can someone please explain splines?

Being new to using autocad I am a bit confused about splines and the best way to use them and the advantage in using them, so if someone can enlighten me I will be very gratyeful

Being new to using autocad I am a bit confused about splines and the best way to use them and the advantage in using them, so if someone can enlighten me I will be very grateful, thanks

Suddenly I get the feeling we are being asked to do homework. Is that true?

Suddenly I get the feeling we are being asked to do homework. Is that true?

I get the feeling you might be right.

Oh yeah, and br0604bom, please don't double post.

I get the feeling you might be right.

I can't say what the OP's intent is, but I'm fifteen years out of school, and I'm curious. I keep hearing about splines, and have a general sense of what they mean in numerical methods, but Id be interested to read-up on them from an AutoCAD perspective from folks who do use them if anyone ends up replying.

You can't really do anything with them unless you have your PELLIPSE variable set to 1, then FLATTEN the spline to create a 2D polyline. If you use a spline to create a complex curve, you can use it to close off a boundary and use PRESSPULL to create a 3D object without having to join the spline to anything. The more I use them (only when I need to) the more I kinda like them, but I've been told that splines are nearly useless in AutoCAD. There are other programs out there that apparently allow you to do more with splines.

Importantly, you can't dimension a spline and different software (ie CNC Machines) will interperet them differently (Or not understand them at all). So It's not good practice to use a spline for a machined part. Stick to useing splines for artistic reasons.

Suddenly I get the feeling we are being asked to do homework. Is that true?

No rkent, that is not the case, I just wanted to ask as whenever I have asked others they do not have much to say on the subject and do not use them much,

I just wondered if they were used much by someone on here and how beneficial they found them, that's all

I do apologise for the double post too

thanks to others for their replys

Splines are also far superior to plines for animation paths. Plines can have very angular junctions even if they have been _pedit _spline. -David

Suddenly I get the feeling we are being asked to do homework. Is that true?

That's a bit harsh rkent.

Although I wholeheartedly concur with the "we're not here to do your homework" line of thinking, the OP only posted a question asking for clarification of the use of splines, not a drawing to be completed. Homework or not, one must be in receipt of some education to provide the answers. If that hasn't been fully provided by the teaching staff then what's wrong with a little web research to find the information you require?

I only wish I could offer some insight into splines, but I have found very little use for them in my 2D world and am as interested as br0604bom and Crazy J in the information given thus far.

That's a bit harsh rkent.

 

Although I wholeheartedly concur with the "we're not here to do your homework" line of thinking, the OP only posted a question asking for clarification of the use of splines, not a drawing to be completed. Homework or not, one must be in receipt of some education to provide the answers. If that hasn't been fully provided by the teaching staff then what's wrong with a little web research to find the information you require?

I only wish I could offer some insight into splines, but I have found very little use for them in my 2D world and am as interested as br0604bom and Crazy J in the information given thus far.

There are plenty of threads here that have started with a simple question and answer which ends in the OP assuming that this forum will do an entire assigment in the end. I am not surprised that rkent ask this, and I would probably have done the same.

Then again, there are also threads here where the OP clearly states at the start that this is indeed for homework but gets loads of help anyway, simply because he/she is upfront with where the question comes from.

Absolutely. My point is, within education these days, students must rely more and more upon research to get the information required to formulate their answers. This information can come from books, peers, teachers, or asking questions on web based forums, what's the difference? Take all this information and put it all together for a full picture. But yes, we must stop short of physically writing assignments for anyone.

There are plenty of threads here that have started with a simple question and answer which ends in the OP assuming that this forum will do an entire assigment in the end. I am not surprised that rkent ask this, and I would probably have done the same.

 

Then again, there are also threads here where the OP clearly states at the start that this is indeed for homework but gets loads of help anyway, simply because he/she is upfront with where the question comes from.

Steady Tiger, I can assure you I have no assignment or any other type of document to be completed, I am merely curious about something which not many people I have met so far have to a lot to talk about on the subject, I shall persevere and hopefully in the future I can come on here and tell of my findings into the subject

Steady Tiger, I can assure you I have no assignment or any other type of document to be completed, I am merely curious about something which not many people I have met so far have to a lot to talk about on the subject, I shall persevere and hopefully in the future I can come on here and tell of my findings into the subject

Nothing against you at all BR, most here are happy to answer any and all questions that come our way - but when you every year see a sudden influx at around exam time of the type "plz help me, plz do this for me, I need this done today, I haven't done anything all year" - then you get a bit leery of questions as your own with no explaination on why you ask them.

So don't take any offence at all, I was mearly explaining why I think that Rkent responded like he did.

Hope you explore Splines more mate, I don't know a thing about them either

Hope you explore Splines more mate, I don't know a thing about them either

I know they're curvy but thats about it!

The general idea behind spline curves is to allow for geometry exhibiting continuous change in curvature at variable rates of change. This is done via a mathematical interpolation scheme, with the spline’s Degree determining the order of the interpolation function (Quadratic, Cubic, Quartic, Quintic, etc.). Splines can accurately describe all sorts of curves (see sample).

References:

http://en.wikipedia.org/wiki/Non-uniform_rational_B-spline

AutoCAD splines (NURBS) are somewhat lacking in a full implementation from Autodesk. Part of the reason may be as an effort to steer potential customers to vertical apps (Inventor, Alias Studio). Another possibility is that the spline entity is so poorly utilized by the average AutoCAD user that enhancements to the spline workflow are never requested. I could see how that last bit of speculation, if true, had a persistent cyclical effect.

It seems that the steady upgrade in AutoCAD’s 3D functionality will force a more spline centric mentality. A lot of the new surfacing features (Loft, Sweep, etc) are NURBS based and work particularly well with spline construction curves. The one notable exception; AutoCAD can still not extrude/sweep a filleted 3d Curve (it fails on the 3d path in the attached sample).

Splines.dwg

The general idea behind spline curves is to allow for geometry exhibiting continuous change in curvature at variable rates of change. This is done via a mathematical interpolation scheme, with the spline’s Degree determining the order of the interpolation function (Quadratic, Cubic, Quartic, Quintic, etc.)....

 

hmm....Greek?

hmm....Greek?

Agreed, lost me on the "geometry exibiting continuous"

(Quadratic, Cubic, Quartic, Quintic, etc.).

hmm....Greek?

Actually, I think the word origins are Latin.

But, yes, it is a bit of a handful to get a grip on.

Splines are very useful, even in 2D AutoCAD. I would recommend taking a class. Offhand I can't think of a single design discipline that uses AutoCAD that doesn't have a use for splines.

Splines are very useful, even in 2D AutoCAD. I would recommend taking a class. Offhand I can't think of a single design discipline that uses AutoCAD that doesn't have a use for splines.

Rail! I've never used them!