【转帖】cant make 3d-line snap to heli

yang686526

can't make 3d-line snap to helix
hello all,
i have a helix, say, coming out of the front plane.
then i plot a 3d-line sketch.
i am trying to either:
1) make one end of the 3d-line snap to one end of the helix (in the very moment i am plotting the 3d-line)
or
2) sketch the 3d-line,
     exit 3d-sketch,
     edit the 3d-line,
     click on one of its ends
     click 'add relation'
     click the helix
     try to force "coincident" constraint
it never works.
if i do all the above with sketching a 3d-point, both coincidence/snapping always work.
please post if you have an idea why the 3d-line won't snap/coincide...

eng-tips forums is member supported.
using the pierce constraint between the end of the 3d line and the helix, will 'snap' the end of the line to the end of the helix.
another method is to convert the helix into a 3d sketch, and constrain to that instead of the helix.

to use pierce constraint i have to be given access to it. that is the problem, that i'm not, unless i build a reference plane @ helix endpoint and plot the 3d-line inside that plane.
i'll try your suggestion about converting the helix to 3d sketch.
hmmm, my apologies! i gave you false info. unlike a 2d sketch line, it appears that a pierce constraint is not available for a 3d sketch line. the end of the 3d sketch line does however attach itself to the helix, and can be dragged no further than helix end-point ... but it doesn't become constrained to it.

then this is snap, or coincident relation. i definitely can't get this either when sketching line in 3d. should i hold down ctrl?
the converted helix should be left in its own 3d sketch to avoid accidentally moving the end points. it will remain associative with the original helix, but if edited, the end points of the converted helix can be moved.
the pierce constraint and regular 'snapping' should be available between a 3d line and the converted helix.
yes, i started this thread to make sure i can properly connect straight lines to the helices. once this is done, the sweeping will probably work
try this method. it eliminates the need for the helix function.

thank you; your tip for converting the helix into 3d-sketch works. then 3d-line can have coincident constraint with the 3d-sketch of the helix.