Best Practice Dimensioning

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Best Practice Dimensioning

flywire
This post was updated on .
I'm trying to improve my dimensioning skills and the User Guide for Dimensioning is a big help but I still can't get the finish I'm after.

This project is a bracket made out of 4mm steel to be cut out with hand tools. It was drawn with the origin at the bottom right of the side elevation to work from the nice right-angle then mirrored to the best of LibreCAD's ability. The external measurements in the side elevation are required for layout.

I'd like to tidy the drawing up and squeeze it vertically to fit nicely on an A4 sheet from my printer.

Issues:
* best way to evenly space parallel dimension lines (I snap to grid)
* how to adjust the spacing between existing parallel dimension lines from 10mm to say 7mm without deleting them and starting again (move is tedious)
* show 12.5mm circle diameter dimensions outside circles (like user manual example)
* show half circle dimension for top of Side which goes through same centre as hole
* show internal and external radius on Front
* any comments on line type and how to draw for centre of circle in example above welcome

bracket-mirrored.pdf Bracket.dxf
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Re: Best Practice Dimensioning

fa201
End view should be on the other side (if you follow the European rule).
Line at 45° is a help to draw but you can move views to optimize your layout.
I added some missing features to improve the readility of the blueprint.
At bottom I proposed a new layout.
You can move dimension using the // line fonction (7 mm) to draw construction lines. Then move the dimensions using the handles (blue squares).
Improved circle dimensionning: no idea I guess it is a limitation of LibreCAD.

I made some modification on linetypes to show an improvement (explaining would take pages and it is difficult). I suggested some Youtube tutorials on dimensions to understand the customs and basic rules.

The most important for dimensions is not to strictly follows the rule but to have all necessary data to manufacture and to be "quite" easy to understand (regarding part design).Bracket_fab.dxf

hope it helps.
Fabrice

French hobbyist interested in 2D design.
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Re: Best Practice Dimensioning

flywire
@fa201 Thank you for your reply. I appreciate the help and the result is much more like I was after.

You missed two things:
* It was drawn ... then mirrored [to produce the pdf, so by chance the final end view was on the correct side]
* The external measurements in the side view are required for layout [specifically 83.7mm and 71.8mm]

I mirrored it then followed your advice with the dimensions. I'm not clear how to adjust the dimension lines at the bottom of the Front bracket or extend the one to the Top hole. Is the axis in the holes really drawn as a vertical and horizontal line trimmed with some arbitrarily sized circle?

Calculating the layout lines was the whole reason for drafting it. How would you label the layout lines in the revised attached drawing? I also understand it is bad practice to dimension off hidden [construction] lines but that is exactly what those layout lines are as they extend off the tangent to the circle to a square edge. Similar for the 44mm height in the Side view.

Maybe someone else can jump in with an idea how to better dimension two small entities with the same central point (ie Side view hole and outer curve diameter and Front view inside and outside radius. The diameter is more useful than the radius on the Side view.

A reference to dimensioning rules would be useful.

My experience is with labelling in mapping packages rather than dimensioning in drafting package. Dimensioning, moving and mirroring seem archaic by comparison but I agree they do work and allow for calculated dimension line spacing. btw, I've seen too many 45min Youtube videos which could be summarised with a good diagram to be a fan.

Bracket_FabA.pdf Bracket_FabA.dxf
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Re: Best Practice Dimensioning

dellus
I don't really know how to draw and dimension a mechanical drawing properly, I just want to show a way I have found to place parallel dimensions evenly spaced. It even works on inclined dimensions, if you have Snap on Entity enabled. The triangle just is to demonstrate this. In the dxf make the layer DimAux visible. You can shift or copy these concentric circles around as you need them. Fun.
You know you can drag the dimension to a different place by the blue square handle? But if you change dimension settings this gets all lost again.
Bracket_dell.dxf  Bracket_dell.pdf