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Nov 17, 2021, 01:07 PM
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Of course with 3d CAD and 3d printing you only need to design/"build" one part then can print as many as you want..

Still just printing quick medium resolution "honeycombed" PLA parts but looking good enough to test fit as soon as I make the mounting in the fiberglass fuse for the rear wheel struts. I had filled in the original with fiberglass. May not get to test fit until after the holidays tho. This Airwolf 250 doesn't have wheel retracts like the 450 does stock but you never know, I may try that eventually.

Its not tilted forward like I want but at least its close to level and not slouched back so much with the tail rotor dragging in the grass like it was stock. It raises the bottom of the tail fin 1-1/16" further off the ground which may be good enough that I don't have to keep my lawn mowed like a golf course. My micro/mini helis take off on a 24"x 24" car/suv floor mat but that's a smaller target that I like to land on- I don't like to mess around for several minutes landing.
Last edited by Mortimerex; Nov 17, 2021 at 08:22 PM.
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Nov 17, 2021, 09:37 PM
springer's Avatar
I use sketchup V7 (yes, ancient!) Because it has been the fastest, most stable of the free versions (before trimble bought SU from google and turned into bloatware). While it doesn't natively export .stl or .Dxf files, I found plugins to do both. However, SU v7 does export collada .dae files, and coincidently the version of Cura that shipped with my Anet A8 can read and slice .dae files, so I have a seamless process. Design part, export .dae, open .dae, print. I have used SU v8 and it is about the same as V7, but the version I have is buggy and crashes. Same with v13 . I downloaded v15 and v17, but they are awful - 3 minutes to select an item using the select tool! My computer is 2013 HP 2000, so I'm sure drivers and probably graphics card is too obsolete for Trimble versions. V7 will run on a couple gig flash drive and does all I want with plugins I've found. It is getting harder to find online, but I can email it, i think. PM me if you are interested.

Just for fun I searched, found this link:
I didn't try it, but it may work.

Also, there are two threads in the foamies-scratchbuilt forum about SU and plugins with a good number of them posted. We probably renamed them .text to allow posting, so just rename back to .rb if you download any.
Last edited by springer; Nov 18, 2021 at 07:57 AM.
Nov 17, 2021, 11:08 PM
Registered User
I plan to look more into sketchup type possibilities too as sketching is more natural for me and a program that has that as its main focus may be much easier for much more complicated parts. FreeCAD sketching is kindof ugly. I would prefer if I could see the dimensions better. Guess I shouldn't complain because its free, exports to .stl, and all that.. To me snapping to a grid isn't sketching, sketching for me is always freehand.

Maybe there's some other tricks for FreeCAD, but moving the sketch closer to the construction axis xyz center makes it easier to zoom in and see the dimensions better. Moving the sketch around also shows which constraints are undefined but I chose to leave the last two degrees of freedom "free".
Last edited by Mortimerex; Nov 18, 2021 at 03:32 AM.
Nov 18, 2021, 07:56 AM
springer's Avatar
The most important thing a user learns about sketchup and 3d printing is he must "close" the part. Since SU is only lines and surfaces, the "solids" created aren't true solids, but if there are no gaps between surfaces the slicers treat them as if they were solids. This is easy with simple shapes like the gear legs Mortimerex showed above. But when one gets into compound curves, I usually find myself making a lot of triangles to close surfaces.

Another must do is insure the faces are all "outside" i.e. the same color (white). A right click opens a menu, one entry is "reverse faces". Selecting all the "blue" faces and clicking reverse faces makes them white. This has tripped me up many times with through and partial holes. The hole surface will be blue, but with the shading relative to the "light" , sometimes isn't obvious. After I have made sure the complete exterior surface is "white", to test, I load the .dae into Cura and look at the layers. Reversed faces won't print and you can see that in the layers.

This all may sound complicated and tedious, but as I got more and more familiar with the SU to Cura process, i found myself automatically closing surfaces and reversing faces as i design so the parts printed the first time.
Nov 18, 2021, 12:14 PM
Registered User
Same thing for FreeCAD or any parametric CAD I think. Unlike some ancient parametric CAD programs, as long as the 2d sketch profile is "closed" it will generate a valid solid even with probably 30 or more "degrees of freedom". The ancient parametric CAD programs had to be fully constrained to generate a solid at all. FreeCAD does have options to reverse the face normals (flip them) or whatever but it generates valid solids by default so no messing around with reversed faces. At least for simple parts, for boolean cuts and stuff it may generate some "trash" -I don't know, most of the older CAD programs I used did to some extent. For real complex solids you may have to manually build individual faces to seal them. Or use a Nurbs surface design software like Rhino.

