3D Printing Please forgive me... But perhaps a little guidance?

[Blast it Tom!]

The request for forgiveness comes from the fact that there will probably be many "Let Me Google That For You" questions herein...

You see, over here I am detailing my build of the venerable ACME Spitfire. I'd like to do this in a "Calvin and Hobbes" theme, with the venerable "Spaceman Spiff" riding in the nose cone. This requires:

1. A 3D Print of Spaceman Spiff. Thingverse has a model labelled a "work in progress". It's old. I D/L'd and got a 59.1 MB file with the .OBJ suffix. My home computer (quite capable for a lot of tough things, flight simulation, Solidworks, Finite Element Analysis) blue-screened trying to load it with the default Microsoft 3d viewer, so I don't know if it's a bad file or...?

2. A 3D print of a nose cone, hopefully with a slight bubble canopy, but likely just windows flush with the original contour. Here I did my homework and modeled the actual Spitfire nose cone in Solidworks. Which was NOT easy! I never did work with surfaces and lofts much, and to loft a cone-shaped surface when in fact that cone is not a right circular cone required some picking around, but it's done. I knit the inner, outer and bottom surfaces and filled it solid. I used a .047" thickness but now the questions start...

Q1: Assuming I massage this model to include canopy windows... I'd assume these would be thin membranes in the 3D print, to be cut out and repalced with clear plastic. But you have to have the right plastic to glue to other plastics - and the paper "off-centering" ring. I have .005" clear polystyrene sheet which would easily flex for my purposes, but how does that adhere to the sort of plastics used most often for 3D printing? I've seen nylon used on Shapeways, I don't think that would work too well...

Q2: What are your thoughts on the .047" thickness? That would I imagine, hinge somewhat on material... The "stock" nose cone is cardstock, the rolling and gluing of which would make a master origami artist start cussing, stomping, and throwing furniture through windows...

Here's a screenshot:


It's roughly 4 in. high and 3" in diameter at the base. The lip around the inside is where the "off-centering"ring would sit. There are two alignment notches cut out of it. The base is obviously cut at an angle to that lip, and it occurred to me that it might be better for 3D printing purposes if I rolled the model back to before I made that cut and have the base parallel with the lip, and presumably the bed, amd then just saw it off; I could even leave a cutting line in the model. But would anyone suggest any other changes/preparations? I know just enough to be dangerous, i.e sometimes interior supports are needed, etc...

And then comes the output file. Solidworks offeres several, including .STL, but what do folks around here use? I assume each printer has it's own "slicer" software?

Finally, I don't have a printer (yet). That takes a LOT of research, very confusing, many factors. My son wants one too - he does a lot of stuff with architectural miniatures at 1:12 scale, and we thought if we were careful we could each get a printer that used different processes/size/detail capabilties so as to have a wider range of capability "in the family", as it were. But in the meanwhile I would need this printed. I am not a freeloader, so anyone here that volunteered would be compensated. Or, I suppose I could use an on-line service, but I still need help specifying everything - it's a long way from "art" to "part", I've always said, not the least of which is tolerance requirements, which is a sideways way for asking about accuracy!

Much thanks to all who help!

 

[Blast it Tom!]

Updated to add: I'm reading Xometry's guide to 3D printing now.

I learned that the OBJ file of Spaceman Spiff that I lined to above may not be scaleable as it is a mesh without units...

 

[Bravo52]

Here are a couple of thoughts.

Q1: Most printers will just leave any "windows" open. Unless you design in a super thin panel, you'll likely print it with the window cut out. That said, if you are going the "flush mount" style of window, I'd recommend you build in a small lip with enough thickness to flush mount the clear styrene. .005 might not be the best choice unless the windows are small. It will flex a lot under boost. .040 or even .060 would be good depending on the thickness of the part. CA works great gluing PLA. However, I've never tried gluing styrene to PLA. That's where the window channel will come into play to help reinforce the joint.

