Hi Burr,

Yeah, with NURBS accuracy is important and there are 3 words I will use here, Zoom, Zoom, Zoom. ;)

This is what I found that might be causing the problem, in the screen dump your eyelet on the sinker is not exactly in line with the body, it's about 0.00124 units out.
So when you try to split it exactly in half it try's to split those surfaces around that misaligned area into tiny surfaces which it can't handle and fails.
Michael will probably elaborate on this but I think that is the problem try and get everything aligned nicely first and give it another go.

Hi Burr, Danny's analysis is right on.

The pieces are just slightly off center in a couple of different ways, that tends to create difficulty with producing an intersection right through there.

Like Danny was showing, the 2 pieces don't quite align at their juncture, and also each piece is itself not exactly lined up on the base line:

Viewing from the Front, towards the left side of the model:




Viewing from the front, towards the right side of the model:




Notice how the left side is kind of above the base line and the right-side is below it? The piece is basically not all aligned on that base line.


One way it might have got like this is this one curve piece seems to be sticking out downwards a bit:




Once you get one piece kind of misaligned, then if you mirror it and snap the mirror points on to the misaligned piece, your mirrored result will also tend to get a slant to it.


The other thing is that it looks like you want to have half pieces at the end? If you have modeled half of it, you should be able to solidify that half by selecting it and using Construct / Planar to seal off the planar opening (if it is all aligned and planar that is), and then mirror that solid half-piece to get your other solid half-piece, rather than sort of gluing it into a solid then cutting it again...

I'll see if I can do something to line up the pieces.

- Michael

Hi Burr, I have attached a tuned up version here as redo2.zip .

I think it was the one curve piece for the donut part sticking down a bit too much which kind of instigated the misalignment. It seemed to be sticking down further more on one end than the other.

To tune it up, I turned on control points and used Transform/Align to make sure all the bottom points were all lined up on that base axis line.

Then I built the longer sweep part, and the donut sweep part, then selected them both and used Edit/Trim to cut them with each other. Then Edit/Join to glue them together.

That results in the surface in the file there which I slid a bit over to the side from the curve framework.

This piece now has a planar opening on the bottom, so you can turn it into a solid by selecting it and then running Construct/Planar - that will seal off the open bottom and you will have your half-solid piece already there without actually doing any boolean.

Then if you want to make a matching bottom solid half, you can use Mirror on that and you will have your bottom solid piece.

I hope this helps, and please let me know if you need any more info on the above steps, and thanks to Danny for zeroing on the problem!

- Michael

Thanks guys,

I didnt think to look at my original curves. I thought the messed up stuff was coming from the booleans,joins,trims,booleans. I suppose I have to lean that nurbs ARE exact. Also Am learning to expect what SHOULD work and if it doesnt, ZOOM ZOOM ZOOM!

I appreciate the time,

Burr

One last question Michael,

>Then I built the longer sweep part, and the donut sweep part, then selected them both and used Edit/Trim to cut them with each other. Then Edit/Join to glue them together.>

When I try this I have to do:

Select long object, trim with doughnut.

Boolean union.

Join.

I cant get it to become 1 with just trim and join as you described.

Am I missing something here?

Thanks again,
Burr

Hi Burr, for this kind of thing you can do a "mutual trim".

That means to select both objects you want to trim, then run Edit/Trim, and at the prompt where it says to select cutting objects, just push Done (or right-click) instead of picking anything, that signals that each object will trim the other.

Here is a step-by-step which is a bit clearer:

To start with, select both pieces:



Then run Edit/Trim - the following prompt will appear:



But in this case you don't want to select any additional cutting objects, you want each of these pieces to cut the other, so push "Done" or right-click in a viewport to signal a "mutual trim" operation.

Then the next stage of Trim is that it cuts up everything, and you pick which pieces you want to discard or keep, the model will look like this:



In this particular case it happens to be easier to pick the pieces that you want to keep, rather than picking the pieces you want to discard. So to do that, you can switch to Mode: Keep, like this:



Now pick on the pieces you want to keep, the 2 big outer pieces:



Then push "Done" or right-click and the mutual trim will be complete:



Those pieces are now ready to be joined. Then after they are joined there is a planar opening on the bottom which can be sealed by picking the object and running Construct / Planar.

Hope this helps!

- Michael

Thank you Sir!

Detail seems to be a fault of mine. Must...Pay....Attn!

Burr