Better to have multiple simple features, or 1 complex feature?

Ive always wondered if its better to have multiple simple features in
model, or 1 complex feature. Example, cut extrusion. I have some
parts that have 30+ holes, and I have each set of holes as its own
feature (also named for easy viewing). 5 holes may be for sideguards,
and another 10 can be mounting points, etc. Is it better to group some
of these holes in 1 feature, or does it really make a difference?

 

Performance wise, I don't know - I have never tried to test it. I do know
that simple sketches work better than complex ones, but where that point is,
I don't know.

I think what will make a bigger difference is doing it like you do. It is a
bit more organized as you can name the features accordingly, you can
suppress certain ones for different configs, and you can populate hardware
with feature patterns, rather than manually.

WT

 

Hi Monkey -

Heart felt rules for myself-

- 1 sketch for everything if possible: it allows me to adjust the whole
mess from one point. I have even taken this to draw "phantoms" in one
sketch and convert them in a subsequent feature to make the feature
supressable, but to have both features controlled by a single sketch.
This, for me, is a very valuable thing - maybe not for others. I
usually also do all fillets in a sketch - perhaps bad in other
ciscumstances.

- Holes are always made by the hole wizard. My only exception to this
is when I know for sure that I only need one hole and will not ever
need two of a certain size - also on revolved parts - the center is
always part of the base revolve. Having patterns helps me when
patterning hardware in assemblies later.

- Sketch patterns when not too big, but external patterns when they get
big - supressible.

- Supressible features if showing a progression is needed for machining
or forming.

I always try for the tightest feature tree - it's a little bit of an
obsession, but a needful one for me. Most of my parts are prismatic
solids - no splines or surfaces.

For what it's worth. Do what makes the best for you - no two working
styles are the same and sometimes mixing styles is a problem.

Later,

SMA

 

Avoid complex sketches. Rule of thumb: if you're struggling to make a
sketch work you should be doing it with more than one feature.

Sketches are dumb. Features are smart. Don't do a revolved cut for a
hole, use the hole feature. You'll also benefit when you go to do the
drawing, you'll get a hole callout if you use a hole feature, etc. etc.
Also, don't sketch fillets unless you have to. Seperate features can
be reordered, supressed, or easily modified, they have properties
specific to their just their feature type.

Overall you should strive to have a short well ordered model tree, but
at the same time you should not try to do everything with one or two
features.

Layout sketches are very helpful too. And if you're smart you can
reuse sketches for several features, especially by selecting contours.

On top that use folders to organize related features. Always name your
features and sketches, with descriptions if possible.

I can't say for sure in SolidWorks but in Pro/E using the approriate
feature for every aspect of your model decreases regeneration time.

As per your holes, I'd use the hole wizard and a sketch pattern for
each set. Then put them in a folder that identifies what they mount
to.

OT: why doesn't SW have derived feature patterns? In Pro/E they are
called reference patterns. I used to define a hole patern(s) in a mold
plate and then do a reference pattern in the mating plate(s). It was
great b/c all my holes were tied together and all I had to (re)design
was the mold plate.

 

I dont see why you would not be able to do this. At the Assembly level,
you could make a component/feature pattern and base it off the other
part file so that if the one changes they both do.

 

Others have hit on some good points. I'll just add my votes for a few of
them.

- Simple sketches. Complex sketches fail easily when changed and take a
long time to regenerate.

- Sketch fillets are notorious for busting up the sketch when things
change. Plus, if you want to get rid of them it's a real pain. Use
feature fillets unless you absolutely have to use a sketch fillet.

- Definitely try to use patterns. SW has some nice ways to pattern stuff.
Don't overlook the sketch driven pattern (feature position driven by a
bunch of points). The hole wizard pattern with multiple points works just
like the sketch driven pattern. Remember that for the Hole Wiz, by default
the pattern sketch is a 3D sketch and you can pattern holes to faces other
than the first face, and the holes will all be normal to the faces they are
placed on, including on non-planar faces.

- Using the sketch "step and repeat" patterns always kills speed. I avoid
this like the plague.

- If you have a single fillet feature with 100 edges selected, it is faster
than having 100 fillet features with 1 edge selected. Of course this is
assuming that the two would give you equivalent geometry.

matt

 

Another thing that might be useful is the Feature Statistics, if speed
is an issue.

I played around with this a bit and it can tell you where your
"fattest" features are.

I made a simple model with Sketched Vs. Feature Fillets and found that
they took an identical amount of time. My example was simple, but it
should tell us what techniques are bad or good (performance wise).

