# Union Failure - Boolean Error

**URL:** <https://discourse.shapr3d.com/t/union-failure-boolean-error/38458>\
**Category:** Modeling Questions\
**Created:** [June 20, 2025, 6:36am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458 "2025-06-20T06:36:25Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![KiwiPete](https://avatars.discourse-cdn.com/v4/letter/k/8baadc/32.png) [@KiwiPete](https://discourse.shapr3d.com/u/KiwiPete)\
**Post date:** [June 20, 2025, 6:36am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/1 "2025-06-20T06:36:25Z")

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Hi - I have a problem with the Union Command. I have two overlapping bodies which I want to turn into one body. Every time I use the Union command, I get a Boolean Error (not sure what that means). I have checked out various online threads and the theme seems to be to make sure the surfaces touch of overlap - I went for overlap. Any suggestions? Cheers Pete

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**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 6:42am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/2 "2025-06-20T06:42:41Z")

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Hard to say anything not seeing your project. Can you share the one you have problems with?

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**Author:** ![KiwiPete](https://avatars.discourse-cdn.com/v4/letter/k/8baadc/32.png) [@KiwiPete](https://discourse.shapr3d.com/u/KiwiPete)\
**Post date:** [June 20, 2025, 6:48am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/3 "2025-06-20T06:48:09Z")

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Thanks - a screen shots:  
Body 1:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/e/4/e460801659c58556fb25d15d53c60a37102da8d0.png)

I want to “Union” this body with the other one in the shot. The clearly overlap.

I want to make them one body…Thanks for your help.  
Cheers Pete

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**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 6:54am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/4 "2025-06-20T06:54:36Z")

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Can you share the file so I can look closer?

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**Author:** ![KiwiPete](https://avatars.discourse-cdn.com/v4/letter/k/8baadc/32.png) [@KiwiPete](https://discourse.shapr3d.com/u/KiwiPete)\
**Post date:** [June 20, 2025, 6:55am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/5 "2025-06-20T06:55:24Z")

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yes- how do I do share the file?

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**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 6:57am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/6 "2025-06-20T06:57:46Z")

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Also, a question: how are you selecting these bodies? In your screenshot, it looks like you’ve selected not only bodies, but also a sketch. If you’re trying to union bodies with sketches, nothing will work 🙂

So first of all, try hiding everything except these two bodies. Then select the entire body — not just one face — and try to union them.

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**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 6:59am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/7 "2025-06-20T06:59:17Z")

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> [@KiwiPete](#):
>
> yes- how do I do share the file?

As a new user you cant send files here, but you can send it to me as a private message or send to my email [shapr3d@tsbl.net](mailto:shapr3d@tsbl.net)

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**Author:** ![KiwiPete](https://avatars.discourse-cdn.com/v4/letter/k/8baadc/32.png) [@KiwiPete](https://discourse.shapr3d.com/u/KiwiPete)\
**Post date:** [June 20, 2025, 7:06am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/8 "2025-06-20T07:06:49Z")

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> [@Xdrakosha](#):
>
> [shapr3d@tsbl.net](mailto:shapr3d@tsbl.net)

thank you - project emailed. Cheers

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**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 7:13am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/9 "2025-06-20T07:13:43Z")

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> [@KiwiPete](#):
>
> thank you - project emailed.

Yep, I see where is your problem.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/8/f/8f21f1012f61d211759671af0fc9e9e0eca1d7f5.jpeg)

As you can see, the two bodies are touching at only one edge. This kind of connection will create a malformed object, so it’s not allowed in Shapr3D.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/5/d/5d1ea3fbfc5f864a3470c10ac38ffa544c3fd0c0.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/0/8/085e586f9276716f46d479986734c54ea32a574b.jpeg)

You can use the Replace Face tool to connect them properly.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/5/8/58ddf0b5afdecfa563f6278b30d21acb6d7f4fbb.jpeg)

After that, they will unite without any problems.

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<div class="post-metadata">

**Author:** ![KiwiPete](https://avatars.discourse-cdn.com/v4/letter/k/8baadc/32.png) [@KiwiPete](https://discourse.shapr3d.com/u/KiwiPete)\
**Post date:** [June 20, 2025, 7:14am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/10 "2025-06-20T07:14:06Z")

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thanks - tried hiding everything and then running Union - no joy… Cheers Pete

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<div class="post-metadata">

**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 7:16am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/11 "2025-06-20T07:16:12Z")

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Or you must disconnect them in this area

 ![image](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/d/e/dea61650d08cd2cfb908e8bcc63d97c31070dc6a.jpeg)

That will also work.

