Hi Tony: That's great information to know. I have a feeling the bolting method through glass or the metal structure would be better than the "car mirror" method.
I wonder what method the glassers use to drill glass? I'll have to ask them. But, you know what I'm gonna do? I'm going to try to drill a hole the same way I drill holes in stone using a high speed diamond sphere with H2O. But I have no intension of make stained glass sundial windows myself. But I might try some stone inlays someday. John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com> ----- Original Message ----- From: <[EMAIL PROTECTED]> To: "Sundial Mail List" <[email protected]> Sent: Friday, July 25, 2003 8:14 AM Subject: Re: SGS Gnomon Attachment > John Carmichael asked: > > > >What do you think is the best method to attach a metal rod gnomon to a > >stained glass sundial window? > > > >It's the most frequent question I've been getting from the "Glassers". I > >do have an article that Mike Cowham sent me that mentions that in the > >seventeenth century, a threaded gnomon was usually bolted to a hole cut in > >the glass. Of course that resulted in a lot of cracked glass and missing > >gnomons, especially if the glass was thin. > > > I've no practical experience of attaching gnomons to glass but would like > to experiment with: > > 1. modern adhesives to attach a gnomon with a small baseplate. If it > drops off after twenty years just clean it up and re-attach. The glues > used to stick interior mirrors on car windscreens would be a useful > beginning perhaps? > > 2. attaching through a drilled hole with e.g. a 20mm brass disc on each > side of the glass and soft vinyl washers in a sort of 'sandwich' squeezed > gently tight with a nut on the inside. The gnomon could be silver > soldered to the outer disc before assembly. Twin bolts would prevent > rotation. > > A very safe way to 'drill' glass is to use a short piece of thick-walled > copper tube of e.g. 6mm outer diameter with a few radial sawcuts in an > electric drill. > Garages are a good source of the right stuff. > > Place the glass flat on a firm/soft supporting surface, e.g. cork, and > build a tiny 'dam' around the intended hole site with Plasticene. Mix a > little turpentine with carborundum powder, place a few drops within the > dam and you can abrade a neat clean hole in no time but reduce the > pressure at breakthrough or the hole edges may flake. A thin piece of > wood with a 6mm hole will guide the tube until it begins cutting after > which it is just gently lifted and replaced to refresh the abrasive. > > Have fun > > Tony Moss > - > -
