Thursday, 14 September 2017

Repair a mesh to make a solid body

I have a couple of messy complex models of horses heads that I want to import in to Fusion 360.

Tom

I've converted a couple of much simpler models with Blender just using the 3D Printer Tools add-on to highlight the incompatible areas and manually repair the few minor bits found.

The horses heads have far more problems. They are made of several non-manifold components and  have hundreds of overlapping faces. This is mainly as a result of creating the windswept looking mane and forelock.

After experimenting with the shrink wrap and subsurface modifiers I concluded the only way to end up with a good reliable solid was yet more manual work.


The first job was to use the Boolean modifier on the components to get them to either join or at least have a seam where each component meets. Then join them all together (Ctrl-J in Object mode.)

Boolean Union in Blender is not as reliable as I would like. One component distorted and lost detail.


I used the subsurface modifier to adjust the mesh and then it joined without significant loss.

Limit selection to visible

To get rid of the unwanted internal structure, I found a tip on a forum. That was to use the option to only select visible vertices. By rotating the model and using the 'B' block select in Edit mode I was able to get just the surface vertices. I separated them (Ctrl-P) to create a new object.


That just left me with the job of filling the holes where the components did not meet at a visible vertex.


Labour intensive but the quickest method I could find to get a clean result.

Wednesday, 13 September 2017

Fixing an iPhone that would not update it's apps

For anyone that knows me they will know that I find working with iPhones perhaps the most infuriating thing.

For some time Shelley's iPhone 6 has not been updating Apps. This was not a problem until she wanted to install the FitBit app to go with her new FitBit Alta HR.

I tried all the non-destructive options on various web sites:
https://www.lifewire.com/iphone-cant-update-apps-fix-4057706
https://www.payetteforward.com/iphone-apps-wont-update-heres-fix/
https://www.igeeksblog.com/cannot-update-apps-on-iphone-or-ipad/

This went on for a couple of evenings, while we had time.
Eventually, after backing up the important content, Shelley rang Apple to get some support.


The thing that they suggested that finally worked was to reset the network settings. Even that had to be done a couple of times.


The various reset options are off of the General menu within settings.
==


Monday, 11 September 2017

Fusion 360 Mesh to Body

It has proved challenging to get existing meshes in to Fusion 360 in a form that can be used.
I am sure many people have existing STL files and other 3D models that they want to use.


I've spent many hours over the last couple of days experimenting and reading articles before I came up with a solution that worked.


The first thing to note is that the Conversion option required is ONLY visible in the MODEL mode when the history is turned OFF.

I find Fusion 360's user interface unhelpful. In this case, why is it not simply greyed out instead of being completely hidden, I don't understand.

If you are looking at menus showing 'Mesh to T-Spline' or 'T-Spline to BRep', you are in the wrong place.


For most mesh imports, I would suggest using 'Mesh to BRep' from the Browser menu in MODEL mode.

Boundary-Representation (BRep) is the format used for new bodies created from within Fusion 360. Although it can handle T-Spline and Mesh, only BRep has all the features.


First Upload your mesh and wait for it to complete the import process.
Open the model containing the newly uploaded mesh.

It is likely to open in Sculpt mode. Swap to Model mode.
Make sure the history is disabled, which it probably will be.

Right click on the mesh body.
Select 'Mesh to BRep'.

If it has errors or completes but shows, in orange, as a patch, then you have more work to do.

Good quality, manifold (solid body) models should convert correctly as a complete solid body.

I found that meshes with holes or superfluous edges and faces would either fail to convert or complete as a patch instead of a body. I was unable to repair those in Fusion 360 and had to use an external tool to fix the mesh before importing.

Repairing The Mesh

This is where it gets complicated.

I tried several free tools in an attempt to find an automated process but failed to find a solution.
I used, MeshMixer, MeshLab and FreeCAD but I could not get any of them to repair a non-manifold mesh where the mesh had other issues.

I ended up back with my go-to tool, Blender.


I used the Add-on '3D Print Toolbox'. This includes various checks that can be run to find potential errors and can highlight them to aid in finding a fix.
The 'Make Manifold' button does what it says. That alone fixed my mesh enough for it to work correctly in Fusion 360.



As I expected to use this model multiple times, I chose to manually clean up all the errors found by the tool in Blender. That left me with a clean good quality mesh to import in to Fusion 360.



I exported from Blender as an OBJ file.


Remember to only output the current selection.

Exporting to STL would work but I believe it will convert polygons to triangles which is not always desirable.

High Poly Models


I used Blender to subdivide the surfaces to create a smoother better looking model.


When converting the more detailed model, in Fusion 360, it warned that the model might slow down the application and it did. From then on, there was a noticeable lag in processing operations.


It's therefore worth noting that Fusion 360 is not ideal for working with highly detailed mesh type models.

Fusion 360 Body Manipulation

Once I had my model imported and converted I checked that the result behaved as I expected.


It did, I had the full set of tools available for modelling.

