Yes Andrew, I agree that we should give a little more info on forked or single stay supports. I think I'll even add a drawing and more comments since we don't have ANY good photos of the outside of a stained glass window, with or without stays. This is the photo that the site really lack. Can I use your wording?
We've got a somewhat poor photo of Chris Daniel's Merchant Adventure Hall Dial (see tech page on site) from the outside, but it is difficult to see the gnomon. But it looks like it might have a single stay. you wrote a pertinent comment: > Have you also considered the difference between drawing the hour lines > on the inside and outside of the glass? The diagram shows the centre as > outside, but if the paint is inside surely the gnomon root should pass > through the dial centre on the inside surface, allowing also for > refraction? Most stained glass dials are painted on the outside I believe, so I doubt refraction is a problem, especially if the glass is only 3mm thick. A glass artisan in Japan contacted me and told me that it is customary there to put a protective glass or acrylic cover on the outside of stained glass windows to prevent damage. He said that the covers are usually between 2 and 10 inches away from the window and wanted to know it the protective cover would interfere with the gnomon. Well all sorts of red lights went off in my head about complications such as refraction if the gnomon was attached outside the protective cover. I couldn't answer his question and told him to contact Fer! John L. Carmichael Jr. 925 E. Foothills Dr. Tucson Arizona, USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Sundial Sculptures Website: http://www.sundialsculptures.com Stained Glass Sundials Website: http://advanceassociates.com/Sundials/Stained_Glass ----- Original Message ----- From: "Andrew James" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, August 04, 2003 7:16 AM Subject: RE: Rod Gnomon Hole Placement > John Carmichael wrote (01 August 2003 16:12): > <<Because of the importance of rod gnomon attachment on stained glass > sundials and the interest in the subject, I thought I'd make a Delta Cad > scale drawing for the website showing a sideview of the hardware used to > attach it to a pane of glass, using the bolting method.>> > > I should think that fixing a gnomon by just one attachment at its root > would be problematic. For one thing it will be awkward to align > accurately, but more importantly it will exert great leverage at the > fixing point, and if the end is pushed by whatever means it will be far > more likely to break the glass. Better to do what most of the old ones > did and have a forked stay supporting the bottom end or the middle of > the gnomon similarly fixed by nuts and washers into two more holes. That > both assures rigidity and placement and ensures that very little strain > is on any one of the fixing points, if properly fitted. It may be worth > pointing this out to avoid short lived designs! Incidentally the outside > of Bucklebury seems clearly to show the washer positions. > > Have you also considered the difference between drawing the hour lines > on the inside and outside of the glass? The diagram shows the centre as > outside, but if the paint is inside surely the gnomon root should pass > through the dial centre on the inside surface, allowing also for > refraction? > > Regards > Andrew James > > - > -
