Fillets and old iron

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drmacro
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Fillets and old iron

Postby drmacro » Sat Feb 22, 2020 4:14 pm

I mentioned in a post the other day that I was working through exercises in an old drafting text.

I saw this one and thought it would give filleting a hard time...I was right. 8-)

I've attempted this in Part Design only, mixed Part/Part Design (i.e. think base features), and Part only.
I've been unable to get all the fillets.
Fig_6-91.jpg
Fig_6-91.jpg (516.18 KiB) Viewed 345 times
I'm willing to be proven wrong. :!: :lol:

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Fig_6-91-3.FCStd
Latest attempt, Part WB only
(61.04 KiB) Downloaded 8 times
carlopav
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Re: Fillets and old iron

Postby carlopav » Sat Feb 22, 2020 5:00 pm

I think much of the problem with fillets it's here:
Cattura.JPG
Cattura.JPG (25.71 KiB) Viewed 328 times
You can set different fillets for every edge, so you have enough surface to be filleted.
EDIT: also you can treat every fillet at the end and not include some of them in the sketches.
Attachments
Fig_6-91-3.FCStd
(49.19 KiB) Downloaded 7 times
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drmacro
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Re: Fillets and old iron

Postby drmacro » Sat Feb 22, 2020 6:10 pm

carlopav wrote:
Sat Feb 22, 2020 5:00 pm
I think much of the problem with fillets it's here:
Cattura.JPG
You can set different fillets for every edge, so you have enough surface to be filleted.
EDIT: also you can treat every fillet at the end and not include some of them in the sketches.
Everything you said.

But, the reason that I attempted to do it along the way (in that attempt) was, doing the fillets at the end literally crashed FC. :o

In addition, different fillet radii can be used...but, would not complete the exercise as prescribed. I.e. the note: "FILLETS & ROUNDS 1/8 R" 8-)

If you look close, I even fudged the area you highlight by making the extrusion extend past the flange of the revolve. To avoid sliver faces where the flange revolve meets the pad. ;)
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bejant
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Re: Fillets and old iron

Postby bejant » Sat Feb 22, 2020 7:47 pm

When that textbook was written the mold pattern would have been made by hand from wood and the outside corner fillets abraded away (file, sandpaper) and the inside corner fillets made by filing them in with a bead of some material that hardened afterwards.

I don't think that directly trying to model the piece in the as-machined condition can produce a proper model. Instead, I think that the un-machined casting should be modeled, and once that raw casting is complete, the machined holes and flats should be pocketed away.

Even so, I don't think the 2D drawing is a true representation of the 3D part, especially at the back where the fillets on the vertical side faces meet the curve flange thickness and at the front where the machined face meets the flange corner fillets. (Quick61 had a word or phrase for that type of visual hocus-pocus but I don't remember what it was).
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tanderson69
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Re: Fillets and old iron

Postby tanderson69 » Sun Feb 23, 2020 3:38 am

opencascade can do it with the proper amount of swearing. I had the most trouble in the front area without the boss.
Attachments
oldIronBlobfishRev03_02.png
oldIronBlobfishRev03_02.png (54.5 KiB) Viewed 261 times
oldIronBlobfishRev03_01.png
oldIronBlobfishRev03_01.png (61.87 KiB) Viewed 261 times
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bejant
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Re: Fillets and old iron

Postby bejant » Sun Feb 23, 2020 3:48 am

Wow ! Looks nicely done - can you post the file?
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tanderson69
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Re: Fillets and old iron

Postby tanderson69 » Sun Feb 23, 2020 4:39 am

bejant wrote:
Sun Feb 23, 2020 3:48 am
Wow ! Looks nicely done - can you post the file?
I used opencascade, but not freecad. So all I can give you is a brep. If you want to know how I did something specific, just ask.
Attachments
oldIronBlobfishRev03.brep
(375.35 KiB) Downloaded 12 times
carlopav
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Re: Fillets and old iron

Postby carlopav » Sun Feb 23, 2020 11:40 am

tanderson69 wrote:
Sun Feb 23, 2020 4:39 am
I used opencascade, but not freecad. So all I can give you is a brep. If you want to know how I did something specific, just ask.
What does I mean exactly? Sorry but I'm very curious...
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user1234
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Re: Fillets and old iron

Postby user1234 » Sun Feb 23, 2020 11:59 am

Just for testing. Works without problems here (PartDesign). But i was expecting errors on the corner (like other CADs) so i the way i model it was a little different (like i do when i see corners like that). You can model it much easier (treestructure) but for me it is ok. I rounded all measures in metric.

Greetings

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Screenshot.png
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carlopav
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Re: Fillets and old iron

Postby carlopav » Sun Feb 23, 2020 1:00 pm

Great! this would be a nice tutorial btw
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