Re: A Sundial as a Prize
> ... A photo of a dial similar to the one made for Patrick Moore can > be seen on the internet at > http://www.lindisun.demon.co.uk/smallest.htm I have a question for Tony Moss about the dial pictured. Unless there is another scale on the back we can't see or the dial plate can be turned over, this dial can only be used in summer. That's OK, but then why do you include the Equation of Time for the whole year? --Art Carlson
Re: A Sundial as a Prize
In a message dated 10/15/00 11:58:49 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: > Hi Tony: > > I now polish the engraved brass compass rosettes that I often inlay into my > dials. I have been using an electric palm sander with 1500 grit sandpaper > wetted with water and a tiny bit of detergent. I want the surface to be as > shiny as possible. > > This procedure works fairly well but the gloss isn't quite as bright as it > could be. Even using this fine grit, I can still see very small scratch > lines from the abrasive. Do you think emery sandpaper would give a higher > gloss than 1500 grit? Also, do you prefer electric or hand sanding? 3M makes polishing paper (Don't use lapping film), as fine as 1 micron. I used this to get a near perfect mirror finish on my bronze focusing mirrors (before rhodium plating them). It is about $2.00/sheet from Precision Surfaces International (www.psidragon.com) in Houston, Texas. You can also buy diamond paste in a finer grit from Grainger or a host of other sources. This is applied by a cloth, and a little goes a long way. Lastly, there are some wonderful lapping compounds available from PSI above, and from United States Products Co. in Pittsburgh (412-621-2130). I recommend USP's "38-1200" aluminum oxide applied by felt (billiard table) cloth, followed by "Linde-C" (1 micron) then "Linde-A" (0.3 micron) for a beautiful mirror finish. Bill Gottesman Burlington, VT 44.4674 N, 73.2027 W
Re: A Sundial as a Prize
Arthur Carlson wrote: > > ... A photo of a dial similar to the one made for Patrick Moore can > > be seen on the internet at > > http://www.lindisun.demon.co.uk/smallest.htm > > I have a question for Tony Moss about the dial pictured. Unless there > is another scale on the back we can't see or the dial plate can be > turned over, this dial can only be used in summer. That's OK, but > then why do you include the Equation of Time for the whole year? > > --Art Carlson Congratulations to Tim on being given this commission. I am sure Patrick Moore will treasure it. Without having seen the dial, I cannot be sure of the answer to Art's question, but note that use in the winter requires that the lower face be read. It must be marked as the mirror image of the visible face. Turning the dial plate over allows its use in the southern hemisphere. Whereever used, the gnomon visible in http://www.lindisun.demon.co.uk/smallest.htm must point to the north celestial pole, the upper surface functions in the summer and the lower surface in the winter. When the correspondence on the Schmoyer dial was going on, everyone seemed to assume that the numerals needed to be drawn for one hemisphere or the other, which isn't strictly true, although with a ring design the numerals should perhaps be drawn both ways up so as to be more easily read. Chris Lusby Taylor 51.3N 1.4W
Re: A Sundial as a Prize
choice. I made a large equatorial disk dial. At 30" diameter it was large enough to have a steel core with brass around the outside in which the numbers and minute ticks were engraved. Adjacent to this is matte white terrazzo. The terrazzo shows even dim shadows. The brass has never been good for defining shadows, neither new and shiny nor weathered. When I made the dial, I blackened the engraved letters, numbers and time ticks. When the dial was new, the contrast made the numbers easy to read. As the dial aged, the contrast became less and although the engraving is deep, there was no crisp contrast. Once while applying paste wax to the brass, I noticed that the white in the letters was much easier to read than the black and now I leave the white wax in the engraved spaces. Some day I hope to figure out how to neatly fill the engraving with matte white epoxy. It would have been easy during construction, but as is, it looks difficult. I am so impressed with the white matte shadow definition and ease of reading white letters and marks, that if I build new dials, big or small, I will fill the letters with white, and supply a white filled ring near the time ticks, at least 1/4" (6 mm) wide, so the gnomon's shadow can be clearly seen. People who ooh and ah over large shiny machined pieces of brass may not find this composite as their ideal of perfection, but I see a functional beauty that continues from shiny new through weathering. Chuck Nafziger Seattle Washington 47 deg 40.7' N 122 deg 23.7 W >Toni: I see the gnomon being refelcted on the surface. My experience is in >that case that it is rather difficult to read the shadow instead of the >refelxion. I suggest to mat the surface slightly to increase the readability. >Thibaud > Agreed! This is the eternal problem of anyone making sundials for 'presentation' purposes. The client wants something that looks 'sparkling new' and certainly NOT the dull matt surface which is ideal for shadow casting. I try to compromise with a 'brushed' finish using 600 grit abrasive. This yields a surface which produces a feint 'compromise' shadow on a 'bright' surface for presentation, after which the natural patination process will take placeand then there is gold plating on a bead-blasted surface for a lovely golden 'eggshell' finish if funds permit. One thing I have never been able to fathom is WHY, if confronted with polished brass, people feel an overpowering compulsion to finger it! :-( :-) You can't win! Best Wishes Tony I have some JPEGs of Patrick, presentation dial in hand, but am something loth to inflict them on the main List!...perhaps to my faithful JPEGGERS! _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com.
