

[Damien Roux]

May I know what you said (now I'm curious)?

[Philippe Hurbain]

I've corrected the pinholes diameters. Now a pin can fit (there is one within the file).

Much better indeed!

Then, to know what could be the Z position: do you think that this part should be "clippable" on a 1x16 technic brick for example? If yes, I can move all the pins to fulfill this condition.

No, I don't think so. Generally the pins/axlehole are somewhat recessed.
Edit: For example, on similar 32020 wheel, the back is recessed by 3ldu.

Another thing that can help: do you think I should use only 0 digit values for the Z position.
As an example: something like "from 0 to 16", and not like "from 0.5 to 16.5".

Yes, generally values are rounded to integer ldu values

[Travis Cobbs]

I said it had way too many polygons, but rereading your original post, it seems you're going to use this as a reference when recreating the part, not use it as-is.

[Damien Roux]

Yes, yes. Instead of spending hours to create a part without even being sure the dimensions are correct, I preferred to do it in 10 minutes with a cad software allowing easy changes. Then, will subpart it and create primitives.

But, the part wouldn't have been that big if I had been able to make the primitive substitution feature of stl2dat work. Got no results at all.

[Orion Pobursky]

But, the part wouldn't have been that big if I had been able to make the primitive substitution feature of stl2dat work. Got no results at all.

It never really worked right. It would have been nice when I used it to author my first part:

[Philippe Hurbain]

Maybe a workable scheme would be to export LDraw primitives to STL, build the part around the imported primitives, then go back in LDraw domain and replace primitives. But I don't know if that would work well since AFAIK Solidworks is a volume modeller, not a surface one like LDraw?

[Damien Roux]

I'm working with Catia, but Solidworks should be similar. STL is only defining surfaces, so working with volumes or surfaces gives the same results. Besides, you can also model surfaces only, so it can work as Ldraw.

Problem is that it uses the mathematical definitions of surfaces. Not a facettized one like Ldraw. If I reproduce the primitives with their facettes in Catia, I would have to model the part only with triangles to make sure verticles are matching. And then, all the advantages of such a software are gone.

I think I will make the part, export to STL, export to dat (which will give me too much triangles). And try to delete and substitute until I get a good result.

[Travis Cobbs]

Yes, yes. Instead of spending hours to create a part without even being sure the dimensions are correct, I preferred to do it in 10 minutes with a cad software allowing easy changes. Then, will subpart it and create primitives.

I basically figured that out when I reread your original post, which is why I essentially deleted my own post.

[Damien Roux]

Speaking about 32020 (Wheel 62.4 x 20), the parts are very similar, maybe I can get most of the dimensions from this one, and reproduce them with 32004b.

Could you tell me what do the 62.4 and 20 correspond to? I guess it's a diameter and a thickness, but which ones?

Then, I'm thinking of doing the same geometry in both.

[Damien Roux]

I gave a try. I think it's not that bad now.

[Philippe Hurbain]

Could you tell me what do the 62.4 and 20 correspond to? I guess it's a diameter and a thickness, but which ones?

I think these numbers refer to matching tire dimensions. LEGO calls 32020 "RIM Ø 43,2 X 18".

I gave a try. I think it's not that bad now.

Agreed, looks pretty good...

[Damien Roux]

Ok, so I'll take this one as the one.

I will try to subpattern it, and submit it to the tracker.