[Premium-Rx] Nylon gears

[John Perlick]

Gee, do you suppose there might be replacement gears out there?  Has anyone checked a boston gear catalog or something?  A replacement gear set would be a hot seller! The Collins Collector Assn does this for a lot of Collins parts...and seems like everyone loses gears in the popular 8640's.....
  ----- Original Message ----- 
  From: Jim Carrington 
  To: premium-rx at ml.skirrow.org 
  Sent: Thursday, August 21, 2003 2:22 AM
  Subject: Fw: [Premium-Rx] Nylon gears


  Hi folks,
  I've been a quiet member of the group so far but decided to throw my 2 cents in here. I have several of the 8640B's with cracked gear problems and have talked with 2 people who also have tackled the cracked gears but in different ways. The first guy thought that the nylon had shrunk with time, causing the gear to crack around the shaft. His solution was to remove the damaged gear ,  glue the pieces back together (I forget if he used epoxy or super glue) and then carefully enlarge the shaft hole very slightly so it was a slide on fit to the shaft. He then glued the gear back onto the shaft and said it worked well. 
  The second guy thought that the cracking problem was caused by excessive force on the gears from old hardened grease in the mechanisms that the gears drive. He has had some success wrapping wire around the base of the cracked gear to keep it from cracking further ( I suppose after cleaning and relubing the mechanism) . Note, my own try at this with some fine steel wire was not successful as the wire broke when I tried to twist it tight. 
  I think I lean towards the glue it back together solution after cleaning and relubing but havent had a chance to try this yet. It might be a good idea to also soak the pieces in water first before glueing. 

  Regards
  Jim Carrington
  KD6JTY

  ----- Original Message ----- 
  From: john phillips 
  To: premium-rx at ml.skirrow.org 
  Sent: Wednesday, August 20, 2003 4:47 PM
  Subject: [Premium-Rx] Nylon gears


  Hi Guys:
  Nylon needs to have moisture in its chemistry to stay srong & resilient. Age 
  drives out the moisture and the stuff gets very brittle. Model airplane builders discovered this decades ago and there have been instances of shattering props. 
  So, they would place the props in warm water for 24 hours or so and restore the moisture content and a return to a non-shattering state. 

  So I would think the same could be done for the gears under recent discussion if otherwise they are in good condition. By good condition I mean not cracked. If its an old gear it looks good but does not have the strength it had due to drying out. Give it the H2O treatment to preserve its continued strength.

  For what its worth. 

  Cheers, 
  John Phillips
  VE6XI




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