fillet issues. Is it just me? =P

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 From:  twofoot
3917.1 
I'm sure it is just me.

I'm trying to fillet the edges on this piece to allow the pattern to be easily pulled from a sandcasting mold. The highlighted edges simply refuse to do anything for me.

I apologize if it is obvious to more experienced users.

Thanks!

Chris





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 From:  DannyT (DANTAS)
3917.2 In reply to 3917.1 
Nothing obvious Chris,

MoI hasn't got the strongest filleting engine out there so it does struggle to solve some fillets on occasions.

Your model could do with a little cleaning up, but on doing that the fillet still failed, so one work around would be to cut the model up using Boolean>Diff with a couple of lines as shown in the picture, apply the fillets then 'glue' everything back again with Boolean>Union.



Cheers
~Danny~
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 From:  Michael Gibson
3917.3 In reply to 3917.1 
Hi Chris, the part about that fillet that is difficult for MoI's filleting engine to handle is that it would kind of open up some holes in the model.

So take this edge for example, this is one of the ones that you had highlighted:



When a fillet is constructed along that edge, it's going to have some gaps open up in the bottom and top of it here:



So I'm not exactly sure what kind of shape you want to get out of that, do you want something with those holes filled in with planar pieces? That may be kind of weird on the top part though making a kind of shelf sticking out.

Also could you tell me what fillet radius you're trying to use? That can be difficult to put a larger fillet radius on top of an already filleted smaller radius like you've got along the top edge there already. You'll usually want to apply fillets starting with the larger sized one first instead of doing the smaller ones first in areas where they are going to be running into one another.

The way I produced the fillet that I show above was to extract out these 2 faces from the main object:



And then that edge between them will fillet because it doesn't have all those side pieces on the top and bottom that it doesn't know how to deal with. The faces are extracted into their own object by selecting them and using the Edit > Separate command. You may need to do some of that kind of work to get this how you want it. Then you use Edit > Join later on to glue the pieces back into a solid again.


But if you could tell me what radius you want, that would help give me a better idea of what kind of shape you are looking for.

Also depending on how you want things to look like on the top edge, you may need to select not just that one larger edge but also this one here:



So that the filleter will also try to round off that piece as well, making a rounded juncture there instead of it trying to open up a hole there:



This example above was with the whole upper part separated off with Edit > Separate.

- Michael

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 From:  twofoot
3917.4 In reply to 3917.3 
Hi Michael. I'm still having problems, even when I try to construct the piece from scratch. The radius I was looking for is .05. (I believe)

Cheers,

Chris
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 From:  Michael Gibson
3917.5 In reply to 3917.4 
Hi Chris, so a radius of 0.05 on this edge here:



Is going to try to make a fillet that looks like this:



I created this one above by selecting those 2 faces there and breaking them apart from the main model using Edit > Separate, and then filleting their joined edge.

So there are a couple of different problems with trying to put a fillet on just that one edge on this model.

One is that it will open up a hole in the bottom spot here:



What kind of shape do you actually want there? Do you want an empty hole in that spot, or do you want to fill in that spot with a little planar piece? Or do you kind of want something smooth in there? To get something smooth would probably involve filleting a whole line of edges all the way down the shape or something like that.

Then there is another problem in the top area here:



So note that there's another hole up there with the other already existing smaller fillet pieces kind of hanging out over top of it like a kind of shelf. That's probably not what you want, but I'm not sure exactly what it is that you want here either. If you want something smooth you will probably need to put that small fillet on last, rather than having it already in place when you try to put in the larger 0.05 fillet along the vertical edges.

That would look something like this - put in your larger 0.05 fillet first:





Then once that larger vertical fillet is in place, you can then put in the smaller fillet on the very top edge, like this:





So note there that putting in fillets in this order of larger ones first and then smaller ones second makes that kind of rounded corner piece circled above. That's going to be hard to get if you do it in the reverse order of putting in the smaller radius ones before you do the larger radius ones.


> I'm still having problems, even when I try to
> construct the piece from scratch.

Could you please post your new model that you did from scratch? That may help me to give you some other tips.

But right now I'd say the main thing is to put your larger fillets in first before trying to do smaller fillets. And also I'm not quite sure what you're looking for in the final result shape near the bottom of that fillet, do you want it to terminate in a planar piece at the bottom, or do you want rounded corners going all the way down the sides?

- Michael

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 From:  twofoot
3917.6 In reply to 3917.5 
Hi Michael. I genuinely appreciate your help. After a good night's sleep and a nice cup of French Roast, I redrew the piece. NOW the fillets work! LOL I think I had some bad geometry that threw me off and confused the fillet engine.

I need to think ahead when designing parts.

Cheers!

Chris
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 From:  Michael Gibson
3917.7 In reply to 3917.6 
Hi Chris, that's great that you've got it to work now!

And yes, filleting is one of the most sensitive areas, along with shelling - there are quite a few things that can mess it up. It can help a lot to have as simple of a model as possible though, things like avoid pieces fragmented into some small face fragments or small edges or stuff like that.

- Michael
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