2.4 Blending of lines and curves

• The meaning of blending (a smooth, tangential join) in drawing
• Blending an arc to two straight lines
• Blending an arc to a line and a circle, and blending two circles
• Using blending to construct shapes

• describe blending of lines and arcs as used in drawing
• construct arcs that blend lines
• construct arcs that blend two circles
• use blending to construct given shapes
• appreciate the application of blending in power mechanics

“Why is blending of lines and curves important in drawing?”

The titles are open to everyone. Reading a lesson needs an account — sign in or create one.

1. Blending of lines and curves
   40 min · 1 practice tasks · quiz
   What blending means - joining lines and curves with a smooth tangential arc - how to blend two lines, a line and a circle, and two circles, using blends to build shapes, and why blending matters in power-mechanics drawing.
2. What blending means
   40 min · 1 practice tasks · quiz
   Blending is joining a line or curve to another with a smooth arc that meets each at a tangent - no sharp corner and no crossing.
3. The tangent and the radius-R rule
   40 min · 1 practice tasks · quiz
   Every blending arc of radius R has its centre R from each line or curve it must touch. Parallels and concentric arcs are the loci of that centre.
4. Locating the tangent points
   40 min · 1 practice tasks · quiz
   After the centre is found, the arc starts and stops at tangent points: a perpendicular to a line, or the join of centres through a circle.
5. Blending two straight lines
   40 min · 1 practice tasks · quiz
   A rounded corner is an arc that blends two straight lines. Parallels R inside the corner cross at the centre.
6. Constructing a rounded corner
   40 min · 1 practice tasks · quiz
   Practise the two-line blend as a four-step construction: lines, parallels, centre and tangent points, then the arc - compasses, not freehand.
7. Blending a line and a circle
   40 min · 1 practice tasks · quiz
   To blend a straight line and a circle, cross a parallel R from the line with a concentric arc r+R (external) or |r-R| (internal).
8. Internal and external blends
   40 min · 1 practice tasks · quiz
   External blends sit outside a circle (locus r+R). Internal blends turn against it (locus |r-R|). Choose from the required outline, then pick the matching locus.
9. External blend of two circles
   40 min · 1 practice tasks · quiz
   To join two circles with an outer blending arc, swing r1+R and r2+R from the two centres; their crossing is O.
10. Internal blend of two circles
    40 min · 1 practice tasks · quiz
    An internal blend is a reverse curve between two circles. Loci are |R-r1| and |R-r2|; the arc cups into the gap like a waist.
11. Blending two equal circles
    40 min · 1 practice tasks · quiz
    Practise the curriculum task: the same two equal circles blended externally and internally on one sheet.
12. Fillets and rounds on vehicle parts
    40 min · 1 practice tasks · quiz
    A fillet is an internal blend; a round is an external blend. They are specified because sharp corners crack, cut, and look unfinished.
13. Constructing a hook
    40 min · 1 practice tasks · quiz
    A hook is a given-shape exercise: shank, inner and outer arcs, then blends at the junctions and the tip.
14. Constructing a spanner outline
    40 min · 1 practice tasks · quiz
    An open-ended spanner combines equal jaw circles, internal and external blends, a straight handle, and a rounded end - the full blending toolkit.
15. Vehicle shapes with blending
    40 min · 1 practice tasks · quiz
    Mudguards, sills, bumper ends and lamp holes are line-and-circle or circle-and-circle blends. Power-mechanics drawing is vehicle geometry.
16. Why blending of lines and curves matters
    40 min · 1 practice tasks · quiz
    The inquiry: blending draws the smooth, strong, buildable shapes of real machine and vehicle parts. Accuracy prevents kinks that become cracks or misfits.