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PRP  
#1 Posted : Monday, October 22, 2018 5:55:22 PM(UTC)
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Hello,

It would be very helpful to have a wall thickness tool for parts that are to be molded.

Maybe a flag or indicator for the region of the part could be available!

Best,

PRP
rockyroad_us  
#2 Posted : Monday, October 22, 2018 6:52:02 PM(UTC)
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Are you referring to a measuring tool? Just use the measuring tape tool. If you want to know an overall size of the part, you can use the bounding box command. It then tells you the extent of the part.

When you say region, is this some sort of condition you want to set for a thickness? Not sure what the purpose of that will be.
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BillB  
#3 Posted : Tuesday, October 23, 2018 2:43:55 AM(UTC)
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Originally Posted by: rockyroad_us Go to Quoted Post
When you say region, is this some sort of condition you want to set for a thickness? Not sure what the purpose of that will be.


It's for 3D printing, where bureaus set minimum wall thicknesses as a limit on what can be successfully printed
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rockyroad_us  
#4 Posted : Tuesday, October 23, 2018 8:42:21 AM(UTC)
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Well, you said for molding first. Molding and 3D printing are two different things.

The powerpack has a feature called thickness. Maybe that's what you want.
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digitalphaser  
#5 Posted : Wednesday, October 24, 2018 2:58:50 AM(UTC)
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As I understand powerpack print tools are only for analyzing an object. Thickness feature only shows places that are too thin for printing. Not more. @PRP probably means a shell tool.

Indeed shell tool works great with simple forms. But more or less complex objects are an irresistible obstacle for shelling. This applies to all VC's solid utilities.
In 90% of cases it does not work(I mean organic forms not primitives). Often it works with extremely small values. For example 0,1mm. But this is too thin wall for printing. ;)

Edited by user Wednesday, October 24, 2018 3:00:32 AM(UTC)  | Reason: Not specified

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murray  
#6 Posted : Thursday, October 25, 2018 2:50:50 PM(UTC)
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The relationship for successful shelling is wall thickness vs. local curvature, not complexity. Boolean out the region with the most acute curvature and the remainder of the object will shell to a thicker value. Objects can usually be shelled to a thicker value outwards, where their ultimate thickness is governed by their relationships to adjoining faces. In those cases, it's the complexity of their adjoining edges that determine success.
PRP  
#7 Posted : Thursday, October 25, 2018 7:12:32 PM(UTC)
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Hi All,

Sorry to be late in response to your thoughtful comments. I am referring to molded parts. I do many 3D prints in the prototyping phase, but my wall thickness issues are with the molding process.

Plastic injection molded parts typically have a specified wall thickness. Where the thickness is reduced, the hot plastic melt has a higher resistance to flow and can result in thinner areas where the mold is not completely filled, and even voids where plastic never actually flows into that part of the mold.

Where the walls are thicker (effectively at wall junctions, etc.) the plastic takes longer to harden and typically results in 'sinks' where the cooling plastic shrinks and causes a dimple on the outer side of the wall.

So it is important to strive for constant wall thickness which also helps in the reduction of cycle time.

It is difficult to design constant wall thickness in very complex 3D parts. The tray image attached has complex traps designed to quickly capture pills to deliver exactly 7 pills into a weekly pill organizer. The design of those areas is messy, much too complex for the Thicken Wall tool.

The second image is a wall thickness tool at Shapeways. It shows that my part has some areas that are thin with respect to 3D printing standards, and what I am requesting in ViaCad is a similar tool but would hopefully indicate thickness throughout the part, probably a color display. If a central surface were generated, distances from all points on that surface to the outside surfaces of the part would be very helpful for designing parts to be injection molded.

I haven't found rockyroad's suggested Thickness tool in Powerpack; is that in a Shark version of Powerpack?

I normally use two infinite planes located close together, one rotated 180° and both set as clip planes. Two of these on the left of the object while viewing with two viewport layouts. As the two selected infinite planes are moved up and down, the wall thickness can be viewed. To scan vertically, use two infinite planes above the object and scan horizontally.

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murray  
#8 Posted : Thursday, October 25, 2018 10:46:41 PM(UTC)
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How do you model it if you can't quantify the wall thickness until afterwards?
digitalphaser  
#9 Posted : Friday, October 26, 2018 4:08:03 AM(UTC)
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Originally Posted by: PRP Go to Quoted Post


I haven't found rockyroad's suggested Thickness tool in Powerpack; is that in a Shark version of Powerpack?



