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How to fully define a spline
Logan_Nguyen
Member Posts: 6 ✭
So I've been trying to make an acoustic wooden speaker for a phone since it's a school project. However, I've been stuck for a bit while trying to fully define the splines. I've looked at other people having the same issue, but I can't replicate how they defined theirs.
Please respond soon
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You will want to fully constrain splines with constraints or dimension which are constraints as well.
Could you provide a less complex example? That'd be great
Any grey dimensions are ref only to clarify results. Hope this helps. All points along a spline must be located by some means to fix for a fully defined spline.
I managed to define one spline, but when I tried to define the other the already defined spline undefined itself. Is there a reason for this?
Hey @Logan_Nguyen,
I think it might also be helpful to use the mirror feature to mirror left and right side of your sketch, they seem like you would want them symmetrical.
If you don't care about dimensionally constraining your spline but rather the shape and connection points, you can also fix it to fully define.
In most cases you would probably want it to be tangent to the curves that it connects to. Hope this helps. Cheers
I mirrored the splines, however as I tried to trim an opening in the circles the sketch couldn't be solved.
Usually the process i take with this is removing Dimensions one at a time to see if it stops being overdefined. If it's still overdefined i just Ctrl + Z. Overdefining can be annoyingly common with splines so i recommend you start by first defining all your construction lines in one sketch, then another sketch on the same plane that Uses bits of the last sketch working forward spline-by-spline until it works. Then, Fix everything if it's freeform. This'll 100% overdefine it, and it'll be because of all the Intersects conflicting with the Fixes. Dimensions will also do this a lot, so if you have your construction lines and actual splines seperate you can de-overwhelm it quite a lot.
Finally, i recommend in this scenario to keep the circle as a construction line to Use on the next one with a Centre-Point Arc so you can Tangent it cleanly
Do they need to be fully defined? In some case maybe. but it might be more headache than its worth.
Hey @Logan_Nguyen,
Please mind also to only define the half that is NOT mirrored, the other side will just follow.
Hey
fully defining a sketch is best practice so stuff cannot accidentally change when you drag something or when underlying geometry changes.
I'll sometimes try and define the major elements of a spline, but when you try to fully define it, including tangency/continuity, stuff usually get's overcomplicated and easily jumps from fully to overdefined.
so I treat splines as the exception to the rule for requiring full definition.
the icon that appears on the sketch when not fully defined is blue for a reason: it's just FYI.
moreover for this sketch, i would draw only half. leave the mirroring out and do that with the mirror feature after the extrude or whatever you're going to do with it. the later you mirror the better. it may also include the fillets, drafts whatever else you'll need and save you (and onshape) from clicking and solving all that twice also.
I only use sketch mirror and pattern as a last resort when feature pattern/mirror's are not usable, which is not often…