But I'm just talking about simple mechanical solid parts like most often used. If you're designing curvy thin wall solids like custom scale RC helicopter fuselages, etc you would want something more than a simple free CAD program or even an expensive CAD program costing thousands of dollars. That's beyond them. Or at least most of them without spending thousands more on special plug-ins, and upgrade packages. Something like Rhino maybe will do complex curved surfaces in the base package, I don't really know what they mostly use nowdays. Most design programs support some limited nurbs surface functionality but if that's what you're going to do you really want software that has a really complete suite of editing tools just for that.
Last edited by Mortimerex; Nov 18, 2021 at 01:22 PM.
Nov 18, 2021, 09:34 PM
springer's Avatar
For what it's worth here's a group of parts I've designed in SU and printed on my A8 using .dae files and Cura. None are curvy as a chopper fuse, but some compound curves and complex shapes. The back row from left is a couple of 3 blade prop spinners and a female F6 Hellcat cowl cavity i cast plaster in then shrunk the final PET cowl from a creamer bottle. Front row is a pair of exhaust stack sets, radial engine, wheel and a motor/cowl mount for my Beech 18, some covers and a group of strut mounts (I use 4mm CF tube for the struts. )

If you look close, you can see the segmented surfaces, but most of that gets lost in the print layers and general printed surface texture. For the Hellcat cowl, I used an automotive glazing compound to fill surface before casting, then sanded the plaster to get the final smooth surface. In other cases i increase the segments per arc from the default 24 to 48. That generally looks smooth as the print. I also should add that I initially printed a male plug, but found the heat to shrink the PET was higher than PLA melt temp. . . Glued them together.
Nov 19, 2021, 05:23 AM
Registered User
That does look pretty good and probably as much as most people would ever use for RC models -and might even be able to be used for some of the scale heli bodies although it might take a whole lot of work.

When I import the FreeCAD .stl objects into Blender it thinks they are mesh solids or at least displays them as such. I no longer use 3d Studio Max so don't know what it thinks. I don't understand why you said the FreeCAD stl files weren't "real" solids. They look like normal mesh solids to me.

Even the faces of the "hole" on a FreeCAD mesh look correct. Doesn't seem like any shortcuts to me in FreeCAD's method of building the meshes. There doesn't seem any way in FreeCAD to increase the poly count/detail level when you export the file but various mesh editing programs will provide some kind of "meshsmooth" command. Actually I think I did see something in FreeCAD about tesselation and stuff but don't remember where..The default level of mesh detail seems fine for small parts tho may look segmented on larger parts probably. The way the faces are arranged to build the mesh seems even more efficient than I remember from other programs. I'm actually kind of impressed for that kind of output from a free program. That's the way I would arrange the faces if I built (vertex by vertex) and "capped" the mesh by hand. When I removed the small hole from the current version of the part (I drill and tap it for m2 anyway) it dropped the STL file size from about 20kb to 12-14kb, lol. And that was only a single hole. More holes really increase the poly count. This is just a simple "flat" surface mesh, a curved surface on a mesh requires exponentially more vertexes and polygons and much higher precision in building and arranging it all. And if the wall is real thin the distance between the top and bottom surface is so small that the geometry needs even much more higher detail and precision to keep the top and bottom surfaces from intersecting each other and producing a "junk" mesh.

