Extruding over features to eliminate
Extruding over features to eliminate
(OP)
I was wondering if anyone sees any issues with extruding over features to eliminate them. There comes times when you are deep in a model, and you are unable to delete a certain feature (nor modify it) because it is the parent feature for several other things that you have in your model. Thus, instead of deleting the feature and building everything up again, I was using extrudes to do things such as eliminate fillets, as an example. Sometime during an extrude there is some overlap where the extrude is going through an existing piece of the model. So far I have not seen any issues with this, but I dont know if this can cause errors later when running FEA and meshing, or calculating mass, etc. I know I can test this but I thought it would be a good discussion. Obviously this is bad practice but sometimes speed trumps everything.






RE: Extruding over features to eliminate
RE: Extruding over features to eliminate
RE: Extruding over features to eliminate
Jeff Mirisola, CSWE
My Blog
RE: Extruding over features to eliminate
It's good that you recognize this as bad practice, but stability should always trump speed.
Like Jeff, having had to work on such bad models I can attest to how frustrating and time wasting it can be.
Having said that, you should not experience problems with FEA or mass calcs.
RE: Extruding over features to eliminate
Scott Baugh, CSWP
FAQ731-376: Eng-Tips.com Forum PoliciesGryphon Environmental
www.2gryphon.com
RE: Extruding over features to eliminate
RE: Extruding over features to eliminate
That said, in your case it may be a good thing. Simplifying models for FEA--removing gaps, getting rid of small features--is a good thing. Just don't do it on the model used for design. Save a copy!
RE: Extruding over features to eliminate
You could also try using the Defeature tool...
http://help.solidworks.com/2014/english/solidworks...
... and then saving the result as a dumb solid.
RE: Extruding over features to eliminate
RE: Extruding over features to eliminate
RE: Extruding over features to eliminate
Doing it on a production model used in drawings is bad...
It obviously, will affect mass properties if you're filling in chamfers and holes...
A former coworker told us how a firm in India took his model, and had to move some holes. Instead of redefining the feature, they extruded a new feature to fill the holes, and created new features where the holes needed to be.
Move bodies is another command I hate dealing with...
Trying to figure out why I can't redefine a feature, only to discover a move body command will move it back no matter where I want it is a big time waster... I've learned to look for them first thing, now, but it's still hard to modify a model with move/delete bodies in the tree.
David
Connect with me on LinkedIn. http://lnkd.in/fY7-QK
Quote: "If it ain't broke, I must not've fixed it good enough"
RE: Extruding over features to eliminate
I'd like to suggest an alternative approach. Make a new part file from a blank file and Insert->Part as the first feature, selecting the original part file. This will give dynamic linkage to the original part so that if it changes this new file will see those changes. However, in this new file the part appears as a dumb solid. Here you can make (and name) new features to deal with the simplifications you desire. You will not be able to suppress features in the original file nor change dimensions from here, but you will be able to add cuts and fills which will very likely be easier to control and understand.
We use Insert->Part a lot just for these very benefits. It has become an extremely valuable and reliable technique for us.
I hope this helps.
- - -Updraft
RE: Extruding over features to eliminate
@Updraft, excellent "cake and eat it too" idea! Thanks for sharing.
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RE: Extruding over features to eliminate
First; Way too many engineers don't know diddly about CAD modeling. Because they are constantly creating features for no other purpose than to "remove" a previous feature. As a result, their history trees become excessively long and complicated. Trying to interpret their "design intent" is a lesson in futility.
And the second thing I've learned; The software should really be called Solidwrecks. Because, sooner or later, your model is going to crash.
"Go direct. Do not pass Go. Save yourself 200 hundred hours."
RE: Extruding over features to eliminate
Updraft describes the best workflow for those situations where one does not need to make any changes to the base model. If the model needs to be rebuilt, it needs to be rebuilt, even if you are not the one who began it.
My $.02...
RE: Extruding over features to eliminate
RE: Extruding over features to eliminate
Updraft's suggestion I will consider in the future though.
Thank you.
Rob Stupplebeen
OptimalDevice.com
My Personal WP
RE: Extruding over features to eliminate
As already mentioned by some guys; I do not see (neither ever found) a probem doing it for FEA purposes. But, I then do it as a last resort - if an upstream feature cannot simply be suppressed. Also, sometimes one only want to remove part of an upstream feature..
Regards
RE: Extruding over features to eliminate
Thanks for this input, I tried this out and it is a nifty option that I never knew about. How is this different than just saving something as a STEP file and then importing it?
It seems to me the consensus is that extruding over features is looked down upon, obviously bad practice, and is "ok" but not ideal way of modifying models to make them compatible for FEA. I, like many of those that posted here, have also been down the long and treacherous road of trying to correct/change a model that has been passed on to me that was headed toward the Solidwrecks crash model [GimpLizard, 2015]. As several of you have stated , Updrafts post on inserting models into a new part is clutch. I tried it out and it works flawlessly, now I have a featureless model that updates to a master copy in my main assembly. There were alot of "shoulds" above if anyone comes across this in the future.. We have done several simulations (shock, vibe, frequency etc.) and have had no issues with any of our models that have the sketchy "extrude over" modeling practices. Thanks for all the input.