Another airship underway: 1/144 Z XII Scratchbuild.

[MoFo]

Okay, moving forward...

I thought I'd do a deeper dive into the construction of the gondolas.  So here's a bit of a step-by-step.  This is just the processes involved; every process involves at least one sketch, which is the time consuming bit as you try to interpret the references and make an accurate part.  These sketches and processes tend to layer on top of each other, so if you find out you did something wrong earlier in the design, it can break subsequent steps, which means you've got to go back and repair things, so it can be a tedious process.  Tl;dr: it's not as easy as it looks


I decided to start with the main windows.  You have to start somewhere, and they seemed like a fairly central detail to 'hang' subsequent operations on.


(hard to see, but) next is a loft underneath, to blend the main, square section of window with the bottom of the gondola.


Then the front bottom of the gondola is extruded with a slight taper.


...and cut to shape.


The mid section is extruded from the roughed out front section.


And the various sketches completed so I can create a loft for the aft end of the gondola.  The cross-sectional sketches form, well, the cross-sections of the loft, but they have to be told where to go, or else they'll simply take the straightest path (or occasionally, a random, wild path...).  This requires additional sketches floating in space, to connect the cross sections.  It's actually a bit of a process to create these - flat planes are simple to trace, but sketches that are fully 3D end up requiring a ton of preparation and tweaking to perfect.  I'll often extrude, cut and loft temporary bodies so I can trace their (3D) outlines to get the necessary 3D sketch... then delete the bodies and use the resulting sketch to guide the loft.


All that prep work done, the loft is completed.  I only did one half as it was easier to force the loft to do what I wanted.  I can mirror it later.


The roof is then extruded...


... and the entire model gets chopped in half.  This wasn't my original plan (or else I'd only have done one side of the front section) but after screwing around with the loft for a while, I decided it was the best option.  Doing two lofts side by side ran the risk of causing problems meshing with the rest of the model; mirroring just the loft might have worked, but in the end, cutting it in half gives me a single, flat surface I can use to mirror the other side, for a simpler construction.  It boosts the file size a bit, since it's more process-intensive, but I felt it was worth it.


Mirrored.  The final step to rough-out the gondola is to create a loft at the front of the roof.  This is a great example of using sketches to 'force' the loft into place - I'm trying to merge a triangle into a weird, six-sided shape.  Each of those grey lines tells the loft to go from point A to point B.  Without them it would fail, as it can't reconcile the the 'start' and 'end' sketches.


And the gondola is roughed out.  This completed body is then duplicated so that I can add details.  One body is hollowed out to create the main part of the gondola.  The other body is shelled outwards, adding thickness, so that I can model the raised surface details.


Here you can see a portion of the outward shelled body cut away, exposing the window area. 


The ribs are then cut out and merged with the main body.  I now have raised ribs on a hollow gondola.


Time for some windows.  The rear, open section is cut out.


Front windows are recessed.


Front windows are then cut out.  I've left a .25mm lip around each pane to fit a piece of acetate, once printed.


The left side's windows then get mirrored onto the right, and the front window is cut out.


And the side windows are done in the same manner.


The access hatch is cut in the roof.  Incidentally, most Zeppelin kits seem to include this as a 'tube' between the gondola and envelope; this doesn't seem to be correct, from my readings.  As far as I can tell, it was open there, so you'd get a blast of icy air traversing the Zeppelin.


This solid bit is added.  Not quite sure what to call it - it covers the connections between the gondola and the airship.


Finally, the rear bumper is added and the gondola is complete.  I'm probably not going to detail the interior of this one; you really can't see it on the finished Q class, so there isn't much point.

[MoFo]

Phew. 

And THEN, I did all that all over again, for the rear gondola!



And with THAT done, I could start buttoning up the envelope model.

A new assembly was created and the scale drawings were turned back on, to help with locating everything.  Note that, after correcting the section spacing, the model no longer lines up with the scale drawings - they're wrong, mine is (more) right.  Hence the slight discrepancy.


The gondolas are imported and lined up.  I can now make location holes for the struts, rigging, access hatches and such.


Like this.  They may not fully print, but the holes should at least give me a slight recess as a location point for drilling.

Next up: completing the gun platform, then prepping all the individual parts for print.  This is about where my enthusiasm wanes, as I'm still waiting for my large-format printer; the itch to wrap my head around the shapes is mostly scratched, and I'm stuck twiddling my thumbs.

