topic Re: 3D Printing how to remove material from all surfaces? in Inventor Forum

3D Printing how to remove material from all surfaces?

roncruikshank3996 — Thu, 10 Feb 2022 04:29:01 GMT

Hi,

I need to have a part 3D printed. I have found that for parts to come out reasonably to size that I need to essentially remove 0.15mm from all surfaces. So outside dimensions become smaller and inside dimensions become larger.

If I shell the part the resulting cavity is what I want. How can I obtain a solid model of the cavity or otherwise achieve the result I need?

Thanks,

Ron

Re: 3D Printing how to remove material from all surfaces?

James_Willo — Thu, 10 Feb 2022 06:34:05 GMT

Hi Ron, it depends on the complexity, but one way to do this is to use the thicken command. You can add or subtract material with that.

Re: 3D Printing how to remove material from all surfaces?

roncruikshank3996 — Thu, 10 Feb 2022 07:17:40 GMT

Hi James,

Thanks heaps for that, It worked well for one of my parts. The other will need more work as it didn't like it. It has a pattern of features so will do the thicken before the pattern and see.

Cheers,

Ron

Re: 3D Printing how to remove material from all surfaces?

James_Willo — Thu, 10 Feb 2022 07:38:18 GMT

Another option might be to use delete face.

Delete a face, maybe the base face?

This will turn it into a surface part.

Use thicken to make the part a single thickness.

It all depends on the complexity of the geometry.

Re: 3D Printing how to remove material from all surfaces?

tomasz.sztejka — Thu, 10 Feb 2022 12:39:23 GMT

If it is an FDM print make sure You have a correct extrusion multiplier. Too large multiplier causes an excess of material to be pumped up and thicken the outline. Also make sure to print external perimeters first.

If it is not the case select from a selection tool "Select faces and edges" and drag mouse over Your part selecting all faces. The use "Thicken/Offset" to move surfaces to Your liking inside a material.

If thicken fails (which it often do) You may try a bit more complex approach using "shell".

First use "Rectangular pattern" to create a copy of Your solid body

This way You should now have two solid bodies, identical.

Then use "shell" command with "solids" to select one of solids.

Then use "Combine" tool selecting non-shelled body as "base" and shelled body as "tool". Choose "cut".

Click ok and viola, it should be now working.

Re: 3D Printing how to remove material from all surfaces?

roncruikshank3996 — Fri, 11 Feb 2022 07:39:41 GMT

Hi James,

Thanks for your leads. I have never needed to get into the surfacing areas of inventor, so know nothing about it. Your ideas worked for the more complex one: -

Model normally with normal finished sizes.

Then use DELETE FACE to delete a face such as the base face. This turns the solid into a surface.

Now use THICKEN selecting FACE and the direction required. Set the distance to how much you want taken off all surfaces (0.15mm). This will create another surface offset by 0.15mm.

Now use PATCH and select the edge of the inner surface. This creates a "base" surface again.

Now use STITCH to stitch the patch to the inner surface. This should create a solid again with 0.15mm removed from all surfaces.

Now select DELETE FACE again and select SELECT LUMP OR VOID. Select the outer (original) surface. You should now be left with a solid that is sized such that 0.15mm has been removed from the original solid.

At least that is what worked for me.

Thanks again for your help.

Re: 3D Printing how to remove material from all surfaces?

roncruikshank3996 — Fri, 11 Feb 2022 08:39:06 GMT

Hi Tomasz,

That sounds a simple way to do it and should work well. However I found that when using combine with the unshelled solid as the base solid and the shelled solid as the toolbody and using "cut" that I received an error to the effect "operation did not change the number of faces and the model may not be changed..." or something like that. I could not get around this problem. The shell worked properly and the unshelled solid was just that...solid. So cutting the shelled one from the solid one should have worked beautifully and I don't know why it didn't. I have been too busy to update from v2019! maybe it's an issue with Inventor 2019?

Thanks very much for your input.

Ron

Re: 3D Printing how to remove material from all surfaces?

roncruikshank3996 — Fri, 11 Feb 2022 08:47:44 GMT

Hi Tomasz,

I have never used a 3D printer before so unaware of "extrusion multiplier" The printing is done on a FDM type printer. All I know is that I had some mating parts made using the normal finished size models to create the .STL file and they would not fit. It seemed that they had about 0.15mm excess all over. When I changed the model to effectively remove 0.15mm from all faces the fit turned out quite good. But I needed a more efficient way to remove material from all surfaces and your way sounds great but for some strange reason I is not working for me. Any help appreciated!

Thanks,

Ron

Re: 3D Printing how to remove material from all surfaces?

tomasz.sztejka — Fri, 11 Feb 2022 13:01:34 GMT

If You are not experienced with 3D printing I do really recommend to prepare some test shapes and try how different parameters do influence the print size and surface quality. It is really worth doing even if You will have to spend a day or two on it. Remember 99% of printers on the market do work in "open loop" control mode, so some tweaking is necessary even from a roll of filament to roll. Especially when You use FDM printer with 0,4 mm nozzle hole diameter to print something down to 0,1mm dimensional accuracy.

The only error which, from my experience, is necessary to be corrected in 3D model is a hole size which is affected due to strong the curvature of the extrusion track. Most of slicing software I tried do not have a "curve compensation" so the holes tends to be one track width smaller in diameter than planed. Using derived parts to correct it is a right path to go.

If You really need to modify 3D model I would also suspect that sooner or later You will have to play differently with horizontal and vertical dimensions so maybe using the thickening of all surfaces is not the right way to go.

Somehow I am not surprised that the method I have shown does not work for You. Honestly I was surprised it worked, because I had a lot of struggle with thickening. The subtraction of the shell however should work, because the creation of the shell is the most complex job. Inventor is usually throwing out such a message when the operation is directed in an incorrect way. For an example if You try to extrude a hole towards outside of a material. Are You sure, You have created the shell inwards, not the outwards?

This is a frequent case for an Inventor to just not work as advertised. I don't think that upgrade would do You any good. I made a "jump" from 2010 version this year to 2021 and I must say I don't see any improvement worth the subscription price. I can't help You any more in this area.

Re: 3D Printing how to remove material from all surfaces?

johnsonshiue — Fri, 18 Feb 2022 14:27:31 GMT

Hi! To simplify geometry using Delete Face, you need to check "Heal" option. This helps re-intersect adjacent faces. When the options is off, Delete Face will turn a solid into a surface.

Many thanks!

Re: 3D Printing how to remove material from all surfaces?

johnsonshiue — Fri, 18 Feb 2022 14:32:30 GMT

Hi! Regarding making the model smaller, you may consider rescaling the model. You may use Direct Edit -> Bodies -> Scale. Or, derive the part as another part (start a new part -> Derive -> pick the old part) and set the scale factor.

The exact scale factor to use may need a little bit trial and error to get to 0.15mm.

Beyond that, Inventor has limited ability to assist 3D Printing. I suggest you may want to look into Fusion 360. It has a dedicated Mesh Modeling environment and other tools to assist 3D Printing.

Many thanks!