Hello All:  (I've added more info to this list so it's not a duplicate of a previous email)
 
I have some helpful information I'd like to pass along to those of you who may design a stained glass sundial someday.  I've just finished a design for an SE decliner with the technical help of a few glass artisans on the Bunji Glass List (an email discussion group like the Sundial List) and I've learned a lot in the past two weeks.
 
1. The width of the lead that joins the pieces of glass (called the "came") is very important to the design. Usually the came is "H" shaped and comes in widths of 1/8" to 1". You pick a width that is artistically pleasing for your design. You can use several different widths in the same design if you want. The center part of the came is called the "heart".  Lead cames of all widths have hearts that are 1/16" thick.  The two pieces of glass butt up against the heart of the lead came, which means that two adjoining panes are always separated by a distance of 1/16". (I don't know the metric equivalents of glass and came used in Europe, but will try to find out).
 
2. This means that when you design a stained glass sundial window you need to make two different drawings of the sundial face.  One drawing shows an interior view the sundial as it would actually look and shows the actual width of the lead came. This is the drawing that you would show your client.  The other drawing is the glass cutting template for the glass artisan. The cutting template drawing will show 1/16" gaps between the panes. On other words, the glass template will have thinner lines than the client's drawing.
 
3. It just so happens that Delta Cad is the perfect program for drawing stained glass windows because it allows you to draw lines of exact thicknesses. Go to "Options" then "Drawing Data" and you can enter different values for line widths. What's neat about Delta Cad is that you can easily play around with different lead came widths using this feature because it will change all the line widths in your drawing with the click of a button. Or you can change the line width of individual lines using the edit feature.  But Delta Cad will not add color to the spaces between the lines.
 
4. Your client will surely want to see a drawing in color and you will need one too.  The glass artisan does not need a colored drawing for his glass cutting template just as long as he knows what colors to use. Since large color drawings are expensive to make, you can just give the artisan a black and white version and write in text the colors of glass in the drawing. To colorize a Delta Cad drawing, I convert it to a PDF and then open the PDF in Photoshop Elements to add color. (check out the magic wand tool for this).  I found that you get very good resolution in Photoshop if you get your Delta Cad image from a PDF.  If you use a DXF or BMP exported copy, or if you use the copy/paste method, the resolution is horrible compared to a PDF. This was an important discovery.
 
5.  I think it is important to test your design.  You can easily test it with a paper version with a cardboard gnomon taped to a window or board where the window will be. (You can see test dial photos on the Technical Page of the SGS website.)  It only took me a half an hour to print, tape and test the paper test dial.
 
6. I noticed when testing that it is important to take into consideration the thickness of the glass when designing the height of the gnomon.  If the dial is painted on the interior side of the glass, then you must decrease the height of the gnomon by an amount that is equal to the glass thickness or else the gnomon will be too tall.  This is especially important if the dial is small.
 
7. Place the dial as high as possible on the window to get maximum duration of solar exposure by minimizing horizon pollution, being careful not to place it so high that the roof overhang shades it at noon  or in the summer when the sun is high.  Placing it high up also makes it look better and makes it more visible and therefore more useful inside the room, and more importantly, it protects the gnomon from curious hands by placing it high out of reach.  Installing bay windows for the sundial window can sometimes solve in a beautiful way the problem of shading due to roof overhang.  (Roof overhang is the enemy of SGS!)
 
8. Silicone adhesive works just fine to hold the gnomon onto glass, be it cardboard or metal. I don't know how long it will last, but it's a great alternative to drilling holes in the window.  I haven't tried rearview mirror or fishtank adhesive.
 
If you'd like to see my design drawing it is now posted in the Photo Collection in Stained Glass Sundials/ 21st Century.   I used 3/8" wide lead came in the decorative border and thinner 3/16" wide came on the sundial face  because the came is the hour lines and I didn't want them too thick.
 
 
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Hope this info comes in handy,
 
John 

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