6-pounder, Royal Navy cannon barrel - George III era

[Dr PR]

I have seen this problem with Chitubox. With a single surface (like an "O") with a hole in it the hole is often filled in. But if I cut it into two "C" shaped surfaces fitted together to enclose the hole there isn't a problem. The gap between the two surfaces is zero thickness so it doesn't appear in the printed part.

 

Since this seems to be a problem with different CAD programs and different slicers I suspect it is a problem in the STL file format, or at least the description telling how to create the STL object.

[thibaultron]

On the trunons (sp), move the outside supports to the ends. This gives better repeatability, and less chance of an oblong end.

[Gabek]

On 9/24/2023 at 4:44 PM, thibaultron said:

On the trunons (sp), move the outside supports to the ends. This gives better repeatability, and less chance of an oblong end.

Thanks!  I had spotted that earlier and they were placed on the end like you recommend on this version. 
Regards,

Gabe

[Gabek]

On 9/23/2023 at 12:02 AM, Dr PR said:

I have seen this problem with Chitubox. …

Thanks, Phil.  I do use Chitubox on occasion so I'll make a point of checking for these errors.

Regards,

Gabe

[Gabek]

On 9/23/2023 at 12:02 AM, Dr PR said:

I have seen this problem with Chitubox. With a single surface (like an "O") with a hole in it the hole is often filled in.

...

Since this seems to be a problem with different CAD programs and different slicers I suspect it is a problem in the STL file format, or at least the description telling how to create the STL object.

Hello everyone, 

In response to people who have warned that there might be a split in the .stl where I created the complicated curved bodies I checked the meshes in Fusion 360 and I do believe that they are stitched correctly:

Thanks for your input, folks.  I will be posting the .stl for this file shortly.

Clear skies and sharp tools!

- Gabe

[Lieste]

The issue I raised and was confirmed in replies as being a more general issue than merely with Cura, is where the slice is joined as the outside ring and filled, then the inside ring filled to the outside in random layers of the print, rather than the 'proper' filling of the ring between the inside and outside loops.

It is a slicer issue or one with the definition of an STL file and how it interacts with the slicer.

Breaking each 'ring' into two parts (halves or a 'big wedge'/'little wedge' prevents the treatment of the outer loop and inner loop as two objects and the forcing of the proper handling of each closed loop without holes/islands. I've seen it particularly where the object originates as a profile and is a solid of revolution. It is only secondarily an issue of the linking of different longitudinal elements. Cura sometimes does the same thing with the automatic 'tree supports' if they are needed 'all around' and form an external loop (which is where I first noticed the behaviour before I saw it repeat on a model ordnance barrel).

[Gabek]

Final (?) product. 

1:64 6-pounder Royal Navy Cannon - George III era

 

I printed these at 0.03mm resolution in Anycubic ABS+.  If anyone wants the .cbddlp file created for these prints (with supports) just send me a message. 

 

If anyone chooses to print these out I would appreciate a photo!

 

I hope this helps,

Gabe

6-pounder cannon_.stl

[Knocklouder]

Those look really good , everyone will be sending you 20 lbs of Potatoes  for sure lol

[allanyed]

7 hours ago, Gabek said:

1:64 6-pounder Royal Navy Cannon - George III era

This looks like an Armstrong Frederick pattern  (circa 1760-1794) which came about when George was made king.  There was also the Blomefield pattern which is quite different but also in the George III era as it was introduced in the early 1790's and replaced the Armstrong Fredericks.  

Allan