How-To Destructively Test?

I’m testing my 3d printed picatinny rail mount for mounting big things on boards. Well, bigger than a flash light anyway. Idk about batteries.

Here’s a thing I did.
Printables design

Here’s a polycarbonate print:

I printed two, George ate one and ruined the rail interface.

Mounting the mock-up esc enclosure on a very ‘special’ test sled. Bonus, I’ll test petg and abs printed hubs from @Tanuki. In reality, I’ve already skated nylon cf versions of these hubs and they are fine if printed well.

For ESC’s, I’ve installed a crescent wrench I found on the road and old pliers I permanently borrowed from someone. The point here is, the total ESC enclosure unit weighs in at a hair over 6 lbs, 2.75 kg.

@glyphiks besides throwing it off the roof at the end, I plan on putting a lead on it and dragging it all over the place. George is going to help. Got any suggestions? I might load the board with a 30lbs brake caliper.


Also, #boty :sunglasses:

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Haha excellent science.

I feel like whipping the board back and forth side to side would be ideal testing

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Testing was derailed by a lost husky that wandered up to the fence.

Ok, dog break over. His name was Otis. His owner walked by with a flash light and I flagged him down.

The test sled weighs close to a booster board. (25-30ish lbs).

I ran around in big circles letting the wheels catch in the sand. It flipped a few times.

I ran up and down small stairs. I pulled it over ledges.

After 20mins, I was winded and decided to move to the next phase of testing.

I threw it off the roof. I did expect this impact to break it. I didn’t mean for it to hit the brick wall.

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Close ups of failure pattern:





@glyphiks not layer line failure, that shattered. I should note the print settings. 0.6 nozzle, 6 walls, 3 base, 5 top, gyroid 30%.

Could be denser, but warping is a concern. This PC profile was manually tuned for Temp, extrusion multiplier, and pressure advance (earlier that night).

It was printed at half normal x1c PC speed. Filament was bone dry (hygrometer at 10% relative humidity sitting in sealed bin with 1kg alumina desiccant, not the silica dioxide stuff)

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The dumb front truck setup broke near the end of the donut laps. I cut that truck up awhile back. It was solid enough for me to stand on and kick push on before it broke during pulled laps.

Last bit of data, the cheap lcd hygrometers do not inspire confidence. I have a much better wireless humidity sensor I keep in the AMS of the X1C. My AMS sits on top of the printer.

The printer room has the windows screwed shut, the AC vent closed, and the door shut.

The sensor data from inside the AMS during printing. (I also use alumina desiccant in the AMS. It can absorb more moisture than the silica blue beads)

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And finally, my conclusion.

This ‘testing’ has plenty of holes. It was substantial really only to me. I felt how hard it hit ledges, and I’m not about to pull out the accelerometer and raspberry pi off my klippered cr10 (which I did finally get input shaping working) and put it on the test sled.

The enclosure weight was 6 lbs. if your ESC enclosure weighs that much, WTF are you putting in it?

I wouldn’t trust someone else’s 3d printed claims of durability unless I could touch and use the part myself.

I am reassured by the following:
-AT boards have inherent dampening which improves printed parts resistance to shear forces
-the part did not break on layer lines, it shattered. I bet a good nylon like taulman would do better.
-this was not a high infill part, it was a draft.
-it survived the donut laps and stairs which is how I might actually ride. The roof fall is not how I ride.

This experiment satisfied my expectations for printed feasibility.

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This is all awesome data! And that is definitely not how I expected it to fail!

One thing I recently read about to make prints stronger is to bump up the extrusion width. Bumping up the width can help for better layer adhesion and just stronger walls in general.

From memory, the strongest extrusion width is 130-140% of the nozzle width

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Yeah, a lot of extrusion pressure can fuck up corners. I do have a 0.8 nozzle I might try later.

I think eskate has room for parts that should or can be printed, and some parts that should be metal. I’m guilty of assuming and insisting that everything be metal.

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I love 3dp parts, but I’m very wary of their limitations.

Super keen on getting my hands on an x1c one day to expand my filament arsenal/printing capabilities.

The p1p is great, but i feel like i would make good use of the x1c as well. Maybe by the time I can afford, they’ll have a bigger one :grin:

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I spent more money on dumb Creality upgrades and printers than the X1C.

Not to mention time and cost of failed prints, tinkering, and so-so prints.

I learned volumes on the incremental struggle bus trip from stock Creality printer to klipperizing a semi custom frame.

But I’m not touching bed slingers again, nope. Maybe someday I’ll put an annex k2 together, but not anytime soon.

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You should look into some of the metal rails used for PLCs and see if those will fit what you want. The PLC I’ve used was kind of heavy and yet it stayed on the rail without issue in a lab environment and they’re designed for heavy vibration environments too.

At the very least you can steal some design ideas from those existing systems to improve what you’re making.

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Like DIN rails? That’s a pretty good idea.

TBH, half the motivation to follow through from idea to usable part was that could print it.

DIN rails are wider and cheaper than picatinny rail mounts. :+1:

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That looks like the name used for them, so yes. I had troubles getting some parts on the damn things but also I have trash hands so that might have made them seem like a stronger mount.?

Although some of the hardware used could still be slid around side to side depending on what mechanism they used to hold onto the rail. It was usually the smaller parts that were less than an inch wide that would let you slide them side to side if needed. The heavy parts didn’t budge at all once on the rail.

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I’ve only seen din rails in the context of wire management for Voron 3d printers. I’ve never touched one or know how they are set in a fixed position.

This one made me laugh harder than it should :joy::joy:

Love for George!!

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Ok if you’re looking to make duper super strong print.

PC is brittle above it’s characteristics so I’m not surprised it just broke like that.

For a rigid solid print, SUNLU PLA+ then you can add UV proof varnish or epoxy resin. With a small nozzle you will keep good size and all.

Based on the design it will retain some minimal flex, not enough for functional deformation but enough against impacts.

As reference I skated a dummy part only made of PLA+ with metal bolts and wheels with Zealous bearings and metal spacers. It didn’t break with human weight and leg strength. I didn’t trust it enough to jump on it tho because it was not meant for jumps.

Still, was convincing enough to proof design before going to aluminum machining!

Sooo I found it to be more resilient than printed PC but that was only my experience.

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Yeah that’s not been my experience at all. As soon as it gets above like 90 degrees PLA+ softens just enough and screws pull through. I have direct relevant experience with this and went through PLA+, PETG, and settled on PC after how garbage my roll of nylon was that I got.

As far as I know none of my testers have broken my PC part yet, but time will tell. I use PLA+ in other parts of the design, including the baseplate, and designed right, it’s an excellent material. It can deform in the summer though if spanning large horizontal spaces that are exposed to the sun.

Agreed PLA+ isn’t for high temps and prolonged sun exposure!

How did you test PC? I went with 7mm plates and could literally skate PLA+ but break the PC like glass shard.

It makes wonder when injection mold or similar but the printable material available isn’t that great IMHO.

For higher temp sustainability I’d go ASA with thickened parts.

It’s in a mechanism that I designed, not really public yet but it is about 10mm thick? It’s fastened with three M6 bolts and has axial forces transferred in the vertical direction