Full Version: Joining failure

Hi.

I have two elements but, try as I might, I can't get them to boolian join together. What am I doing wrongs please. I'm a newbie at CAD obvs!

Thanks

Gordon.

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Trying to upload the file, but it's 10Mb and keeps throwing it out....

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Hi Gordon, are you just selecting everything and trying to join it? With multiple separate parts that are touching each other that can be confusing for the joiner to be able to figure out which surfaces are supposed to belong to an individual part. So you may need to select just the surfaces for one individual part at a time to join.

If you zip up the file does it shrink enough that you can upload the zip file? If not then you could use a file sharing service like Dropbox or Microsoft One Drive and upload your file there and share a link to it here.

- Michael

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OK. Thanks. Try this link - https://we.tl/t-vOXJSmJyb0

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Hi Gord, what is it that you are trying to achieve by combining these objects together?

From what I can see I would recommend keeping them as separate objects, because there are numerous areas like this where 2 solids touch each just along a common edge:





That's similar to trying to combine 2 boxes like this that only touch at an edge:



But CAD programs are not designed to have a single solid object that is arranged in such a manner, something like that should be 2 separate objects rather than attempted to be combined into one single booleaned together piece.

- Michael

Image Attachments:
gord_boolean1.jpg  gord_boolean2.jpg  gord_boolean3.jpg 

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OK. It is all to be SLA printed, will this effect anything then?

Thanks

G

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Hi Gord, yeah unfortunately that makes things pretty complicated. 3D printing also will not like to have that type of what's called "non-manifold" structure where you've got 4 surfaces coming off of one edge instead of just 2 surfaces at any one edge.

You'll probably need to redesign this to make it structured properly for both booleans and 3D printing, you would want those areas to be pushing through each other a little bit more like this:



rather than having them just exactly touch like you've got now.

If you weren't 3D printing it you'd probably want to keep those things as separate objects but if you're 3D printing you are going to want get things combined but it will need some amount of overlap.

- Michael

Image Attachments:
gord_boolean4.jpg 

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OK, so I need to go through the whole design and push some of the joints together. I have many parts that have been boolian joined, along whole faces. I take it that this will be OK? It's just the edge to edge joints that need looking at then?

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Hi Gord, well those look like the main things that just won't work at all. But there are also some areas where things are just off alignment by a small amount which may cause some problems with little slivery gaps or very small excess surfaces. Probably the 3D printing slicer is not going to like that kind of thing either.

Here's an example of that kind of thing:





Those pieces have a gap between them of only 0.0067 mm, it is kind of likely that your 3D printing slicer software is going to consider those to be badly formed areas that are intersecting each other and may not be able to figure out a clean slice through there.

It's not good in general to have such small gaps when doing 3D printing.

- Michael

Image Attachments:
gord_boolean5.jpg  gord_boolean6.jpg 

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Many thanks. Looks like I'll have to go through it with a fine tooth comb then! Is there any way I can quickly find tiny gaps, or do I need to totally reassemble the whole thing again. Fortunately, I saved some of it before joining it together, unless there is also a fix for unboolianing (a verb I have previously never used before!) the sections?

Tx G

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Hi Gord, there isn't really any way other than zooming in and inspecting things closely.

re: unboolean - it is possible to separate surfaces from the main piece by using Edit > Separate on them and then doing things like using "untrim" to erase trim curves. But you'll be working at the surface level for that it's not quite the same thing as an "unboolean" exactly. There is a tutorial on that kind of surface level repair work here though: http://moi3d.com/forum/index.php?webtag=MOI&msg=446.17

- Michael

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Hi Gord,
If you want to 3D print that model "as is" I would say just select everything and export it as STL.
I found this workaround OK as long as you won't split your object in slicer program.
I've had hard time combining complex objects and if I export everything selected, slicer program accepts it as one object.
I use slic3r PE and it works fine.
However I recommend to check layer preview before hitting print.

Juraj

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I have gone over everything again and it is now joined up. I have saved as .STL and am sending a test piece off to the print company for their comments.

Thanks!

Gordon

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Just a thought
You can try not joining your parts and export the stl file with all of the components , I find that if they are touching or intersecting each other it should print.
I find unioning parts sometimes generates errors
Also Un unioned models are easy to change later if there any problem parts
cheers
shayne

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