Oh, and as a particularly annoying kick in the balls...  a different company has announced ANOTHER large-format printer, which is a whopping 1cm bigger, should be available sooner, and only slightly more expensive.  That 1cm may not sound like much, but it's JUUUUST enough to print all of the height climbers.

[Alexis]

Don't understand a lot of this printing stuff , but it is impressive !


Alexis

[RAGIII]

Don't understand a lot of this printing stuff , but it is impressive !


Alexis

Same Here!
RAGIII

[Beto]

Very well done!!! - BTW, what printer do you recommend? I have an Elegoo Mars, but the printing surface is only 120x68mm

[KiwiZac]

Seeing the CAD step by step makes the process seem so simple - I think the thing stopping me from attempting it is my mind telling me "this is too complicated, you can't do it" but this makes me think again! Beautiful work!

[MoFo]

Very well done!!! - BTW, what printer do you recommend? I have an Elegoo Mars, but the printing surface is only 120x68mm

For printing this?  There aren't a lot of options.  I'm awaiting delivery of an Elegoo Jupiter, which seems well reviewed.  Anycubic has just released the Photon M3 Max, which is slightly bigger and slightly less expensive, IIRC, but Anycubic are a bit more 'walled garden' which can limit some features.  Phrozen's Mega 8K is bigger still, but they're Taiwanese, so have expensive, un-subsidized shipping which really raises costs. 

In general?  That's kind of a big question.  Anything from Anycubic, Elegoo, Epax or Phrozen will be solid, so it's mostly a question of matching size and features to your budget.  As I said, Anycubic is a little more 'walled garden' and seem to lack some features (like anti-aliasing) in some printers.  Elegoo's levelling method is weaker than the competition, so it's more prone to shifting (IMO).  Epax and Phrozen are based in the US and Taiwan, respectively, so tend to be more expensive, though IMO they're also a bit better built and a little more leading edge.

If I were buying today, I'd probably go with either the Phrozen Mini 8K or Elegoo Mars 3 for a small printer; The Saturn S or Mighty 4K for a medium size printer; and probably the M3 Max or Mega 8K for a large format printer.

Don't understand a lot of this printing stuff , but it is impressive !


Alexis

Same Here!
RAGIII

It's not too hard.  Fundamentally, a machine makes thin, 2D slices of an object, each on top of the last, slowly building up the completed 3D shape.  Think of it like a loaf of bread - each slice is kind of 2D, but when you stack them all together, you get the 3 dimensional loaf. 

Seeing the CAD step by step makes the process seem so simple - I think the thing stopping me from attempting it is my mind telling me "this is too complicated, you can't do it" but this makes me think again! Beautiful work!

I'm a little torn replying to comments like this, because on the one hand, I don't want to be a gatekeeper or scare people away, but on the other hand, it drives me nuts when I see people dismiss 3D modelling as "oh, you can just do that in CAD, then print it out!" 

CAD modelling is like plastic modelling: theoretically it's not hard, but it does take skill to do it well.  Like, plastic modelling is just "glue the parts together, then paint", but we all know it's a lot(!) more nuanced than that.  Similarly, CAD modelling is just 'draw sketches then print them', but the reality is a lot more complicated.  It's a skill.  It's a skill that can be learned, but like any skill, it takes time, patience, and practice to master.  But it comes with the upside that anything you screw up, you can just hit the delete key and start over.  It's not exactly hard, but it can be incredibly frustrating at times - particularly when you KNOW there must be a way to do what you want to do, you just don't know how to do it.

I will say, it really, really helps if you've got experience scratchbuilding, because probably the single hardest part, IMO, is knowing how to break complex shapes down into constituent parts.  Doing the CAD is almost the easy part; thinking about HOW to do the CAD is harder.  And that's partly what I'm trying to show with this thread - it's partly the step-by-step process of designing something but behind that is the thought process of how to break it down into something that can be done step-by-step.

[Dirigible-Al]

RE, that comment you made about people thinking "Oh you can just do that in CAD then print it out"
Believe me I myself am under no illusion this is easy and like many skills it would need to be mastered at the expense of many mistakes. At some stage in the future I probably will try this but I certainly don't expect to just print out engines and fuselages hours after setting it up.
Alan.

[KiwiZac]

I will say, it really, really helps if you've got experience scratchbuilding, because probably the single hardest part, IMO, is knowing how to break complex shapes down into constituent parts.  Doing the CAD is almost the easy part; thinking about HOW to do the CAD is harder.  And that's partly what I'm trying to show with this thread - it's partly the step-by-step process of designing something but behind that is the thought process of how to break it down into something that can be done step-by-step.

