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Re: How can I fix a loft twisting?
I can link it here, and will edit the post so it is linked in the post https://cad.onshape.com/documents/7b5c948934dab1717167f29c/w/8440194c5c881e91e0276d72/e/c5fa51d402d9f497174d247djohn_mcclary said:Can you link your document?
Have you also tried using guide curves?
Re: Constraints are a voodoo magic
It helps to think in terms of degrees of freedom:
- You draw a circle on the origin. That constrains its x and y translation but leaves the radius. Constrain it tangent to a line somewhere. That constrains the radius.
- If you draw a circle in free space instead, then constrain it horizontal to the origin, that constrains the x translation only, leaving y and radius. The set of constraints in your sketch should hopefully be exactly enough that nothing can wiggle around. If something can wiggle around, it'll be blue.
- Line segments are essentially defined by their two endpoints. Draw a line from the origin and drop the other endpoint in free space. One of the endpoints is constrained; you can move the other one around. If you set the line vertical, or one endpoint vertical relative to the other, that leaves just the y degree of freedom for the free point.
A typical workflow might be something like: sketch on the top plane, center rectangle on the origin, dimension its sides, extrude.
Prefer to keep sketches as simple as possible; prefer to use face and part patterns instead of sketch patterns; prefer to rely on the constraint solver rather than a grid. Be aware that, if you put a sketch on a face, you can use the "Disable imprinting" option to avoid imprinting that face into the sketch, which tends to make the sketch easier to work with.
_anton
Re: replicate parts in assembly to sketch?
I made this gif to help me remember. What you select for source geometry for the initial mate matters.
Re: Displacement boundary condition?
Re: Mid-surface Custom FeatureScript
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I can't think of any that have already been written. Would be a neat feature though.
May take a few extra steps then what you were imagining, but it looks like Derek's feature could work for what your trying to do.
@romeograham Let me know if your need gets serious and you end up needing a developer for it. I can connect you with CADSharp. 😎
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Re: Mid-surface Custom FeatureScript
I've been working on a curve tweening script this weekend actually, which is a few dimensions away from a mid-surface script. I just got done handling the cases where the CVs match and have been implementing the elevation logic for those mismatched cases. Originally I was just parameterizing by curve length segments but that wasn't very robust at local curvature. The final version is probably going to spit out everything as some kind of splines simply to avoid the massive switch statement mapping every possible input geometry to every other possible input geometry.
I did also write a "find me all face pairs" script the other week as well for a different project that I'm publishing later this week.
Re: Mid-surface Custom FeatureScript
If the two surfaces are parameterized identically (or one can be elevated or re-parameterized to be identical) then creating a new surface with all the CVs being averages of the respective CVs should work. As you say, there are likely a lot of cases which would be odd or challenging. Do you untrim the input surfaces? If they are two planes do you treat them as infinite and create another plane?
Extending this beyond two input surfaces to bodies where the surfaces needed to be paired up would be really tricky.
S1mon
Re: Improvements to Onshape - May 16th, 2025
Wait a minute, I just realized that the new replace face function enables lofted sheet metal by letting me replace lofted spline faces with "extrude" faces. That'll come in handy.
Re: Constraints are a voodoo magic
I revue'd your link early today but had to run out for an appointment.
I noticed something interesting about your use of grid feature. You set set transparency to 0 for hiding. I think you'll find it simpler to set above 0 so as not to be so confusing with other sketch entities then simply hide and unhide from the feature list as needed. Having said that, here is a sample that works quite easily without a grid at all. I think your dragging some thinking from a previous program like ACAD that is hampering progress.
Read MDesign's notes about learning how to work with the OS tools. I think your putting in too much work to accomplish the task.
Use of tools like the sketch slot tool are way faster and cleaner for subsequent updates than complete redraw of all entities. Learn to use feature arrays. In your sketches the constraints are likely over lapping with the grid. They may not show as an error but will make future updates more difficult. Under standing of constraints and how they work is paramount. See Learning Center.
I don't see the grids as value added in this part design.
