Printing self starting siphon

[pineirod 2]

Hi

I printed this:

https://www.thingiverse.com/thing:2249711

 

I put too much support (PVA) and it is impossible to remove.

 

The idea now would be putting very little so water can flow and clean the PVA easily.

 

I think the best scenario would be two vertical walls following the axis to help to close the pipe.

 

How can I build the support like this?

 

I created a 10% infill with line pattern, with the result of the attached pictures, but:

 

 - the walls on the right side are cutting the flow of water

 - it creates a base (like a brim) PVA, why so big?

 - it creates support on the inner bottom and top walls, why? the bottom one doesn't help; the top will be not be supported to help with the upper PLA wall

 - the crossing walls on the right side go out of the pipe, why?

 

thanks

regards,

 

 

[Smithy 1,141]

Have you tried to print the pipe without support? I think it can work without any support and you don't have to wait to dissolve the PVA which will take hours to days in your case.

[pineirod 2]

In the description of Thingiverse they suggest not using support, but I was worried about the very top of the tube.

 

I also took this as an exercise to understand supports better

 

thanks

 

[ultiarjan 1,222]

the model seems indeed perfectly ok without support, but if you ever need "custom" support you can model it in in CAD, and safe the object and the support structure as 2 separate STL's, then just print like a nomal dual extrusion print (without support) and  select the 2th nozzle for the custom support structure.

[pineirod 2]

Good idea

 

How can I set both origins to the same place?

[ultiarjan 1,222]

if you 'merge' the 2 models in Cura after importing them, they will be placed correctly in cura automatically, just like with any other dual extrusion model.

[pineirod 2]

Great

thanks

 

[geert_2 556]

Does the inside of the tube have to be round? If you would give it a sort of teardrop shape, overhangs on top would be less steep. Then it could be printed in one material without supports. Or maybe you could even try a square tube, with pointed roof, similar to the "home" icon 🏠 in your browser? The tube would look weird, for sure, but it might work? Try this on a very small part first.

 

[pineirod 2]

Or triangular; as long as it has a closed cross section would work.

 

I asked partly to learn more about supports.

 

I'll try the round shape (for demonstration purposes it looks nicer, we have students from schools visiting some times) with a small layer height

 

cheers,

 

[pineirod 2]

So,

 

I tried to print the siphon again.

 

I wanted to try the finest layer height, 0.06mm; it turned out to be a failure, not because of the supports but because of the attachment to the bed. 

 

Attached some pictures.

 

There was no brim, was that the problem?

 

I didn't follow the print out, and at the end I saw the failure: I guess the nozzles were going over the lifted (not attached to the bed) parts; could they get damaged?

 

thanks

 

[peggyb 169]

no, the nozzle doesn't get damaged. Just clean it if there is crap on it.

Brim is a good idea, the model itself has very little to stick to the glass.

Is the inside of the good end what you want?

[geert_2 556]

On my printers overhangs work better with thick layer heights: 0.3mm and 0.2mm are more beautiful than 0.1mm (haven't tried 0.06mm with huge overhangs). In 0.1mm layers, the edges of overhangs tend to curl up.

 

Try to optimise the settings and design on *small test pieces* first, so you don't waste too much time and material.

 

And indeed, a round underside might need a brim, or a custom flange designed in CAD, to make it stick.

 

If it has to be a demo-model, I do understand your concerns about elegance: square tubing doesn't look as nice as round tubing. And especially a house-shape (=square with roof) might look ugly due to the unsymmetry.

 

Maybe you could try a couple of small test pieces in different shapes next to each other? A round shape with brim, a house-shape (=square with roof), a true pentagon shape, triangular shape? Although personally I wouldn't use a triangular shape, due to the restricted volume and huge inner surface area, causing more friction to the flow.

 

Then the students can see all the alternatives, and the benefits and disadvantages of each.

 

[peggyb 169]

...and.... you can also make your own modified 'brim'. Place a normal cube or cylinder on the bed and adjust the size and height, make the height the same as the first layer and move them to the end of your tubing. They will act as 'Mickey Mouse ears' to hold your model to the glass, without the trouble of removing a complete brim, only remove the ears at the ends.

(in the preferences disable 'keep models apart')

Edited February 15, 2019 by peggyb

[aag 5]

Peggyb can you post a pic? I am interested in your technique but I do not understand what you mean. Thanks in advance.

[peggyb 169]

important is to scale the shape, whatever shape you want, to the same height as the initial layer. I have a folder with some basic shapes, cilinder, cube, and bring them in multiply and scale them to my liking. 

 

 

 

[aag 5]

ahh, very smart, thanks.

[pineirod 2]

Hi,

 

There was no good end (both failed, but one much more than the other), in any case the not failed sections look nice.

 

Thanks for the tips, very useful

 

I'm still puzzled with the support; it always builds around the walls, even if there is nothing on the top. Here attached some pictures of a glass, the PVA goes all the way up

 

cheers