Re: A Sundial as a Prize
Hi Tony: I now polish the engraved brass compass rosettes that I often inlay into my dials. I have been using an electric palm sander with 1500 grit sandpaper wetted with water and a tiny bit of detergent. I want the surface to be as shiny as possible. This procedure works fairly well but the gloss isn't quite as bright as it could be. Even using this fine grit, I can still see very small scratch lines from the abrasive. Do you think emery sandpaper would give a higher gloss than 1500 grit? Also, do you prefer electric or hand sanding? thanks John Thibaud Taudin-Chabot commented > >>Toni: I see the gnomon being refelcted on the surface. My experience is in >>that case that it is rather difficult to read the shadow instead of the >>refelxion. I suggest to mat the surface slightly to increase the readability. >>Thibaud >> > >Agreed! This is the eternal problem of anyone making sundials for >'presentation' purposes. The client wants something that looks >'sparkling new' and certainly NOT the dull matt surface which is ideal >for shadow casting. I try to compromise with a 'brushed' finish using 600 >grit abrasive. This yields a surface which produces a feint 'compromise' >shadow on a 'bright' surface for presentation, after which the natural >patination process will take placeand then there is gold plating on a >bead-blasted surface for a lovely golden 'eggshell' finish if funds >permit. > >One thing I have never been able to fathom is WHY, if confronted with >polished brass, people feel an overpowering compulsion to finger it! :-( > :-) > >You can't win! > >Best Wishes > >Tony > >I have some JPEGs of Patrick, presentation dial in hand, but am something >loth to inflict them on the main List!...perhaps to my faithful JPEGGERS! > > >
Re: A Sundial as a Prize
Message text written by Tony Moss >I usually recommend a white fill for just the same reasons but client preference mostly tends towards black, although not for any diallistic consideration, and the customer is always right!< Another excellent use of white infilling is the use of talcum powder on an old eroded dial in order to be able to see and indeed photograph the engraving. I first heard of this trick some time ago but had never seen it used until John Davis sent me some images of a very worn horizontal dial for the BSS Register. The result of using the talc was amazing. It certainly confirms your view. I now carry some with me in my camera bag - much to the family's amusement! [And thanks to you John for that.] Patrick
Re: A Sundial as a Prize
-Original Message/Oorspronkelijk bericht-- > ... A photo of a dial similar to the one made for Patrick Moore can > be seen on the internet at > http://www.lindisun.demon.co.uk/smallest.htm I have a question for Tony Moss about the dial pictured. Unless there is another scale on the back we can't see or the dial plate can be turned over, this dial can only be used in summer. That's OK, but then why do you include the Equation of Time for the whole year? --Art Carlson You have to turn over the scale only for use in the southern hemisphere. In order to read the other side: put the dial on a mirror. Toni: I see the gnomon being refelcted on the surface. My experience is in that case that it is rather difficult to read the shadow instead of the refelxion. I suggest to mat the surface slightly to increase the readability. Thibaud - Thibaud Taudin-Chabot 52°18'19.85" North 04°51'09.45" East home email: [EMAIL PROTECTED] (attachments max. 500kB; for larger attachments contact me first)
Re: A Sundial as a Prize
-Original Message/Oorspronkelijk bericht-- Chuck Nafziger contributed: >In regards to finishes friendly to shadow definition: matte white is my >choice. I don't think anyone could disagree with that. Well, you might consider a slightly darker colour like sand or beige. My experience is that when you use white the shadow will be less sharp because the white colour is also reflecting some sunlight. I found this when I noticed that the shadow on a dark brown surface seemed to be better visible than the shadow on a white surface Thibaud - Thibaud Taudin-Chabot 52°18'19.85" North 04°51'09.45" East home email: [EMAIL PROTECTED] (attachments max. 500kB; for larger attachments contact me first)
