Linetype predicament

I am trying to create a script that will insert a Smoke/Fire Damper symbol after picking two sides of a duct. I would like to create a linetype so that there is a short dash in the center of the line....
___ _ ___

Even if it is a large duct...
_______________ _ _______________

Is this possible? Any suggestions on another way to accomplish this? (Maybe a block inserted at the center with scaling in one direction only)

 

I don't think it's possible with a linetype, if the range of duct width is
that large. Either the shorter ones will come out continuous, or the longer
ones will have more than one dash cycle.

You could pick one side of the duct using Osnap Nearest, then pick the other
side using Osnap Perpendicular, and save both those points. Then change the
User Coordinate system to be based around the first one and rotated so the X
direction is toward the other one.

Measure the distance between the points, and save half the value as the X
coordinate (in the new UCS) of the midpoint. If you want the dash and the
gaps the same size, calculate one-and-a-half times that size and subtract it
from that X coordinate. Then do two break commands, starting there and
moving up the X coordinate each time by the dash/gap size. The Y coordinate
of all four points would be zero.

Then set the UCS back to what it was before.

The block idea with scaling for the duct width is easy enough, if it's
acceptable that the dash and gaps in the center would vary in size, too
(wouldn't look like your "sketch"). But it would be easier if you don't
insert it at the center. Draw the block horizontally, with a total length
of one drawing unit, with its base point at the left end. Then use that
first Nearest point as the insertion point, the distance to the
Perpendicular point as the scale factor, and the direction to there for the
rotation. [And with a simple line-based block, you could scale it in both
directions if that's easier.]

Other cockamamie ideas:
A middle-justified piece of text consisting of a hyphen or rotated capital
I, masked.
A line, two concentric circles, trim the line between the circles, erase the
circles.

 

Duh... It would also help if you DREW A LINE between those two saved
points, before breaking it.
--
Kent Cooper, AIA


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Try putting a * in front of the command this should repeat the command over
and over.

[Supply
Damper]*^C^C_-layer;make;M-HVAC-SUPP-ACCS;color;132;;ltype;continuous;;;^C^C-insert;"H:/MCP
BS3 Standards/Blocks/Mech/Symbols/SFD.dwg";x;\\

Rick