Thursday, 7 September 2017

Profile following a curved path

Using Fusion 360, it took me a while to work out how to get a profile extrusion to follow a curved path in three dimensions.


I didn't get as fine control as I would have liked. Deviating too much in any direction prevented the profile from forming a body however I was able to get fairly close to what I wanted.

There were a few tips I needed to know:

1. Project a sketch on to a surface to form the path for the sweep.
2. Create the profile sketch close to the path.
3. Create the Sweep as a PATCH.
4. Fill the ends using Create - Patch, not Modify, to form the finished body.

That's not all of it but they are the bits that were not intuitive to me.

1. The Path

- Add an offset plane roughly parallel to the main surface that the path will be projected on to.
- Create a sketch on that plane.


- Draw a line.
- Stop the sketch, the next stage creates an additional sketch.


Select 'Project to Surface' from the Sketch menu.
- Select all the surfaces you want to project on to.
The projected line will stop if any face it projects on to is missing.


- Select the line from the sketch.
- OK.

You should now have a line following the surface of your model.

2. The Profile

Create an offset plane at roughly the top of your path. Perpendicular to that line.
Create a new sketch from that plane.
- Draw the profile you desire at roughly where you want it to protrude from the surface.


If the profile is too far from the surface, the end result may double back on itself instead of following the surface as intended.


If the profile is too far from the path it is likely to cause errors and not allow the Sweep to create at all!


3. The Sweep

I tried lots of times to create a sweep in MODEL mode but I kept getting an error about it overlapping itself or being an illegal result.
Swap to PATCH mode and it becomes obvious that it creates a hollow tube so the result is never a valid body!
In PATCH mode.


Select Create - Sweep.
- Select the profile.


- Select the path that follows the surface.
- OK.

You should have a hollow shape in the profile you have designed following the surface. If it does not you might find adjusting the position of the sketch of the profile may help.
Do not expect the shape to be exactly where you want it. That can be adjusted later when you have the finished body.

4. Create a solid body

To turn the patch into a solid body it is necessary to fill the ends.


Still in PATCH mode, use Create - Patch
'Patch' is on the Create menu not, as I expected, on the Modify menu!

- Select the end edges.


That should put a face across the end.
Do the same at the other end.

Now make it in to a solid body.
Select Modify - Stitch.


- Select all the patch pieces.
- New Body


You should have a new solid body and the patch parts have disappeared from the browser.
You can now go back to MODEL mode.
In that mode move the new body to the exact position desired.

Wednesday, 6 September 2017

Hot glue gun

I was reading a question on Facebook about what Hot Glue Gun people use. The question was asked because they had problems with the ones they had used.


I've had mine for a couple of years and I have not had any problems and I like it. I thought it was worth recording that.


It is a high temperature 195C glue gun that fits 11mm glue sticks. A Dremel 940. The built in fold up stand is more useful that I had expected. I chose this one partly because of the detachable cord. That feature has been invaluable because it can be used for a few minutes untethered so it can get in to awkward places more easily.

Tuesday, 5 September 2017

Fusion 360 outage

The disadvantage of using a cloud based system is that sometimes the back end system stops working. As has happened today.


This is most frustrating because the error messages were inadequate and I re-installed Fusion 360 in an attempt to get it working. Initially there were no error messages just a '(Not Responding)' in the title bar. I left it ages and retried several times before resorting to re-installing.


It was only after the re-install that I got the error stating that AutoDesk had some issues.


I had assumed it was related to me installing the latest Intel graphics drivers earlier today. I now know that was unrelated!
The re-install of Fusion 360 was painful because I had to delete all references to AutoDesk and Fusion 360 from the Windows registry before the install would complete.


Finally back in to Fusion 360 and it took me a few minutes more to work out how to open a previously saved archived version of one of my files. It's 'New Design From File'! What's wrong with the traditional 'Open'.

Now I'm in, it works offline. Not ideal but able to work. At least I would be able to if lunch time was not over and I need to get back to my other work.

To fully work offline you can use the 'Export' function to save the changed file back to local storage. Not particularly user friendly when working offline.


Monday, 4 September 2017

Stihl 36V dust cover

Following on from the dust cover for my Makita 18V tools I've create a comparable cover for our 36V Stihl tools. As the heading implies it helps prevent the ingress of dust and dirt when the tool is stored with the battery removed.


This is not as compact as I was originally intending. That is due to the size of the battery bay and the the clip arrangements used to hold it in.

I tried a shallow version with lugs to attempt to hold against the upper edge of the battery bay but not all of the tools have an inner face in the same place. The only guaranteed fixing was the original battery latch.


This design has an open structure tower to minimise the plastic used in the print. The latch is deliberately fairly loose compared to that used to hold the heavy battery in place.

Failed Print

The first few prints kept failing so I had to make some minor modifications to make it more stable while it is printing.




The end result fits well.

==

Downloads:
Stihl 36v Dust Cover STL file
Licence attribution - small business exception

My designs on YouMagine.com

==