Re: A Sundial as a Prize
Art Carlson queried > >> ... A photo of a dial similar to the one made for Patrick Moore can >> be seen on the internet at >> http://www.lindisun.demon.co.uk/smallest.htm > >I have a question for Tony Moss about the dial pictured. Unless there >is another scale on the back we can't see or the dial plate can be >turned over, this dial can only be used in summer. That's OK, but >then why do you include the Equation of Time for the whole year? > There's a scale on the underside going 'backwards'.although you may get a crick in the neck trying to read it. The small challenge involved was to make sure that both scales accurately centre on the central pin gnomon with both noon lines truly co-planar. It actually took twice as long to make the octagonal presentation casket in black walnut for this item as it took to make the metal parts of the dial. Tony M.
Re: A Sundial as a Prize
Thibaud Taudin-Chabot commented >Toni: I see the gnomon being refelcted on the surface. My experience is in >that case that it is rather difficult to read the shadow instead of the >refelxion. I suggest to mat the surface slightly to increase the readability. >Thibaud > Agreed! This is the eternal problem of anyone making sundials for 'presentation' purposes. The client wants something that looks 'sparkling new' and certainly NOT the dull matt surface which is ideal for shadow casting. I try to compromise with a 'brushed' finish using 600 grit abrasive. This yields a surface which produces a feint 'compromise' shadow on a 'bright' surface for presentation, after which the natural patination process will take placeand then there is gold plating on a bead-blasted surface for a lovely golden 'eggshell' finish if funds permit. One thing I have never been able to fathom is WHY, if confronted with polished brass, people feel an overpowering compulsion to finger it! :-( :-) You can't win! Best Wishes Tony I have some JPEGs of Patrick, presentation dial in hand, but am something loth to inflict them on the main List!...perhaps to my faithful JPEGGERS!
Re: A Sundial as a Prize
Chuck Nafziger contributed: >In regards to finishes friendly to shadow definition: matte white is my >choice. I don't think anyone could disagree with that. > >When I made the dial, I blackened the engraved letters, numbers and time >ticks. When the dial was new, the contrast made the numbers easy to read. >As the dial aged, the contrast became less and although the engraving is >deep, there was no crisp contrast. Once while applying paste wax to the >brass, I noticed that the white in the letters was much easier to read than >the black and now I leave the white wax in the engraved spaces. I usually recommend a white fill for just the same reasons but client preference mostly tends towards black, although not for any diallistic consideration, and the customer is always right! SNIP > >I am so impressed with the white matte shadow definition and ease of reading >white letters and marks, that if I build new dials, big or small, I will >fill the letters with white, and supply a white filled ring near the time >ticks, at least 1/4" (6 mm) wide, so the gnomon's shadow can be clearly >seen. A nice idea, which I shall certainly experiment with. >People who ooh and ah over large shiny machined pieces of brass may not find >this composite as their ideal of perfection, but I see a functional beauty >that continues from shiny new through weathering. Some useful ideas here Chuck, particularly for anyone who is new to dialling. Thanks Tony M.
Re: A Sundial as a Prize
Thibaud Taudin-Chabot added: >> >> >In regards to finishes friendly to shadow definition: matte white is my >> >choice. >> >>I don't think anyone could disagree with that. > >Well, you might consider a slightly darker colour like sand or beige. A useful thought! Surface texture is also important and a matte surface seems likely to retain atmospheric grime which would show up badly on white perhaps? Tony M.
