Concerning "classic" hoses and LDCad

[N. W. Perry]

I think this ground has been partially trodden before, but I'm not sure this exact issue has been solidly settled.

How do we tackle the "classic" flexible hose in LDCad—i.e., the old rubber hose used in Classic Space and early Technic sets? This is a 4mm diameter hose, so I think it's the same as the hoses later used in the pneumatic system. I know these are used in the example 8860 model, but what happens when you need a free end that's not connected to anything? In 8860, the ends are simply left off, because the hoses are tucked inside other parts. But what if the free end is meant to be visible (like in set 920/483)? Is there a suitable end part, and how would I go about replacing the beveled end with the non-beveled one?

(And to perhaps get overly precise, would the end part be different depending on whether it's a pneumatic hose or a "classic" one? Are the inside diameters different on these two parts? Are they even two different parts, or are they in fact identical?)

[Roland Melkert]

Is there a suitable end part, and how would I go about replacing the beveled end with the non-beveled one?

I don't think there is an official non beveled version of 165.dat

You could make one yourself and place it in the donors folder "%appdata%\LDCad\donors"

Then...

- use the normal hose template in your model.
- Go to the hose's own session (double click it in non nested editing mode).
- Go to grouping level 0 (top right session panel).
- Select the cap you want to change.
- Double click it's replacement in the bin.
- Click the coordinate panel or press enter to open the cap's properties and check 'inline'. (this prevents a dependency on the unofficial part)

If you need it often you can make a dedicated template for it by coping the normal one and applying the above steps to the template it self.

[N. W. Perry]

I don't think there is an official non beveled version of 165.dat

You could make one yourself and place it in the donors folder "%appdata%\LDCad\donors"

Hmm, I wonder if I could use the end piece from LSynth (ls20.dat)?

EDIT: Or better yet, edit the existing end cap for the 3mm hose and make it 4mm? Although, I'm not really sure what I'm doing there, as I haven't delved into parts authoring much at all.

[Roland Melkert]

Hmm, I wonder if I could use the end piece from LSynth (ls20.dat)?

EDIT: Or better yet, edit the existing end cap for the 3mm hose and make it 4mm? Although, I'm not really sure what I'm doing there, as I haven't delved into parts authoring much at all.

End caps should be 'normal' parts (non scaled) preferable including snap information.

You could put the scaled ls20.dat in a wrapper though, just be sure it has the same orientation and origin as 165.

This solution would create a dependency on ls20.dat meaning anyone you give the model to needs to have it in their library too.

[N. W. Perry]

End caps should be 'normal' parts (non scaled) preferable including snap information.

You could put the scaled ls20.dat in a wrapper though, just be sure it has the same orientation and origin as 165.

This solution would create a dependency on ls20.dat meaning anyone you give the model to needs to have it in their library too.

I think the parts I'm creating are "normal"—well, at least as normal as the parts they're derived from. All I've done is change some values in the matrix to get the correct diameter.

I tried the same method starting with three different end parts: LS20.dat (pneumatic end cap) and LS50.dat (flex hose end cap) from LSynth, as well as LDCad's 3mm rigid hose end cap. I ended up choosing LS50 since it looks closest to the correct ratio of outer to inner diameter. The geometry from that file is:

1 16 0 0 0 4 0 0 0 1 0 0 0 4 4-4cyli.dat
0 BFC CERTIFY INVERTNEXT
1 16 0 0 0 2 0 0 0 1 0 0 0 2 4-4cyli.dat
1 16 0 0 0 4 0 0 0 1 0 0 0 4 4-4edge.dat
1 16 0 0 0 2 0 0 0 1 0 0 0 2 4-4edge.dat
1 16 0 0 0 2 0 0 0 1 0 0 0 2 RING1.DAT
1 16 0 1 0 2 0 0 0 -1 0 0 0 -2 RING1.DAT

LS50 is a 3.2mm diameter hose, so to get 4mm I just have to scale by 125% (trying it first in Studio's Part Designer to confirm it actually works this way). :-) That means I just have to change the 4's to 5's and the 2's to 2.5's, giving this resulting geometry:

1 16 0 0 0 5 0 0 0 1 0 0 0 5 4-4cyli.dat
0 BFC CERTIFY INVERTNEXT
1 16 0 0 0 2.5 0 0 0 1 0 0 0 2.5 4-4cyli.dat
1 16 0 0 0 5 0 0 0 1 0 0 0 5 4-4edge.dat
1 16 0 0 0 2.5 0 0 0 1 0 0 0 2.5 4-4edge.dat
1 16 0 0 0 2.5 0 0 0 1 0 0 0 2.5 RING1.DAT
1 16 0 1 0 2.5 0 0 0 -1 0 0 0 -2.5 RING1.DAT

I saved that into a new file, and it worked—almost:
   

Obviously I shouldn't be able to see through the hose that way, but I'm pretty sure I know why that is (the inner diameter of my end piece doesn't match that of the hose). So that's where I'm at; I'm sure there's a more correct way to do this, but I'm pretty much making this up as I go along. 

[Roland Melkert]

Obviously I shouldn't be able to see through the hose that way, but I'm pretty sure I know why that is (the inner diameter of my end piece doesn't match that of the hose). So that's where I'm at; I'm sure there's a more correct way to do this, but I'm pretty much making this up as I go along. 

You need an inverted inner tube, because the outer tube is only visible from the outside due to BFC.

[N. W. Perry]

You need an inverted inner tube, because the outer tube is only visible from the outside due to BFC.

Mm, yeah…I figured out later that this was just an aspect of the HQ template itself, not anything to do with the end caps. But in fact I need to use the LQ version since I'm going to render this in Studio, and that does have the inner tube—which leads me to my next question…

The donor segment of the LQ template (166.dat) has outer and inner radii of 5 and 3, respectively—but I couldn't figure out how to get a ring primitive with those radii. Surely there must be a way?

(What I ended up doing was making a custom version of 166.dat, such that its inner radius is 2.5 instead of 3, which matches the radii of my end cap. That works fine, but I have to assume there would be a way to make an end cap to match the official part, no?)

Anyway, here's a shot of the finished end cap (with the "wrong" inner diameter, anyway), along with the custom parts I created…feedback welcome!
   

[Philippe Hurbain]

has outer and inner radii of 5 and 3, respectively—but I couldn't figure out how to get a ring primitive with those radii. Surely there must be a way?

The simple solution is to use a ring3 and a ring4 (scaled 1x). For more complex cases there is the ring and cones calculator, in tools section of LDPE (see also http://www.philohome.com/isecalc/rings.htm for a stand alone version) . Technically (less vertices) it would be better to use chrd+ndis primitives+quads but it's more complex and not worth the trouble here.

[N. W. Perry]

The simple solution is to use a ring3 and a ring4 (scaled 1x). For more complex cases there is the ring and cones calculator, in tools section of LDPE (see also http://www.philohome.com/isecalc/rings.htm for a stand alone version) . Technically (less vertices) it would be better to use chrd+ndis primitives+quads but it's more complex and not worth the trouble here.

Aha—two concentric rings. I think that did occur to me, but I wasn't sure if it would be "ethical" in LDraw. And they'll line up correctly, with no visible gap in between?

I do look forward to delving into LDPE and its tools, although I'm currently held up by my inability to launch the program (posted about here). I may try the standalone version, if I can get it to work under Wine, and if the situation arises again.