Strengthening 3D printed parts… with Holes?..

Hello, Sunday!

 

Silence reigns as it rains down on this blog, but bear with me, for I yet persevere through my final year.

I’ve been doing a lot of 3D printing recently on my self built CoreXY “ETA”, and I had to make a case for a portable speaker I have. The speaker in question had rudimentary loops for tying it to something, but was rather insufficient for actually wearing on a belt. Having a 3D printer, I decided to print a case for it.

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The blue object is the case, and the black body is a mock-up of the speaker

I quickly modeled a case for the speaker on Fusion 360, it’s a simple design where you slide the speaker into the case from the top, and a pair of clips snap onto indents on the speaker. Pretty straightforward, but during self review, I ran into a little problem. The case was 3mm thick on most sides, and as FDM/FFF 3D prints by nature are weak along the vertical Z axis, the clips looked like they would wear and break fairly quickly.

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This is the orientation at which the print would be on the bed. The thin section just below the clasp is the weakest section, as repeated bending would result in it snapping off eventually.

Traditional knowledge would lead one to assume the simplest solution would be to increase the thickness of the section, or add structural elements like ribs to strengthen it.

Practical knowledge would assume that it would be unlikely that I would want to repeatedly remove the speaker from it’s case. Perhaps there could be better designs that would have eliminated the flaw entirely. However, I came up with a little trick to take full advantage of my medium, Fused Filament Fabrication, and exploit the way slicers work.

I started with making a void in my part. Yes, I plan on making it stronger by removing material. Removing material is typically used to maintain strength while keeping the weight down like with I-beams or fullers. However I use it here to induce a certain feature in the slicer. I created a side profile of the weak point in question, and hollowed out a tiny sliver, 0.1mm thick.

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A sectional analysis of the case reveals the paper thin void modeled into the case

“What’s that going to change?”, you may be asking your screen, but rhetoric questions to a monitor aren’t going to get you answers, scrolling down will. This is the result when the model is sliced in Cura.

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The original shell thickness would have been 4 shell lines + the infill, but here it’s 8 shells, which should result in greater strength and bonding.

In my experience, infill has a marginal influence on strength. Around 15% is good for structural integrity, 30% for decent rigidity, and about 50-70% if you really want it as strong as possible. However, increasing shells is also an effective way to boost strength. By creating a hollow inside the weak section, the slicer prints additional shell lines in the area, and the shells fuse together to make it stronger.

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Here you can see just 4 lines, infill, and 4 lines again in Cura’s Layer mode

Here is a view of the same layer in another section of the part, which is not reinforced with a void. You can see that when compared to the previous image, the number of perimeter loops is nearly doubled, effectively making the weak areas a nearly solid part.

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Here you can see a close-up of the part being printed. The clip on the left is nearly solid, whereas the wall on the right is hollow but for the infill.

If this case was to be injection molded, it’s strength would be vastly superior to a 3D print of the same. However, by exploiting the nature of 3D printer slicers, we are able to selectively increase the strength of our prints in areas where it is required without increasing the entire part’s material and time cost.

 

I hope this little tip aids you in your designs, please let me know your thoughts via the comments below, and if you would like more tips and tricks in 3D printing.

Thank you, and have a great week.

~Adithyaa

Maker: Venus de Venus

My printer ETA just finished a sculpture I designed a while back, which I called “Venus de Venus”. It stands 27cm tall, and took 11 1/2 hours to print, the largest object I’ve printed on ETA thus far.

A little back story on this piece. I had a class on wood and metal working a while back, and for that class I carved a statue of Venus de Milo, an ancient greek sculpture, with a little difference.
The head is an oblate spheroid, to represent the planet Venus, from whence Women are said to have originated from, for there are two mysteries that have always, and presumably always will elude man, and that is the eternity of space, and Women in general.

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A close-up of my hand carved piece

TL:DR Classical Medium vs Contemporary Medium, the ongoing battle of mediums since classical times.

Until next time,

Adithyaa

Final Past Poem:

Hello, Monday!

It would have been splendid had I dug this particular poem up earlier, for it is one dedicated to mothers. Let’s get onto the reading,

 

Mother

The path has been long,

The journey makes me tired,

All the beauties of the world, passing unadmired,

I pull my self up, and gather my strength,

My brow weary, my back bent.

I look ahead, staring into space,

I find hope and peace, when I see your face,

The path is long And tis hard to stay true,

All that pulls me on, is my love for you,

For you guide me through the dark, like a beam o’ light,

You are the only thing that makes my life bright,

You guide me on, the voice of reason,

A faithful companion, in all seasons,

When I am lost, in the evil of night,

You are the thing that helps me stay right.

When I am lost in the deep with no other,

You will always be there for me, My Dearest Mother.

-Adithyaa.R

22-03-2012

Time certainly flies, doesn’t it? Mother’s are the first other being that the child recognizes, and play an irreplaceable role in our lives, from our births until our independence.

Until next time,

~Adithyaa

Poem: More past poetry

Hello, Friday!

Here the second poem I dug out of the archives, a poem that has about as much depth as a kiddie pool, but uses what used to be a oft spoken phrase of mine,

 

Me, Myself and I

 

Me, Myself and I

Three people yet the same

Me, Myself and I

Quite different but the name

Me, Myself and I

People times triplicate

Me, Myself and I

One and its duplicates

Me, Myself and I

Not but a phrase

Me, Myself and I

But one which would amaze

Me, Myself and I

Describes the same person

Me, Myself and I

And yet applies to daughter and son

Me, Myself and I

This hast cometh to end

Me, Myself and I

Such a delightful phrase to bend!

