Coordinate system vs compound angled planes 1

[dtctx]

Did a search but did not find what I am looking for. In a solid, I would like to create a cutout (say round hole) at a compound angle...say 10deg from xy and 10deg from xz. I created a sketch line in xy..then attached a coordinate to it's endpoint. Then edited the angles of the coordinate system...10deg, 10deg. I made a simple round cutout with it's centerpoint attached to the origin....now...if I measure the angle of the cutout in draft from the top and side view I get 10.000deg from the top and 10.151deg from the side..???

I then tested the same problem using two angled planes. I noticed the same problem, however, the order in which the two angled planes are created determines in which view I will measure 10.151deg....

I also created these cutouts starting at the same origin and extended them in opposite directions to make sure of what I was measuring the top and side views....the two cutouts were not co-linear...

any ideas??

Regards,
dtctx

 

[donyoung]

Hi,

hmm, you are measuring one angle between two lines that do
not coincide therefore the angle will be .15 larger and
.15 smaller.

Put a coordinate system in an empty file just on the 0,0,0
point and specify the angle for x and y to be 10 degrees
Now look at the top (x/y plane) Note the deviation of
the Z-axis and the X-Axis of your coordinate system.
This is due to the fact that either rotation turns an already
'slanted' coordinate sytem about an additional axis. All
axis/planes, however must be perpendicular to each other

Hope I got the explanation the correct way. I have no ideas
how to measure the correct angle -- your cutout, however,
is OK.


dy

 

[swertel]

dy explains very well what is going on. You are rotating 10 degrees about an axis that has already been rotated 10 degrees. If I understand correctly, you want to rotate 10 degrees relative to the global axis. To do that, you are going to have to piece-meal things together.

Start with a plane that is angled by 10 degrees.
Draw a sketch on that plane of a single line that is at a 10 degree angle relative to your other "global" datum.
Create a plane normal to that sketch line and create the hole on that plane.

--Scott

http://wertel.eng.pro

 

[donyoung]

/Edit

or try this:

using function 'plane by 3 points'. Sample

- on the x/z plane sketch a line of arbitray length
from 0,0 at an angle of 10

- repeat the above but now on the xz plane

- function plane by 3 points
- endpoint of one line (where both lines 'meet')
- opposite endpoint of that line
- far endpont of second line

Now you have a plane to draw on an your cutout will measure
an angle of 10 regardless from which side you view it

dy

 

[dtctx]

Thank you everyone. Just as DY mentioned, the second angled plane is not true to the original three planes because it is constructed from an angled plane. I was trying to visualize this scenario when explaining it to my co-workers. The three point plane method proves it graphically.

Thanks again,
dtctx