7/31/2019 RTC Drawing Guidelines
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DimensionsLocation
Locate dimension lines and text outside the object outline
Dimension lines to be in. (6mm) from the outline, other
dimension lines .15 in. (4mm) apart
Place dimensions between the views if possible
Cylindrical diameters should be shown on the rectangular view,
preceded by a diameter symbol
Show enough dimensions to avoid calculating or assuming any
distances
Place each dimension so that it has only one interpretation
Dimension the most descriptive view, where the profile or true
shape appears
Dimension from visible lines, not from hidden lines
Do not repeat dimensions
Stagger or move dimension text if necessary to prevent
crowding
Dimension lines should not cross other lines. If unavoidable,
break the dimension lines
Apply dimensions so that accumulation of tolerances is
minimized
Format
Dimension and leader arrows to be .12 in. (2.5mm) long, solid
filled Dimension text to be horizontal, centered between the arrows
where possible
If moved away from the dimension line, linear dimension text
should not have a leader
Dimension rounded corners and fillets to the theoretical
intersection
Show hole sizes in their circular views with a diameter
dimension or a hole note
Holes, diameters and arcs should have centre marks and centre
lines
Dimension arcs with a radial dimension
Fillets and corner radii can be dimensioned by a leader note,
preceded by R
Inch dimensions should have no leading zero
Metric dimensions should have no trailing zero, except for the
number 1.0
Tolerances should all use the same number of digits, except for
unilateral 0 in metric
Threads and Fasteners
Use simplified format external threads show a continuousthick
line for the crest and thin line for the root, internalthreads show
a thin hidden line for the crest and root
Sectioned threads use a thick continuous line for the crestand
thin line for the root diameters
End view of a thread shows a thick circle for the crest and
a thin 270 circle for the root
Threads should be specified using standard specification
External threads should show a chamfer at the end
Internal threads should show the thread depth and holedepth in
hidden and section views
Show standard fasteners only on assembly drawings, withthe type
and size correctly specified
Do not section standard fasteners on either full or
sectionedassembly drawings
