3D printing Widgets

The 'strong printing' explore continues...

After doing a pair of prints with 6% gyroid infil (so I have a base case to join together) of Simon's 'strong print 270mm leading wing section' I took the FreeCAD model and made a variant which uses the 'subtract thin slightly offset ribs'.It is now printing in pure vase mode 1 perimeter 42mm/s, 0.62 flow rate, 250C.  Would seem to take 30m less time and be ~7g lighter. 

 

Below is the start point - a 270mm section of wing with an outer flange added to one end and an inner flange added to the other. 

 

The workflow is, essentially the same as in the following YouTube video - which of course I watched before I attempted this variant.  And a good thing I did.
 

I made two 'simple copy' of the wing-with-flanges in FreeCAD (they tend to get hidden when combining them with other entities and working with a copy protects in case of a crash) and then added a cube which I sized to be slightly bigger than the wing. I then shifted it -1mm in the X Y Z

I highlighted one face of the cube and used the 'Curves' workbench to add a ISOgrid which was 1 grid by 15 grid and I then did some extrusions to get rectangular bodies which could do a 'slice-apart' with the wing and get a couple of dozen slices. The rib-shaped sliced I then extruded again by 0.2mm to form the thin 'ribs' to offset and then remove from the wing.

 

 

 

And now the magic.... I shifted the ribs 0.5mm in the Y axis so that they were slightly 'proud' at the top of the wing. 



I then did a boolean cut of the ribs from the wing and then exported the result as an STL.  It pulled up nicely in the Prusa Slicer.  I laid it flat and turned it so it could print on the diagonal.  I toggled on 'vase mode' and the preview showed that it would print that way.

 
 

jon
Thant certainly looks interesting.
Just a point but a true "D box" wing does not have a "spar" as such. The D box is deemed to be both strong and stiff enough with just the same skin thickness all round including the vertical back edge. To this end it is common for the D Box to go back past the point of maximum wing thickness where the spar would normally be placed.
My original concept was to use a stiff strong D box but glued to a super light weight rear part. 
 
I actually found printing the super light rear part more troublesome than the D box!. 
 

Ah, the thing about a pure vase print is that by definition it does not print the top.  So there is a wee gap.  In the lower part of the image is the strong print with gyro infil and above is the vase print version with those classic surface marking of where the internal ribs sit.  The vase print I certainly cleaner around the flanges.

Both feel about the same in terms of stiffness. The gyroid print is stiffer at the point of the leading edge.  So I will toggle off the vase mode and add 2-3 top layers and report back...

 

I didn't know that about a D box. I imagined that there would also be a spar to help transfer stresses between sections. I am going to do some reading about 'D box'.

jon
"D" box wing. 
It was discovered that to make a wing strong enough to handle both the bending and torsional loads in high g load maneuvers it was lighter to effectively use a box spar which has excellent torsion resistance. When using a stressed skin construction it was only a short step to simply make the box spar in the shape of the leading edge more or less back to where the spar would have been.
The exact design of the box depends on the degree of resistance between bending and torsion.
In most cases, particularly in models, a box spar is so rigid in torsion that a second rear spar is no longer required.

A bit of history. When Fokker wanted 3 smaller unbraced wings rather than a fully braced biplane his designer Reinhold Platz realised that torsion resistance would be an issue. As the chord of these small wings was small he chose to simply join the two spars with ply to create a box structure. It proved rigid enough to allow the rest of the wing to be simple built from it in fact the ribs were simple threaded over the spar and glued in place, simple and quick. Fokker although a brilliant pilot was at heart a business man.
This sketch of the Triplane wing was part of a detailed set covering the construction of the Triplane commissioned by the British Air Ministry just after WW1 as the Triplane was judged to be so advanced.
 
It is of note that despite this the UK aircraft manufacturers continued with their traditional braced biplane methods for at least a further ten years.   

The battery video was a good review! Thanks.

I decided to create some 'wall storage' for RC models / and / or parts.  A bit of sanded pallet board attached to the side wall near my bench.

I created a series of 100mm wide units:

the top two have Clarke Y angled cut-outs (slightly different sizes to take different chord depths,

next down are two supports that take the CF fuse for models with some larger cutouts for square / round stock

next down supports a number of slightly angled 6mm bamboo for planks

and at the bottom, an array of 6mm and 8mm holes to take CF and steel rods.

Happy to share the CAD and/or STL files for these.

 

 

Perhaps this is a 'widget' post and it might also fall under the "how can I make a printable copy of this RC part"

As part of my tweaking of the FX707S foamy I didn't really want to hack messily at the cockpit cover to hollow it out for the electrics.  I wanted to create a printed canopy. It took some exploring as to how best to replicate the shape of the canopy without going through a dozen iterations of 'does-not-quite-fit'.

 

 

Some time ago I posted about taking photos of a stone wall in order to design a printed support for a house number sign.  Well I looked over that post and decided I would try to photo the canopy of the foamy, take a few measurements and see if I could use that to design and tweak a replacement.  What you see below is the 2nd printed iteration (rather than the 6th or whatever failed attempt). Rather chuffed about that. 

     

   

In order not to forget how I did it and the assumptions I was making I created a 10 minute tutorial and uploaded it on YouTube.  If you are confronted by trying to replicate some RC part the workflow might be a good starting point for you.

I just checked on Youtube and that video about using photos in FreeCAD has over 290 views.  Chuffed about that.  Comment is that I do need to tune my 3D printer (it does have a rather high acelleration as Tony found)

I am at next stage of the printed canopy for the FX707S...  I revised it to take 6mm diam. magnets for holding it to the fuse.  Does anyone have opinions as to what kind of stuff to use to

a) fix magnets to LW-PLA
b) fix magnets into the EPO of the fuselage

 

A front peg and a rear magnet is exactly how the "hollowed out" canopy on my Albatross is secured. It also has side pegs to ensure the canopy can only be opened upwards directly against the pull of the magnets.
 
The pegs are simply bits of printer filament.As Eric suggest a pair of magnets are used but they are tiny 2.5mm to save weight.The canopy weighs just 2.7g.

And do you use CA or some other glue or epoxy for the magnet?

I like the idea of a big of filament....