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Originally Posted by JDPhillips
I want to place holes around a cylinder as discussed in this thread, but I need to make them _parametric_, so that I can slide them around after drawing them, both along the cylinder axis and in azimuth. I do not need to change the number of holes after drawing them.
This seems to contradict an Autocad paradigm, that one establishes a sketch plane which is *not* adjustable parametrically, and works parametrically in it. Is my impression correct, and does anyone know a workaround?
For example, I can put a sketch or work plane perpendicular to the cylinder axis, but I don't know how to set up an adjustable dimension between that plane and the cylinder base. Further, I don't know how to make holes without a work plane perpendicular to each hole, at least perpendicular to the first hole of an array of holes. And I don't know how to set up an adjustable angular dimension to the first hole of the array.
I'm using Mechanical Desktop 2004 DX, but I'm not wedded to it, and if someone convinces me that this is easy in Inventor, I'll learn enough of that to do the job.
Thanks.
Jim
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My AUTOCAD is pretty rusty, but here's how I'd do it in Inventor:
1) Construct the first cylinder by extruding along an axis. For convenience I'll use the Z-axis.
2) Construct a work plane that passes through the Z-axis and at an angle to the Z-X plane. Call it 30 degrees.
3) Create a sketch on the work plane. In the sketch, create a circle of the desired hole diameter and center it on the Z-axis. Project the bottom of the cylinder onto the sketch plane. The resulting line should be perpendicular to the Z-axis. Dimension from the projected line to the center of the circle.
4) Extrude and subtract the sketch with the circle. Be sure to extrude farther than the radius of the tube.
5) Use the circular pattern command to create multiple copies of the hole rotated around the Z-axis.
If you want to change the height of the holes from the bottom of the cylinder, change the dimension in the sketch. If you want to adjust the azimuth of the first hole, change the angle on the work plane. If you want to change the number or spacing of the holes, edit the circular pattern command.
ChrisH