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Whats the use of CTB  

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therock003
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I'm a land surveyor and i whenever i send drawings to civil engineers they ask me for CTB files. I dont use ctb, since my drawings are black and white and i plot them on printing facilities. Whats the meaning of ctb files and why would someone use them

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DAVID DRAHN
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If you're using autodesk products, you're using either ctb or stb files to control plotting (or 'none' but that would probably give you unacceptably strange output if you take advantage of layers and/or colors to draft).  You can see what you're using in the upper right of the plot or page setup dialog box.  ctb's are part of autodesks original plot control methods and so many people and agencies still use it as their standard (as opposed to the enlightened stb users).  Probably the only thing it controls other than the plotted lineweight (of the particular color) is its "grayness".  Any color may be given a "plot black with a screening value", which is used effectively in most professional plan sets.  If you use the OOB monochrome.ctb, every color is plotted the same lineweight and black with the screened or grayish colors reserved for the last colors 250-255.  This can work fine and if this is how you cad you can just tell the civil you're using (unmodified) monochrome to plot.

You can also do an ETRANSMIT when preparing dwg file for clients and it will include the ctb and other support files in the package.

 

Capture

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StLSurveyor
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I believe it contains all the pen weights etc. If you don't have the associated .ctb file the plot will not look like it should. 

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therock003
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This is what i dont understand. Since i dont own a specific plottter, or have any color information to do the mixmatching, and each line has each corresponding information, why use pens in the first place?

Lets say i have weighted polylines, and inside the properties dialog they have their corresponing width. What more will a pen weight do, to help a fellow engineer

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BlitzkriegBob
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Interesting. First, let me clarify that CTB files are not specifically for plotter information. That is handled in PC3 files. CTB files were the original way to deal with pen weights in AutoCAD. Now, I've never done a drawing in the manner you describe, nor have I ever received a drawing in that manner, so this will just be an educated guess.

You're right. The way I envision it, they shouldn't need a CTB file from you. A polyline with a width will plot the same regardless of its pen weight. If you use true type fonts, they also will plot the same regardless of its pen weight. If you don't use true type fonts, then they won't.

So why are they asking for one? Did they actually try to print it and have it not come out the way they would like? Be aware that if they try to use None as the Plot Style Table they will get color plots regardless of your intent, unless you make all your layers color white. You could suggest that they use the standard Monochrome CTB file. I think that would work for them.

They also could just be asking because they are used to plotting with them and can't wrap their heads around not using one. I prefer using STB files rather than CTB files, but even with that, I don't ever ask a surveyor for their CTB file because in the end, I want to be able to use my STB file to plot drawings, so I always edit a surveyor's drawing file to match my STB file for desired pen weights (light), and screening.

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Totalsurv
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I use a ctb file because it allows me to use many different colours in the Cad drawing to aid in drafting and then plot in black and white using the ctb. Also it allows me to use screening which makes the printed drawings look really well.

I used to do something similar to you previous to using the ctb but would not do it any other way now.

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