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jweaver

Tall objects keep falling over.. Any tips?

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I generally don't have a problem with bed adhesion.. I am quiet happy with my setup.

But I am currently printing a number of narrow/tall objects (15mm wide, 100mm tall) and sometimes they fall over towards the top of the print.

So I started using "brim" and thought I had cracked it... But last night, I was watching the last few layers of the print and right at the end, the model just toppled over.. I managed to hold onto it and got the last few layers printed (which obviously arn't perfect), but alteast it wasn't a waste.

When I looked at the failure, it actually snapped off at the brim.. So the brim was still stuck to the bed.. But the model had fallen over. So even if I added more brim, the model would still have failed in the same way.

Does anyone have any tips on how I can make this more stable? What about using a 'raft'?

Jon

 

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Make sure the first layer is really pressed into the bed. Consider levelling the bed slightly closer than you really should.

Add a bit of glue if you haven't? Oh wait, just noticed you're using a Printrbot and I'm assuming no heated bed? Just tape? If tape make sure it's clean to promote adhesion. Wipe it down with some alcohol to get rid of any fingerprints and/or wax from the surface of the tape.

Try adding the brim in the actual model. This way the brim will be printed differently and possibly hold better. This way you can also make it slightly thicker and stronger.

 

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Another approach might be to eliminate the source of the toppling over. With small prints the origin is the curling of the edges when printing too hot. The raised edges do harden enough from layer to layer to represent a solid piece of resistance for the nozzle. Z hopping can also cause similar raised structures. In this case try lowering the temperature (and speed) for the last layers.

 

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Another approach might be to eliminate the source of the toppling over. With small prints the origin is the curling of the edges when printing too hot. The raised edges do harden enough from layer to layer to represent a solid piece of resistance for the nozzle. Z hopping can also cause similar raised structures. In this case try lowering the temperature (and speed) for the last layers.

 

Interesting.. I currently print the first layer at 205.. And the rest at 190.. Although I have been experimenting with 200/185

I was actually thinking of going a bit hotter for the top layers.. And I will explain why.

When the piece fell over, there were only 5 layer to go, so I grabed hold of it at the base and held it to the bed.. As it was printing, I could feel the head 'dragging' very slightly and it was no surprise that it fell over..

I figured that if the filament was hotter, it would be more liquid and this might stop the head from 'dragging'.. It was only an idea and I am not sure if it would have worked in practice.

As for lowering the head.. My head hight is currently Z-0.45.. It was Z-0.50 but I felt that -0.45 was slightly better.. -0.55 is certainly too low as the head touches the bed.. So my only option is somewhere between -0.45 and -0.5

Would a raft not help?

Jon

 

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Brim should prevent this, normally it should be attached to the print. If you use Cura you can also increase the first layer percentage to 110% to get a better adhesion between the lines. It's crucial to have a good first layer in this case

 

With the brim, its joined to the model with a kind of perforated edge, making it easy to snap off.. And it failed along this line.

Looking at the Expert Settings, there are very few brim options, other than to make it bigger (Which in this case wouldn't help).

Where do you set the first layer %? What does this do? Make the first layer bigger???

Jon

PS. I just remembered something.. My last print before this one was a Sim Adaptor.. And because its thin, I set the first layer to 0.1mm, where as I normally have it to 0.3mm.. I suspect CURA is still set to 0.1mm and I wonder if this is why its failed?

 

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Yes it's better to set the first layer to 0.3mm so that it can compensate for any small irregularity in the bed level. The Brim will also be stronger i think

 

I think that was a schoolboy error on my part! I had 2 models topple over last week, so enabled brim and it was all good.. That why I was surprised that one did this yesterday.. But it suddenly dawned on my that my first layer is probably to thin.. So let me check that first..

Cheers all..

 

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I usually model some kind of support for tall objects, even with a brim it's too easy to knock over when the head is traveling fast. Even if it doesn't get knocked off the plate completely, it gets knocked around enough for it not to be a cylinder anymore.

If you look at the blade sections, I have this tapered cylinder object thingie that keeps it in place. I find it works well for that kinda object.

https://www.youmagine.com/designs/star-wars-lightsaber-complex-version#!comments

The slight gap is enough for some oozing or strings to connect the pieces but easy enough to break off. It also makes the brim super big which is great.

 

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