Now I understand better - having played around with CAD a little I'm under no impressions about what it takes, and that is a very good explanation of how to approach it.

[MoFo]

Glad someone gets it. 

So, another update.  I figure, whilst waiting for my Elegoo Jupiter (hopefully arriving in May?), I might as well scale things down and print it in 1/350.  It's pretty much just a direct scale-down - I made the envelope itself thicker so it would be rigid, but I haven't played with the 'rib tape' dimensions or anything - so it'll be interesting to see what prints and what doesn't, but it *should* be okay.


Step 1 in print prep: add vent holes to the envelope.  I'm using a resin printer, which uses a vat of liquid resin over top of an LCD screen (like a cell phone or tablet screen); a UV light shines from underneath, and the LCD screen masks off everything but the outline of each layer.  A metal build plate comes down from above, the first layer is exposed and sticks to this, then it lifts up to peel that layer of cured resin off the the vat, then lowers back down to expose the next layer, repeating this cure, lift, lower pattern.

This is important because, if you've got a hollow tube, it will create a strong suction force as the build plate raises and lowers.  Like lifting an upturned mug out of a sink full of water.  The way to solve this is to add an air hole at the top (or bottom, depending on your perspective - closest to the build plate) of the part, so that air and resin can freely flow in and out as it raises and lowers.  As an added benefit, these air holes serve as alignment points to help assemble the completed envelope.


Next the envelope is chopped into individual sections.  Again, you can see the vent hole I've cut in the part.


Smaller items like the tailplanes and gondolas are prepped for print, with pour stub-like supports.  I could add individual supports in the print software (you may have seen the forest of rod-like supports on other 3D printed parts), but felt this would produce better results for these parts.  Then the parts are all saved in a format the 3D print software can read.


And opened in said 3D print software.  This converts the various 3D models into individual layer slices.  In this case, it's basically a whole bunch of JPEG files stacked on top of each other, with a little bit of machine code to tell the printer how long to expose each layer, how fast to raise and lower, etc.  I've doubled up the gondolas and tailplanes because they don't take much resin, and being smaller, they're more prone to failure.  This way, I'm more likely to get a good print.  (now watch the biggest envelope part fail...)


And then the models are converted for printing.  The left side shows the printer's build plate at a particular layer; the right side shows what the LCD will expose for that layer - in this case, layer 145 of 3001 total layers, or some 12 hours total print time.

[MoFo]

Success! (mostly).



All the parts turned out well.  Had a bit of trouble with the first cm or so of the prints, so they're a little wobbly - not sure why, but it might have been due to mixing resins in the vat (had a bit of older, grey in there, topped it up with a bunch of clear).  Ah well, it's certainly fine for a test run, and bodes well for any future 1/350 prints of the model I might want to do.  (hint, hint )


Close up on the tailplanes, showing the nice, subtle ribbing.  It's a little more opaque than I'd like - I used a clear resin to play with the translucency if/when I get around to painting it.


Even the fine door framing rendered well.


Not as happy with the gondolas.  They're a bit meh, and I'd reprint them if I wanted the model in this scale, but still...  you can see the ribbing on the sides of the gondola, and the hollow windows/interior.  Bit of a step up from Takom's parts. 


Tailplanes rendered nicely.  Sharp, crisp detail.


And SUPER thin trailing edges.  Again, a nice detail improvement over Takom's parts.


Penultimately, a close-up of the envelope, showing the post-print surface.  I haven't done anything more than cure the print here.  Pretty much ready for a filler-primer, IMO.  Might need the slightest rub down with some 0000 steel wool, or similar.

The coolest thing about resin prints, though, is that you can use the same resin to join parts.  Just a tiny smear of liquid resin, hold the parts in position, then give them a slight blast of UV light and they're cured as solid as the rest of the print.  It's even more instant than CA.  So of course, I put this to use, and a couple of minutes later...

[RAGIII]

To Me this looks awesome! Congratulations on achieving your goals!
RAGIII

[Bughunter]

Impressive!
You seems to have the whole process under control, from CAD to setup of the printer ... great skills!

Cheers,
Frank

[KiwiZac]

Amazing, what a fascinating process - and the quality of the prints look superb!

[sobrien]

This is looking great. Can't wait to see the 144 scale model.

Did you ever finish your Q class ship?

Sean