1. Dimensiynu Dimensioning

2. Dimensiynu Cyfochrog / Parallel Dimensioning
Nifer o dimensiynau yn cychwyn o un llinell tafliad
Several dimensions originating from one projection line

3. Dimensiynu Cadwyn / Chain Dimensioning
Dim ond ei ddefnyddio os nad yw’r darn yn cael ei effeithio gan goddefiant cynyddol
Only to be used if the object is not affected by the accumulation of tolerances

4. Dimensiynu Cyfuno / Combined Dimensioning
Dimensiynu sy’n cyfuno cyfochrog a chadwyn
Dimensioning that combines parallel and chain

5. Dimensiynu Cylchoedd / Dimensioning Circles
Dimensiynu tu fewn i’r cylch / dimensioning internally
Dimensiynu tu allan i’r cylch / dimensioning externally
+ D) Dimensiynu tu allan os yw’r cylch rhy fychan /
External dimensioning if the circle is too small

6. Dimensiynu Radiws / Dimensioning Radii
Dimensiynu gyda canol y radiws ar y gwaith / dimensioning with the centre of the radius on the work
Dimensiynu radiws heb angen lleoliad canol y radiws / dimensioning a radius that doesn’t require the location of the radius centre
Dimensiynu radiws sfferaidd / Spherical radius dimesioning

7. Dimensiynu Tyllau / Dimensioning Holes

8. Dylunio Edau / Drawing Threads
A) Pan yn dylnuio edau or pen, maer llinell adau yn cael ei ddangos gan cylch sydd wedi torri
A) When drawing threads end on, the threaded line is shown by a broken circle
B) Yn aml fydd edau yn cael ei ddangos tu fewn i rhan gan llinell wedi torri
B) Frequently a thread will be shown inside a part by a broken line
C) Dyma sut i ddylunio edau ar ddyluniad trychiadol
c) This is how to show a thread on a sectional drawing

9. Dangos GARWEDD ar luniadau Peirianneg - Showing ROUGHNESS on Drawings
BS EN ISO 1302:2002 Geometrical product specifications (GPS).
Indication of surface texture in technical product documentation
Mae’r gwybodaeth isod wedi ei tynnu or British Standards 1302 ar gyfer labelu diagramau er mwyn ddisgrifio garwedd
The information below is taken from the British Standards 1302 for labelling diagrams to describe the surface finish:
Esiampl o ddiagram yn dangos y symbol ar gorffeniad
Example showing the symbol being used on an engineering drawing
Esiamplau gwerthoedd Ra gwahanol / Rules of Thumb for surface finish in Ra values
Turnio garw – medru gweld y marciau / Rough turned with visible toolmarks....Ra = 12.5μm (micro.m)
Peiriannu llyfn / Smooth machined surface....Ra = 3.2 μm (micro.m)
Greindio / Surface Grinding… Ra = 1.6 μm(micro.m)
Gwynebau Lapio Llyfn / Fine lapped surfaces.... Ra= μm (micro.m)