Remnants after boole cut is made.

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 From:  nycL45
3217.1 
Happy New Year!

I made a threaded section, inserted a core and boole unioned them. After using a straight line to cut to size, there are rough edges. The threaded section is small.

All the parts are in the file, turned off.

I thought Moi's screw process to be v. easy; but maybe I missed something.

Thanks.

Leonard

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 From:  Michael Gibson
3217.2 In reply to 3217.1 
Hi Leonard, when you see things like that it usually means that there is a bad configuration of trim curves on the resulting object.

Something like the trim curves are self-intersecting (crossing one another) rather than having a clean arrangement.

Your object is probably getting to be of a little bit too small scale here, I notice that some of the pieces are a little wiggly - this is likely happening because you are approaching too closely to the default 0.001 fitting tolerance.

Also normally it is actually not a very good idea to model individual screws that are going to be part of a larger object.... It just adds such a tremendous amount of weight to your model it is usually better to make threads with a texture map in your rendering program rather than trying to actually model the threads individually, especially if there will be many of them.


I'll see if I can find out anything else by taking a closer look at your objects.

- Michael
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 From:  Michael Gibson
3217.3 In reply to 3217.1 
Hi Leonard, so your profile for your sweep is quite small in size, you may want to scale all this stuff up by 10 times so that you are not working on sweeping such a small object that is getting close to the 0.001 fitting tolerance.

But that does not seem to actually be the main cause of your problem - it seems that your threads you created actually runs into itself:



The booleans cannot process objects that have pieces of their surfaces running into themselves, I think you need to have some more space there so that you don't create that kind of self-intersecting object in order for the booleans to work properly.

- Michael
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 From:  nycL45
3217.4 In reply to 3217.2 
Hi Michael,

The screw is one of two set screws on the front of a Bauhaus clock that hold the faceplate. I thought its size might be contributing to the rough edges. That said, typically set screws are about this size.

If you have not looked, I included in the file the thread profile and helix used as well as the center core.

I can eliminate the threaded section and be careful with close ups in that area.

Thanks.

Leonard
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 From:  Michael Gibson
3217.5 In reply to 3217.4 
Hi Leonard, I think we may have posted those last messages at the same time, so you may not have seen my other reply above where it seems that your thread object is self-intersecting which will tend to cause problems with booleans.

I'll try to make slightly different version to show you what I mean.

- Michael
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 From:  nycL45
3217.6 In reply to 3217.3 
I just received your update.

That is interesting. When I created the thread profile I made it so the legs extended half way between the helix cycle so there would not be a gap. I will cut the profile legs back a bit. I will also scale up.

Thanks.

L.
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 From:  Michael Gibson
3217.7 In reply to 3217.4 
Hi Leonard, check out the attached model - it should now boolean for you properly and give you a clean cut.

I scaled it up by 10 times in size - you can scale it down again if you need to have the final model smaller, but really the key thing is that when I created the sweep I made sure it did not run over top of itself and had some clearance here:



- Michael

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 From:  Michael Gibson
3217.8 In reply to 3217.6 
Hi Leonard,

> When I created the thread profile I made it so the legs
> extended half way between the helix cycle so there would
> not be a gap.

That could be good if it was like 2 separate objects that were meeting up and then would be joined together.

But having a closed object kind of skim along its own self like that creates ambiguity in the intersection calculations.

- Michael
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 From:  nycL45
3217.9 In reply to 3217.8 
I enlarged everything 10X and adjusted the profile and presto!

Edit: Added pic of the clock. You can see the two screws on the front. The width is 8"+.

Thanks for the help, Michael.

L.

EDITED: 2 Jan 2010 by NYCL45

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