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<div class="post-metadata">

**Author:** ![Xdrakosha](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/xdrakosha/32/24881_2.png) [@Xdrakosha](https://discourse.shapr3d.com/u/Xdrakosha)\
**Post date:** [June 20, 2025, 7:19am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/12 "2025-06-20T07:19:41Z")

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I cant send you .shapr file back, you wont be able to open it after me, but here is the result in .step

[Launcher Top Plate (with gap).step](https://discourse.shapr3d.com/uploads/short-url/lob7ws2ojPmm2rBx2jVL6zGzwqM.step) (202.4 KB)

[Launcher Top Plate (merged).step](https://discourse.shapr3d.com/uploads/short-url/tgdO4IuKn1zdBlfbgpDNqFy83ZU.step) (202.4 KB)

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<div class="post-metadata">

**Author:** ![KiwiPete](https://avatars.discourse-cdn.com/v4/letter/k/8baadc/32.png) [@KiwiPete](https://discourse.shapr3d.com/u/KiwiPete)\
**Post date:** [June 20, 2025, 7:27am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/13 "2025-06-20T07:27:00Z")

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thank you for your help - I shaved 0.1mm off each face that had a touching line and then it worked…!

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<div class="post-metadata">

**Author:** ![Bad\_at\_Cad](https://avatars.discourse-cdn.com/v4/letter/b/a88e4f/32.png) [@Bad\_at\_Cad](https://discourse.shapr3d.com/u/Bad_at_Cad)\
**Post date:** [June 20, 2025, 9:04pm UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/14 "2025-06-20T21:04:50Z")

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I feel your pain-- if I had a nickel for every time I got “boolean Operation Failed” at the top of the screen, I’d be a rich man indeed.

Sometimes Shapr3 has a “Shapr tantrum” and won’t go through with a command. Sometimes it will tell you what the issue is-- but not how to correct it-- and other times it will just say “error” as in the case with booleans and union.

You mentioned overlapping-- actually, the Union tool does give a specific message if that’s the issue-- it will usually say something like “bodies can not be united because they don’t intersect”.

So if you’re not getting that message, it might be something else going on.

I find with the boolean that it has to do with stuff going on beneath the faces of a body-- like if you already did multiple operations, even though the part looks good cosmetically, and the faces are all good, there’s some weird internal geometry or something that prevents the Union command from working.

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**Author:** ![SCALEMODEL](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@SCALEMODEL](https://discourse.shapr3d.com/u/SCALEMODEL)\
**Post date:** [June 21, 2025, 5:56am UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/15 "2025-06-21T05:56:59Z")

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Boolean either works or doesn’t work not sure what other information the feature can give?

In the forum I solved some funky boolean issue and 100% of the times it was just not touching. But issue is noticeable during closer inspection by zoom or section view.

My Fav Union issue:

> [@Boolean operation failed after Union](https://discourse.shapr3d.com/t/boolean-operation-failed-after-union/36028):
>
> Have seen several different occurrences of this topic, but still I can not figure out what I’m doing wrong. Could someone have a look at the attached video and perhaps offer some suggestions. Much appreciated. I’m trying to make a boat hull wink

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**Author:** ![Oregonerd](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/oregonerd/32/8012_2.png) [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)\
**Post date:** [June 21, 2025, 3:25pm UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/16 "2025-06-21T15:25:42Z")

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Used to be, in the author of this thread’s case, it warned you of a “non manifold body”. To which we all had to look that up… 😄

‘What the F… is a Non Manifold Body???’ (freshly pulled out hair on the keyboard) 🤣

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**Author:** ![Oregonerd](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/oregonerd/32/8012_2.png) [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)\
**Post date:** [June 21, 2025, 3:27pm UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/17 "2025-06-21T15:27:35Z")

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Also sometimes change the order of the union solves it.

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<div class="post-metadata">

**Author:** ![SCALEMODEL](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@SCALEMODEL](https://discourse.shapr3d.com/u/SCALEMODEL)\
**Post date:** [June 21, 2025, 3:35pm UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/18 "2025-06-21T15:35:24Z")

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😂 like you pointed out even more detailed error messages can confuse you even more.

ERROR: Lookup what NON Manifold is.

ERROR: Change order of UNION.  
I would be like what?  
Whats the correct order?  
Shapr AI CHAT!  
Tell me union order.  
Shapr AI CHAT: union part 1 with part 3 first and union part 2 after.

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<div class="post-metadata">

**Author:** ![Oregonerd](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/oregonerd/32/8012_2.png) [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)\
**Post date:** [June 21, 2025, 3:48pm UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/19 "2025-06-21T15:48:35Z")

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There is no order per se… however I have found that the order in which you select the items to be added or subtracted can make a difference in success or failure. I was having a hell of a time with the union tool on nameplates. Some letters just wouldn’t join the group. most of the time selecting those letters first, or in combination with other letters would solve it. Quite often actually. I made quite a few nameplates. [Seasonal nameplates for my gal](https://discourse.shapr3d.com/t/seasonal-nameplates-for-my-gal/29327)

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<div class="post-metadata">

**Author:** ![SCALEMODEL](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@SCALEMODEL](https://discourse.shapr3d.com/u/SCALEMODEL)\
**Post date:** [June 21, 2025, 3:54pm UTC](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458/20 "2025-06-21T15:54:44Z")

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What you described came with experience of using the app over time.

I would prefer not to be flooded with error messages, dialog boxes, and the current trend of turning everything into chatboxes.

[Next page](https://discourse.shapr3d.com/t/union-failure-boolean-error/38458.md?page=2)