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can't close a sketch profile using a spline
I have four splines. One makes a simple two point spline curve, the second is it's offset. The remaining two are 3 point splines enclosing the ends of the of the first two. I'm having a hard time getting one of the end splines to close for a profile. I use the coincident constraint when I start and end the spline, and the constraints show when I turn them on, but if I zoom way in on the ends f the spline, I can see that it's not actually coincident. What's going on? The enclosure spline on the top end seemed to work this time but I've been struggling with it in several sketches.
thanks
Isotherm
Answers
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@IsoThermwell, this is a very interesting oneFirst thing I would do is probably quit the program — sign out and then sign back in and see if that helps
I’d also try drawing some arcs — first around one of those points at the bottom, and then around the other. I would do one at a time to see which one in particular might be the malfunctioning one
The next thing I would do is just eliminate that bottom spline and redraw it
If there’s anyway you could post a link to that sketch only, that would be interesting to look at
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I've done both of those things. I've recreated all of the splines, several times. I've placed points at locations along the two offset splines for the end splines to anchor to. When I highlight the constraints it shows that the end points of the splines coincide with the others, but when you pan in...they just won't close.
Hate to be a noob - how do I share the sketch without sharing the rest of the document?
grazzi0 -
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@IsoTherm
you will need to make the document public for us to work with it.
Here are instructions for posting -
https://forum.onshape.com/discussion/9107/forum-post-checklist-read-this-first#latest
www.accuratepattern.com0 -
sorry, thought I had. It's public now.
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@IsoTherm
I started playing with 'binary dividing lines' and found the lower right intersection is problem. Once I trimmed the excess it enclosed.
seems like one for support. Although unconstrained splines are goofy...
www.accuratepattern.com0 -
btw I am patternmaker and did a lot of impellers over the years. nice to see this one!
www.accuratepattern.com1 -
thanks for the help Bruce.
Splines are strange beasts in every cad system I've ever used (many).0 -
bruce_williams said:
I wasn’t sure if you were going to allow us to copy the sketch. So I used the measurement tool to note the diameters and then I sketched over the imageIsoTherm said:Splines are strange beasts in every cad system I've ever used (many).
Below are your constrained splines. And man is it a busy sketch with all those numbers — unless you zoom in
https://cad.onshape.com/documents/f48b0bce6bd61aa7b65332b7/w/df441d2f5248c3e85bb7a8e9/e/365d3d4236cb75e0f265634e0 -
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@IsoTherm
@bruce_williams
I’m always curious to see how the program works.
So I wanted to look at the document IsoTherm posted of the sketch
Wanted to see if I could sketch an arc around that lower right hand point (where Bruce showed was a problematic area), and have that banana shape enclose
But when I opened up the sketch, I noticed that it was already modified.
In the mean time, I notice the outside arc of the (impeller blade ?) had a line that I thought could be eliminated if things were made tangent
So I went into the sketch that I made from scratch, and made the outermost spline tangent at the top and bottom in hopes of eliminating any unnecessary lines on the extruded part
All of a sudden, I no longer have an enclosed shape.
So I do the trick where you start drawing intermediary lines to see what part of the shape is not closed up
By chance, I happen to start drawing a line on the inside of the inside spline, only I stopped before I crossed over that spline. I stopped right on the spline
What happens? All of a sudden, the banana shape shows as being a closed shape. It’s gray between the splines
1) OK so isotherm who has used a number of CAD programs is having a hard time getting this thing to work
2) Bruce makes the statement that it looks like one for support
3) I definitely got some peculiar behavior
Hey tech — you guys should look at this
Below is a link to the document I made from scratch, completely separate from IsoTherms document
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www.accuratepattern.com0
