Tips for Creating the Lug Design
1. A rough sketch is drawn onto the lug with a pencil and perhaps enhanced with a pen to get an approximate idea of what would look good.
2. You want to create and refine your lug design on a sheet (or sheets) of graph paper. Each lug has 2 design sets, one for each tube socket. For example a down tube lug needs a separate design for the down tube socket and another one for the head tube socket. Graph paper has a bunch of horizontal and vertical lines (that make little boxes) and sometimes diagonal lines to help assist in drawing your design.
3. The round section of each lug socket is made into a flat blank rectangular outline shape on paper. It is within this template you will eventually draw your lug design. The top of this rectangular outline is the wavy miter shape. It looks like the miter profiles that can be printed and wrapped on a tube to assist in hand mitering. The distance between this top miter shaped line and the straight line on the bottom (representing the lug opening) is the length of the lug socket. The outside circumference of the lug determines the width of this blank pattern. The width lines taper a bit towards the bottom because a lug is slightly thicker in its middle than on its end. This taper allows the lines on each side to just meet together on the underside of the lug along their entire length when it is wrapped around the lug.
4. The top miter line of the outline can be refined by rolling a cut out trial piece onto the lug and nipping a bit off here and there to more closely match the lug’s intersecting shape. Fold the design in half to cut the offending extra away evenly on both sides. The goal is to have just this entire lug section covered without any of it overlapping or starting to creep into the lug’s transition to the other socket. This refined outline shape can now be retraced onto clean graph paper. Make sure there is a stronger vertical line in the center and horizontal line along the base of the outline. For convenience, I put all 6 outlines on one standard size piece of graph paper. It can help to enhance the outline tracings to make them easier to copy. They are now ready to be copied again.
5. It is extremely helpful to draw your pattern at least twice (or more) the actual size of the lug. This makes it much easier to create your design with drafting tools and get all the proportions just right. Small changes don’t make as radical a difference. The outline shape can be doubled in size in a copy machine and then traced back onto the graph paper where the design will be created. Be sure and square the outline with the lines on the graph paper. You want its center and base to be on a more clearly dominate line. Sometimes it is helpful to trace the lug outline on the backside of cheaper paper (if that is what you have) so erasing mistakes won’t affect it.
6. Create your unique lug design within the double size traced outline. Start by drawing a corresponding 2nd line 9 or 10 mm actual length (18 to 20 mm on a double sized drawing) away from the miter line. This inland matching-the-curves-of-the-miter line can help you better visualize your actual working space since you probably aren’t going to cut in too close to the lug’s junction. The curves in this line will probably influence the placement and shape of the curves in your design. You might want to make it a dotted line.
7. Creating a good design is about getting the right proportions for the space available on a lug. And the limitations of how fine a pattern a jeweler’s saw can cut. Typically you don’t want all the design to be on the outside edge of a lug leaving too much blank space behind it or it won’t seem balanced. It can really help to have windows. Neither can the design be overly complicated or too small. One of your biggest challenges is going to be that the space available on the top of each lug has a different amount of real estate. This probably requires modifying the size and/or shape of each design on each lug so they appear matched when grouped together (since they can’t be identical).
8. It is important that centerline points or lines be added to your design to help position it correctly on the lug. The base line of the outline will be matched to the end of the lug’s opening. Sometimes other points in the center of a circle can make them easier to drill accurately (so you don’t have to guess where to position the center punch to leave an indent for drilling). Other distinctive points (like the tip of a fleur-de-lis) can help in creating the mirror image on the other side of your design.
9. Once the design is drawn to your satisfaction, it can be reduced to actual size and printed on sticky-backed paper by a copy machine
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