Welcome to MCAD Central

Join our MCAD Central community forums, the largest resource for MCAD (Mechanical Computer-Aided Design) professionals, including files, forums, jobs, articles, calendar, and more.

Register Log in

Variable Section Pipe Modeling


New member

Having driven myself nuts trying to figure it out using the wonderful help screens, could someone explain in simple terms for a Pro E idiot how to create a tubular elbow that has a round hole at one end and a rectangular one at the other.

Details are as follows 1.6mm thick tubewith o/d 0f 31.7 that has to sweep through 90 degreeswith a central axis radius of 25mmto a 30 x 22 rectangle with 3mm rads in the corners.

The end centre point is 45.85 offset in x and 64.15 offset in y from the start point


New member

you can use a 90 degress arc with 25mm radius as a VSS original trajectory,30*22 rectangle with 3mm rads as start section.and then ,in sketcher,add the relations likes this image:

View attachment 468

if you need the tube normal the start and the end plane,simpley replace trajpar with sin(trajpar*90) in relation.

wildfire2.0 part attached below:



New member

Don't make things complicated if you can do it the easy way, simple solution is to create a swept blend protrusion, create your sweep profile within the feature or as a separate curve, only accept the first and last vectors for sketching.

First sketch is a circle 31.7mm diameter, divide equally into eight (8) pieces, second sketch is a 30 x 22 rectangle with R3 corners, make sure that your start point is in the same location (eg, top right), finish the protrusion.

Create a shell feature, select both ends, done refs, wall thickness is 1.6

2001 part attached


Good luck.



New member
htbear's idea is right!for this case, Swept Blend is a good method.

but the first section,divide a circle equally into eight pieces,for my opinion,is not a good logic solution.shorter edge blend to shorter arc and longer edge blend to longer arc will be more reasonable.so,the circle section should divide to eight pieces juse as image below.

View attachment 471

in this section, the first draw a 30*22mm rectangle with 3mm round,then toggle all entities to construction and draw a new dia31.7 circle.the last ,divide the circle to 8 pieces according to the rectangle construction.

now the result:

View attachment 472

wildfire2.0 part attached



New member
considering ofthe usage and transition of the tube.The section change linearly is not so good.

the method is described below may be a better way.

the first ,we extrude two surfaces at two end plane .for more exact length ratio ,convertall rectangle secton entities to a spline.

View attachment 473

now swept blend and select the edge of two extrude surface to act as two section.

define the blend option to make the new surface tangent to the two extrude surface at two end .

View attachment 474

and the result is

View attachment 475

wildfire2.0 part attached below:

Edited by: IceFai