mirrored parts not acceptable
mirrored parts not acceptable
(OP)
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






RE: mirrored parts not acceptable
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.
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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.
RE: mirrored parts not acceptable
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.
ht
RE: mirrored parts not acceptable
Such that neither part's feature tree is thereafter dependent on the other's?
Mike Halloran
Pembroke Pines, FL, USA
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
RE: mirrored parts not acceptable
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.
RE: mirrored parts not acceptable
RE: mirrored parts not acceptable
I love your analysis. You have my vote for the position of "CAD Psychologist".
- - -Updraft
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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.
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
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
RE: mirrored parts not acceptable
The benefits can be huge if used correctly, and the "police" would be much more effective if they helped develop such procedures, updating them as problems surface instead of creating short-sighted, expensive rules.
If you have thousands of LH parts on an aircraft, do you really think upper management would choose effectively modeling and detailing every part twice to document the RH parts, or establishing working procedures allowing the the effort to be nearly halved? I have created single details with opposite parts for years, and while it is true that they may be a bit more difficult to decipher on the floor, once the machinists and QA get used to it, it becomes second nature to them. And never forget, time = $, especially to management.
Technically, the glass is always full.
RE: mirrored parts not acceptable
Some of the other sugestions here scare me; is
pushingpulling lead on the drawing board next?In some industries, everything has to be documented and controlled from production of raw material thru to the product reaching the customer. You can't let the floor change the product definition without full documentation. If they do, those resultant files still have to be documented and controlled in the same manner as the originals. By separating the parts to make them independent, you have essentially doubled the costs and efforts involved in any future modifications.
Planning and training are much more cost effective solutions.
Technically, the glass is always full.
RE: mirrored parts not acceptable
There is no difference between mirroring and any other tabulated part or assembly. Tabulation saves modelling and drafting time, and it makes explicitly clear the similarities between a group of parts.
For example, I have drawings of a steel angle space frame in which each and every angle has the same hole pattern at the end. The fabricator can see that he can make one template or fixture to locate and punch the holes on every part. If each part had its own drawing, the template would not be a safe idea. In this case, manufacturing costs go up.
In-context models are what is dangerous in production. Done cleverly enough, your models will reconfigure your fabrication drawings depending on what assemblies you have open.
Your designers need to be able to decide when tabulation is good practise. At a lot of sites, management does not have this confidence.
At my site, tabulation is not allowed. We are extremely rule-driven. We want a process in which designers do not think. Tabulation looked complicated to our PDM group.
One of our designers worked around this. He created multiple configurations of his assembly model. He attached a separate assembly drawing to each configuration. No one noticed until I had to work on the top level assembly. What a mess!
If I am managing a tabulated production drawing generated in SolidWorks, I know there are multiple configurations to the model. The standard production design rule is to not change form, fit or function. If I intend to do such a change, I either must add a tabulation, or I must copy the drawing and model out and create a new drawing and part(s).
If you are manufacturing directly from the models, I don't see how you will recognize tabulation. In this scenario, the practise is dangerous. In mass production, design and drafting time is less important. In die-casting for example, similarities between parts probably cannot be exploited by production.
If you allow the village idiot to update your tabulated SolidWorks drawings, or any other SolidWorks drawings for that matter, you will get what you deserve.
RE: mirrored parts not acceptable
RE: mirrored parts not acceptable
RE: mirrored parts not acceptable
Thank goodness and Dassault for the tutorials and a super supportive local SW rep.
No thanks to the IT wizards who moved old (and multiply referenced) SW files among servers without warning, and Top Management who moved SW servers across town over protests. You haven't lived until you've loaded and edited a really big SW model over a T1 line.
Then the designer and I were eliminated and replaced by an EE who could sort of drive AutoCAD, and a fresh cheap MSME. At least they moved the SW servers back to the same net as the engineering workstations.
The results were pretty much what you'd expect...
Mike Halloran
Pembroke Pines, FL, USA
RE: mirrored parts not acceptable
there is a difference; a mirrored part is exactly the same except opposite.
Tabulated drawings and configurations are related subjects. I was only attempting to address mirrored parts.
Technically, the glass is always full.
RE: mirrored parts not acceptable
Mirroring or different lengths -- to tabulate or not to tabulate. It is the same problem.
If my sheet metal drawing shows right hand and indicates that left hand is opposite, the sheet metal guy makes one flat layout, punches two pieces and bends them opposite. The tabulated drawing shows an opportunity for the fabricator to save money and pass some of it back to us.
If I have a complex machined part shown as left hand and right hand, there might be an opportunity to flip the CAM program. There is a high probability of non-mirrored features creeping in. The tabulation is much less desirable, and way more likely to cause confusion.
If I have a drawing showing twenty angles of different lengths, all with the same hole pattern at the end, tabulation shows the fabricator an opportunity to work more efficiently. Again, it is a good policy. If the hole patterns at the end are different for each angle, tabulation creates an unreadable mess.
RE: mirrored parts not acceptable
Technically, the glass is always full.
RE: mirrored parts not acceptable
Tabulated parts do not always have changes to one which affect every other item tabulated (thus some of the documentation problems), as is the case with mirrored items. If the LH changes then by definition the RH changes. This can simplify design documentation significantly where it is taken advantage of.
It is not the same as tabulated parts.
Technically, the glass is always full.
RE: mirrored parts not acceptable
I feel that there are no blanket, totally hard and fast ways to do things, but make sure that what you are doing actually works. Many fancy systems are set up without much thought about what can (and therefore will) go wrong. If you agree not to do things in SW that are error prone, and if you think everything through, you can decide how your group will do things. This must lead to setting policy, and enforcing it. If someone has a bright idea, then you look at it and decide whether is will actually work, and won't scuttle other things you already have in place.
At our company we are very creative in SW, we heavily use macros and code to speed up mundane tasks, our file structure is very refined, and we can open assemblies with 1000's of parts, years later without any errors. That said, our system is not perfect, and would not neccessarily be agood fit for others. It is stable, and reliable. We do not use PDM, we generate all our BOM's directly from the model in realtime, and we can do that because we have reasonable rules, and we enforce them.