This tool is not in Powerpack. Window-->3D Print Tools
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PRP on 10/26/2018(UTC)
digitalphaser  
#10 Posted : Friday, October 26, 2018 4:28:03 AM(UTC)
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Originally Posted by: murray Go to Quoted Post
The relationship for successful shelling is wall thickness vs. local curvature, not complexity. Boolean out the region with the most acute curvature and the remainder of the object will shell to a thicker value. Objects can usually be shelled to a thicker value outwards, where their ultimate thickness is governed by their relationships to adjoining faces. In those cases, it's the complexity of their adjoining edges that determine success.


I think this process can be easier to 3D print. For example. Voxelization ---> Shelling ---> Conversion to Solid.
I don’t think anyone is using ViaCad to develop complex units and machines. The main tasks are a bit easier. Accordingly, the tools can be more flexible. :)

Edited by user Friday, October 26, 2018 4:28:48 AM(UTC)  | Reason: Not specified

PRP  
#11 Posted : Friday, October 26, 2018 8:59:06 AM(UTC)
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Digitalphaser - Thanks! The 3D Print tool does what I needed. From my Shapeways "thin areas" image I was concerned about just how thin...

So with the VC 3D Print tool I set thickness to .020, no region showing that thickness. worked up to thickness 0.035 found the same areas the Shapeways image found. Great tool I hadn't seen before!
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PRP  
#12 Posted : Friday, October 26, 2018 10:03:08 AM(UTC)
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Murray,

ORIGINAL POST: "How do you model it if you can't quantify the wall thickness until afterwards?"

I quantify as 0.050" wall thickness throughout in the following process:

I generate a top surface (see blue profiles in image) according to the desired top 3D shape, using Skin Surface tool.

Then I generate a bottom surface from profiles (see green profiles) that are everywhere 0.050" below and away from the top profiles.

Then I get 8 edges of the two surfaces (Offset Face Edges tool, offset .001") that allow for border surfaces using again Skin Surface. Then I use the Stitch tool to create a solid from the six surfaces.

How do I generate the bottom profiles that are substantially 0.050" from the upper profile you ask? You can't just copy/translate down in 'z' because of the complex 3D shape involved. It's a long involved procedure I can explain if anyone is interested.

All the best,

PRP

Edited by user Monday, October 29, 2018 11:43:29 AM(UTC)  | Reason: Using 050 instead of 060

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murray  
#13 Posted : Sunday, October 28, 2018 8:59:21 PM(UTC)
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Isn't offset the function you want for the curves? It should do what you're doing manually? Another way to generate the solid is by extruding your upper surface downwards in z, the lower surface extruded upwards, the two extrusions intersected.
PRP  
#14 Posted : Monday, October 29, 2018 11:14:21 AM(UTC)
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Hello Murray,

Thanks for your thoughtful suggestions!

The extrude surface tool makes a surface from a curve so that doesn't apply to this problem.

I haven't tried the Mesh Extrude tool.

My top surface has extreme curvature in x and y. The Offset Surface tool theoretically works but is limited to distances less than the local radius of curvature. See the image attached where the green surface is my bottom surface generated with the bottom profiles described in the attached discussion "Bottom Profile Generation" and the grey surface comes from the Offset Surface tool set to 0.050".

The Offset Edges image uses two infinite planes as clip planes (one 180° rotated) to view the distance between surfaces (later to become wall thickness in a plastic part). Here the resulting (limited) offset surface set for 0.050" appears generally 0.010 lower, at a distance of about 0.060. I use the two infinite clip planes to scan throughout the top and bottom surfaces, then another pair above the surfaces to scan horizontally.

I would think this method, though complicated, would be applicable to many plastic part designs.

Cheers,

PRP

Edited by user Monday, October 29, 2018 11:27:27 AM(UTC)  | Reason: Not specified

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Bottom Profile Generation.pdf (1,539kb) downloaded 7 time(s).
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murray  
#15 Posted : Monday, October 29, 2018 7:35:43 PM(UTC)
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No, l meant extrude the surfaces that you've lofted from your curves, PunchCAD extrudes surfaces/faces as closed profiles, the result is a solid with the silhouette of the face/s as the profile, capped both ends with the face/s. Solids made that way can be intersected. You can sweep and revolve surfaces, too, or use them as cutout or protrusion profiles.

