LOFT CUT ERROR

[dlewis1000]

It took me days to make is as far as I have on figuring out this shape. Now that I have the shape I want, Inventor doesn't want to cut it out of my part. Trying to explain exactly what I'm doing would be a nightmare so I attached my part file.

The loft command wont let me add, cut or intersect, but it will let me make a new solid. What i don't understand is why I can't cut it. It's the exact shape I want, I can even confirm that by the shaded preview that pops up and from the solid it creates. I tried to merge the solids and cut it that way, but still won't work. For some reason I thought Fusion might act differently, so I imported my part file after I created the lofted solid. I tried to cut the solid from my part with no success but Fusion at least gave me an error message. (Inconsistent edge-face relationships) 

Hopefully someone can see whats going on with this. Any suggestions would be appreciated. 

Thanks everyone!

[JDMather]

Here is my first attempt.

Now that I have an idea where you are going I can make a second attempt.

[dlewis1000]

That is almost exactly what i'm looking for! The only thing different about that is that at the top of each flute, it should be a full radius instead of having the flat if that is possible. 

[JDMather]

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@dlewis1000 wrote:

... at the top of each flute, it should be a full radius instead of having the flat if that is possible. 

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That is what I figured once I got this far.
Do you need a variable radius fillet getting larger as going out to edge, or do you want a constant radius fillet on that edge>

[dlewis1000]

I'm assuming it would need to be variable since at the ID of the part the radius is .015 at the top of the rib and at the highest point on the face is .03. I thought it would create that by changing the sketch the way I did on the file you sent me, but it looks like it opens back up to a flat at the top of each rib and then back to the full radius. 

[JDMather]

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@dlewis1000 wrote:

I'm assuming it would need to be variable ... 

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It could be .015 the entire way.

Depends on your manufacturing process and design intent.

I can do it either way, but don't want to make it variable radius if you can't manufacture that way.

Note that the bottom you kept constant radius.008.

[johnsonshiue]

Hi! Instead of using Loft, I used Guide Rail Sweep to have more predictable shape (see attached part). Certainly, more steps are required but the resultant surface is much simpler. Please note that Loft, though, looks nice, the geometry is sort of Freeform and under-constrained. You may run into downstream modeling issues.

Many thanks!

[dlewis1000]

I wanted to maintain the .008 at the bottom for sure but the radius at the top needs to get bigger towards the OD so I guess i should have said yes for sure to the variable radius. It just needs to tangent from flute to flute. I am going to use a very small ball mill to surface these so it should be fine manufacturing wise. 

[kelly.young]

If you want to keep the Loft Cut idea here is how to achieve it. I created a custom scale to grow from so the end would remain tangent as it is patterned, see Parameters. It is a little goofy at the start of the bend but a bit of tweaking you might be able to flush it out a bit more. The parameters are named for easy editing, if you aren't familiar with iLogic Forms go to View > User Interface > iLogic then under Forms tab should see Form1. Change the numbers-slightly so it doesn't break- and see what happens!

[JDMather]

@dlewis1000

This was interesting.

See 2 solutions attached - 1 with constant .015 radius on top edges and the other one with Variable radius .015 from edge of straight section to .03 at edge of cylinder.

@kelly.young

You should check iProperties when responding to users here.

The OP is using 2017 and will not be able to view your 2018 solution feature tree.

Edit:  Ahh, I named the files backwards.  Back in a moment with the correction and a solution with both fillets variable radius.

[kelly.young]

Whoops, good call, looks like you got it down pretty good with the Surface Sculpt.

[JDMather]

This example might be a bit easier to follow.

[dlewis1000]

After messing with this a few days, i've learned a couple things. Thanks for the solutions, they have helped a lot. Taught me a few things. I think i want to go with the constant radius option. The only thing that needs to be different is the angle of the flutes on the face. Specifically on the face, the flutes need to have a 60° included angle. The part that is tripping me up is that the top of the flute needs to maintain the same width from along the entire flute from top to bottom. It seems like I need to figure out the difference in the 15° face angle and the angle I cut the 60° to achieve that. 

[JDMather · Accepted solution]

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@dlewis1000 wrote:

.... It seems like I need to figure out... ....to achieve that. 

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Whenever I run into geometry like this - my first thought is, how am I going to manufacture this part.

We can design stuff that isn't manufacturable (at least not at a reasonable cost) so the manufacturing process might dictate the design rather than the design being the sole consideration.

With that in mind - you might discover that what is manufacturable (at a reasonable cost) is a bit different than the "fantasy" geometry created in a CAD program.

I was reluctant to use the Loft for this very reason.  I would want cylindrical geometry and  planar face sides with conic transition and circular profile fillets.  All basic primitive analytic geometries.

Edit:  Ahhh, I think I uploaded the wrong file for Rev 6 - back in a minute.

@dlewis1000

Examine the attached Rev7 file.

[dlewis1000]

I don't have the years of experience and training. Most of what you just said is pretty foreign to me. I understand what you mean about designing for manufacturing. We have made these parts before. The problem is they were made 20 years ago and no drawings were made. I have some old parts that I'm trying to recreate in CAD.

From what i know about the past parts, they would turn the OD, ID, and put on the face angle. Then using a 60° included angle cutter, cut at a different angle than the 15°. Than the radius on top of the flutes and the transition between the face and ID was hand benched after the flutes with both radii on the ID are cut with a wire EDM. From what I've been told, they would make small cuts and change the angle they cut the 60° on until the ribs were the same width all the way down. 

[JDMather]

I just added a revised file - see edited post above.

Do you have any photos of actual parts?

[dlewis1000]

I do actually. But keep in mind, this part is old and worn. 

[JDMather]

It is not really possible to say looking at a static image - but this 3/16 radius looks out of proportion (too big)?

Do you have radius gauges and/or an optical comparitor to check the radii and angles?

It looks like you are getting pretty darn close.

What is the function of the part?

[dlewis1000]

There is no need to check the angles or any of that. This one is being made a little different size as well as using a 15° face angle instead of 10° like the one in the photo. As for the flutes at the ID. They need to be .06 deep from the ID to the bottom of the radius and get deeper as they transition to the face. The shape you have came up with so far is very very close. The edited model doesn't look like it holds the 60° included angle on the flutes in the face. The angle in the flutes can only change during the transition radius from the 15° face angle and the ID. 

[kelly.young · Accepted solution]

Here is the model in 2017 forgot to verify what version you are using, check out the View > User Interface > iLogic Browser > Form1 to change the shape. Can't really tell what angles/radii you are looking to stay constant but should be able to adjust the sketches 3,4,5 to get your groove dialed in. Not as clean as Surface but sticks with your original attempt of using Loft.