1-Visitor

Question

Domed surface

Forum|Forum|3 years ago
July 26, 2022
8 replies
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Hi all, i have been trying to create a domed surface from this flat surface. I need to maintain the outside shape & draw the surface up towards the centre about 5mm up ideally with a single arc. The outside profile cannot lift off the datum on which it sits. The flat surface does not have to be used, i just figured there might be some way of pulling/dragging or distorting it using warp or free form surface manipulation but i have not managed to, thus far. I have tried boundary blend too but cannot achieve the flawless surface i require. Any ideas?

John

tbraxton

22-Sapphire II

If the shape you posted in the picture represents the boundary of the surface on a plane then you can not "dome" that using a single arc of constant radius. Can you sketch a view of what the 3D "domed" surface should look like? With a 3D representation of the goal I may be able to offer some options.

kdirth

21-Topaz I

This is a swept blend to point tangent to "rim" and smooth at top. To get the best surface, the sharp points needed to be excluded. A more controlled version could be made with a revolve. If you are looking to loft it to the outer edges, the result will be much "dirtier" with the varying perimeter and sharp points.

There is always more to learn.

Patriot_1776

22-Sapphire II

Hey John. I'd try this approach, it gives you curvature continuous (instead of merely tangent) to the flat outer rim, AND it gives you drag handles in the boundary blend to adjust your tangency to the rim and to the datum plane at the top. If it has to be a defined radius, then this wouldn't work. BUT, for that you could revolve the top and connect them with a boundary blend and then adjust the curvature as needed. I've included both models and the image is from the -01 model with the entire dome as a B/B and not the defined radius. Have fun!

1_2022-07-26_johns_dome-01.zip

Patriot_1776

22-Sapphire II

Actually these was some weird glitch with the B/B on the first -02 part, this one works better, the drag handles in the B/B actually work now.

1_REVISED-2022-07-26_johns_dome-02.zip

J

John.Pryal

Author

1-Visitor

Thank you for the replies. I have attached a model which better shows what i am trying to achieve. I am reasonably happy with it but i realise it could be better around the indent.

John

1_prt0002.zip

P

pausob

19-Tanzanite

Since I tried it, might as well share this approach:

1) basic shape

2) old-school radius dome feature:

3) edges need to be flat, so overbuild

4) add variable-section Sweep:

Sweep is surface with a cross section that of a single spline, with curvature on the dome side and tangency on the end of the flat ledge side:

5) Solidified result:

5) Reflection analysis:

tbraxton

22-Sapphire II

As @pausob has mentioned a radius dome and you have asked about "pulling" the surface I will mention some hidden feature creation tools in Creo. These are legacy Pro/E features. There are several that may be useful in this exercise. It will depend on how much direct control you need on the resultant topology. The Push, and both dome options have potential applications here.

Set this config option to access all of the features in the all commands list below.

allow_anatomic_features configuration option yes

Several advanced features are available to deform or alter (tweak) the surface of a part:

•Local Push—Deforms a surface by pushing or pulling on a circular or rectangular region of a surface.

•Radius Dome—Creates a dome on a limited region of a surface.

•Section Dome—Creates a dome from sketched sections.

•Ear—Creates a protrusion that is extruded along the top of a surface and bent at the base.

•Lip—Creates a lip on selected edges that can be used for interlocking parts. This feature cannot be created as an Assembly feature, but the dimensions on mating parts can be controlled through relations.

•Toroidal Bend—Bends a selected solid, surface, or datum feature in two directions to produce a toroidal or revolved shape.

•Spinal Bend—Bend an object about a curved spine by continuously repositioning cross sections along a curve.

•Solid Free Form—Tweaks a surface by dynamic manipulation.

•Bend Solid—Bends solids or curves using the references of a flatten quilt feature.

•Flatten Quilt—Flatten surfaces by transformation.

Patriot_1776

22-Sapphire II

I think PTC should revive and expand on some of these great old features, ESPECIALLY N-sided Mesh

Patriot_1776

22-Sapphire II

Hey Paul! I took your .igs file and played with it a bit. From what you did, there's a couple things you can try. It's kind of hard to reverse-engineer something without knowing what it's SUPPOSED to look like (i,e, is the CAD model actually what is REALLY desired, or just someone's stab at it?). So, I did it one way in the -04 model (as if you swept a constant arc out of the dome), but then something completely different in the -05 model (pictured in green - my fave) that ended up pretty smooth but a little different towards the bottom. Yours in is grey in the upper right Anyways, this was a kinda fun diversion, thanks!

2022-08-02_johns_dome-05.prt