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AutoCAD - What is the point of a CTB file?

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Message 1 of 14
fkuznets
6994 Views, 13 Replies

AutoCAD - What is the point of a CTB file?

I'm new to AutoCAD, so sorry if this is a bit of a silly question, but aren't CTB files redundant? Why would I ever need to use them? From what I understand, they're just a way to assign a bunch of properties to things in my drawing, but couldn't I just do that using layer properties? 

 

[ The subject line of this post has been edited for clarity by @handjonathan Original: What is the point if a CTB file? ]

13 REPLIES 13
Message 2 of 14
illusionistNUGXG
in reply to: fkuznets

It is harder to work with drawings, if all everything is set in the layer properties. All lines look alike.

I can differentiate line styles with ease.

(i use a dark background) white lines  = wide

green = thin

magenta = thin, dashed

cyan = middle lines (dash + dot)

...and they all print black

 

Also different ctb files can change the printed (or PDF) outcome with one selection.

e.g. thinner lines overall, or monochrome.ctb for black/white only

Message 3 of 14
imadHabash
in reply to: fkuznets

Hi and Welcome to AutoCAD Forum,

CTB, or color-dependent, plot styles are settings for how the 256 available colors in AutoCAD will appear when you plot them, including the lineweight assigned to each color. When you use CTB styles, you are essentially adapting some or all of the colors 0 through 255 to meet your office standards for plotting. You can use Color Plot Styles to plot in black and white or color.

  • By using a finite list of layer colors, CTB styles make it easier to tell which layer is which in your drawing and makes it easier to rescale for plotting.
  • The CTB file offers myriad options, but you are primarily concerned with three:
    • The color in which the source color should plot
    • Line thickness
    • Screening

Imad Habash

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Message 4 of 14
RSomppi
in reply to: fkuznets


@fkuznets wrote:

aren't CTB files redundant? Why would I ever need to use them? From what I understand, they're just a way to assign a bunch of properties to things in my drawing, but couldn't I just do that using layer properties?


It's not really a redundancy but rather a choice for you to make. 

Message 5 of 14
rkmcswain
in reply to: fkuznets

@fkuznets wrote:

.... but aren't CTB files redundant? Why would I ever need to use them? From what I understand, they're just a way to assign a bunch of properties to things in my drawing, but couldn't I just do that using layer properties?

Prior to ~2004 (not sure of exact release), there were no "lineweights" in AutoCAD. So in order to have objects with various widths, we had to use plot styles, or use polylines with a width (and not all objects can be represented with polylines).

 

Many, dare I say most, people and firms who learned this way still do it this way. As said above, it's a choice.

R.K. McSwain     | CADpanacea | on twitter
Message 6 of 14
ed57gmc2
in reply to: rkmcswain


@rkmcswain wrote:
@fkuznets wrote:

.... but aren't CTB files redundant? Why would I ever need to use them? From what I understand, they're just a way to assign a bunch of properties to things in my drawing, but couldn't I just do that using layer properties?

Prior to ~2004 (not sure of exact release), there were no "lineweights" in AutoCAD. So in order to have objects with various widths, we had to use plot styles, or use polylines with a width (and not all objects can be represented with polylines).

 

Many, dare I say most, people and firms who learned this way still do it this way. As said above, it's a choice.


@fkuznets In addition to what RK mentioned, layers are more for controlling screen appearance, whereas ctp (and also stb) are for controlling plot output. For example, our standard plot size is Arch D. We have a ctb that specifies the lineweights and maps all the layer colors to black. But for a check print (Arch B) we use a ctb that scales the lineweights by half. If all you had were layers, you would have to change the layer settings to get a different plot.

Ed


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Message 7 of 14
RSomppi
in reply to: ed57gmc2


@ed57gmc2 wrote:
If all you had were layers, you would have to change the layer settings to get a different plot.

Are you sure?

 

Scale Lineweights.png

Message 8 of 14
ed57gmc2
in reply to: RSomppi


@RSomppi wrote:

@ed57gmc2 wrote:
If all you had were layers, you would have to change the layer settings to get a different plot.

Are you sure?

 

Scale Lineweights.png


Good catch. oops.

Ed


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Message 9 of 14
payingtoomuch
in reply to: fkuznets

I'm interested in this too. Have been drawing in autocad for 20 years+ and have only dabbled in making a switch to by layer assignments of lineweights, linetypes, transparency & color.

One of the posts above seems to indicate that there is no way to still see color of the lines in model space when working.... but this doesn't seem to be accurate. Question would be that if "none" plot style is selected and line color is assigned by layer if there is a way to still have it plot black (or grey) and ideally when a layout tab is opened, be able to see the color that the line will be plotted at. Thinking this might require changing the vp layer color to black (or gray) for each individual linetype? That could get cumbersome. Not sure that path to take but I do like some of what I'm thinking through on the switch from ctb to assignments by layer.

 

Message 10 of 14
ed57gmc2
in reply to: payingtoomuch


@payingtoomuch wrote:

One of the posts above seems to indicate that there is no way to still see color of the lines in model space when working....


I didn't see that indicated anywhere. Layers have both color and lineweight settings, just like a ctb file has. If you choose "none" for the ctb setting in page setup, then the plot uses the layer settings (and object if it overrides the layer setting). The ctb is just a way to store overrides and easily switch back and forth. Layouts can't completely display what a plot would look like, although you can display lineweights. For that you need to use plot preview. If you want to plot all black, just use the acad-supplied monochrome.ctb.

Ed


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Message 11 of 14
payingtoomuch
in reply to: fkuznets

Not meaning to hijack the thread....

 

Below is where I got the notion that someone was thinking they couldn't see color in model space if they chose to set up drawings with color by layer....

"It is harder to work with drawings, if all everything is set in the layer properties. All lines look alike.

I can differentiate line styles with ease.

(i use a dark background) white lines  = wide

green = thin

magenta = thin, dashed

cyan = middle lines (dash + dot)

...and they all print black"

 

Was trying to get away from ctb.... but already having issues heading that direction.

-1st issue appears to be that because the default lineweight- assigned by "lwdefault"  (which would be the majority of my lineweights "assigned" to the various layers) is apparently a global setting (all drawings would revert to any new setting). So, if anyone arbitrarily selects some obscure lineweight then their (and my drawings) will not plot properly.

- Also. Thinking will be way more cumbersome having to select black or grey for all the various layers in the viewport everytime a new viewport is created and/or a new layer is created.

 

Think I'm bailing already. Can anyone convince me to stay the course and and get away from plot styles?

Message 12 of 14
ed57gmc2
in reply to: payingtoomuch

It depends on your needs, only you would know what works best for you (or your company). But you may want to look at named style table files (stb). Most use color tables because they just never changed from the way that AutoCAD first introduced...too hard to make a change, etc. But named styles have advantages too.

Ed


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Message 13 of 14
payingtoomuch
in reply to: fkuznets

Thanks Ed. I played around with STBs some years back and got away from it for some reason..... Will look again.

Message 14 of 14
payingtoomuch
in reply to: fkuznets

Very quick search revealed...

"If you want to be able to set your lineweights completely independent of the color of things on your screen, the stb is the way to go"

Definitely need to look into them again because after all said and done, this is probably the big reason I'm looking to make a change.

 

Thanks.

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