Re: A Sundial as a Prize
John Carmichael wrote: > >I now polish the engraved brass compass rosettes that I often inlay into my >dials. I have been using an electric palm sander with 1500 grit sandpaper >wetted with water and a tiny bit of detergent. I want the surface to be as >shiny as possible. > >This procedure works fairly well but the gloss isn't quite as bright as it >could be. Even using this fine grit, I can still see very small scratch >lines from the abrasive. Do you think emery sandpaper would give a higher >gloss than 1500 grit? Also, do you prefer electric or hand sanding? There is a time when you have to leave abrasive papers and move on to much finer 'polishing soaps' and a revolving polishing 'mop' made up of cotton discs made up into a thick sandwich. Polishing 'soaps' are bars of hard grease/wax containing abrasive powder. They are applied to the spinning mop and the heat/friction transfers them. They need frequent application. The sequence I use is:- Try not to put any scratches into the metal in the first place! :-) Successive grades of 'wet & dry' paper on a cork block by hand as used for auto bodyfinishing e.g. 400grit - 600 grit - 1000 grit - 1200 grit for as fine as they go with plenty of running water as lubricant. Each grade should be applied at right angles to the previous one and continued until all previous scratches are removed before starting the next grade. At one time this was followed by 'Tripoli' polishing soap on a cloth mop again followed by Jewllers' Rouge soap and then liquid metal/brass polish. Tripoli/rouge 'soaps' continue in use but have been supplanted by modern soaps which do not leave a greasy deposit. A jewllers/dental supply company will advise. DON'T try to polish scratched metal on a mop as all you will get are shiny scratches! If it takes a long time to get a satisfactory gloss then your preparation stages have been insufficient and you will polish away detail and round off clean edges. Dwelling overlong on the mop can produce an 'orange peel' surface especially if you apply high pressure with the coarser grades. For a very fine finish a 'swansdown' (very soft cotton) mop is advisable. For flat surfaces a Selvyt cloth and fine alumina powder in distilled water is an alternative final stage or, if your pocket will stand it, 6 micron and then 1 micron diamond paste. The good thing about diamond paste is that it never wears out - the Selvyt cloth just disintegrates around it eventually. No doubt others have equally successful procedures. Tony M. P.S. Have you considered gold plating?it may be cheaper than you think and the platers will do the fine polishing for you! ;-)
Re: A Sundial as a Prize
Fellow dialists, Re: > >In regards to finishes friendly to shadow definition: matte white is my > >choice. >> >>I don't think anyone could disagree with that. >>Chuck Nafziger >Well, you might consider a slightly darker colour like sand or beige. My >experience is that when you use white the shadow will be less sharp because >the white colour is also reflecting some sunlight. I found this when I >noticed that the shadow on a dark brown surface seemed to be better visible >than the shadow on a white surface >Thibaud (Thibaud Taudin-Chabot) Out of my own observations, I side with Thibaud on this point. Moreover, I'd like to add a bit of speculative interpretation: Of the many factors involved, an important one is the effect of diffuse indirect sunlight that illuminates that dial area which is shadowed from rectilinearly propagated sunlight by the gnomon. Some of this light comes from the sky, some is reflected from structures, foliage, etc. within the large solid angle to which the dial is exposed. This light tends to "dilute" the contrast of the shadow as seen by a logarithmically responding eye. The spectral makeup of this diffuse light is, in general, altered from that of direct (white) sunlight. Most obviously, the sky is blue, the result of differential Rayleigh scattering by tiny particles in the atmosphere; the longer wavelength light being more likely to stay on it's straight course from the sun. Bounce-light from terrestrial objects' surfaces is less predictable in color, but green landscapes are not infrequently associated with sundials. In short, the shadow-revealing light is likely to contain more red and yellow than does the diffuse general illumination, which diverges toward excess blue and green. Thibaud Taudin-Chabot's, "slightly darker colour like sand or beige," or even his "dark brown surface" --- on which the shadow --- "seemed to be better visible than the shadow on a white surface," should by these lights indeed be favorable. Brown and beige pigmented surfaces appear to us as they do by subtraction, for they selectively reflect relatively less of received light in the blue and green parts of the visible spectrum than they reflect in the yellow and red. So they tend to favor the contrast-producing direct sunlight over the contrast-dilluting indirect light. Bill Maddux
