Solved STL file looks fine, but has internal vacancies

I tried to make a small castle (scaled up by 6x) but even though I thought it was clean there were some vacant areas inside the walls when printing (where the walls met the cylinders).

How do I prevent this from happening (I use blender)
and is it possible to fix in the slicer engine?

 

The STL you've attached is just a big ol' S; nothing castle-like to be found

have you tried running it through any repair algorithms like: https://modelrepair.azurewebsites.net/

 

That's a single surface S. Can't print that

 

Oops! Exported the wrong object
This should work: I'll try to get a picture of the problem too.

 

I also have a picture of the result:


As you can see, there are big gaps that compromise the structural integrity.- any way to fix them in netfabb without rebuilding the whole thing?

 

The problem is that there's a whole bunch of different body parts to that file. It's not combined into a single body.

Try running it through netfabb's online repair tool, or see if @PrintedSolid will run it through netfabb pro

 

I was told that Blender was very good at complex and organic modeling.

 

The reason I like blender is because it allows incredible control of location, size and rotation of objects - I can just put the numbers in and be very precise.

Is there another free graphics program for 3D printing that has the same features?

 

Whenever I'm designing something in Blender to print, I use the boolean modifier a LOT. Just click on the item you want to be the main item, click on the wrench in the bottom part of the rightmost window, and click on boolean, select the item you would like to join/cut/etc and type of operation you would like to perform, then once it looks right, click the Apply button.

A REALLY nice feature about Blender is the "flying" mode. Press Shift+F and then you can use WASD + mouse to move and shift to speed up. I'll always go "inside" of the object that I just performed the boolean operation on and ensure that there is no wall separating the two objects. If there is, hit Tab to go into vertice edit mode and play around with deleting/adding faces until you can see inside of the other object from inside of the base object. Here's some pictures to help make my point more clear. For some reason I can't manage to get a quick visible picture of a good example with the two boxes I was using for the bad example, but here's an example of some cylinders connected to a box that I use for a pegboard mount for the good example. Notice how you can see inside of the cylinders from inside of the cube. This will ensure it prints as one solid piece.

Bad

Good


From what I've seen, all of the other forum members use something other than Blender. I only use Blender just because I feel comfortable with it. If you have any problems you can't figure out with the help of google, feel free to drop me a line and I'll see what I can do to help. I'm by no means an expert with Blender, but I do have a good deal of experience with it since I bought my printer in OCT2014.