I think that the problem that comes in is when someone really goes at
modeling in a round about way - there are many stylistic differences
and I simply say "it's not what I would have done, but it's not wrong
either" - other times you just shake your head and know that it is
wrong - no discussions. I have seen point sketches premade for hole
wizard features right on top of the pre-sketched points in a subsequent
sketch. Some seem to only start any model with a cube and whittle away
at it as if they we doing machining. I have seen people mate a hundred
screws in an assembly seemingly unaware that patterning is even an
option, not even using mate reference for screws - like it's easier to
do it the "easy way" than to force ourselves to learn anything new.

In any case, the feature statistic tool will be a fine helper if one
lets it.

Later,

SMA

(Slightly OT: I also wanted to mention that anyone who uses google to
read mail might really like their new toolbar - it spell checks when
you post or in any other web form. Take a look if you use google - its
nice)

 

As far as I can tell you cannot use a feature pattern to drive another
feature pattern.

You can use a feature pattern to drive a component pattern, but that's
it.

 

I think that this would be a fun thing to do and a great way to talk
directly about modeling practices, everyone would probaly learn
something. Any suggestions on what would be a good part to model?

 

This reminded me of a challenge they were always having on the inventor
discussion. Go to http://www.design-excellence.com/worldcup/
There is a monthly challenge to quickly and accurately model a part. It
is mainly designed to challenge inventor users, but could also be done
by SW users. It would be a good head to head competition of Inventor vs. SW

Brian

 

Until you want to remove the fillets or apply draft to the part or do a
pattern or make changes that cause the sketch fillets to fail.

A couple of years ago I did a test for patterning. The results are still
around on my site.

http://mysite.verizon.net/mjlombard/

go to Rules of Thumb, then Patterns.

 

You could try either a derived sketch (and sketch based patterns), or the
hole series (in hole wizard).

Both have worked for different cases in the past for me...

 

Really complex sketches take longer to solve. They can be a bear to
maintain also. I leave fillets to the fillet feature.

I do use sketches in contour mode so that design intent can be carried
across multiple features. Even if the sketch is a little more
complicated it is only solved once.

Pattern features not sketch elements if possible.

Grouping holes by size in a sketch makes sense. Using hole wizard for
this also makes sense. The downside of grouping holes in separate
sketches is when making a drawing with imported dimensions.

 

SolidWorks has held Design Contests from time to time. Cosmos has also
done this. So has PTC. Tenlinks was involved with a SW / Inventor
Shootout a while back. It didn't do much for the credibility of those
that held it because it didn't have the support of one of the
competitors.

 

My two cents:

Marketing cr#p intended to benefit a software developer or fluff
journalism. The Design Contests are interesting nonetheless.

My hat's off to Peer and his efforts to set up and maintain the modeling
challenge idea. It's something that benefits users. Those users are not
necessarily contestants, as finished models are available for
deconstruction, tutorial purposes.

I've thought, in the past, going 'cross platform' would be interesting. It
would be a source of irritation or satisfaction to product boosters for
sure. More importantly it would be the first, that I know of, database of
info going beyond banquerism; demonstrating different software when applied
to a range of identical modeling tasks. Something users might find
interesting and informative unless spoiled by boosters' bickering. If the
"trade press" weren't afraid of stepping on toes, risking the loss of
advertising dollars they'd host it and base a series of monthly articles on
it, or am I overestimating the potential interest or the nature of "press"?

Even without going cross platform it's a pretty neat idea assuming people
willing to donate the time can be found and there's user interest.

 

Perhaps a series of 'interesting modelling challenges' ? Maybe a 2 weekly
one...how about a SW tee shirt prize...could be posted out anywhere in the
world?...maybe SW would oblige in the interests of good publicity and
community spirit ;o)
One of the things I miss about this group of late is the absence of the
'find a soln to this' posts where people generously have a go at fixing
problems or finding clever methods.
A bit of diversionary fun but it got me thinking about how to use the
program features to the max....a really good way to extend your skills and
also enlightening to see others often better methods...

 

I've never been much for contests. Probably for the same reasons you
propound. Your idea sounds like the SW Challenge offered at SWW every
year. That's a good challenge but it would be hard to evaluate over the
NG. Something like this sounds like a job for the National SW User's
group as they could no doubt come up with a decent prize.

We had a sort of a challenge a while back when I made the statement
that SW might not really be a solid modeler. A couple guys came up
with some ingenious solutions.

 

Paul,
I'm on it. I have contacted John off line with a similar suggestion.
We will be putting something together and getting the SWUGN folks
involved. You're right - they have the best goodies!

Richard