Q re: 3d printing sketchup models

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Q re: 3d printing sketchup models

Postby Jim » Wed Dec 31, 2014 10:48 pm

I don't mean to interrupt the dukejazz show, but I had a question or two.

If you want to 3d print an object that you have modeled in SketchUp, how do you tell the printer that the object is hollow? I mean, a typical SketchUp solid does not have an "inner" shell, only an outer shell. Wouldn't it get rather costly to print a SketchUp solid? Does the slicing software automagically "shell" the shape?


A second question I had - does the "small geometry" issue in SketchUp really matter on a hobby-type extruder such as a makerbot? What is the typical diameter of the plastic as it exits the extruder head? If your SketchUp model dropped a few small faces, would the final print really suffer?
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Re: Q re: 3d printing sketchup models

Postby TIG » Wed Dec 31, 2014 10:56 pm

As I understand it...

By default the 3d-printing side will make it a solid 'lump', but many 3d-printing apps will have options to add an internal 'foam' or 'honeycomb' before processing...

So the user has a choice...

Use a tool like my 'Honeycomber' to add internal partitions [whilst keeping the object 'solid'], or manually make a 'shell' solid - perhaps with internal walls or posts...

OR post-process in the 3d-printing app itself to add an inner 'foam' ...
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Re: Q re: 3d printing sketchup models

Postby cotty » Wed Dec 31, 2014 10:58 pm

Jim wrote:A second question I had - does the "small geometry" issue in SketchUp really matter on a hobby-type extruder such as a makerbot? What is the typical diameter of the plastic as it exits the extruder head? If your SketchUp model dropped a few small faces, would the final print really suffer?

If there are faces missing in the model, it will not be solid and it cannot be printed...
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Re: Q re: 3d printing sketchup models

Postby Rich O Brien » Wed Dec 31, 2014 11:31 pm

If you are interested in testing without owning a printer you can try out Axon 3....

http://cubify.com/en/Products/LegacyDownloads

...It will accept .stl files and then put them through a g-code type process.

But for your query it also shows how you can control the internals and wall thickness to manage costs.
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There's a frontroom and a backroom....reverse faces
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Re: Q re: 3d printing sketchup models

Postby d12dozr » Thu Jan 01, 2015 12:59 pm

Jim,

Yes, some slicing programs allow you to set a % infill, and will automagically shell the shape. These generally only work on filament-type printers though, because on a commercial powder printer you still need a way to remove the support material(un-bonded powder). On filament printers, the plastic can 'bridge' a short distance and therefore trap air inside the model.

Here's a link to documentation for Slic3r (a common slicing engine) that will help you understand how the user can tweak the number of outer shell beads laid down by the printer, as well as the pattern and % infill for the center.

On these little desktop filament printers, it's easier to leave the Sketchup model a big solid and hollow the center using the slicing program, but for commercial printers like they use at Shapeways you actually need to model the wall thickness, making the model hollow and leaving them a hole to remove the support material with compressed air.

And yes, like Cotty says, if there are missing faces, no matter how small, the model will not print properly. Most printing nozzles range from .025mm - .05mm diameter. If there is a break in the layer loop, the printer doesn't know where to go, and will not print.

Think of one slice of the model as a polygon - it MUST be a closed loop of edges so the printer can go completely around the shape and fill it in. If there is even a tiny break in the loop, the slicing engine generates an error.
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Re: Q re: 3d printing sketchup models

Postby Jim436 » Thu Jan 01, 2015 3:58 pm

Well, our local library just got a Makerbot Replicator Fifth generation—. Free for all to use. It’s great fun.

So, another way to check your drawing without actually printing it is to download the Makerbot desktop printer application. It’s free and open source.
https://www.makerbot.com/desktop#download
This is the exact same application you would be using if you really did have a Makerbot printer.

Now it accepts only .stl files, so you will need the sketchup-stl file exporter from the extension warehouse.

This printer is like d12dozer mentioned in that it expects your drawing to be hollow, a manifold with no leaks. You then set your infill % (the range of 10 to 20% is common), and the slicer software then takes care of printing an outer solid shell plus then filling the internal void with a honeycomb hex pattern. You can actually see the honeycomb pattern building up as the printer runs.

But anyway, taking “add file”, and adjusting settings, you select “export print file”. This then sets up a long file of plain text motion control commands that you can save to a thumb drive, then later, plug it directly into a printer, no computer required. At any rate, if you get to this point, rest assured your drawing is good and that it is going to print.

