mirrored parts not acceptable 7

[duk748]

hello - our so called solidworks expert where i work has made it clear that we are not to mirror parts because they are too hard to detail & make changes to - i am a part time solidworks user & i am always getting in trouble w/ the so called solidworks police - if it is not acceptable to mirror parts then why does this command exist? - any experts here want to let me in on a secret to modifying & making drawings to mirrored parts - then maybe i can call myself an "expert" - really - any help or advice would be greatly appreciated - thank you

 

[drawoh]

duk748,

I am working in a do-not-mirror environment too, so I feel your pain. Mirror can be very useful, and a big time-saver, especially in frames with a lot of left/right components.

Maybe your administrator is coping with idiots. Maybe your administrator is an idiot.

JHG

 

[ShaggyPE]

The resident SolidWorks Expert where I work loves mirrored parts... but he is me. Sorry for your pain.

Mirroring parts can be done several ways. When done in the context of an assembly, it ties it to that assembly. When done from the context of the parent part, it is clean... no extra baggage.

When we do drawings of mirrored parts, we fully detail the parent and note that the other is a mirror of the first. Our part numbering scheme works for this. All of our part numbers are of the format XXXXXX-001. The mirrored part is identified on the same drawing and is assigned part number XXXXXXX-002.

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[TheTick]

Issues with mirrored parts usuallly have more to do withh document control than CAD capability. I've seen places where the "do not mirror" policy is driven by the inability of MRP systems to handle mirrored part.

Trouble also can arise when a mirrored pair need to decouple from their mirror relationship. It does happen.

QA folks generally loathe mirror prints, as there is potential for confusion when trying to inspect a part that is reversed on paper.

It's inconvenient for CAD jockeys, but easier to accept if one is aware of the needs of the enterprise as a whole.

 

[CorBlimeyLimey]

The command exists for people who know how to use it properly and understand it's shortcomings. Mismanaged it can be a recipe for headaches and, when the CoG is involved, disaster.

Find out exactly what problems the "so called solidworks expert" has with mirrored parts, and then post them here. If a solution is offered, you can return to the "police" as an informer instead of a perpetrator.

This link may shed some light on why some people are averse to using mirrored parts.

https://forum.solidworks.com/thread/46189?start=0&tstart=0

 

[MikeHalloran]

Is there a command that can irrevocably decouple a mirrored pair?

Such that neither part's feature tree is thereafter dependent on the other's?





Mike Halloran
Pembroke Pines, FL, USA

 

[ctopher]

I have used mirror for fixtures where there are top/btm or right/left parts. It's easier to do this than redo each.
I recently did one that had several holes that followed an arc. The other side was the opposite. If I changed one, the other updated.
There is a reason the mirror command is there, to mirror stuff!

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

 

[duk748]

hello again & thank you for the info + the laugh so early here!
also thank you for the thread - we have one person here (read expert)
that is our "police" - our management has given him free reign to set policy & so called standards for this software - so much so that i have become dis interested in using the software due to everytime i use it i get a nasty e-mail on how i create things or how i should do things -
we really need someone here who really knows this software & has used it for a number of years - not just someone who claims to have used it - i have posted other questions regarding our experts claims & have found i am as much of an expert as he is! - thank you again & if i get anymore "expert" advice i will post for the real answers

 

[duk748]

hello again - sorry for the 2nd reply - i found a neat way of changing mirrored parts! - export as a step file, run feature works & presto! - just like a new part!! - i feel like an expert already - have a great weekend! & thank you again

 

[TheTick]

If all your "expert" can do is berate people for not doing things "his way", then he is a failure. Feel free to tell his boss that Tick said so.

I've been in the "expert" position a couple times. I've always taken the view that it is vital for one in such a role to be an educator first (and an approachable one, at that). If your "CAD cop" does not ultimately help to make people more skilled and productive, he is a negative.

 

[Nella95]

I'm going to reiterate what most have said. There's literally no reason to 'not' use the mirror command. Even if problems arise from not knowing the command, they can be corrected effectively and efficiently. Your solidworks expert obviously had a traumatic experience with mirroring as a child, now he's taking out on other SolidWorks users.

 

[Updraft]

Nella95,

I love your analysis. You have my vote for the position of "CAD Psychologist".

- - -Updraft

 

[EEnd]

Mirrored parts, configurations, in-context references and equations share a set of tradeoffs. They speed design and can speed modification during design, but they create dependencies that can produce surprising (unintended) results. If the models are used in multiple products, or revisions to parts are made by other people, or by you a year later, parts other than the ones that are intend to change can be changed. This possibility rightfully makes anyone responsible for ensuring the integrity of the design and revision process uneasy.

If the company’s business is such that the life of the models is short and tracking revisions is not typically done these techniques work great. If the company needs to maintain strict revision control, the use of these techniques can be problematic.

As far as your trick for separating mirrored parts…
Currently SW uses Parasolid in its modeling kernel so it is apt to work better than step when creating a dumb solid from a mirrored part.

The bigger issue that I have with the technique is that it destroys design intent. There is more to creating quality SW models than simply having the correct final geometry. A model that possesses design intent is much easier to modify and dimension than one that does not. The way that a model is created can embed knowledge about how the features should move relative to each other for example: this hole is centered in this slot, these holes are all the same size and move as a group. I do not think featureworks can recreate this knowledge from a dumb solid.

