The dial on my Philco 16B cathedral is warped. Mark Oppat says likely due to shrinkage. Unfortunately, Mark is sold out of that dial and cannot obtain the raw materials needed to make more. So I must at least attempt to straighten the dial I have. Any clues as to how to proceed? I prefer NOT to destroy what I have. I assume that I first drill out the rivets holding the dial scale to the metal hub. Then apply heat (heat gun, slow oven???). Then clamp between two pieces of MDF or other flat material, perhaps with waxed paper between the dial and clamping material.
I do have a 16B tombstone with a good dial, for reference.
Has anyone tried this? Any suggestions? Thanks!
I have a spare 16B dial that came with a parts chassis. It's in fair shape. I'd be happy to send it to you.
If the spare dial doesn't work out you may want to google how the vinyl guys fix warped LP's. Something about low temps in the oven between two sheets of glass and letting it cool slowly overnight.
Good luck,
Mike
Hi DaveMC,
I've tried something similar with warped plastics and vinyl, both of which are much more forgiving substances.
I suspect your dial is celluloid? If so, it would need a much more delicate touch. Real celluloid is flammable.
Most of the techniques I've seen involve a very gradual and slow heating of the celluloid to avoid any possible cracking or undo pressure. Hot steam, low oven and a clothes iron all seem to be possible tools.
Some dangers are:
• More shrinkage due to excessive heat
• Losing the printed dial numbers (rubbing or transfer - again, heat related)
Here are two possible methods you can consider:
Using Steam / Heated Wood
"Straightening Warped Triangles (Drafting Celluloid)" - From Popular Science - Feb. 1926
http://books.google.com/books?id=4SgDAAA...&q&f=false
Using a clothes iron and stiff paper:
From a UK-based Radio Forum - "Warped Celluloid Tuning Dials"
http://www.vintage-radio.net/forum/showt...php?t=9881
I have never tried any of these suggestions on celluloid myself. Seems like a pretty delicate operation, at best.
Hope these links at least give you some help in deciding what you feel comfortable attempting. Good luck!
Michael (mbhdesign)
Thanks to all for the links. Several look promising. I assume that I must obviously remove the dial from the metal hub by drilling out the rivets. And I assume the dial is initially flat and gets its curved shape from the metal hub. Mark Oppat said that his reproduction dials are made from .020 ga paper phenolic (of course, the originals could have been something else). What I have read so far: BE VERY GENTLE!