by John Sedgwick
This aspect of Parquetry falls in between Parquetry and Marquetry. The subject is truncated triangles or variation of the traditional fan design, - 90 deg. for corners - 180 deg. for along a base line, 360 deg. for centre pieces. The traditional fan design was and is precision cut in volume with a saw in stacked components (10 to 20) at a time - each piece is sand shaded and joined to the next piece. (see fig. 1)
Fig. 1 Intersection points are cut out. Amount increases with numbers and length
There are two basic designs:
a) Truncated triangles cut into a background
b) Truncated triangles cut convex or concave or combinations (see figs 2-5)
Shading
To add emphasis to each segment, it is common practice to shade the base along it's length as designated with "XXXX". The base of one triangle touching the adjacent or hypotenuse side. The sectional pieces divide either 90 deg.-180 deg. or 360 deg. in as many pieces as desired 8, 9, 10, 11 etc. This is determined by simply dividing the desired area by the number of appropriate pieces - e.g. CORNER MOTIF 90 deg. - 6 pieces required - each piece will be 90 deg. divided by 6=15 deg. The number of pieces is arbitrary, but as a rule the larger the motif the greater the number - e.g. 1½" 90 deg. CORNER MOTIF not less than 4 or more than 6 - - 6" 90 deg.
CORNER MOTIF not less than 8 or more than 12. The reasons for this ratio becomes obvious when you do this. The further out the sections go, the wider they become and the larger the cut away becomes at the radius intersect points. Either side can be shaded. However, the same side must be common for all or both sides, when alternately placing them. (see drawing)
Shading can be done using either molten lead or sand. The principle difference is not effect, but speed. The molten lead at 600 deg. - 650 deg. F. will scorch the edge of some of our species to unrecognisable cinders in a few seconds - e.g. Pear; whereas Canadian Sugar Maple is perfect for lead. It scorches without undue shrinkage in a couple of seconds. Using hot sand at 350 deg. F., however, will allow for Pear to be scorched without damage and limited shrinkage. Any shrinkage will re-expand during gluing with white glue. Maple on the other hand will shrink and even curl and harden without noticeable or sufficient scorching. The lesson to be learned here is experiment with different veneers at different temperatures. Lead can be obtained by melting fishing sinkers in a piece of 1" pipe sliced in two and capped (see fig. 7)
The Non-scorching Method
Any of the fan designs can achieve a similar, but uniquely different effect by using my method, which I shall refer to as the L.B.D. Method - paraphrased from - "My Fair Lady" and I quote - - - with a "Little Bit of Dark" With a Little Bit of Dark you can have it all and not Sand Shade! --- with a Little Bit --- and so on. This requires a little bit more mathematics --- now hold on --- I did not say this requires you and Mr. Pythagorus to be on a first name basis or that your library include works of Newton, Einstein or Steven Hawking. If you understand that when a clock hands point to 3:00 o'clock, that is 90 deg. and at 6:00 o'clock they are 180 deg. and 12:00 o'clock is 360 deg. and can use a calculator - you are home free.
The principle of the L.B.D. Method is to insert 3 deg. or 5 deg. of dark veneer between each triangle - for example: If a 5-piece were to be cut for a corner, each piece would be 5-piece x 18 deg.=90 deg.. The 18 deg. pieces would be reduced to 15 deg. and a 3 deg. segment placed beside it for a total of 18 deg.. Of course 15 deg. and 18 deg. are whole angles and easy to measure - other segments will require fractions of a degree - - - don't panic now. Although dividing the 180 deg. in say 11 pieces, you will require segment of 16.36 deg.. When making your cutting template consider it 16 deg and a bit, less than half, but more than 16 deg.. There is, as the lawyer would say, some "Wiggle Room" in this procedure during assembly.
Well you heard the magic word - "Template". Templates are for people like me, who cannot make the same measurement twice.
Cutting Templates
So here is how you make and use them. Like most people I make a jig to suit the job required, then when I need it again, two years later, I cannot find it. The writing of this article has prompted the making of a series of angle jigs at once, so that I could make the designs shown. If after reading this you want to try these designs, I recommend making a set using the angles shown, sooner or later you will use them. To my knowledge this method of cutting angles has not been documented before, so for the record, I shall lay claim to it and name them J.A.C.'s (John's Angle Cutters).
MATERIALS
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Clear Plastic 1/8" to 3/16" thick. |
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A plastic ruler will do, but it must be clear. |
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Bristol Board |
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Double sided tape |
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180 deg. Plastic protractor |
7PC. JAC'S TO BE CUT
Cutting Angles
Pleated Design
Tape 18 deg angle sections securely with veneer tape to desired size. Because a point is not required, cut the pieces to allow a ¼" to 3/8" cut off as shown. However, all pieces will be cut to the same width.
Pleated JAC
For pleated design:
Turn over and slide all other pieces in - cut off where shown
Having assembled the angle segments either a circle or oval shape can be selected.
