Toroid stitching and/or sculpt problem

[chipwitch]

I hope someone can help me.

I'm trying to make a mold for a free form toroid-like shape. It's rather complex in that the parting line cannot be created by a simple plane. Therefore the parting line (or surface, rather) is comprised of three concentric patched surfaces all stitched together. With this quilt, I'm able to successfully split, sculpt or combine an extruded cube.

The toroid is a loft of 16 cross-sections. I'm successful in creating a 3-D surface or Solid. Further, I can combine (Boolean operations) with the cube previously mentioned... PROVIDED that the cube has not yet been split by the quilt.

To me, the fact that I can successfully perform either operation suggests that both my quilt AND my toroid are both intact and water-tight. Yet, I'm unable to perform both on the same extrusion.

Any suggestions why this might be?

edit: using Inventor 2010
Thank you. Edited by: chipwitch on Apr 14, 2010 6:17 PM

[Anonymous]

Hard to say without having the part. Can you post the file with EOP
moved to the top?
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Dennis Jeffrey, Autodesk Inventor Certified Expert

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[chipwitch]

That's a neat trick. Didn't understand about EOP to top. But, I tried it and see that it shrinks the file. I assume this is what you were after?

Thanks for taking a look. I've been driving myself nuts with this for the past 2 days.

[BMiller63]

first off, very well done.
have a look at the attached.
I think you were just missing the need for the patch where the "toroid" was.


just a quick Q:
why all the UCS changes?
I've never really used those tools, and was just wondering if I'm missing something.
hope this helps

[cwhetten]

Wow! That's quite a shape. What is it? What do you mold with it?

[chipwitch]

Thanks for the help. You could have at least pretended to sweat a bit. I've been racking my brain over this.

Also thanks for the compliment. I'm still learning how to use Inventor (and 3-d modeling, in general). It's encouraging to know I'm getting at least some of it right. 😉

As for your Q... Since I'm new to this, I'm most likely not doing things in the most efficient manner. I created the UCS to maintain some order to the job. This was a link of chain I was given to digitize for machining a mold. I only had a sample made of wax and the only way I could figure to digitize it was to pour plaster of Paris around the link then cut it into 16ths using a band saw. That gave me the cross sections I could measure (very carefully), and create each cross-section sketch using it's corresponding UCS to keep track of everything.

That being said, I have found some occasion to where UCS are great time savers. but it isn't often. Once was on a rotary tool called an indexable end mill, if you know what that is. Little carbide "inserts" are placed at intervals around the end mill. Each insert is tilted in two axes and were easier to tilt and adjust later, in their own UCS rather than calculating the angles from the origin. The UCS's make it much simpler in some situations. And primarily, where you aren't sure of the exact location of a component, by shifting the UCS, all sketches referencing that UCS move with it. Works great for fine tuning a components position. If you ever run into a situation where the geometry of your drawing starts getting too complex, think about ways you might incorporate UCS's.

Of course, there are other methods one could use for the above purpose. I have a background in software development. Any time I can box something up in its own little isolated system, I do.

Anyway, thanks again! 🙂

[chipwitch]

Just an object d'art. Sorry... not mechanical. 🙂

Inventor has more uses than just machines, just don't tell anyone. :P Edited by: chipwitch on Apr 14, 2010 8:23 PM

[cwhetten]

I hear ya. In my spare time I am making a scale model of the solar system with NASA images of each planet's surface mapped to the little spheroids that represent them. It's just for the fun of it.

I have also modeled a bluegrass band. 🙂

-cwhetten

[BMiller63]

>I have also modeled a bluegrass band. 🙂
possibly the strangest thing I've ever read on here. 🙂 congrats!

[chipwitch]

Whoops... I spoke too soon. Your solution didn't work. The toroid doesn't affect the mold, only the patch between the inside and outside patches.

I still have the problem 😞

[chipwitch]

I just want to know how they sounded? 😛

[BMiller63]

so sorry, I originally did a combine, then apparently backed up at some point and did the stitch and split.
looking at it again, I can't seem to get the three to work together.
I'll keep trying and post back if I have any luck.

[chipwitch]

No problem. I have a less than satisfactory work around. By creating copies of the inner and outer patches, and splitting the toroid in upper and lower surfaces, it's possible to create two independent surfaces to sculpt with. One for the top side of the mold and the other for the bottom side of the mold. My concern is that the stitching operations are moving the parting line slightly on both which will lead to some, indeterminate error in the mating surfaces of the mold. Fortunately, the error should result in a gap fit rather than an interference fit, in theory.

