[ARC5] BC-458 I should have seen this coming

[Roy Morgan]

On Jan 5, 2016, at 8:26 PM, Andrew Kopke via ARC5 <arc5 at mailman.qth.net> wrote:

> Okay ,so I found this fair BC-458 ... If I had a short enough screw driver I might be able to get the screws off that spring which would allow me to drop in some bearings. Sorry for the poor terminology/location numbers .. Any thoughts

Andrew,

I don’t have a BC-348 to look at, so I am guessing at what your challenge is, But:

If you can in any way get bearings into the spot where they need to go, with OUT complete dis assembly of the capacitor, do it.

And based on the overhaul of a SX-88 which has two gear trains with many bearing-supported shafts each:
 - if you need to source new bearings, “pretty close” in diameter is likely good enough.  this is not an 8,000 RPM motor shaft
 - be a careful of capacitor plate shape and alignment - scrupulously avoid changing shape or spacing.
 - a bit of grease is your friend to hold a set of bearings where they need to stay as you have the rest of the shaft and mechanism apart ore loose
- fit new bearings until you can’t get another one into the race - that’s fine even though the ones in there seem to have a little bit of radial play/clearance
- If you can get the axial play adjustment nut and bearing point out, wire brush the threads, clean carefully, trace-lubricate the threads and re-assemble
- WATCH OUT for a single bearing at the end of the shaft under the axial tension adjustment bearing point.  If one set of bearings has been lost, this single one may be missing also.
 - clean out the race and cone or shaft bearing race parts before adding new grease 
(Stuff paper towels under the area and clean with brake cleaner and an “acid brush” trimmed to get better stiffness)
 - just a BIT of grease is enough to hold bearings in their race during reassembly
 - you and your radio will be glad you put new grease in there.
 - careful axial adjustment of the shaft tension/bearing clearance is needed.  Nearly zero axial play is what you want.  Doing this *after* warmup likely is good.
 - don’t forget to lubricate the split gears and pinion(s) and all shaft bearing sleeves (light oil)
 - If the anti-backlash spring loaded gears are clean and lubricated, two or MAYbe three teeth preload is enough
 - Use #22 telephone wire stands to hold spring loaded driven gears at the proper preload as you assemble the mechanism - 

(Whew.   I guess there is more to that than I though.)


Roy

Seasons Greetings to all!

Roy Morgan
k1lky68 at gmail.com
K1LKY Since 1958