Well, I've been at it again. Recently a college professor approached me with a Gurley solar compass that his school had, but it needed some work. The first, and most obvious thing was that the two lens/target blocks on the declination arm were missing along with the tangent screw on the declination arc. Well, sometimes the good Lord smiles upon fools like me and what shows up on eBay - a Gurley declination arc. So, taking a chance that I could make things work, it was purchased.
Of course the parts I needed to use didn't quite fit and the screw holes did not match, but a little machine work on the blocks, some drilling and tapping, and making an extension shoulder for the tangent screw got it all in place. It's obviously not original, but the average person would never know the difference and it's serviceable. Also, the only parts I modified were the replacement parts. I did not make any changes to the solar compass that was presented to me to work on.
Additionally, every tangent screw was seized tight, every silver scale & vernier was so black they couldn't be read, the refraction correction marks were tarnished over, and as a whole it was just generally dirty.
So a complete dis-assembly & cleaning took care of these issues.
So, here's a couple of pics of the finished product:
This stuff is just plain old fun!
Beautiful work.
That kind of craftsmanship requires a lot of knowledge as well
as a lot of ability. You need to know how the instrument was was made and how it was used and the importance of each component.
Very impressive work.
I once polished a plumb bob. It turned out pretty nice.:-)
Don
> This stuff is just plain old fun!
The results are pretty nice indeed. Just out of curiosity, is all of the chemically-darkened finish new?
Oh my Gosh!!!
Don't tell Antiques Road show that you removed the patina.
(?The English version of Antiques Road Show is totally different, they aren't stupid like Americans about that)
> Don't tell Antiques Road show that you removed the patina.
Actually, it doesn't look as if some of the parts were repatinated. The sight vanes still show what looks like original wear.
I wonder what sort of assembly marks Dave found on various pieces of the instrument when disassembled, the traces of the original factory process.
No, the darkened finish is original. The only touch up I did to the finish was the clean brass surfaces that I had to work on.
The inside faces and edges of one site vane I had to clean a little more than I really wanted to so that the refraction marks and vertical angle marks were readable.
Yes, I found makers marks throughout. Punch marks to line up parts, match screws to holes, a batch number throughout, etc.
Dave I admired greatly your previous post. Not the post but your craftsmanship.
I have great respect for those capable of turning bits of brass (or any metal)into fully functioning devices.
That goes to repairs which I know from woodworking can often be challenging.
Absolutely great work.
regards
Richard
So I assume that you completed operational adjustments as part of the restoration. What accuracy can you say that you have?
The adjustment bar was not with the instrument so not much that could be done other than to try it on a known line - which I have not done. It is functional for demonstration purposes, but I would not guarantee past that.
Ideally if used properly, a solar compass will determine the meridian within a minute or two.
That is awesome
:good:
A masterful piece of work !
Here's a few interesting links on the theme:
http://en.wikipedia.org/wiki/William_Austin_Burt
http://miningartifacts.homestead.com/Michigan-Iron-Mines.html
Cheers,
Derek