I'm not that familiar with Blender capabilities, I just use it as a glorified mesh viewer but here I used it to "edge-subdivide" the bottom radius of the part to increase its detail level. You would really only want to subdivide along the top and bottom to keep the file from getting too huge, but then again the file size is tiny and just hitting "edge-subdivide" multiple times does this (with only the radius edges selected-not all the edges in the mesh). As you can see it subdivide the edge in more than one dimension. I think there are some other subdivision/meshsmooth methods (in Blender) that do different things. To be sure you have a valid solid you would probably be safest just subdividing the entire mesh even tho that would exponentially increase the file size. Because as you can see the top and bottom faces weren't subdivided so there are now many tiny gaps in the mesh. Even that may require you to manually "cap"/"stitch up" the top and bottom surfaces, I may play more with that later in Blender. Actually that's not very useful for 3d printing as it subdivided but didn't smooth the mesh so the curvature of the radius is no smoother.
Last edited by Mortimerex; Nov 19, 2021 at 08:45 AM.
Nov 19, 2021, 09:46 AM
springer's Avatar
"I don't understand why you said the FreeCAD stl files weren't "real" solids. They look like normal mesh solids to me."
I wasn't referring to FreeCAD, haven't used it at all, only to Sketchup. Sketchup "solids " have no true solid characteristic, only the closed surfaces. From a quick look at FreeCAD website it appears to be more truly solid construction. The advantage for me using SU and Cura is I don't need to use any other programs (blender, etc) to achieve my goal of a finished part. 90% of the time I design, save, export .dae, open cura, load .dae, turn on A8 and hit print. And wait for print to finish, of course.
Nov 19, 2021, 01:56 PM
Registered User
Oh, sorry. I understand wanting to just use one program to do it all. Or just a very few. I do prefer 3d printer stand alone software instead of trying to use a CAD/CAM plug-in tho to generate G-code. I use Simplify3d for that. Its cheap and there are even free 3d print packages that do that too. But the one that came with my printer was too basic for my liking. And I prefer to do the design and conversion in the comfort of the house then take the microsd with gcode out to the printer in the garage to print stuff. Don't want to mess with plugging in a laptop pc or anything like that. STL/PLA 3d printers aren't very dirty nor is my garage but sometimes I get lazy and just sweep debris onto the floor. I sweep the floor eventually anyway. I can't get away with that in the house.
Last edited by Mortimerex; Nov 19, 2021 at 02:32 PM.
Nov 19, 2021, 03:15 PM
springer's Avatar
Ha! Different strokes for different folks!
My printer sits next to my laptop in my plane "hanger" (extra bedroom). So my process is optimum for my situation. Obviously your house to garage xfer provides opportunity for your process. Whatever works (and is fun!)
Nov 23, 2021, 06:01 PM
Registered User
it depends i use rhino and Simplify3D in the image below a STL model a rhino sloid and a surface model and Simplify3D slices them all differently with complicated shapes and curves surface moulding is all you can use as some times solid moulding can not give you what you need
Nov 25, 2021, 03:02 AM
Registered User
A software development team should be composed of people with good communication skills and respect. Soft skills are essential in a software development team. They should work well together. For example, a software developer should not be afraid to ask questions about the process. Similarly, a project manager should be able to ask questions of other team members. The project manager should be able to give them the best information. A business analyst should be able to answer all of the questions that arise in the development process.
Last edited by DavidSvim; Nov 26, 2021 at 05:18 AM.
Nov 27, 2021, 09:20 PM
Retired Electronics Specialist
vollrathd's Avatar

Another 3D program

Check out the free tinkercad. I've been using it for several years. It has worked quite well for basic 3D printing.
Nov 29, 2021, 07:31 AM
Registered User
software cad cam cad for 3D moulding model airplanes
as most model aeroplanes have rounded edges fileted corners and blended junctions that make it harder to model you will needs a very good understanding of the type software you have chosen to use.

i use rhino 5 because the license was given to me and i fined it easy to use as it is a Direct modelling tool it is a method that boasts flexibility and freedom. These characteristics stem from the fact that direct modelling is a history-free process, meaning that it does not keep any log of features or edits like parametric modelling does. No parameters are defined, so features are not tied to one another. Rather, the face of any given geometrical piece of the model can be pulled, pushed, or otherwise manipulated directly into the place the designer desires. This type of model may be compared to how a sculptor works with modelling clay.

parametric modelling i use Autodesk inventor for work in engineering design of mechanical machines and parts the modelling method is a structured engineering process that is often referred to as history-based modelling. This is because it keeps a log of the models features and is easy to up grade parts and improve the design as the concept of the design is proven in real terms.

for 3d printing you need a 3D model and they needs to be a watertight not so they can float but no holes split or problems wits joining triangles in model so when you look for a good cad software to slice your model you need to look for one that has a 3D printing software with a good repair feature

not just this the way you design or layout the model i went flying and there was a busy flying thing flipping all around the filed hitting the ground and bonusing of it and flying when it landed i had a look and it was in a ball of hexagonal shaped holes perfectly round as a foot ball yes D3 printed my first thought was that need a lot of support suture to print but no it was printed flat then heated and formed around a ball in sections so printing flat was made easy so when you have a part or design to print you need to back it down in to easy parts to print this can save you lots of time and heir puling out moments later
Last edited by dpot; Nov 29, 2021 at 07:51 AM.
Nov 29, 2021, 10:17 AM
Still the "Pro"-crastinator...
Steve85's Avatar

Thanks for that explanation of the difference between parametric and and direct modelling. I do all my modelling in 2D, and after trying to use "real" CAD programs like Draftsight, I've settled on a graphics program (Inkscape) because I find it easier to use. Reading your description of the different approaches to 3D modelling made me realize that Inkscape uses a much more direct modelling approach than traditional CAD.


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