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Massivly overweight prints


GAZZER

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Posted · Massivly overweight prints

I have been using Cura for a couple of years now on a CR10-S (sorry).

Currently printing thin wall stuff (3dlabprint). Everything has been fine but suddenly the prints are slicing and printing over 30% heavier.

No profile settings have changed, I have checked everything including all other normal settings.

Currently on 4.6.1 I thought I'd be clever and downloaded 4.8 but that made no difference whatsoever.

I just tested what should be a 19 gram print and it sliced and printed at 30 gm which is a massive difference.

Now at wits end, you are my last resort! 

What on earth could be causing this issue please?

Gary.

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    Posted (edited) · Massivly overweight prints

    If you load the model and go to "File | Save Project" you will get a 3mf file.  Post that here because without knowing your settings we'd be talking apples and oranges.

    That particular model is "not watertight" and "...and consists of 19 sub-meshes".

     

    Just playing with it, at .4 nozzle, .2 layer height, 1 bottom layer, Spiralize mode, I get 16grams in 4.8.0.

    Edited by GregValiant
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    Posted · Massivly overweight prints

    Greg, just a heads up all the files on this project come up with the watertight jobby, they are especially designed for thin wall lightweight printing, took me ages tweaking profile to get good prints actually weighing a little less than specified then all of a sudden sliced and printed at actually over 30% heavier.

    For example I'm on 105% flow, if I drop that to the normal 100 it makes hardly any difference to weight so the profile must be good. It's almost as though I have told Cura that the filament dia is different, a global issue if you like.

    Pics to show you the project.IMG_20210112_122542.thumb.jpg.56958d430ea215241ba16c3c7435a469.jpgIMG_20210112_122558.thumb.jpg.27eb09005a6b4e93ea0827d6224876a1.jpg

     

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    Posted · Massivly overweight prints

    Yep.  30 grams at 0% infill.  It is what it is.  I changed material to "generic" PLA.  The weight stayed at 30grams.

     

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    Posted · Massivly overweight prints

    It's really odd, all that wing stuff in the pic is the correct weight i.e. 20gm for this stl, just to prove I'm not going mad!

    IMG_20210112_123732.jpg

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    Posted · Massivly overweight prints

    It has it's own internal ribbing.  I'm guessing that's the "non-watertight" complaint from Cura.  The slicing looks good.  

    The density of the PLA is 1.24grams/cm3 in Cura.  Cura says the print will use 10meters of 1.75 filament.  I get 29.82 grams for the 10 meters.

    Assuming that Cura is correct at 10 meters of filament (I don't think it would miss that) that's how much it's going to weigh.  Throwing out the skirt isn't make much of a difference either.

     

    Since the plane would not fly well with a tip missing, I suggest you print the part and weigh it.

     

    There was a DC3 flying the hump during WWII that crashed on landing.  One wing was damaged.  The ground crew had a replacement wing for a DC2 so they stuck it on the DC3.  The older wing was 10 feet shorter.  They flew it the rest of the war like that.

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    Posted · Massivly overweight prints

    Changing it to spiralize gets rid of the internal structure.  That results in a 17gram print.

    I sent the STL up to NetFabb and the repaired model doesn't have the internal ribbing.  It comes out at 16grams in regular mode with your settings.  So it looks like that internal structure is adding the weight.

     

    Sliced in 4.6.1 I get the same 30 gram weight.

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    Posted · Massivly overweight prints

    Can't beat a Dakota Greg!

    In the pic I sent you can see that almost all the wing has been printed already and at the correct weights and the tips as per weight photo are 20g not 30g.

    Something has changed to make everything over 30% heavier.

    All I've changed is to add mesh tools to split parts but unfortunately it split every internal mesh as well so I removed it. Maybe that's got something to do with it. 

    All this lot came out as near as dammit correct but if I reslice the stl's again everything is mega heavy, it just doesn't make any sense.

    IMG_20210112_135016.jpg

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    Posted · Massivly overweight prints

    Weight 20g not 30! inc cobwebs.

    IMG_20210112_135710 (1).jpg

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    Posted · Massivly overweight prints

    Well then there is a calculation error somewhere.  I wonder about the 1.24gr/cm3 that is being used as the filament density.  If you were to weigh  416mm of filament it should weigh 1.24 grams.  That's Detroit school math though.  You'll want to check it.

    I don't know what to tell you.  I did the math on a hand calculator and came up with the same numbers.  An internet search comes up with the density of 1.24gr/cm3 the same as Cura uses.  Cura knows how far it's traveling and extruding.  It knows the layer height and line width.  Pretty simple math after that.

     

    I had about 6 U-control planes.  I'd fly them until they all fit in a 5 gallon bucket.  Then I'd spend a couple weeks rebuilding.  They all had "silhouette" fuselages and there was one that would always shear the wings perfectly at the fuselage on a nose plant (I was good at nose plants!).  I kept having to make the those wings shorter and shorter until finally it just wouldn't fly.  Later in life I got into RC but I didn't fly any better.  I was excellent at repairs.

     

     

     

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    Posted · Massivly overweight prints

    I actually even weighed a full roll to check it was 1 kilo, it was just a tad higher.

    I'll investigate the density thing. I'm on dead stop now lol.

    I've still got two Control line models with Oliver Tigers hanging in the garage from over 50 years ago.

    I'm heavily into jets nowadays, got into 3d printing to make some bits for a 1/4 scale F86 I'm building but with this Covid I thought I'd print a model just for the hell of it. 