-Adithyaa.R

13/8/2011

I wrote this poem about 5 and a half years ago, using a rhyming scheme I rarely practice in, by repeating a particular phrase multiple times. An interesting aspect of this poem is that after one reads it several times, you unconsciously omit the repeating phrase while reading it in your head, and yet, it maintains a good poetic flow even without it.

I used to love throwing idioms and phrases around (As a kid I used to like reading through dictionaries to discover new words), and I used to use “Me, Myself and I” quite frequently when referring to myself. I suppose the phrase had just stuck to me, it has a rather pleasant ring to itself.

Onwards until next time,

Adithyaa~

 

Poetry: Reminiscing on past poetry

Hello, Sunday! Monday!

Today we’re in for a special post, I’ve managed to locate some old poetry of mine, and so for this and the next two posts I’ll be sharing my old poetry written some years ago. Let’s get started,

The Wonder of Nature

In the forest rose the pines,
Overlooking the golden mines.
There, swinging from tree to tree,
Was a great big grinning chimpanzee.

As it swung from here to there,
It had a spied a grizzly bear.
And it started up the call,
Which sounded like a bored drawl.

Others took up the cheer,
Warning all not to come near.
Then the chimp from tree to tree,
Jumped and hooted with sheer glee!!

-Adithyaa Raghavan
VIII

I have no idea how my 14 year old self managed to land a poor chimp in a coniferous forest. I recall I wrote this poem shortly after learning that many species of apes communicate using sounds to warn each other of danger. Either way, I hope you enjoyed this post, and stay tuned metaphorically for next week’s poem.

Signing out,

Adithyaa

Poem: Under Raucous Skies

Under Raucous Skies,
As the sun dies,
And the night city lights,
Spring to life,

And then with a crash,
And a lightning flash,
The bulbs turn dark,
And the city turns black.

The gods are neigh,
Heaven and earth torn asunder,
As the aether burns with fire and thunder!

Hear their cry, ye mortals,
Hide within thy stony abodes,
As night turns to day for a tick,
With the titter of rain on the roof.

Oh ye wise, watch out,
For the powers of yore are about,
Dancing and mocking the sun,
Bending nor kneeling to anyone,

Sway with the wind,
Light up my face,
And celebrate thunder,
As the sun slumbers.

~Adithyaa~

 

Hello, Sunday!

Last Monday evening was selfsame to most Mondays. I was getting ready for dinner, then the lights flicker and the power dies, a most familiar feeling in India during the monsoon season. About 10 seconds later, a huge wave of wind rushes around and through our house, as if it were succeeding the blackout, as lightning does to thunder. Mayhaps the wind laid a branch upon the local transformer on it’s way here. Rain and lightning soon followed suit, and the city was drenched once more.

There I found myself, at near midnight, with nothing but lightning to illuminate my page as I inscribed this poem with the black ink of the night while in an inspired fervor. Rain gently tinkling around, while lightning tore up the sky in a most mesmerizing fashion. To steep in such moments  is all the artist lives for.

Signing off, and until next time,

Adithyaa~

Projects, Plans and Procrastination

Heello, Sunday!

 

It’s good to see you again, I feel melancholic when I don’t update my blog or write poetry, and I haven’t done either in such a long time now. Since my last post, quite a lot of things have happened. I finished another year in college, started an internship, and organized my lab.

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Well, Organized for the most part…

I’ve earned the title of “Scrap Collector”, to all those who know me well, and it is a title well earned. I’ve accumulated a hoard of parts, gadgets, stationary, components, bric-a-brac, and scraps for over a decade, and it’s reached a point where I had to toss out all the things I perceived were not immediately useful to me. My remaining collection is still somewhat wasteful, albeit neatly organized now, and it includes but not limited to, a kilo of plastic strip files, 10kg of e-waste, miscellaneous toxic chemicals and mixing pots, fasteners and random tools, more piping and hose than a Shakespearean reproduction, enough plasticine clay to build a kindergarten, a hot pink toilet seat, and some of my lost marbles (only 3Kg of them).

Regardless of the phrase “One man’s trash is another man’s treasure”, I believe the 10-year’s worth of spring cleaning was slightly overdue.

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ETA, Chilling on the bay window

On the project front, I’ve begun Plan Wololo, a plan to convert Project ETA’s HBot kinematics to CoreXY, using non crossed belts. I’ve already done the CAD work, and I should receive all the parts in a few days. While designing ETA, I’d made sure to include the tolerances for when I transition to CoreXY kinematics in case HBOT’s accuracy was insufficient, so it should go somewhat smoothly.

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Various random concepts for the moon clock

I’ve also started Project Moon clock, a desk or wall mounted gadget which indicates the current phase of the moon, for those who don’t like stepping outside or have cloudy weather. It’ll have a little ball representing the moon, and will use a NodeMCU and a servo motor to rotate said mini-Moon, and indicate how lit it is. It’s a quick little project, as a present for someone.

That’s all for now, but I am going to restart weekly updates on this blog of mine, so please, stay tuned and let me know thy thoughts.

 

Signing off,

Adithyaa~