Q2: .047 is probably marginal for a NC that size. I'd go thicker because the weight is not really going to be a problem (unless you make it solid ). .125 (3mm) is probably too thick but would probably work fine. If you print with a .4mm nozzle, I always thing in multiples of that got get a rough thickness for starters so maybe .08 (1.2mm) might work. That'd be about twice as thick as you are thinking.

Q3: No need to print so to cut. The printer will print the NC at an angle just fine. I'd print it with the overhang lip flat on the print bed.

Q4: Most slicers will output a form of G-code that includes specific coding for the type of printer you are using. Most of the slicers will support different printers that are selected in setup. However, they don't all support all printers so it just depends. I use the Prusa Slicer and consider it the industry standard. There are other good slicers out there but Prusa Slicer works best for me. Simplify3D is another popular slicer that works with just about every printer...but you have to buy it.

Q5: Which printer.... There are a few good threads here to explore for the answer to that. Lots of opinions out there and they are all good... I like the Prusa but, they are spendy and there are others out there that are less expensive for various reasons.

 

[Rschub]

.stl is the output file format you want.

I found the file, I can try to open it in SW when I get home tonight.

Q1. Glue would be problematic, If the windscreen is a flat wrap you could consider attaching it with tiny screws, which might add to the "look".

 

[Rschub]

I learned that the OBJ file of Spaceman Spiff that I lined to above may not be scaleable as it is a mesh without units...

Once it is imported into a cad program and output in .stl, the slicer can scale it easily.

 

[Blast it Tom!]

.stl is the output file format you want.

I found the file, I can try to open it in SW when I get home tonight.

Q1. Glue would be problematic, If the windscreen is a flat wrap you could consider attaching it with tiny screws, which might add to the "look".

Huh! I could conceivably try that myself, but thanks!

Here are a couple of thoughts.

Q1: Most printers will just leave any "windows" open. Unless you design in a super thin panel, you'll likely print it with the window cut out. That said, if you are going the "flush mount" style of window, I'd recommend you build in a small lip with enough thickness to flush mount the clear styrene. .005 might not be the best choice unless the windows are small. It will flex a lot under boost. .040 or even .060 would be good depending on the thickness of the part. CA works great gluing PLA. However, I've never tried gluing styrene to PLA. That's where the window channel will come into play to help reinforce the joint.

Q2: .047 is probably marginal for a NC that size. I'd go thicker because the weight is not really going to be a problem (unless you make it solid ). .125 (3mm) is probably too thick but would probably work fine. If you print with a .4mm nozzle, I always thing in multiples of that got get a rough thickness for starters so maybe .08 (1.2mm) might work. That'd be about twice as thick as you are thinking.

Q3: No need to print so to cut. The printer will print the NC at an angle just fine. I'd print it with the overhang lip flat on the print bed.

Q4: Most slicers will output a form of G-code that includes specific coding for the type of printer you are using. Most of the slicers will support different printers that are selected in setup. However, they don't all support all printers so it just depends. I use the Prusa Slicer and consider it the industry standard. There are other good slicers out there but Prusa Slicer works best for me. Simplify3D is another popular slicer that works with just about every printer...but you have to buy it.

Q5: Which printer.... There are a few good threads here to explore for the answer to that. Lots of opinions out there and they are all good... I like the Prusa but, they are spendy and there are others out there that are less expensive for various reasons.

Wow, lots of good info, thanks! Gotta get outside, more later!

 

[Rschub]

Huh! I could conceivably try that myself, but thanks!

Well, now I want a spaceman spiff model...

 

[Bravo52]

Is this kind of what you are looking for...

 

[Blast it Tom!]

Is this kind of what you are looking for...

Dear glory! How in the world did you do that? I didn't even post my nose cone file!

 

[Bravo52]

Dear glory! How in the world did you do that? I didn't even post my nose cone file!

Just based on what you said in the op. I have no idea if it’s even close to the right size . But, the great thing about parametric design is that it is scalable.

 

[Blast it Tom!]

Just based on what you said in the op. I have no idea if it’s even close to the right size . But, the great thing about parametric design is that it is scalable.

Yes, indeed! I used AutoCAD for years, and as soon as I saw the way the dimensions drive the feature size in Solidworks, I was hooked! But you have a whole additions skill set as well!

