Is there anything special about STL files I should know?

[Bill_Brehm]

Not asking for a book just a little information.  I searched the forum, but didn't really find what I'm looking for.

This is all new to me so I hope I'm not being too elementary.   I'm working on my first project, and I'm a little confused as to the use of components.  I'm making a small 4 cylinder engine block.  I have broken it down into four components even though it will be one solid piece.  Should I have made it one component from the start?  I don't want 4 separate parts printed.  Also, can I make them into 1 component now?  Or won't it even matter once made into a STL file?

I do have one general question.  When I split a body what do I do the unwanted part?  I tried to delete them, but that creates all kinds of errors.

Thank you,

Bill

[TrippyLighting]

Try "Remove" instead of "Delete" to eliminate the unwanted piece.

As to the 3D print, is it really going to be one solid object or separate pieces that can be moved after the printing but which will all be printed in one shot ?

[weshowe]

Many of the 3D printer slicing programs ignore the units specification in the STL file and assume everything is in millimeters.

If you export to Meshmixer and then save as STL, this is not an issue because Meshmixer appears to scale internally and write out millimeters. But if you export the bodies directly, you can end up with issues if you model in other units (like inches). Not Fusion's fault, but still a problem.

I model all my 3D print parts in millimeters now, so I no longer have to scale it at the end.

As for your printing op, you can export all 4 bodies in one file and print them. However, being separate components, they each have their own local coordinate system. This is not a problem if all the origins are at the same place as the "root" component origin. If not, some of the bodies may end up inside of others (or separated).

 - Wes

[Bill_Brehm]

Thanks Trippy

Yes, I want it to be printed as one single piece.   I'll try 'Remove' tonight.

[Bill_Brehm]

Thanks Wes for the heads up on using millimeters.  I don't suppose I can use inches, and then change the units before saving?  It may not be important, but I do all my 2D drawings in full scale and then scale them down when I print them.  I assumed I could do the same thing in Fusion 360.  If that is not the case I may have to start over.

BTW I know metric is the way to go, but not being a young guy I just can't make the leap.

Spoiler

[weshowe]

That should work. If you model in inches and change to millimeters, the part size will be the same, but the numbers change. So a 2" part will be 50.8 mm.

Based on a statement I read somewhere here on these forums, internally your models are calculated in centimeters (and I know some other Autodesk products are that way also). Then Fusion converts that size value to whatever units you want.

I just found mm to be easier than having to remember to convert before I printed (since I inevitably make some edits and reprint). Yeah, there are some other old dudes around here. I am thankful I didn't have to recite any recent (i.e. less than 4 decades old) song lyrics to get accepted. 🙂

 - Wes

[Bill_Brehm]

I watched, or read more information and tutorials on components and bodies.  I probably should have just made my engine block as one piece to start with, but breaking it into components isn't going to hurt anything.  I did move all my components so they are all included under one component, although I really didn't have to do that either.  I removed the unwanted split bodies, and the only problem I can see is that all the origin planes are in different location.

If I understand correctly this will cause my components to be printed in locations relative to the main component origin, and not where I want them to be in the model.  I can see how I moved them out of place by moving components around instead of bodies.  The question I have now is: How do I align the all the origin planes again?   Is there anyway to specify their location on the grid as 0,0,0?

4 decades, piece of cake.  I remember when Elvis was brand new.  Hope I don't get banned now.

Thanks

Bill

[TrippyLighting]

This would be easier to answer if you could share your design.

[weshowe]

We are getting close to my own limits here...

If you look at each component, there is an origin element in the browser. Tick the lightbulb and you can see it, it defines the location of 0, 0, 0 for your component, as well as the orientation of the Axes. The coordinate system for your component is calculated relative to that spot.

If you want to print all 4 parts of your engine block as one print with them all aligned together, then all these origins need to also be aligned, because when you export them as STL the coordinates calculated for each face will be relative to the component origin. If, for example, the origin for each component was basically underneath the center of each of the 4 parts, then all 4 parts would end up being mashed together in the center of your 3D build plate.

Most of the things I make that are to be a single solid part I combine the basic elements into one body (and in one component), and export that as STL. I have also made 2 material prints using a 1 element extruder by making 2 bodies in 1 component (so they share the origin), one stacked on the other, and export both bodies as one file. Afterwards I note the height of the lower body and edit the gcode file to pause the printing at that height so I can change the filament.

That process does not work right if I export 2 separate STL files, because even when I have a common origin, the slicer "drops" the top part such that the bottom of it is on the hotbed. But exporting parts of a design to be printed in different places on your printer in one print job works fine.

I never tried making 4 parts, nor aligning 4 components. I also realized I am uncertain about your objective. I had been assuming that your "engine block" was to be a monilithic mass, like a single casting would be. I am now thinking maybe that assumption could be incorrect, and that these 4 parts might be designed so they are fitted together after they are made? If so, you may not be on the wrong track at all, in fact my advice becomes suspect, based on an incorrect analysis...

 - Wes

[Bill_Brehm]

I would be happy to. How do I do that?

[Bill_Brehm]

Thanks Wes, you have been very helpful.  I just want one solid part when printed.  Making the engine one body is probably what I need to do.

[weshowe]

FIle menu, Export (*.f3d archive file). Save to my computer. Attach it to a post on the forum. There are some really helpful people here!

- Wes

[Bill_Brehm]

Here is the project as it was when I made the first post.

[weshowe]

It looks like all the origins line up except the Breather/Distributor.

Issues I had were I could only get one body selected at a time, (Body1 and Body10) and I am not sure why, but I think because they are in different components.

The other is that when I export the block, it is 4 inches or so too tall for my 3D printer. It looks good (overall your work looks nice all over) but would be unmanufacturable here on my machine. But the export happens and it is a workable file, just not here

As I see it, your options are to merge all those components and bodies, or at least those that are supposed to be in a single chunk. Maybe you want to use the breather as a tool to cut a hole in the block and then print it separately to plug it in.

As for manufacturability, there are machines much larger than mine (200mm x 200mm x 180mm, or 8" x 8" x 7") so maybe that is not an issue for you.

 - Wes

[Bill_Brehm]

Thanks for your help Wes.  I was able to get all the origins lined up again, moved the bodies to their proper locations, and was able to save it as a stl file.

The only question I have is when you said it was too tall for your machine.  Did you mean the full scale model was too tall, or there was a problem with the model?  I only need to scale it down, and save it again so I can get a test print done.

Thanks again

Bill 

[weshowe]

Scaling should work. I didn't know if you intended this to be that size to match something else or not.

I think I covered the slicers ignoring inch units spec before.

 - Wes