Parametrics

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Hey I'm wondering about the term "parametric". I get that it's has something to do with being able to change a parameter/dimension in a part, and have the other dimensions related to change with it. But is it a function that I need to apply to the part when I start drawing and throughout the modelling, or is it just a term used about the general concept about being able to change parameters in a solid and have the solid change accordingly. I'm a bit embarrassed not knowing this.

Thanks Charlotte

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Since this is a SW forum I'll answer in the SW way. Every dimension on a model is changeable and when changed other things related to it change. In this sense SW is parametric. The user must therefore impart some knowledge of how the model should look by specifying relations of which dimensions are one.

Unlike dumb CAD, aka ACAD, in which lines are drawn in specific positions defined by the locations of endpoints, in a parametric modeler like SW a line is defined by how it connects to other lines at vertices and how it is oriented with respect to other geometry.

For example let us say you are arranging your office the ACAD way. You would tell your help to move the desk 30 inches north, 60 inches east and rotate it 180 degrees from where it is now. In SW you would tell the desk to be flush to the north wall and 24 inches from the east wall with the side without drawers against the wall. In SW if the walls moved then so would the desk.

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The main point I make sure that new users understand is that with ACAD, you put lines on the paper and then put dimensions on them to tell you what you just did. With SW you put "lines" on the "paper" and then put dimensions on them to tell them what you want them to do.

WT

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Ok, let me get this right.

Parametrics is just a term used for the capabilities of SW, that is: being parametric, so the whole model changes accordingly to whatever parameter I change the definition for?

And it is not a seperate function i need to learn to use, and apply to each part befor I start?

Charlotte

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That sounds correct to me.

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Good job! You're on your way to making superb parts....have fun.

WT

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Tip. Fully define all sketches before making solids or surfaces from them by using the auto dimension function, then add a relationship to the sketch origin. This will help later in any parametric changes. This is good practice for all construction geometry.

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Pevans

Autodimension/constrain is a handy tool. I use it to constrain complex imported sketches so I can move them around.

I don't think it would be a good idea for a newbie to start relying on it though, because it's very arbitrary. It almost never works in a way that conveys "intent"

It's better for her to learn how to dimension and constrain manually. This way she will learn how to apply predictable intelligence to her models.

Regards

Mark

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Not only will it lead to sketches which do not change, it will keep assemblies of objects to their assigned mates, without strange "red" mates appearing seemingly for no reason.

I design plastic parts mostly, and their tools and have a few starting point rules:

1. My stationary has XX, YY, & ZZ axes included (to complement the 3 planes), so that axes are readily available to create & other angled planes.

1. I pick one plane thru the origin for the parting line when possible (or move it there later, if I start a part in-context in an assembly).

2. Before creating any solid, I immediately create new planes and axes that I know I will need to define specific limits and constraints I know my solid will need, and I name them appropriately (Rt click object in Feature Manager Tree in the Preferences).

1. I build any solid parts from planes and axes where possible, as it makes it extremely easy to recognize & change the size or position of a feature later (as opposed to finding the right sketch) and understand the file later. If not, you sometimes wind up changing one sketch which deletes or modifies another sketch which references the deleted one, and can be a bigger mess to cleanup later (like a year later when the person who drew it forgot how he did it).

2. I use equations to equate specific planes whose angles &/or distances must remain in agreement for the design to remain consistent.

1. I frequently use Save As with a new suffix in the initial development of a complex part, so I can always return to a prior part if I go down a dead end road and bog myself into a Bagdad mess.

2. I sometimes use a technique to construct detail which SolidWorks otherwise will not allow easily: I Cut my part and get rid of a portion of it when it is symmetrical about a plane, and I need to construct an internal detail which is difficult to "get to". Sometimes this works fine, and other times when I suppress the Removal Cut, I have to re-work a sketch, but not often.

1. Working in assemblies, I often just cut a symmetrical assembly "in half" so that I can easily measure & work with actual surfaces in examining a complex multi-part assembly.

Matt Lombard and others have posted very good references for how to work in SolidWorks, and I appologize if I have repeated what they have said here, but this is just from memory quickly.

Bo

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Good tips Bo - thanks

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Thanks for the tips all. I'm not a complete newbie though, but just started my first job after graduating, and was in the jobinterview asked if I was able to work with parametrics in SW. Since English is not my native language, I thought that it was a separate feature in the program, and not just a term describing the bare essentials of SW. he he Think I have to refreshen my knownledge with an advanced course though.

Thanks Charlotte

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Let me guess . . . the person who posed the question to you was a "human resources" type -- correct? That is to say, that person has no actual knowledge of SolidWorks!! That's why they phrased the question that way, and that's why you were misled into thinking that "parametrics" was some particular function instead of being a descriptive attribute of CAD software. Blame the dummy interviewer -- that's just how useful most HR personnel are. The world would be better of without them and without lawyers.

'Sporky'

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Perhaps I'm the exception, but I get a lot of help from our HR person. When it's time to get ugly with your health insurance, it's good to have a real bulldog in HR.

I blame Charlotte's problem on management that thinks HR people can effectively interview technical people. If the HR person is not well-versed in a technical field, they should not be interviewing in that field.

Perhaps I do have unusual experience with this. I do know of HR people who seem to have nothing better to do than make sure you really did nearly die the time you called in sick after a weekend or vacation.

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