See what you think of this, if I may trouble you further. I was told the STEP format preserves dimensions.

 

[Bravo52]

Yes, indeed! I used AutoCAD for years, and as soon as I saw the way the dimensions drive the feature size in Solidworks, I was hooked! But you have a whole additions skill set as well!

See what you think of this, if I may trouble you further. I was told the STEP format preserves dimensions.

Looks great. I like the way the bulkhead transitions smoothly into the cone. The one I did has a lip on the upper edge. Now I'm going to have to go back and change mine to be smooth! I checked the angle of the cut on the bottom and yours measures out to 12.9 deg and I guessed and came up with 12.0 deg so that was a lucky guess on my part!

I'm not sure how you approached the design, but I simply use a "section" type sketch then use the revolve command to get the cone shape. I think that gives you the best opportunity to make it "adjustable" without too much effort. It also allows you to have a hollow model. The only real "gotcha" in doing that is you have to think through the entire design so you can build the components in order. Meaning, if you want to change a base dimension, it doesn't mess up other features that come after in the design process. But that's my technique so it's not a "technedure".

 

[Blast it Tom!]

Looks great. I like the way the bulkhead transitions smoothly into the cone. The one I did has a lip on the upper edge. Now I'm going to have to go back and change mine to be smooth! I checked the angle of the cut on the bottom and yours measures out to 12.9 deg and I guessed and came up with 12.0 deg so that was a lucky guess on my part!

I'm not sure how you approached the design, but I simply use a "section" type sketch then use the revolve command to get the cone shape. I think that gives you the best opportunity to make it "adjustable" without too much effort. It also allows you to have a hollow model. The only real "gotcha" in doing that is you have to think through the entire design so you can build the components in order. Meaning, if you want to change a base dimension, it doesn't mess up other features that come after in the design process. But that's my technique so it's not a "technedure".

Thanks! I probably should have filleted the tip a bit. I had no end of grief "reverse engineering" this. I started with the pattern. The way it is built, you position the bottom face of the .050" thick centering ring 3/4" up the long side of the pattern, and flush with the short side. Measuring from those locations to the tip revealed an uncomfortable fact: it was not a right circular cone, it was inclined slightly. Thus, there is no axis about which you can revolve a cross section. If you saw the Solidworks tree you'd think, "What was this guy thinking?!" There is the 2D sketch of the section through the alignment marks, and then separate sketches for 3 different surfaces, extra planes and circles that I didn't need, and so on... There are two surface lofts - the inside cone surface, the outside cone surface, and a simple annular surface for the base circle (parallel to the plane of the shoulder). To make it solid, I had to "knit" the three surfaces with the "make solid" option checked. Then, SW had heartburn making a bi-directional "through all" cut for the slanted base, so I had to make two individual extruded cuts to get that done. I guess I could have been a little less anal and ignored the slant of the cone, but I was up for a challenge!

But it's still parametric in the thickness!

Sorry for the delay, it was trick or treat here and the grandkids were over!

 

[Bravo52]

Thus, there is no axis about which you can revolve a cross section.

But...I don't think that is how the original kit was designed. That may be a byproduct of the build. The original nose cone was a paper cut out, so likely based on a circle. Now it could have been "off axis" but not likely. I've never built one but found the easiest way to model it is to design a cone then chop the bottom off at an angle.

 

[Blast it Tom!]

But...I don't think that is how the original kit was designed. That may be a byproduct of the build. The original nose cone was a paper cut out, so likely based on a circle. Now it could have been "off axis" but not likely. I've never built one but found the easiest way to model it is to design a cone then chop the bottom off at an angle.

Well, I never rolled the nose cone. I just measured the paper pattern, and as I noted, the circular ring for the base hits the inside wall of the cone at 3/4" up from the long edge (along the glue line) and flush with the opposite alignment line. Now here is where I may be wrong, but my assumption was that the rolled pattern was circular there, so as to mate well with the circular ring.

