Fillet/Chamfer not working

[rinMJQG5]

Hi all, I am having issues with Fillet and or Chamfer (see attached screenshot). I just keep getting errors. These are with drawings I have done in Fusion and extruded. I did one drawing, extruded it and got different size fillets to work on either side of the extrusion. The latest on I am just getting errors at certain points in the design, some corners but not others. Any ideas??

[g-andresen]

Hi,

please share the file for reply

File > export > save as f3d on local drive > attach to post

günther

[rinMJQG5]

thanks for responding, here is the project file, hope that gets me closer to an answer! let me know if ou need anything else!

[davebYYPCU]

Sharp and unusual curve comb outlines are not helping the fillet and chamfer commands.

I don't understand Control Point splines, but if it was a fit point spline then you have so many points on the splines that a curve comb is bound to be irregular.

If there were canvasses, then tracing the pickguard with lines / tangent arcs, will be more successful.

Might help...

[jeff_strater]

I'm a little confused, @rinMJQG5 - the file you shared has a chamfer in it already, that seems to work just fine at 0.75mm.  I was able to increase it to 1 mm, as well.  Can you clarify what does not work?

The one thing I did notice is that you have some "near tangencies" in your edges.  You can tell this if you have "tangent chaining" enabled, and select one edge, it will propagate to all tangent edges.  In this case, you can see that it did not:

I know that these near-tangencies can cause problems with Fillet and Chamfer, so it is good to clean these up.  Just edit the sketch, and apply a sketch tangent constraint between all curves in the sketch.

[TrippyLighting]

Before using splines you should try to use arcs to approximate the shape.

Only when that fails to properly represent the shape should you use splines.

Even then, use sharp "virtual" intersections in a sketch, meaning where the line/arcs/splines would intersect if not filleted.

When you do use control point splines (also called CV splines) , use as few spline control points as you can get away with. Best curvature is achieved with splines where the number of control points is 1+the degree of the spline.

Then extrude and then use fillets.

Decorative fillets should be kept out of sketches and applied as solid features. 

[rinMJQG5]

Thanks for taking the time to look.Most of the pickguard was done with Arcs, but as you can see I had to use fit point splint spline on the tighter curves. It seemed that Arcs weren't capable of doing the tighter ones. I used a dxf drawing from Illustrator and copied it in Fusion 360 using fit point splines, control point splines and any other drawing tools that seemed to get the job done. BUT my lack of experience showed that the use of the in some circumstances didn't produce good results when adding fillets and lofts. So I should try and just use "Arcs"?

 I have added chamfer to the edge of the pickguard but I wanted a higher chamfer than I was able to add. Adding more chamfer produces errors. I am not aware of what "near tangencies" are? If you could explain that a litle more I would be greatly appreciative!

[davebYYPCU]

Not sure how arcs don’t work.  The line tool has the ability to attach a tangent arc to the preceding sketch article.  When you get used to lines, and then a continuation of a tangent arc, you can build chains that are all tangent connections, as you proceed around a canvass outline.

Near Tangency is just that, almost Tangent, but appears to be tangent but is not actually tangent constrained.  Double click a sketch line, Fusion will connect and show the full length of tangent chain articles - if they exist.

Might help….

[rinMJQG5]

Sorry if I appear stupid with some (maybe all) of this. I tried making the Chamfer "Two Distance" and got the distance I wanted to get out of it.

My other issue was the body, which I extruded and was able to get different size Fillets on either size of the body before being struck with errors. I am hoping you experience Fusion warriors will just go "its just because blah blah blah" and all my problems will be solved. I think I mostly used control point splines, so that maybe a good starting point for me. The reason I used control point Splines is a watched a tutorial on drawing shapes and that was pretty much all they used.

Riichard

[davebYYPCU]

Don't be hard on yourself, we were all learners.  Fillets / Chamfers working - great.

The ah ah moment, constrain the arcs that need to be tangent, as Tangent at their connections.

So tracing a canvass - (presumes you have it calibrated and positioned)

I start by drawing / constraining all the straight lines in the item being created. (No fillets)

Followed by each and all arcs that can be made - if connected to a line / arc as a curved continuation, the Line tool with left button down will pull an arc off the connecting end point.  (2 point arc)

Run around the outline and close it out with lines and arcs where appropriate.

In the case of two straight lines that are to be filleted, make the fillet in the Modelling Tool Box, not sketch fillet.

I use Fit Point Splines.  I can usually get a 2 point spline closing a gap in the chain to behave by manipulation and constraining the spline (tangent) handles.  Least amount of spline points the better.  

(I can get the airfoils I trace with 4 points on top, and bottom of the shape.)

All rules are meant to be broken, so fine tune your workflows as you learn new tricks.

Fix yellow icons, when they happen, use the Undo tool.  (Before saving the file)

Ask questions as to why they had appeared.

Might help...

[jeff_strater]

@rinMJQG5 - sorry for the delay in responding.  @davebYYPCU answered the immediate question about "near tangencies".  I was looking for a good example in your design, and saw something strange.  Here is an example of a near tangency:

you can see that tangent chaining is on, but the selection does not propagate to adjacent edges.  Usually the fix is to go to the sketch and apply a tangent constraint between adjacent curves.  But, when I went to the sketch, I saw that this is just a single curve:

and, turning on curvature combs for this curve shows the discontinuity clearly:

which made me very confused.  This is a single CV spline that is not tangent continuous across its whole length.  I thought that was impossible to create, but somehow it has happened here.  There are actually two points like that in this curve.

So, my question to you is:  Do you have any recollection of how you created this curve?  I have no idea how this curve came to have these two discontinuities in it.  I suspect a bug in Fusion, and I would like to fix it, because this can create problems such as failures in Fillet or Chamfer downstream.

As a workaround, if you delete this CV point:

it fixes the problem:

it does change the shape, though, so you will have to fix it up again, unfortunately.

Again, if you have any idea how you got the CV spline into that state, we would really appreciate it.

Jeff

[rinMJQG5]

That's a big question you are asking me there. I see the non tangent line. I was mostly using "Control Point Splines", though I can't 100% guarantee that was what was going on there! I had noticed a few going back where they were not joining up properly and I redid them.  I have experimented and I am trying to use a lot more "Tangent Arc or "3 Point arc" to get the shapes I'm after and maybe that is being a bit better in not producing errors when applying fillets and chamfers.

Sorry I am all vague and don't know what I am doing. But with peoples help with these things I have gotten my fillet around the guitar body up to 7.5 mm

[rinMJQG5]

Thanks everyone for putting There brains into helping me on this issue. I now seem to have come to terms with Tangency and now I'm not having issues with the Fillets and Chamfers. Sometimes things are just staring you in the face and you don't realise! As a beginner making dumb mistakes is a great way to learn!