Dimension Variables
When deciding to make any of these patters, it is important to remember the potential problems. The jig will cut the exact angle every time. However, the angle may be slightly out, in which case the more pieces, the greater the compound error - e.g. (11Pc for 180 deg.) angle is 16.36 deg. - if the error was 1.5 deg. the compound error would be 11 x 1.5 deg.=16.5 deg. In general the pieces you cut will be slightly bigger than the measured angle, principally because you cannot place each piece so tight that no gap exists. If only .2 deg. error exists due to placement, then at 11Pc the compound error is 11 x .2 deg.=2.2 deg. Such things as the angle of your knife or how sharp it is will generate small errors. Fear not - the answer is - be consistent, use a sharp knife and make the angle slightly negative rather than positive. "SMALL" negative template errors will usually offset positive cutting errors. Finally, test the segments through 180 deg. and adjust your cutting template accordingly.
Sand/Lead Shading
Previously I mentioned the shrinking effect due to heat. This will obviously vary with the degree of scorching and the veneer species. However, all will shrink to some degree. If only one edge requires shading, cut the angle after shading. This will do two things. First the angle will be correct - Second the point of the segment will remain intact.
If you are familiar with sand shading, you will know that any point of veneer tends to distort and burn off. This is because the heat cannot dissipate as with a larger area. With the traditional production saw cutting method the angle must be made to compensate for shrinkage and each different species and tonal variation requires adjustments to the pre-cut angle. In addition, because the points burn and distort they are replaced with a full or part circle of black veneer.
This does not look unattractive and you may wish to cut the points off and be traditional - the option is yours.
Variations
Another variation of this design shown previously is a pleated or folded fabric design. This can be used in conjunction with banding as a corner motif. Veneer pieces are cut at a low angle, preferably 12 deg., as it is part of the recommended angle templates to be made. For veneer, I prefer "YEW" as it is very stable during shading joined to A pear or a cherry border stringer
3 to 5 or 7 pieces can be used as desired - tape them together after cutting one motif to the desired shape - position over each of the remaining pieces and mark around with a pencil. Cut in using a saw or knife. If a saw is used the waste from the sections can be simultaneously cut along with the waste from the corners.
Using the J.A.C.'s will give you quick precision cuts with no set-up time. If you keep them together in a box they will always be available to make up a quick inlay motif.
The technique of combining geometric wood pieces into flat surface decoration is very old. The early Egyptians were masters of the art. French furniture makers incorporated parquetry in elaborate ways in their fancy furniture. Most of us today think first of wood floors when the term is mentioned.
To relate the art of parquetry, we will define it as the art of geometric marquetry. Parquetry procedure borrows some of marquetry's methods but limits itself to straight cuts. Veneers are cut into squares, triangles and diamonds. Usually the cut pieces are assembled into a sheet which is laid as a single piece on a flat wood surface. Large cut pieces intended to cover a table top or to decorate a sizeable panel are sometimes laid individually to avoid the hazard of handling an oversize taped assembly of veneer pieces. The primary tools for parquetry are a craft knife or a single edge razor blade, a steel straight edge and an assortment of metal triangles providing 45, 60 and 30 degree corners.
If you cannot buy suitable triangles, cut them from sheet metal. Six-inch triangles are handiest and are large enough for most work. You need a 90 degree steel square and a simple bench hook. The best veneers for parquetry are those having straight grain. A parquetry pattern is inherently busy and would become bizarre if composed of veneers having wild or strongly irregular figure. In general a selection of only two or three colour tones - light, medium and dark - will work best. For your first parquetry experiment it is best to start with a simple design of squares such as those required for a chess board. The next easy step to try is to cut triangles.
Gradually you will find ways of creating interesting design patterns by alternating the grain direction of every other veneer strip in an assembly of two colour strips, or by turning over every other strip, or shifting every strip by a distance of one square to left or right. Cutting an assembly of squares on diagonals and varying the cutting angles can produce some wholly unexpected results. The possibilities are endless. If you enjoy simple parquetry, you will want to experiment with more complicated switches of cuts and variations of assembly.
The progression from cutting squares is to move into diamonds. At its most simple, providing the grain direction is correct, simply turn the square onto its corner. However, a more useful diamond is the 60 deg. one and is made by cutting across the strip assembly at 60 deg. You will note that grain direction becomes important; now the planning begins in earnest. A good example of the use of the 60 deg. diamond is the Louis Cube. To produce equilateral triangles, cut the 60 deg. diamonds, and then cut across in the other direction.
You will appreciate that the assembly will require taping back together between the first and second cut. Before devising fiendishly complicated patterns with pieces of veneers, making a 'map' using graph paper (with he small squares) can be a great help. As mentioned earlier, it is easier to produce parallel strips if you use a simple jig. The intention is to produce pieces of identical width by: a) locating the edge of the veneer against an end fence, and: b) having the cutting line (along the straight edge) a fixed parallel distance away. Your jig may look like this:
shown or hold in place with brads.
Now mitre the ends of the (E) and (F) pieces respectively. Be sure to apply glue to the mitres as well as the flat surface of the door stop. Clamp or hold the place with brads. Note that one of the (E) pieces is supported only at the ends.
After the glue is dry, sand and finish the frame. You can apply the finish of your choice. Thoroughly clean the glass. Insert the mounted art and drive the screw through the centre of the top (A) piece to prevent the art and glass from accidentally sliding out of the frame. Install the screw eyes and braided wire for hanging the frame to complete the job.
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