Still, if you should find a more accurate method, I'd be very interested in seeing it.

Regards.

[BMiller63]

Okay, here you go.
Fingers crossed, this one is what your're after.
It required me to use the existing Top Loft surface in the parting line stitch rather than creating new patches, then it worked like a charm. Took a bit of trial and error to figure that out, though.
Hope this helps.

[chipwitch]

Not exactly what I was going for. Rather, it's half of what I'm trying to accomplish. Your suggestion is essentially what I ended up doing... the only solution I could come up with. Technically, it will work, but it's not very satisfactory due to the fact that the half's counterpart has to be created by the same method. In other words, take the bottom loft and stitch to copies of the inside and outside patches (or create two new ones altogether using the loft edge as you did... which IS better). But, as I understand it, stitching doesn't fill gaps with patches, it cinches up two edges. That's why the lines being stitched are required to be the same size (citation: help docs). When the lines are cinched, they are usually altered a bit. So, when you try to introduce a third line into the same stitch, it pukes. Leastwise, that's my best guess.

If that is in deed the case, then this method will produce two halves that are not a perfect match. The mating surfaces may have gaps or worse, intersections. Neither situation is desirable in a mold. The result is inexact in a world (of CAD) where precision is typically carried out 8 or more decimal places.

Nevertheless, I ran the part on the mill this morning, using this very method. I won't know the exact variance between the two parting lines for a couple hours. But, if you think about it, you'll realize that the parting line, in my two half mold (A/B) is comprised of two nearly identical parting lines. In my way of thinking, there simply HAS to be a way to create a single parting line that can be used to create both halves. If the variance is less than .0001" then no problem, but stitching the surfaces in my drawings have resulted in tolerances in excess of .1" If stitching shifts my edges even .005" and both sides of the mold do that in the opposite direction, the gaps they leave will be unacceptable.

Anyway, thanks for trying!

Regards.

[ROBTRONIX]

> {quote:title=chipwitch wrote:}{quote}

> That being said, I have found some occasion to where UCS are great time savers. but it isn't often. Once was on a rotary tool called an indexable end mill, if you know what that is. Little carbide "inserts" are placed at intervals around the end mill. Each insert is tilted in two axes and were easier to tilt and adjust later, in their own UCS rather than calculating the angles from the origin. The UCS's make it much simpler in some situations. And primarily, where you aren't sure of the exact location of a component, by shifting the UCS, all sketches referencing that UCS move with it. Works great for fine tuning a components position. If you ever run into a situation where the geometry of your drawing starts getting too complex, think about ways you might incorporate UCS's.



I'm curious as to how you work this technique. I work in cutting tools myself, but have not tried working with the UCS yet.
When you say littlte tweaks are easier using their own UCS what exactly do you mean? Are you positioning the inserts using 3d assembly constraints to the inserts origin planes to get your angles/length/diameter?
I myself use a combination of sketches, surfaces, and work geometry contained in my cutter body to get the positioning. Its easy to constrain an insert edge to sketch lines & planes and tweaks are as easy as adjusting a sketch. Still I am curious as to how others are doing it.

Rob

[ROBTRONIX]

chipwitch wrote:


That being said, I have found some occasion to where UCS are great time savers. but it isn't often. Once was on a rotary tool called an indexable end mill, if you know what that is. Little carbide "inserts" are placed at intervals around the end mill. Each insert is tilted in two axes and were easier to tilt and adjust later, in their own UCS rather than calculating the angles from the origin. The UCS's make it much simpler in some situations. And primarily, where you aren't sure of the exact location of a component, by shifting the UCS, all sketches referencing that UCS move with it. Works great for fine tuning a components position. If you ever run into a situation where the geometry of your drawing starts getting too complex, think about ways you might incorporate UCS's.




I'm curious as to how you work this technique. I work in cutting tools myself, but have not tried working with the UCS yet.
When you say littlte tweaks are easier using their own UCS what exactly do you mean? Are you positioning the inserts using 3d assembly constraints to the inserts origin planes to get your angles/length/diameter?
I myself use a combination of sketches, surfaces, and work geometry contained in my cutter body to get the positioning. Its easy to constrain an insert edge to sketch lines & planes and tweaks are as easy as adjusting a sketch. Still I am curious as to how others are doing it.

Rob