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    By Dennis Collin

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    As an AutoCAD user of over 30 years and an instructor of more than 20, I can appreciate users sometimes find controlling linetype scale of AutoCAD drawings confusing. Common questions that I often hear include:

    • "How do I get the correct linetype scale for our AutoCAD drawings?
    • "Why is my linetype not showing, or why do I see just continuous lines?"
    • "Why do my linetypes show in model space, but not in Paperspace?"

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    These issues can be resolved by considering 3 aspects, it’s as easy as A-B-C!

    A. Use the Correct AutoCAD Template file

    B. Check/Set the Annotation Scale

    C. Check/Set AutoCAD's System Variables

    A - Use the Correct AutoCAD Template file!

    This is vital. If working with metric units, use the metric template. (ACADISO.DWT) If working in imperial, use the imperial template (ACAD.DWT). Although the units can be changed there are lots of other elements to consider e.g. annotation styles, linetype definitions, scale lists etc. For most users in the UK the ACADISO template should be used.

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    B - Check the Annotation Scale setting

    The Annotation Scale was a feature introduced within AutoCAD 2008. Set the annotation scale to the intended plot scale to be issued on paper or PDF. The control is located on the statues bar towards the bottom right of the AutoCAD window.

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    If the change of the annotation scale doesn’t update the screen, apply the REGEN command to refresh the screen.

    The main benefit with annotation scaling is that it has the capacity to show how elements should look at different scales. These two viewports below are showing identical objects. The left viewport is shown at 1:100 scale, while the one on the right is 1:50. Notice the line type appears identical within both viewports!

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    For most situations this should be sufficient. However, if there is odd behaviour or further control is required, system variables can be applied.

    C - Check AutoCAD's System Variables

    AutoCAD uses system variables to control all kinds of behaviours. The main variable that controls the linetype scale is LTSCALE. Assuming the correct template is employed, setting Ltscale to 1 is a good default setting. However, in rare instances this value can be adjusted to alter the desired linetype size. Change the LTSCALE to a higher or lower value. LTSCALE is a global document setting and will impact of all patterns within the drawing.

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    There are two additional system variables that controls the linetype appearance: MSLTSCALE and PSLTSCALE. These variables are related to annotation scaling.  MSLTSCALE sets AutoCAD to ignore the Annotation scale setting. If Zero (Annotation Scale is ignored), if set to 1 then linetype display changes with scale as expected. PSLTSCALE controls whether Linetype patterns take the Viewport scale into account.

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    When working in modern practice, it is generally recommended to leave both settings to 1 (or on). However it may be with older drawings provided by third parties, one or both settings have been turned off (set to zero).

    In certain situations, it is required to override a specific element linetype size, this can be achieved by overriding the value from the property’s palette, under the general category section. Although it is desribed as Linetype scale, the value is different from LTSCALE! Inside it should be thought of as a Linetype scale multiplier. In general, this should be set to small numbers from 0.5 to 1 or 2.

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    If a drawing still misbehaves Linetype wise, a good practice is to use the Copy Clipboard function and copy and paste the drawing into a clean template file (usually metric in UK). Reload the linetypes from the ACADISO.LIN file (metric linetype definition library) and set the annotation scale to an appropriate scale, bearing in mind the settings of key system variables; LTSCALE, MSLTSCALE and PSLTSCALE. Ensure these are all set to 1. If this is the case the linetypes should work as expected!

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