1

Hello,

I would like to print a model (lets say a cube). When I upload a hollow model, the price goes down by a lot (less material). When uploading a non-hollow model, the price goes up, even that techniqly the printer will make a speacial filling and the print would be mostly hollow.

My questions: Is uploading a hollow part a valid way to get the price down? could a printer handel such a part?

Thank you for the answers

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It would most likely print terribly. Parts are typically printed with 20% infill. Infill is basically a grid pattern inside the model. Since the model doesnt need to be solid plastic this helps on cost of printing and time. If you printed a cube with 0% infill or hollow, the bottom and sides would look good, but when you got to the top it would fail since theres nothing under it supporting the top layers.

If cost is an issue, you can ask the hub if they would print at a lower infill than the quoted 20%. Lower infill may cause print quality issues also depending on the model. But the hub you interact with should be able to help you find a good value.

Another thing dont hollow the model before sending it, that makes it harder to get a good print and could result in it getting declined.

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Thank you for the quick and full answer!

20% infill means that the infill takes 20% of the hollow space?

I was just wondering how 3dhubs calculates the final price? as a non hollow cube would be about ~60-70% more material as a infilled one.

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Hey @Lior_1,

Standardly, choosing 20% infill means that all the solid structures of the print will be printed with 20% of the internal space filled. If you have a hollow cube, the infill will do nothing because you defined that space as hollow and the printer software won’t recognize it as something it needs to fill at all. The software will only identify the walls of the cube as needing to be printed, and doing this will result in a very poor print. In general, only prints for SLA machines are hollowed to save resin, and I would decline an order if I was sent a hollow shape to print on any of my FDM machines.

A non-hollow cube will not be that much more material, if the infill is kept at 20%-30%. When printing you have 3 main components - infill, perimeter shells and top/bottom layers. The shells make the “walls” of the print and are what you see when you look at the final print. The infill is what is used to fill the space between the shells, so if you print with 0% infill, you would essentially have a hollow shape, made of only the walls. If you print with 20% infill, you are telling the software you want the space between the walls/shells to be 20% full; i.e. if the volume of the print (not including the shells and top/bottom layers) is 100cm3 and you specify 20% infill, then you “fill” the internal space of the print with 20cm3 of material.

By default, I believe the Hub calculation is for 20% infill with 1 perimeter shell.

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Thank you for the information.

So is there a way for me to define the infill parameters using the website? or the parameters are chosen by the guy that prints it for me?

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Once you choose a Hub, you can tell them you want it printed at a certain infill; 3D Hubs does not allow for the customer to specify the infill.

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So a hollowed out cube would appear cheaper on a hub.

I have had many a customer send me hollowed items.

I then have to explain how supports work, so the the print would be printable.

I then add the cost of the supports, and the removal of the supports, and the savings are not much, and the print will not be as nice.

So lets say you take a cube, and hallow it out.

It is possible my slicer will not see it as hollow, because there is not outside area that matches the inside area. In this case, it gets infilled.

Or-When I load it into my slicer, if it is not open, I will have to print supports inside it, which I cannot remove. The supports become, in effect, infill,- requiring additional time and materials for printing. SO I increase the cost.

Sometimes I get models that have been hallowed, and have a hole in them, or have otherwise been hallowed out in parts. In some of those cases, I can print the supports, but can’t get in there to remove them, so the supports are just up in there, and the print is weak, and the customer has created a situation where the print will not be so good, and will be weak.

So you are much better off not hollowing it out. You will likely not save much, and the print will be much better.