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One of the local libraries has a new small Makerbot 3D printer. I have been submitting Sketchup files converted to STL files for printing.

The tech guy who runs the printer for patrons is having trouble getting a project of mine to come out to be the right size. I need this item go be 2 inches wide. The tech guy sizes the item on the screen to 2 inches. I watched him do it. But, the item is printed with a base of 2 inches, and the item itself comes out smaller.

Does anyone have suggestions about this? I can get more info if someone can give me the right questions to ask. The tech is open to taking suggestions. He wants to get the printer running smoothly for patrons.

I submitted a file with my own base with supports made in Sketchup. But, the tech guy said he needs to set the printer to create it's own base and supports.

Additional info:

When I printed it by letting Makerbot create the base and supports, it came out to be 1 3/4" as shown here: https://flic.kr/p/EashnD

Printer: Makerbot Replicator with Smart Extruder (not Plus). (I am now at the library with the technician.)

Here is a screenshot of what I am trying to print. It is a replacement clip for a messenger bag. So, it has to be 2 inches across. https://flic.kr/p/EtdM6s

Here is the printer: https://flic.kr/p/E5F1M6

I used a website to convert the DAE file exported from Sketchup to an STL file. It was GreenToken.com.

If I open the object's STL file in Tinkercad, the object appears two inches wide. And, if I open the file in one of the 3D printer websites in Tinkercad, the object appears two inches wide (in cm).

The security on the library's computers do not allow me to apply plug-ins to Sketchup. The library's Tech staff is going to eventually put the plug-in in there.

If it is resized to 2 inches wide in the MakerBot software to be sent to the printer, why is it printing the generated base 2 inches wide and not the object? Are there some settings the tech guy in the library is missing in this set up window?

Additional notes: The library now has the latest version of SketchUp on Macs. They are working on installing the STL plugin. (Security issues)

My process for producing an STL file to print is now this:

  1. I create something in SU and export it as a DAE file.

  2. I have found that meshconverter.com produces better STL files than greentoken.

  3. I then upload/fix the STL file at the netFabb website.

  4. I then import the STL file into TinkerCad to view it. If there are problems in the file, I can see them. And, I run it through netFabb again. I can also modify the file in TinkerCad. It is no where near as sophisticated as SketchUp. But, it doesn't claim to be.

I have found that there is a way to export the STL file to 3D printer hubs through TinkerCad. You can see the prices, the material available and the location of the company/person doing the printing. You can contact the printer ahead of time and they can look at your file to give you advice.

Update

I just wanted to add that the netFabb website does not export STL files after it fixes them. It now gives you a 3MF file format when you upload an STL file. I am not sure why this happens. But, this has put a big wrench in my process. I can no longer fix SketchUp STL files with netFabb. When I bring them into TinkerCad, I see errors in the object. It seems like there are issues with complex curves.

1 Answer 1

My advice is to use a micrometer (i.e., sliding dial caliper) accurate to within .001" and measure the printed object. If it is 1 7/8" for example, you would open the STL file in Makerbot software and use their scaling tool to scale the object to 1.0666666...., which is what you get when you divide the desired size (2") by the actual printed size (1.875"). I have found that it is much simpler to do that than to reinvent the wheel and try to figure out what each software engineer was thinking on each program and each conversion process and try to make it work right every time. Chances are that the same conversion factor might work right for any file originating from the same source and going through the same conversion software package. Also, 3D printers in general don't like edges that aren't completely "welded", or continuous seams. With Sketchup if you keep zooming in on an edge you almost always get seams that are stitched at intervals determined by Sketchup algorithms. They are "unwelded" seams. Some 3D printers can handle them. Many don't. I have used various 3D software packages, including Sketchup, and the best one so far has been Rhinoceros 3D. It handles multiple complex curvaceous planes and can radius adjoining curved edges and can "weld" them. Aeronautical and boat building companies use it for CAD/CAM applications.
... The STL file converter you mentioned is probably taking the Sketchup file and "cleaning it up" so Makerbot likes it. You would almost have to know exactly what algorithms each developer uses. to try and 'fix' it mathematically Like I said, do your own measuring and scale accordingly. BTW, it's better in my opinion to let Makerbot do the rafts and supports. Their engineers typically do a pretty good job. Where I have had issues is on things with a shallow angle (almost horizontal) hanging out into empty space. If you can re-orient the object in the makerbot software so those types of angles are minimized, the print is alot cleaner.