# Boolean difference surface with polysurface failed

I have a cylinder 1 (139.7mm diameter) polysurface and cylinder 2 (90mm diameter) surface. I want to union those and then adapt / cut the ving to the new shape. Boolean diffrence maybe…
I am sure i do something wrong as usual. Then i wonder how we create a round cylinder from the polysurface and keep the original diameter?
boolean.3dm (4.4 MB)

Hello- the cylinder is an open surface - use `Cap` to close it up, then your Boolean operation.

-Pascal

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Thank you! Still boolean difference dont work between the cylinder and the surface. What i am trying to do is to cut the “ving” surface on the intersection off the cylinders. Maybe there is an other method to make the edges off the surface follow the shape/edge of the cylinders.

I tryed with > dupborder to create a curve and >cap but still dont work.

Hei -

The “ving” surface is already cut to “Cylinder 1”. If you switch to Wireframe, you can simply select “Cylinder2”, run `Trim` and select the inside part of the “ving”. Alternatively, use `Intersect` on “Cylinder 2” and “ving” to create a curve and use that to trim the “ving”.
-wim

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Thank you so. I try to help a friend that build a sculpture. Those vings will support the steel skin. The skelet inside will be 2 steel tubes. I need to recreate those open polysurfaces to cylinders before i trim the vings. Before i make a new topic maybe i ask here. Cause the tubes are in angle i have issues to create circles for lofting a tube with the correct dimensions. When i use circle from 3points i get 135.700 mm diameter and not the correct 139.7. I tried to draw with the 3 points cplane moved but still. I am sure i do it wrong. Maybe some projection off points to a plane and draw there? I have make a drawing of what i try to archive. 2 cylinders that correspond to the original angle and have a 31.5 mm offset. I hope what i write make sense. is not the solution its more i try to learn what i am doing wrong.
Tubes.3dm (4.4 MB)

Hei igjen -

I’m really not sure what you are doing I understand that you have two tubes that are supporting a structure. I suppose those tubes have a uniform diameter and are bent in 3D space. So far, so good.

Why do your drawings contain “cylinders” that are drawn as 12-sided polygons? Shouldn’t these be just tubes?

Also, I take it that the one tube has a diameter of 90 mm and the other of 135.7 mm? How are these intersecting as in the file you posted? I don’t understand the production method here.
-wim

This was the old drawing from a engineer that have draw it as 12 sided polygons!!! Therefore i need to recreate all. The new tubes need to replace those polygon surfaces. The need to be in the same place same size / length and the same angle. Only difference is the one (Green) need to be 90mm diameter. The red tube is 139.7 and they interesect as the example bellow. Hope its make sense.
Tubes2.3dm (3.5 MB)