A short presentation on how to cut a cavetto mould on sandstone

1. Cutting a Cavetto Mould
Introduction for Stonemasons
Stonemasonry Department 2012

2. Mould Recognition
A cavetto moulding consists of a TOP BED OF
STONE
number of elements which can be FILLET
seen in the diagram. It is essential
that you are able to readily
CAVETTO
identify each element so that you
can follow the correct procedures
for setting out and cutting a
cavetto mould.
FILLET
FACE OF
STONE

3. Roman Mould Development
Begin by marking the
total width of the mould
on the base line to form
points A and B.
A 140mm B

4. Roman Mould Development
Begin by marking the
total width of the mould
on the base line to form
points A and B.
Strike lines at 90 to the
base line which run
through points A and B
140mm
A 140mm B

5. Roman Mould Development
C D
Begin by marking the
total width of the mould
on the base line to form
points A and B.
Strike lines at 90 to the
base line which run
through points A and B
140mm
Mark the total height of
the mould from point A
and strike a line to form a
perfect square and form
points C and D
A 140mm B

6. Roman Mould Development
Begin by marking the
20mm
total width of the mould
on the base line to form
points A and B.
Strike lines at 90 to the
base line which run
60mm
through points A and B
Mark the total height of
the mould from point A
and strike a line to form a
perfect square and form
points C and D
20mm
Construct the grid for the
mould using the
appropriate sizes
20mm 60mm 20mm

7. Roman Mould Development
Begin by marking the
total width of the mould
E on the base line to form
F
points A and B.
Strike lines at 90 to the
base line which run
through points A and B
Mark the total height of
the mould from point A
G and strike a line to form a
perfect square and form
points C and D
Construct the grid for the
mould using the
appropriate sizes
Using centre E strike a
curve hitting points F and
G to form the cavetto.

8. Roman Mould Development
TOP
At this stage the mould is
BED
complete and you should
darken the appropriate
lines to better define the
mould. If you are
producing a template you
should complete the
template by including all
relevant information eg
mould name, type of
template, your name, top
bed and joint etc.
A STUDENT
FACE CAVETTO
JOINT TEMPLATE

9. Cutting a Splay
Mark splay lines on Make the lines safe using a Pitch the joints to the working
the joints and scribe half inch chisel. Always lines. You may wish to
lines across the face work away from the line support your stone at an
and top bed to join and toward the centre of angle so that your splay is
the splays. the splay. sitting level.
Chisel centre section to flat. Using marginal
Rough out the centre
If splay is to be seen, Check for flat across the drafts, set in the
section using mel-
polish to fine finish. length, width and diagonals of joints, top and
point and teeth tool.
the splay. bottom of the splay.

10. Cutting a Cavetto
Hold template to top bed and face of Mark template to both Cut a splay to remove
stone, making sure to align it properly joints and scribe across the waste stone. The
by holding a straight edge against the the top bed and face to splay should be 2-
aligned face and bringing the template join the profiles. 4mm above any
to meet the straight edge. cutting lines.
Run the mould through by
setting in along the arrises, Set in the mould on Set in the fillets at the top and
both joints and check Join the fillets bottom of the mould, checking
teething down and chiselling.
The mould should be checked accuracy with joint along the length with a sinking square that they
for straight between the joints and reverse of the mould. are square and at the correct
and a reverse template can be templates. depth.
used to check for accuracy.

11. Cutting a Cavetto Video

12. Marking a Mitre
A mitre is the term used to describe the arris formed when adjacent mouldings
intersect. There are both external and internal mitres.
EXTERNAL MITRE MITRE BLOCKS STEEL SQUARES
There are two common methods of marking a mitre line; using mitre blocks and
using two steel squares. The mitre block method is often easier but a stonemason is
more likely to carry the squares in their toolkit. Your course tutor will demonstrate
each method in the workshop.

13. Cutting a Return Mould
Begin by marking an external mitre line
on the existing mould. The top point of Cut a splay to remove
Mark a splay to remove
this line is determined by applying the the waste stone. The
the wastage from the
joint template to the back of the stone splay should be 2-
return mould.
and squaring, from the face, to the top 4mm above any
of the fillet cutting lines.
Run the mould through by
setting in along the Set in the mould at Set in the fillets at the top and
arrises, teething down and the mitre and close to Join the fillets bottom of the mould, checking
chiselling. The mould should the ashlar stop and along the length with a sinking square that they
be checked for straight check accuracy with of the mould. are square and at the correct
between the joints and a reverse template. depth.
reverse template can be used
to check for accuracy.

14. Developed by The Stonemasonry Department
City of Glasgow College
2012