    Pics of my L39.

    BIG L39 GROUND TESTS_3.JPG

    34447489_414465205694128_1707080428772392960_o.jpg

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    Posted · Massivly overweight prints

    I'm not seeing a hole for a ducted fan.

    45 years ago - the Gee Bee Model D Sportster.  I flew it once and got it back on the ground.  It was terribly nose heavy from the poor quality balsa in the kit.  It was way cheaper to crash a U-control.

     

    542383545_GeeBeemodelDsportster.jpg.9de7bfa403187b4890da29d4fcb45a23.jpg

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    Posted · Massivly overweight prints

    I admit to having had a few loose lines on 35 Stunters.

    Problem with jets it's a few grand if it goes in.

    My Sabre.

    20190622_113544.jpg

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    Posted · Massivly overweight prints

    I always wanted to build an F-16.  A beautiful plane.  I never got around to it though.  It would have had to be a ducted fan back then since the real jets hadn't come out yet.

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    Posted · Massivly overweight prints

    We're showing our age now lol. Here's mine.

    20090517_9_9.JPG

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    Posted · Massivly overweight prints

    It's good to talk to someone who knows about flying, at least you understand why the weights are so important to me on a 3d flying model. 

    With this weight increase problem it would never get off the deck.

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    Posted · Massivly overweight prints

    Just a question: this "increased weight", is that: (1) Calculated and indicated weight in Cura, prior to printing? Or (2) is it a measured increase on a scale, after printing? If (1), then could it be that Cura also calculates the weight of printing supports? Just a thought that crossed my mind, I don't know how realistic it is...

     

    About RC-planes: has anyone of you ever built one with a live camera, and a VR-headset, so you can fly it from a real pilot's viewpoint? Should be much easier to fly, I think? I never understood how some great pilots can accurately control an RC-plane from a kilometer distance, when I can't even see its orientation anymore? They must have some sort of sixth sense or telepathy with their plane. Some time ago there was a video of an RC-jet that reached almost 700km/h, and that went off to a little dot in the sky on each turn...

     

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    Posted · Massivly overweight prints

    It's both, calculated and printed is identical within a gram anyway. In my case a third heavier than it was two days ago. There are no supports on these stl's. Thanks for trying though.

     

    You are talking about FPV flying. Usually used on drones but becoming more common on foamy models.

     

    The rules are strict, an extra person has to be with the pilot and the model always has to be within the line of site and less than 400 feet altitude otherwise it's illegal. The exception is for Police and some commercial activities.

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    Posted · Massivly overweight prints

    You've both gone way beyond me now.  The best I did was to be able to look over my shoulder for landing so the controls wouldn't act reversed.  I'd still stick it in the occasional tree though.  The first day at the flight field for sefety inspection of my Sig Kadet, the inspector looking at it said "Some of us are builders and some of us are flyers.  I can see you're a builder.".  Time proved him right.

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    Posted · Massivly overweight prints

    Lol, flying fast jets it has to be automatic, I always tell newbies that when it'scoming towards you whichever side drops move the aileron stick the same direction to keep level.

    Tbh I still keep saying to myself push, push when I'm inverted!

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    Posted · Massivly overweight prints
    3 minutes ago, GregValiant said:

    You've both gone way beyond me now.  The best I did was to be able to look over my shoulder for landing so the controls wouldn't act reversed.  I'd still stick it in the occasional tree though.  The first day at the flight field for sefety inspection of my Sig Kadet, the inspector looking at it said "Some of us are builders and some of us are flyers.  I can see you're a builder.".  Time proved him right.

     

    I wanted to fly RC-planes, but I can't even drive and park an RC-car: I keep getting left and right mixed-up. So I dare not try a plane where fast reactions are required, and in a roll even up and down get inverted. Maybe a huge RC-containership would go, because it is so slow I would have enough time to think the inversions through. But I am not into ships...

     

    Concerning the weight, if you visually compare old lightweight and new heavier prints, isn't there any visible difference? Are there added structures, or is just everything thicker? A 30% increase should be visible somewhere, I think?

     

    PS: if you print it in PLA, never let it sit in your car in the sun. Because it *will* warp, even in a very mild spring or autumn sun (="waterzonnetje" in Dutch, a dim sun shining through the haze or clouds). A had several PLA-parts warp in my car: clamps, hooks, and demo-models I forgot.

     

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    Posted (edited) · Massivly overweight prints

    Hi Folks,

     

    Very interesting this..  🙂

    In order to go light weight, just go to "special mode" and select "surface" mode.

    With this you'll have the "wall" (so the original spares come to view), select one line wall and the model go into diet mode..

    I've got it down to just above 10g, but assume it's to skinny..

     

    I do deal a little with this, but mostly electrical super light, easy to fly with high fun factor. 😁

     

    Edit. RC is not that difficult, -with a proper RC trainer for PC you practice this yourself. The real test is when you try the real thing..  Have A look at PhoenixRC for PC, one of the best there is IMHO..

     

    Safe flying.

    Thanks

    Torgeir

     

     

    Edited by Torgeir
    More info.
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    Posted · Massivly overweight prints

    I fooled around and got it to 19grams with the internal ribbing intact.  However, that was with my Ender 3Pro as the active machine.  As soon as I switched it to the CR-10 the weight jumped up.  Here is the 3mf with my machine active.

    19gr_wing6.3mf

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