On that basis, then, I measured to the apex along both lines, and the two were off by 1/8", indicating a slightly inclined cone. That's how I constructed my layout in Solidworks. My lovely Starret machinist's rule is graduated clear down to 64ths, and I double-checked it. So my assumption about the circularity of the cone at that point may be incorrect - he used circular rings in the elliptical openings made by the angle cuts of the body tube sections - but I didn't think he'd do it here due to the need to support the card stock fully and "tension" it evenly.

Anyway, that's my story and I'm sticking to it!

I sure appreciate all you've done. Do you use Solidworks? I could send you the file...

 

[Blast it Tom!]

Here's a shot of my pattern and my measurements.

 

[Bravo52]

Well, I never rolled the nose cone. I just measured the paper pattern, and as I noted, the circular ring for the base hits the inside wall of the cone at 3/4" up from the long edge (along the glue line) and flush with the opposite alignment line. Now here is where I may be wrong, but my assumption was that the rolled pattern was circular there, so as to mate well with the circular ring.

On that basis, then, I measured to the apex along both lines, and the two were off by 1/8", indicating a slightly inclined cone. That's how I constructed my layout in Solidworks. My lovely Starret machinist's rule is graduated clear down to 64ths, and I double-checked it. So my assumption about the circularity of the cone at that point may be incorrect - he used circular rings in the elliptical openings made by the angle cuts of the body tube sections - but I didn't think he'd do it here due to the need to support the card stock fully and "tension" it evenly.

Anyway, that's my story and I'm sticking to it!

I sure appreciate all you've done. Do you use Solidworks? I could send you the file...

Ahhh....I see what Jim did with the pattern. Started with a circle and moved the centerpoint out towards the circumference. There's probably a geometry term for that but I have no clue!

I work in Fusion 360. Most of the stuff I do is detail parts for scale models. Strickly on an amature basis . I get a lot of "hey, can you make a right side mirror for my model...the cat knocked it off and I can't find it now." That, or broken pieces to static models. The last thing I did was a rotor hub for S3 that goes on a desk model. It was pretty easy to print (in resin) so I did some blades as well. Other things like a 1/24 scale bomb rack for a Spitfire. Things you can't find for sale in the wild!

 

[Blast it Tom!]

Ahhh....I see what Jim did with the pattern. Started with a circle and moved the centerpoint out towards the circumference. There's probably a geometry term for that but I have no clue!

I work in Fusion 360. Most of the stuff I do is detail parts for scale models. Strickly on an amature basis . I get a lot of "hey, can you make a right side mirror for my model...the cat knocked it off and I can't find it now." That, or broken pieces to static models. The last thing I did was a rotor hub for S3 that goes on a desk model. It was pretty easy to print (in resin) so I did some blades as well. Other things like a 1/24 scale bomb rack for a Spitfire. Things you can't find for sale in the wild!
View attachment 613071

Wow, that's interesting! Over on another thread I was asking about resin printers, for pretty much the same reason - nicely, with a detailed parts. I was hooked after I got some 1/100 parts for my static Saturn V from a fellow named Michael Key on Shapeways- he's done a ton of that stuff. I wanted to check into their strength, though, as rocket parts must be strong first, pretty second. And they are expensive, with a smaller build space.

Solidworks is not that great for free-form stuff, like people's heads. How's Fusion 360 that way?

Yep, that's what Jim did. Made it tough for us reverse engineers! But I've captured the geometry, at least. Now I have to see about getting Spiff in there! I still can't get over how quickly you did Spiff, cockpit, nose cone and all!

 

[Bravo52]

I like my resin printer for detail. I have an Elegoo Saturn 2 and it does a great job printing the things I need it to print. It has a large build plate and great resolution. I don't even use it to it's max capabilities most of the time. I print and sell resin F1 engines for the Revell/Airfix 1/144th Saturn Vs and do a set of SSMEs for the 1/144th scale static kits.

I've printed some resin parts for flying model rockets and I've had no problem with the NCs or details (greeblies). I haven't tried any fins as the shear load on those could be high in a landing scenario! I started mixing flex resin and standard resin to get a pretty resilient mixture. It doesn't do the super detail well but it won't explode on impact.