There is an option for creating an independent part during the mirror command. My recollection is that it was not perfect. The sketches stayed in their original / unmirrored position and form.

Eric

 

[ShaggyPE]

I agree with EEnd's concern about the proposed work around to the mirror issue.

I am curious what the CAD Police's rationalle is for not allowing mirrored parts. I agree with CBL find out what his concerns are and share them here.

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[duk748]

hello again & thank you for the replies - our sw policeman is a very
hands off person to deal w/ - he likes to run his police state rather then explain his reasons - i will take to heart what others have said here about mirroring parts - this is not the only issue he had w/ our parts - there was a list of things - all this arose from my making parts & giving them to be detailed to an inexperienced sw drafter -
our sw people believe that it is just ok to throw parts on paper & presto - dimensions no matter what they are are ok to send out - solidworks is god here - do not think just make a drawing & get it done - i had to send back one part 6 times this week alone to this person to correct - this just opens up another can of worms as to why no one is able to read & make drawings anymore - i began my engineering carreer as a draftsman back in the 70's so now i get alot of flack from the younger guys when i check drawings - this department needs some help but i am just one person & an old guy at that - thank you again for letting me rant - a great weekend to all

 

[jassco]

Hi, duk748:

I kind of agree with this police (mirrored parts not acceptable
) in your organization. In fact, it is not just for a mirrored parts. It also involves with derived parts, configuration, in-context parts and assemblies, and so on.

There is a normalization requirement for all parts and assemblies in production environments. You can do anything you want (use mirrored parts, or derived part, etc). But in production, you should make it independent. That is why the police was setup in your company. I would do some thing.

3D math data are supposed to be normalized database. It is best to create normalized models (i.e, no part depends on other parts or assemblies). Relationship exists only one way from parts to its immediate parent assembly.

Best regards,

Alex

 

[ShaggyPE]

jassco,
You are making some blanket statements there. Do you have data to back up the "it is best to" and "not acceptable"?

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[TheTick]

There is a normalization requirement for all parts and assemblies in production environments. You can do anything you want (use mirrored parts, or derived part, etc). But in production, you should make it independent.

Well stated. I've seen what kind of headaches these things can cause after the models have left the nursery and gone into production. I remember on employer in particular had trouble with over-configured parts. These parts are still causing trouble for people I don't like.

 

[Updraft]

Boxers or briefs? Depends!

We all have opinions so here is mine. Some of the things you can do in development should NOT be kept when you move into production. For instance, in-context relationships to other parts or assembly states is great for developing the design, but they should, in my opinion, be broken and replaced with a part that is completely defined by its own dimensions and constraints when moving that part into production. Configurations are also wonderful for development and should be separated into separate parts when going to production. However, there are good reasons for exceptions to this for configurations. Keep in mind that configurations are not separately controlled with PDM. PDM only controls revisions of the part file.

A mirrored part is something different and you really have take into consideration its use. In the aircraft industry mirrored parts are quite common and often pretty involved so making a mirrored detailed drawing would have been a pain. Necessity is the mother of invention so they developed a simple means to deal with mirrored parts. Mirrored parts had different dash number series. The parent part might have a part number such as 74A123456-1009. The drawing for that part would detail that part and then show an image of the mirrored part with a view label of "-2009 MIRRORED PART". This worked for two reasons, 1) because it was well communicated throughout the company and industry so everyone understood it and knew how to work with it, and 2) because the mirrored part was truly a mirror, i.e., whatever happened to one part also happened to its mirror. Any revisions to the part, by definition, also happened to its mirror. If this relationship could not be maintained then the parts were separated into independent part numbers with no association to each other.

So, if you want to make mirrored parts that are true mirrors of each other it would make sense to follow the lead of the aircraft industry and make sure it is well understood how to deal with them. Otherwise you should keep them separate.

If the parts are not too complex it would likely be better to model a mirrored part using the same features as the original. FeatureWorks is a very handy tool (and I would also recommend exporting as Parasolid instead of other formats), but FeatureWorks cannot see how the part was modeled, as Eric said, and therefore will miss the design intent. Sure, you might get a fully constrained model, but if the dimensions automatically dumped into the drawing are different then what's the point.

If the reasoning behind the restrictions on mirrored parts is that they need their own drawings then I would suggest keeping the mirrored part itself, pulling it onto a drawing and manually dimensioning in a mirrored fashion to the original part. This way there is no export/FeatureWorks issue and it is pretty simple to copy duplicate the dimensions of the original drawing.

On another note, if your expert cannot adequately explain his reasoning then he is just an arrogant ash. Sound reason and good justification should rule, not someone's opinion. But then, that's just my opinion.

- - -Updraft

 

[DiegoLGraves]

What makes sense to the designer, in organizing his files for a project, does not always make sense to the manufacturer. We worked with a designer who used the same part file for multiple, completely different parts, by using configurations. Some of the configurations were linked together, some were completely separate. These were mostly, but not all sheet metal parts. Trying to keep the flat patterns correctly separated was a real pain, especially for a newer user here.

Mirrored sheet metal parts have gotten better to work with than they were years ago, but I'll admit to steering away from them, mostly because of future modifications by other users.

Diego