How to create a mold from a step file with many bodies

[Anonymous]

Hi there,

I'm trying to make a mold out of a step file of a PCB. Each component is being interpreted as a body, with even the individual legs of the integrated circuits being recognized as bodies. By making a cube that overlaps the PCB, selecting every body in that PCB and doing Combine -> Cut it gives the following error:

Error: There was a problem combining geometry together.
If attempting a Join/Cut/Intersect, try to ensure that the bodies have a clear overlap (problems can occur where faces and edges are nearly coincident).
Failed to Boolean bodies together

How can I fix this issue?

[jhackney1972]

Please attach your STEP file.

[mango.freund]

Hello, the error message says, the smallest bumps prevent the almost perfectly fitting surfaces can be brought together. So you have to extrude these surfaces a little or replace them with surfaces to connect them to one another.

[Anonymous]

Here's the step file

[jhackney1972]

I messed with your file for a few minutes and decided it was not worth trying to get it to join into one body.  Besides being gaps between individual bodies, your model consist of a good quantity of surface bodies as well.  You did not say where this model came from but maybe if you have access to the original the STEP was made from, you could export it again as a solid body.  

[Anonymous]

This was exported from Altium, I tried different ways of exporting, still get the same results every time... I just can't get a single solid body to come out of it so I can proceed with what I want to do from there on out.

[jhackney1972]

According to this page from Altium support site, this is the option you want to use, at least the way I read it.

[Anonymous]

The step file I sent you was exported with that option enabled. It still does the same thing ... I have used every option possible in multiple files and still gives the same output. Is there any other way of doing this ? I just need an envelope around the PCB so that a mold can be made

[TheCADWhisperer]

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@Anonymous wrote:

By making a cube that overlaps the PCB, selecting every body in that PCB and doing Combine -> Cut it gives the following error:

How can I fix this issue?

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What is the purpose of this "mold"?

Do you want it to fill the volume underneath each one of these chip legs (and other locations)?

[jhackney1972]

If all you need is an envelope of the area the complete circuit board will perfectly fit in, then that is easy.  In the Screencast you can see my method.  If you wish to add any size to it, simple dimension the original rectangle to be larger and add to the two directions of the surface command.  You can leave the bounding box envelope as a surface or make it a solid body.  You can use this body to create your mounting enclosure or whatever other purpose you desire.  Model is attached.

[Anonymous]

Hi John,

Thank you for the help. Maybe envelope was a wrong term, since what I want is to be able to create a body with cavities for each component, like the one in this video: https://youtu.be/vKZx9eHEL6o?t=168

That is a two-part mold, I only need the top part which is where the components are. I assume that for this method (combine->cut) the PCB needs to be one body and the mold another body and you just cut the first from the second one. But maybe there's an alternative and that's why I called it an envelope. But it should be tight to the board and the components. More like a shrinkwrap.

[Anonymous]

Hi there,

No, the purpose is not to fill the space below the components. The purpose is to create a jig for through hole components. So you place all the through hole components, put the mold on top, rotate the board, the mold keeps the components in place and you solder them on the under side of the PCB.

[TheCADWhisperer]

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@Anonymous wrote:

 So you place all the through hole components, put the mold on top, rotate the board, the mold keeps the components in place and you solder them on the under side of the PCB.

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I am perplexed as to why you did not include this information in your original problem description?

How did you think Combine-Subtract would magically handle all of those cavities under chip legs and the connectors.

The solution is doable but requires an understanding of the true nature of the intent.

A bit of clearance is needed to get it over the thru-mount components and it need only go to the board in a 3 or 4 open locations.  I will see if I see if I can work something up but I have other work to complete first.  (I nearly had this done yesterday - but I didn't understand your True Design Intent and discarded my work.)

[mango.freund]

follow the instructions and later connect the different hollow bodies with a bridge. greetings mango

[TheCADWhisperer]

@Anonymous 

See Attached.

If you make it too tight - will not be able to place over all components.

It should not go all the way to the board to permit some clamping pressure to hold components tight against board for soldering.

You might chamfer the edges of the cavities to aide in placement over the components.

Some cavities are quite close to the edge - so perhaps you should make it a bit wider than the board.

[Anonymous]

But how did you do it?

[TheCADWhisperer]

How much Fusion training/experience do you have?

All is recorded in the Timeline.

Extrude stock block.

Sketch the cavity profiles.

Extrude-Cut to Vertex of component (then hide the board assembly so that it doesn't cut those components).

OK

Unhide the board assembly and repeat.