Print Page | Close Window

Dimensioning arrows for Mechanical drawings

Printed From: CAD Forum
Category: EN
Forum Name: AutoCAD
Forum Description: Discussion about AutoCAD and AutoCAD LT, viewers, DWG and DXF formats, Design Review, AutoCAD web, Drive, add-ons
URL: https://www.cadforum.cz/forum_en/forum_posts.asp?TID=9095
Printed Date: 10.Jun.2026 at 15:21


Topic: Dimensioning arrows for Mechanical drawings
Posted By: Gmork
Subject: Dimensioning arrows for Mechanical drawings
Date Posted: 29.Mar.2013 at 16:06
Hi,

I found on my book a simple observance about the shape of dimensioning arrow in mechanical drawings:

the height (from top to base) have to be 1.75*base width

How can I apply this rule on Autocad?

Always in that book, another observance is about relationship between arrow dimensions and drawing scale, but I didn't find some mathematical relationship to rule them. Some suggestions?

Thanks


Replies:
Posted By: John Connor
Date Posted: 29.Mar.2013 at 21:52
You apply the rule by doing the math then constructing your custom arrowhead.  Once done you can add it to the list of available Arrowheads that appears in your Dimension Styles on the Symbols and Arrows tab.  The exact procedure for adding custom content is covered in your AutoCAD Help files I believe.

You want your arrowheads to be visible; not so small they cannot be seen, but not so large as to unduly call attention to themselves.  Personally I think you are getting your pants in a twist over something that is rather minor.  Use common sense and you should be fine.


-------------
"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."

<<AutoCAD 2015>>

Posted By: philippe JOSEPH
Date Posted: 02.Apr.2013 at 09:17
Hello Gmork, I did some search on the different dwt files acadiso, am_ansi and am_bsi and it looks that the ratio between base and height is 3 ( it looks OK for me for years ).
Of course you can do custom setings but it's going to be an other unecessary complication.
Of course it's different from what you see in school books ( length 3 with a total angle of 30° to 45° ) but in AutoCAD it will be drawn with a plain triangle and not with 2 separated lines.
 
For the ratio between text height and arrow length, we use the ratio of 1 for example.
It's got to see with the readability of documents  :
Drawing at scale 1/1 - text height : 3.5 mm on formats A0 to A2 , 2.5 mm for formats A3 and A4
Distance under the text : 1 ( if you use a negative value it will put your text in a rectangle )
Arrow length : 3,5 mm for formats A0 to A2 , 2.5 mm for formats A3 and A4.
For the other scales apply the scale factor for your texts and arrow dimensions.
In old school books you will find text heights of 7 mm on formats A0 to A2 but with the moderns printers it has been lowered a lot.
Ask for more...


Print Page | Close Window