Edited by user Monday, October 29, 2018 7:39:11 PM(UTC)  | Reason: Not specified

PRP  
#16 Posted : Monday, October 29, 2018 8:55:20 PM(UTC)
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Murray,

I can't find the tool you refer to. Extrude surface and Offset surface don't apply.

The challenge has been to generate the bottom profiles.

I have attached a small file of reduced width profiles top and bottom, and the resulting top and bottom surfaces. You're welcome to try to generate a bottom surface (say orange) from the top profiles or from the top surface and superimpose it onto the bottom surface (green). I expect it won't match.

All the best,

PRP

Edited by user Monday, October 29, 2018 8:57:37 PM(UTC)  | Reason: Not specified

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rockyroad_us  
#17 Posted : Monday, October 29, 2018 10:15:37 PM(UTC)
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Originally Posted by: PRP Go to Quoted Post
Murray,

I expect it won't match.



PRP


Is your goal to match the profiles? Why not just duplicate the surface? Trying to follow what is the problem.

Originally Posted by: PRP Go to Quoted Post
Murray,

Challenge to generate the bottom surface.


PRP

In the sample provided, you indicated that you widened the profiles. Not only do I see that but also the profiles where shifted so obviously they won't match if that is your goal. When you shift, it is obvious that the peaks of one gets closer to the other peak and the thickness will diminish.

Edited by user Tuesday, October 30, 2018 7:46:45 AM(UTC)  | Reason: Not specified

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PRP on 10/31/2018(UTC)
murray  
#18 Posted : Wednesday, October 31, 2018 4:35:25 AM(UTC)
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Why not make a block that passes through both surfaces and split it (split solid) with both surfaces, delete the parts you don't need? We're both over-complicating this.

Edited by user Wednesday, October 31, 2018 4:41:09 AM(UTC)  | Reason: Not specified

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PRP  
#19 Posted : Wednesday, October 31, 2018 8:48:52 AM(UTC)
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Hello Rockyroad,

You're exactly right. Sorry about my unclear term 'match'. What I mean is matching a suggested bottom surface made somehow, to my green bottom surface made from my bottom profiles.

To clarify directions, see my image of the aqua colored tray of post #7. The 3 axes are shown there and we see very steep gradients in the 'y' direction and also the 'x' direction, and in many regions in both directions at the same spot.

If you just copy/drag down the top surface you get the desired 0.050 thickness in totally flat areas. But in areas with steep gradients in the 'y' direction you need to shift the bottom profile in the 'y' direction. This is seen in your observation of some bottom (green) profiles wrt corresponding top profiles. Where the gradient is negative you need to shift to the right in a right side view, and left if the gradient is positive. Without these shifts the final wall thickness is reduced as you point out.

But we also have steep gradients in some regions in the 'x' direction which requires WIDENING a bottom profile wrt its corresponding top profile, otherwise the thickness of the part will be reduced right in the region where the 'x' gradient is steep. Picture a case where the 'x' gradient along a top profile approaches 90°. Just shifting the top profile down 0.050" in that area causes the wall thickness to approach zero.

See my next post that illustrates this 'x' direction issue.

Thanks for your thoughtful discussion!

PRP
PRP  
#20 Posted : Wednesday, October 31, 2018 11:35:26 AM(UTC)
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Hello Murray,

You mention "Why not make a block that passes through both surfaces and split it (split solid) with both surfaces, delete the parts you don't need?... ."

Your Block Split method works well and results in the same solid as mine using 6 surfaces and the Stitch tool- see image "Block vs Stitch" where gray is your block split and green is my stitch method (I used a block somewhat smaller in x and y than the surfaces) Both methods are uncomplicated. I've attached images leading to the stitch method FYI.

The really complicated thing in all this is creating those bottom profiles. The only way I've found is to use the method described in #14 Posted "Bottom Profile Generation.doc".
I attach here a revision A to that document.

I encourage anyone finding an alternate method to create proper bottom profiles that deal with the steep gradients in 'x' and 'y' directions to share their method. You can demonstrate with file Test Profiles.vcp in #16 Posted.

As a footnote to this fun discussion, where I found some thin wall areas with ViaCad tool: Windows/3D Print/Thickness and the Shapeways image, I just added another top profile over that area, made the bottom profile, and re-did the solid. That solved the problem. I expect my instant slope approximation using 2 neighboring top profiles caused the problem; adding another profile made the slope approximation more accurate. To get the new top profile I used tool Project Curve Surface using a line above the top surface right over the surface leading to the thin wall region.

Thanks for the great discussion,

PRP
File Attachment(s):
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