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    By Dennis Collin

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    Linetypes seem to be the bane of many AutoCAD users. This is often due to insufficient training, or the challenges faced when receiving poorly configured or produced drawings from third parties. Whilst we may draw at 1:1, annotation such as text and line patterns are for visual purposes only and need to be scaled up for larger drawing productions such as site plans and buildings.

    Sometimes, problems occur where lines should show as patterned, but stubbornly refuse all attempts to display correctly, both on screen and when plotting. This blog will hopefully shed light on the things we need to check and adjust in AutoCAD to obtain a successful outcome.

    The first thing to look at is to verify that the drawing has been drawn at 1:1 and establish what units have been used. This is achieved by measuring something that is known, a wall width, length or similar and then check the drawing units. Once this has been established we can set our drawing to plotting ratios, also referred as the plot scale.

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    The modern method of controlling AutoCAD linetypes is via the annotative scale list at the bottom of the screen. This list is ideally defined in a template, representing the list of scales we might need to plot from the plotting space layout.

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    Changing the scale adjusts the ratio of drawn to plotted units and after performing a screen regen the linetypes should usually appear as expected.

    If linetypes do not show there are several possible things to check:

    • Has the drawing been derived and developed from the correct drawing template? In the UK this should be the metric, ACADISO.DWT file with the units set to millimetres or metres.
    • The system MSLTSCALE should be set to 1. On older drawings this might be set to zero, which is useful if you want to control the linetype via the LTSCALE variable outlined below.
    • Global Linetype scale factor: LTSCALE should be left at 1 if using the annotative scale feature.
    • Current Entity Linetype scale factor: CELTSCALE should be set to 1.

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    If the problem relates to just the paperspace entities not showing correctly, it may be worth checking the PSLTSCALE variable. Setting it to 1 or 0 depending upon the desired functionality. Typically, I would recommend setting the value to 1 as this ensures a consistent display of patterned lines through plotting viewports even at different scales.

    If you don’t wish to use the annotative scale option, use the LTSCALE variable to change the scale factor of linetypes for all objects in a drawing. Changing the linetype scale factor causes the drawing to be regenerated. This is how AutoCAD traditionally worked with linetype patterns before annotative scale back in the year 2007!

    As a general guide if you wish to plot 1:1, leave the Ltscale setting as 1, plotting at 1:50 set the value to 50 and so on. Working in this classic mode the variable MSLTSCALE, should be set to 0 to avoid scaling the linetype pattern twice.

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    Whilst it may seem AutoCAD is a bit complicated regarding linetypes, one must remember it is like any other software package. It is used by lots of disciplines in many industries and as such must remain flexible to cater for all users. No matter what your situation, if you have a properly configured template and well-trained users who follow good CAD protocols, drawing linetype issues are a rare occurrence. Even if they do occur they can be fixed easily and promptly by following a set process.

    This document whilst making several points and perhaps proving useful, is no substitute for an ‘at elbow’ day or training course. Should training be required we have several course types available. From scheduled New user to Intermediate or Advanced training. If your needs are more specific, then we can provide more bespoke private training and run at the pace most appropriate for you.

    For more details please visit:  https://training.cadline.co.uk/ 

    Or alternatively call one of our team on 01784 419922 where we will be more than happy to help.