I'm a huge fan of Fusion 360 and that's all I use. I've tried others but found Fusion more to my liking. I was gifted a full version for many years and got to love the interface and capabilities. Now I just use the "free" version and it does everything I need. The only downside is it limits the number of models you can host on the platform. Once I go over that number, I have to export the model onto my computer. Not a big deal at all.

I've been thinking about how to model the nose cone more in line with the way the original was designed. I've been able to do that pretty easily once you showed me how it was originally done. I just use a "loft command" to a point that is off-center and it works fine. Having said that, it's much easier to revolve a profile then cut the base at an angle. It looks close but as we now know, it's not exactly the same! Let's call that version a "tribute" clone cone!

 

[Blast it Tom!]

Very cool! I use Solidworks because I still have access through my former company, as long as a license is available.

It sounds like you had to take my path, though. Lofts FTW!

 

[Blast it Tom!]

If you want to hang on a bit, I can send you my base sketch this evening.

 

[Blast it Tom!]

Sooo.... Here is where I'm at...




This is without any ribs that we might use to strengthen the nose cone; but there is a little problem. I wanted a bigger Spiff, so I scaled him up 2.25:1 and I like what I got but the steering wheel is too long and the instrument panel protrudes. I figure he'll be separate from the nose cone so I could trim as needed, but I think I'll try to cut that steering wheel shaft down about half. Then I can get going on a canopy design... Unless you (@Bravo52 ) can do it very easily... I don't want to presume; just getting me ol' Spiff in his cockpit was a game changer!

 

[Bravo52]

Easy Peezy…but I’m away from my computer so it will be Tuesday before I can.

 

[Blast it Tom!]

That's fine, I know what you mean! If I have it by then I'll let you know.

 

[Blast it Tom!]

Easy Peezy…but I’m away from my computer so it will be Tuesday before I can.

Well, thanks to you I've got a Spiff that fits and a model that is... still in progress. I may have to revisit the canopy cutout; the idea being, just split it into separate bodies, not take it away, and then I'd have a model for the canopy sections. While as far as I know, you can't easily print clear stuff in 3D, at least I'd have a pattern. Have a look, and much thanks for the help!


I still feel like I'm not close enough to making the part from the art, yet. Spiff, of course, will be separate, as will the centering ring. And I don't like the sharp corners, but I'm out of time for tonight.

 

[NTP2]

you can't easily print clear stuff in 3D,

Maybe resin printing?

 

[Bravo52]

Maybe resin printing?

Even resin doesn't come out "clear" in most cases. There are some techniques used in resin to make it better but the best is always to sand and clear after printing. Even then, the thickness of the material will distort the opacity. That said, for hobbies, it is probably good enough.

 

[NTP2]

Even resin doesn't come out "clear" in most cases. There are some techniques used in resin to make it better but the best is always to sand and clear after printing. Even then, the thickness of the material will distort the opacity. That said, for hobbies, it is probably good enough.

That was what I was thinking it’s a small part that isn’t really all that important and can be a little distorted.

 

[OzHybrid]

And this thread is why I love you'ze all....

 

[Blast it Tom!]

Even resin doesn't come out "clear" in most cases. There are some techniques used in resin to make it better but the best is always to sand and clear after printing. Even then, the thickness of the material will distort the opacity. That said, for hobbies, it is probably good enough.

That was what I was thinking it’s a small part that isn’t really all that important and can be a little distorted.

Good enough?! GOOD ENOUGH?! Not important?!?! For Spaceman Spiff? I'd have Leica grind that beauty if I could! Polish it like the mirrors on James Webb! Spiff has to see where he's going!

Oh, gents, this build has languished with the onslaught of Christmas, and grandchildren with shepherd and sheep costumes and angels flittering about the plastic baby in the manger, and of course "A Charlie Brown Christmas" on the TV (58th year for me), and George C. Scott as Ebneezer Scrooge. And of course the impasse about how to get this nose cone design finished and printed. I have to get back into the model and make a canopy pattern, and I think I'll add a few ribs to the nose. If I play my cards right, I may be able to forego the clay nose weight!