It's funny that you posted this... we too are debating this very thing (just minutes ago). I agree with everything you said, however after reviewing how the notes/descriptions section of the revision table is used, it’s obvious in my company that it’s not necessary.
Frequently we get comments like: “redesigned”, “updated per mfg request”, “changed several tolerances”, etc.
Notes like this are not very useful. I’m of the opinion that if you can get the draftsman and engineers to properly and consistently indicate the changes with a revision triangle… you be better off.
That said, if you don’t have the option of a notes/description field anywhere, you don’t have any link to WHY the changes were made… just what the changes were.
Think of the 5Ws…
Who – who made the changes? This is recorded by the file and the PDM system
What – what changed? This can be indicated by rev triangles, comments, design journals, etc.
When – when the changes were made. This is recorded by the file and the PDM system
Where - what computer was used? If you need to know what computer the changes were made on.
Why – Why the changes were made. Could be the rev table description, PDM comments, design journal.
One last comment. Rarely does the 3rd party manufacturer need to know WHY. They mainly need WHO, WHAT, and WHEN.
I agree that I would like to see more specifics in the rev table. This is not possible without writing a short novel in some cases. That is part of the reason for changes only being made after some Engineering Change form has been prepared. In this case, a general idea of the changes is good enough provided there is a column on the drawing showing the Engineering change number. In 40 years of creating drawings, one good rule has been that the Engineering Change document should be written in a manner that it is capable of being used to recreate the previous drawing condition. Regardless of how much leeway your company allows in the change process, I fully expect to see a reference to the change in a rev block placed on the drawing so that someone with only a copy of it can ask pertinent questions - even if that is simply "what changes have been made as a result of ECO # XX?".
A drawing on the shop floor needs to tell the story as to what rev that drawing represents. Without a rev table, how does anyone in the shop know what they have?? Keep in mind that decisions will be made based on having paper drawings in hand.
I think if you were a fully paperless company, and everyone on the shop floor had access to PDM. I would say you would not need the revision box at all. PDM takes care of everything. I know here we are trying to go paperless and I am sure eventually we will "weed out" the revision box as well.
Are Revision Tables Necessary? Probably not, but they are very usefull.
I am on the other side of a company that does not have revision tables on thier drawings. They reference the ECR / ECO, but I don't have access to that system and getting them to supply that information to me in a timely manner isn't easy. When I get a new version of a print, I take the old version and set it next to the new version and compare them side by side to find the difference (Where's Waldo). It's time consuming, but easier than trying to get the ECO documents. Most of the time the change is something on the order of "Dimension X tolerance changed to Y from Z". Putting that on the print and then reading that from a rev block is a lot quicker than going to the ECO package even if you have easy access to it.
I understand that it may be more expedient to just put the info on the drawing but that is only by-passing the problem which is the difficulty you run into in getting a copy of the EC document. If your company has a system in place, they should certainly be willing to provide a copy of it in an efficient manner.
I also think some info in the rev table is very helpful (even when I'm the one that changed the drawing, a year ago). If you changed a few dimensions then it does not take that much time to put the "4.5 was 4.7" type info. If you changed a ton then I think it is acceptable to reference the EC number for more info. And revision symbols (only current ones) on the changed dimensions are a must.
Ryan, you may want to look at DrawCompare.
Assuming you can get the drawings as .slddrw files - SolidWorks can run DrawCompare to highlight additions in one color and removals in another.
It is free with all versions of SolidWorks. However, if you are running SolidWorks Standard - you have to trick the system by picking Professional or Premium on install tool, then you can access it (lame that this is necessary).
My opinion is that the revision tables are necessary. Regardless if PDM is in the picture
or not. One sometimes can never have enough history when it comes to documenting
changes. We have an ECN/ECR system and I have been used to this in many companies.
Some had PDM and some do not, but like you said, having it on the drawing is useful to those
that don't have access to the vault. But I also think that having good ties like ECN numbers documented
on the drawings is key as well.
I will tell you what I do think is useless and that is the revision symbology. I could write pages on why I think
those are so in the way and inconvienant.
I am with you Scott, but I do think keeping the latest revision symbol is a good idea. It shows what changed from the last revision.
I do remove all the old ones though.
Well my biggest beef with the symbols is is they cannot connect to anything
and are just flying loose around the drawing. That alone drives me nuts.
Plus the fact that if you delete one (which it will not allow you to do that I have found)
it will delete all of them along with teh revision line.
My feeling is if you have formats with zone designators (i.e. A2, D3) one can nail down the locations
of where changes happened pretty well.
If you can't delete a single revision symbol, you have probably told it to ignore the message that asks if you want to delete just a single symbol or all of that revision. Check your dismissed messages.
I am glad you said this because I was told by someone else who said there
was a message that prompts you like what you just said and when I revisited this
I still didn't see this message. I will chek the dismissed messages.
The only problem is I wonder if this is masked under the umbrella of another message.
But regardless I will look.
There are two that can be there.
"Do you wish to delete corresponding revision symbols?"
"Do you wish to delete corresponding revision table row?"
Thanks Wayne. I will look for those, but I have to be honest. I was looking at my list
yesterday for another reason and I do not remember seeing anything that looked like the
ones you posted. But another day looking maybe I overlooked them.
I will let you know.
Scott - What do you mean?
""""""""my biggest beef with the symbols is is they cannot connect to anythingand are just flying loose around the drawing.""""""""
If you drop the symbols inside the border of a drawing view then they travel with that view. You can also add leaders.
We actually don't use the SolidWorks revision table, I do find them a bit sensitive. We use a general table, and for symbols we just create a letter with a border around it - and then copy and paste it as needed. But both types of symbols seem to behave the same.
You need some way of conveying what has changed from one revision to the next. Do you want an NC programmer to completely rewrite his G code or just change what needs to change? That being said, it could be done on a Change Notice.