Containers for sundials
Fellow Shadow Watchers, Sending assembled sundials by mail is a perpetual problem if they are to be safely contained with little added weight and no possibility of crushing damage. A very stout box made of double-wall corrugated cardboard is ideal but finding suitable items cheaply has been a problem for me until recently. 12 bore shotgun cartridges are supplied in boxes of 25 in strong cartons containing 10 boxes and measuring 12.5 x 8.5 x 4.5 inches internally. These outer containers are discarded in quantity at any clay pigeon shooting club with a 'shop' where they will probably be available for free. They can then be stored flat until required. It is also possible to 'telescope' two of these boxes using strong parcel tape to double the internal capacity. Waste notwant not! Tony Moss --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Glynne replica dial
4/25.4 = .1575 inch 8*13+60 = .164 inch That's not much difference at all. (These are nominal, both will be under) I would tap it out to 8-32.? It would be easy to do with so little metal to remove.? You're lucky it's close to 32 TPI. (25.4/32 = 0.79 mm) To get gnomons on in a repeatably correct position, I've been doweling the gnomon to the dial plate.? (Pressing dowels into the gnomon with matching holes in the plate.) By having one dowel between the screw holes and one outside, the gnomon can't be put on backwards. More about pinning: I screw the gnomon to the dial plate, adjust its position, then drill the dowel holes (match drill, since it's already assembled).? After drilling, I dis- assemble and ream the holes in the gnomon for a press fit and the holes in the dial plate for a slip fit.? Press in the dowels and Bob's your uncle.? I hope this doesn't sound difficult; it's terribly easy. John B -Original Message- From: Richard M Koolish [EMAIL PROTECTED] To: sundial@uni-koeln.de Sent: Thu, 7 Jun 2007 6:42 am Subject: Glynne replica dial I have been given a sundial that may be a Glynne replica drawn by Fer deVries. I found it at a friends house in the suburbs of Boston, Massachusetts USA. The gnomon was mounted backwards. There are some pictures at: http://www.dickkoolish.com/rmk_page/pictures_060407.html The screws were steel and rusted, and I had to drill the heads off in order to remove them. When I went to replace them, I discovered that they were not a standard english or metric thread. The dial plate is about 12 in diameter and the gnomon angle is 54.5 degrees. It says Fer J. deVries 1982 under the gnomon. An old message in the sundial archive mentions a similar but smaller dial. http://www.mail-archive.com/sundial@uni-koeln.de/msg04470.html The old screws are the same diameter as a 4mm metric screw, but the thread is .8 pitch or 32/in, so an 8-32 is too big and a 4mm-.7 is too fine a thread, so I'm wondering what to do about re-attaching it. Also, it looks like the dial plate was once glued to the marble base disk, but the adhesvie has long since dried out and failed. I assume glue was used to prevent the thin dial plate from being lifted and bent. So, should adhesive be used, and what kind? --- https://lists.uni-koeln.de/mailman/listinfo/sundial AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Equation of Time
Mac and others, Here is a first attempt, using Google Sketchup. -- Roger Hi Roger, Any chance you could post pictures of your prototype? Maybe even drawings? Best wishes, Mac Oglesby attachment: Poncet1.jpg--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Equation of Time
Roger Sinnott wrote: Mac and others, Here is a first attempt, using Google Sketchup. -- Roger Nice!! So, you have two matching inclined surfaces, one on the pedestle, and one on the carrier. If you were doing this for a telescope, I guess you'd put two Teflon pads on the carrier's surface. For this application, more friction is actually beneficial, so that's not necessary. I've seen Poncet mounts that use a ball/socket for the pivot point. How are you suggesting the pivot be made? Maybe a rounded pin into a conical hole in a hardwood block? And it looks like the pin would lie in an equatorial plane, parallel to the polar end plane... Is there a height alignment requirement for the pivot point, relative to the inclined plane? Horizontally, it should be centered, but I have a feeling it needs to be placed at the right height on the meridian end, as well. Great sketch - I have to get around to learning Sketchup! Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Equation of Time
Dave Bell wrote: Nice!! So, you have two matching inclined surfaces, one on the pedestle, and one on the carrier. Actually no, there is only one surface (the big one in front) that *has* to be inclined. I gave the rear one a similar tilt to catch the pivot point more securely and prevent the upper table from sliding foward under gravity. But its angle is not critical. If you were doing this for a telescope, I guess you'd put two Teflon pads on the carrier's surface. For this application, more friction is actually beneficial, so that's not necessary. Good points. I've seen Poncet mounts that use a ball/socket for the pivot point. How are you suggesting the pivot be made? Maybe a rounded pin into a conical hole in a hardwood block? And it looks like the pin would lie in an equatorial plane, parallel to the polar end plane... The pivot can be almost anything -- even a nail through the upper table. Its angle is nothing special. Is there a height alignment requirement for the pivot point, relative to the inclined plane? Horizontally, it should be centered, but I have a feeling it needs to be placed at the right height on the meridian end, as well. Nope -- the height is not important, nor does it have to be centered. But you are right that the unit will be more stable this way. If the table tilts too much, as can happen when star-tracking with a heavy camera or telescope on top, things can get out of balance and there is a risk of the upper board toppling off. But this problem shouldn't arise in a sundial with an equation-of-time correction, and maybe not with a daylight-saving-time correction either. Great sketch - I have to get around to learning Sketchup! I first heard of SketchUp about a year ago, on this list, and I've been having a BLAST with it! -- Roger --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Equation of Time
From Edley McKnight: Hi Roger and all, Not ever having seen one, I'd imagined it as a horizontal slice through an equatorial dial, with the pivot on the gnomon and the sliding on the dial face, but this looks easier to adjust. I would imagine now that so long as the pivot point and the inclined plane contact points all start out in a horizontal triangle that it would work. The inclined plane appears to be parallel with the equatorial plane, yes? Hi Edley, The pivot and contacts on the inclined plane don't *have* to define a horizontal plane, but they might as well, since they are being used to carry a horizontal sundial. Also, everything will be more stable that way. You're right, the inclined plane must be parallel to the plane of the celestial equator (and Earth's equator). Therebore, this original form of Poncet table works well at high and temperate latitudes. But when you get close to the Earth's equator (say, within the latitude band from 15 N to 15 S), the inclined plane would become so steep that it wouldn't support the table properly. -- Roger --- https://lists.uni-koeln.de/mailman/listinfo/sundial
