Markup CAD Prints

When changes have to be made to hard copies of prints I have heard that called red lining? I see prints marked up in red pen before changes so I assume that is where the name comes from.

Is there a specific way you are supposed to do this such as when adding a wire or when marking things for deletion or is it just whatever feels right?

Most drawing title blocks have a revisions block, with a change mark and space for date and draftsman. I fill this out, and then put the change mark adjacent to the changes so they can be identified.

Put yourself in the place of the person who is going to have to use those redlined prints. Does he have enough information to do what needs to be done? Is the information you've given him clear and unambiguous?

Other than that, just follow the same conventions as the person who made the originals.

Don't be afraid to add written notes to the person who will be doing the work, although its probably best to write those notes on a separate sheet. I once redlined a set of prints to show the "as installed" condition. The draftsman had drawn every limit switch as normally open. I drew a circle around the limit switch and wrote "NC" for each switch that was actually wired as normally closed. The draftsman took my instructions literally and added the text "NC" without changing the picture of the limit switch.

as Tom said, use the title blocks.

here is what we do.

when you install a system toy have the as builts. they get marked up. make sure everyone is aware that all prints released for construction must be returned. the individual returning the prints must go over each page and discuss the changes.

when doing the cad work - use the title blocks.
backup the drawings to a backup directory for safety.
the cover sheet has a title block with all pages and revisions. each sheet title block is then changed to a different rev level. for example drawing D-12345 now becomes D-12345-A for rev A. the title block should say that the sheet superceeds D-12345.
the edits block references the changes and why.

time consuming, but it got me out of hot water several times.

regards,
james

Is there a specific way you are supposed to do this such as when adding a wire or when marking things for deletion or is it just whatever feels right?

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"Red-lining" may be the slang for the process of correcting errors, but the drawings are generally called "Mark-ups" or "Error correction prints". I have worked at places that had a color for deletions (usually red) and a color for additions (blue), and a color for this and a color for that. I do not care for that system - too fussy and I never could keep a supply of all the different-colored marking pencils.

The simplest system is to use a red pencil or pen for any change that needs to be made to the drawing. I have worn out several thousand red pencils and pens. A drawing reviewer has a large responsibility to NOT get carried away and mark things just for the fun of it. Often there are different views and different ways, and you have to be able to recognize something that really will cause problems and should be changed, as opposed to something that only shows your own preferences and whims.

I've always used the "Control Set/Field Set" method. Keep in mind it is the responsibility of the person making the redlines to make sure they are drafted correctly.

doing research I had found the red only method and the multiple color method. I think the red only method will be best for me.

Is there a certain way to mark a deletion vs an addition or just red x and scribble lines through a deletion with a small note like delete or something.

I just wanted to make sure there was not an industry standard way of making these markings and it does not sound like there is. Sounds like do your own method just use good sense.

Appreciate all the help everyone.

Its typically bad practice to scribble things out. You would mark deletions with a simple X. This way people coming behind you can see what was there originally, that it was deleted, and what the correction is. This way you still have the original information if things don't match up with the real world.

There are several things to consider here.

First, keep "FROM/TO" in mind. The field people need to be clearly shown on the prints the wirng they are changing FROM TO how the new wiring will be connected. You need to draw a line either in CAD or freehand to show where the exisitng wire moves to or the new wire that needs to be added. Just handing them a drawing showing only the new wiring makes it difficult to see what all is really being changed.

Second, clearly illustrate on the drawings the areas where the change is to occur. Using AutoCAD's REVCLOUD command is easy and it shows up better than just drawing a box around the area to be changed.

Third, don't be afraid to include clear and succint notes on the drawing. This helps out alot.

Fouth, use the revision block on the drawing to indicate what's going on.

There are a few other things to do also but this response is getting too long.

Current and new drawing pages with JOB DESCRIPTION without any "red marks" and "revisions".

One thing to remember is that all required information can't be included on the drawing. Most companies have an engineering change notice (ECN) form that covers the whys, the details of the change, and the person responsible among other things. This ECN can be referenced the change notice section of the title block.