I should mention too, while you are getting the sketchup-stl extension, you may as well get Tomtom’s Cleanup3 too. This way you can pull any stl drawing off of Thingiverse, import into sketchup, and easily clean up the coplanar edges. Then customize as you like, and export for printing.
Loads of fun.

Edit: regarding nozzle size, I should mention that makerbot suggests a ballpark minimum edge length in your drawings to be equal to the nozzle diameter. On this machine is .4mm . So, with this in mind, sketchup has always handled the faces. So far at least, I haven’t had to fuss with scaling up and down.
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Re: Q re: 3d printing sketchup models

Postby dukejazz » Sat Jan 03, 2015 2:09 am

Hey Jim

This is what I found on the web for your frist Question

"by Jim » December 31st, 2014, 2:48 pm "
"If you want to 3d print an object that you have modeled in SketchUp, how do you tell the printer that the object is hollow?"

SketchUp has info tool that tell you and this (Tutorial) may help you understand this better.

3D Printing from SketchUp | SketchUp Show #68 (Tutorial)
https://www.youtube.com/watch?v=RPQliNKJKto

"I mean, a typical SketchUp solid does not have an "inner" shell, only an outer shell.
Wouldn't it get rather costly to print a SketchUp solid?"

Yes,
the printer can adjust the fill density.

"Does the slicing software automagically "shell" the shape?"
I think so if you leave a open bottom and inform makerbot its a line drawing, but you can alway cut the inside yourself to make two surface, a inside and outside shell, which also will has to be a normal face facing away form each other and the width adjust for a thickness.
Here a basic insite what makerbox dose.


Making a 3D printed box and cup in Makerware (advanced settings 101)
https://www.youtube.com/watch?v=1iRlVtrrdow

you can advance adjust skin width and fill density in note pad of the card file you give to makerbot printer to print.
"A second question I had - does the "small geometry" issue in SketchUp really matter on a hobby-type extruder such as a makerbot? What is the typical diameter of the plastic as it exits the extruder head? If your SketchUp model dropped a few small faces, would the final print really suffer?"

makerbox has unit of inch an a nozzles range in the accurcy i think
Making a 3D printed box and cup in Makerware (advanced settings 101)
hint about this fact.
if you make deminsion in inch and make you veiw grid the nozzles range then what you see is what you get.
I dont think using sketchup will be a problem with "small geometry" hobby-type extruder machines



Now that I anwser your the question

I have a question on how do a hobbies like us make a ball on a extruder? with out the ball rolling away?

This is what i found so far

Hitting Golf Balls Printed on a 3D Printer
https://www.youtube.com/watch?v=YqTG36cSHd4

3D Printed Soccer Ball | Made with Living Hinges and Snap Features
https://www.youtube.com/watch?v=3jh3Ms0DPkg

Printing a ball bearing (http://www.PP3DP.com)
https://www.youtube.com/watch?v=GOEbZ98J1Ks

the old way is still a better part

How It's Made - Ball Bearings (NTN)|
https://www.youtube.com/watch?v=b6svVy1lYOA

Must be a pod issue?
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Re: Q re: 3d printing sketchup models

Postby Jim » Sat Jan 03, 2015 10:03 pm

Wow, thanks for the great answers, links and videos everyone! I understand the process better.

I installed several of the applications listed here. It looks like most do have a number options for selecting an infill pattern. This removes a huge burden from SketchUp users (and 3d file exporters) by not needing them to generate an inner shell.

It is because of how the exporters currently work that missing faces are a problem. An STL file a simple list of triangle vertices. Even if a face is missing in the SketchUp model, their vertices do still exist. So maybe an exporter could "make up" the missing faces just from the vertices.

@marcus: Thanks for the info. I bought a copy of your book; would recommend it to anyone interested in using SketchUp for 3d printing.

@jim: I do have the Stl plugin (since I wrote much of it,) and Cleanup, but would also recommend thom's Solid Tools 2. Making better exporters is the main reason I asked.
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Re: Q re: 3d printing sketchup models

Postby d12dozr » Sun Jan 04, 2015 11:58 am

Jim wrote:It is because of how the exporters currently work that missing faces are a problem. An STL file a simple list of triangle vertices. Even if a face is missing in the SketchUp model, their vertices do still exist. So maybe an exporter could "make up" the missing faces just from the vertices.

That would be awesome :thumb: Right now if there are missing faces, I run the model through Netfabb, which is a program that will fix minor problems like that really quickly.

Jim wrote:@marcus: Thanks for the info. I bought a copy of your book; would recommend it to anyone interested in using SketchUp for 3d printing.

Much appreciated, Jim!
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