[Hallicrafters] Cleaning dials

[Roger K8RI]

To create a photograph of a dial while keeping the aspect ratio (length to 
width) proper takes a bit of preparation. You need a lens that is at least a 
medium to short telephoto that can focus at the required distance.  Using, 
or making the equivalent of a copy stand (horizontal or vertical) is 
essential. (that can be done with a tripod, level, and a lot of measuring, 
but the copy stand is easier.  I said the equivalent of a copy stand as it's 
quite likely most copy stands would not be large enough for some of the 
longer slide rule type scales.

Yes, the camera has to be perpendicular to the scale and aligned with the 
center (right, left,  top, and bottom) hence it's a good idea to take the 
scale out to make the copy.  The longer focal length lens is required to 
keep the lines straight. (spherical aberration)  The alignment is critical. 
It'll make the difference between something that looks professional and 
something that *might* be acceptable.

There "used to be" and most likely still are, places that will make custom 
decals.
IF the aspect ratio of the image is correct you only need tell them how long 
you want the image to be..
The nice thing about using a digital image is (with practice) you can 
correct for imperfections in the original. So you don't need a perfect 
example to start.

Which BTW brings up one of the reasons for not washing dial scales on some 
equipment.  They are decals and after 20, 30, 40, or even more years have 
dried out and become very fragile. Water and most liquids do a very good job 
of removing them, or at least parts of them.  They only get stubborn when 
you want to remove the whole thing.

BTW, you can make the photosensitive material, the glass, and actually print 
the image on the dial face. Most of us don't have this kind of equipment and 
I've not heard of any one trying it, but back in one of the advanced college 
photography classes we had to make our own photographic paper for a couple 
of assignments.  No, I don't have the chemicals and I don't remember what 
they were as that was a long time back.  A bit of research should be able to 
turn them up, but I think the decal would be a whole lot easier even if it 
did cost more and you still run the risk of not getting quite what you want.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com


I think that is an excellent idea Ian, especially since I have an
S-108 dial glass whose printing has been liquefied by the previous
owner.  Taking the photo is no problem.  Scanning could be a different
story since many are too long for (my) the scanner and would have to
be done in two passes and then merged together.  I wonder how
difficult it would be to get the scaling correct from a photo? It
seems the photo would have to be taken straight on from the direct
center of the dial.  Any offset could introduce some distortion to a
full sized image.  Anyhow, it is worth a try.

Jim/Castroville, CA

See my radio museum at:
http://www.freewebs.com/wa6dij

Please also visit:
www.californiahistoricalradio.com


-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Ian
Sent: Sunday, December 18, 2005 10:10 AM
To: 'john'; hallicrafters at mailman.qth.net
Subject: RE: [Hallicrafters] Cleaning dials

If you have the dial removed from an old piece of radio gear consider
taking
a scan of it if you have a flatbed scanner.  We should all have
scanners
since they're, after rebate, frequently available for well less than
$25.
It's cheap insurance to save an image that can be lost forever.

Or if necessary set up your digital camera, if you have one, on a
tripod and
take a good close up.

>From the scan or image adjusted to 1:1 the dial can be brought back
from the
dead if necessary by some creative work with a photo manipulation
program
(Photoshop, Corel, etc.) and with a color printer that can make
transparencies a pretty good copy can be created.

Of course if you have the talent and tools to do silk screens you're
even
further ahead or you can pay to have a silk screen made.  It's been 55
years
since I've done silk screening but even then I don't remember it being
all
that difficult if you had a good image to start with.

Maybe the group should start a "dial image bank" consisting of at
least 300
dpi images of dials contributed by members of the group.

Happy Holidays --- like it or not!
Ian, K6SDE




______________________________________________________________
Hallicrafters mailing list
Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:Hallicrafters at mailman.qth.net
----
List Administrator: Duane Fischer, W8DBF **for assistance**
dfischer at usol.com
----
Hallicrafters Collectors International: http://www.w9wze.org