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Old January 9th 09, 04:50 AM posted to alt.binaries.pictures.radio
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Default Phono idler repair

1. remove original tire from metal hub of idler wheel.

2. Chuck a piece of 1-1/2" PVC pipe in the lathe and use a boring bar to
cut the inside diameter to the same as the outside of the metal disc.

3. Glue the PVC to the metal disc with Weldwood contact adhesive.

4. Measure original thickness of drive tire and face both sides of the
PVC (centered to the disc).

5. Do a finish cut on the circumference to make sure the PVC sleeve is
concentric to the idler shaft.

6. Take a piece of 0.103" square Buna-N O-Ring stock and cut to length
to be just a bit short so it's a slightly stretch fit to the PVC.

7. Glue the ends of the cord together. Having an O-Ring cutting and
gluing fixture makes this really easy.

8. Glue the completed "tire" to the outside of the PVC sleeve.

9. Using a grinder on the tool post, grind the tire concentric to the
idler shaft.

10. Install back in phonograph.

Jeff


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Old January 9th 09, 05:24 AM posted to alt.binaries.pictures.radio
JP JP is offline
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Default Phono idler repair

Wow, fantastic work! - JP

"Jeffrey D Angus" wrote in message
...
1. remove original tire from metal hub of idler wheel.

2. Chuck a piece of 1-1/2" PVC pipe in the lathe and use a boring bar to
cut the inside diameter to the same as the outside of the metal disc.

3. Glue the PVC to the metal disc with Weldwood contact adhesive.

4. Measure original thickness of drive tire and face both sides of the
PVC (centered to the disc).

5. Do a finish cut on the circumference to make sure the PVC sleeve is
concentric to the idler shaft.

6. Take a piece of 0.103" square Buna-N O-Ring stock and cut to length
to be just a bit short so it's a slightly stretch fit to the PVC.

7. Glue the ends of the cord together. Having an O-Ring cutting and
gluing fixture makes this really easy.

8. Glue the completed "tire" to the outside of the PVC sleeve.

9. Using a grinder on the tool post, grind the tire concentric to the
idler shaft.

10. Install back in phonograph.

Jeff



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Old January 9th 09, 12:57 PM posted to alt.binaries.pictures.radio
Ken Ken is offline
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First recorded activity by RadioBanter: Sep 2006
Posts: 68
Default Phono idler repair

JP wrote:
Wow, fantastic work! - JP

"Jeffrey D Angus" wrote in message
...
1. remove original tire from metal hub of idler wheel.

2. Chuck a piece of 1-1/2" PVC pipe in the lathe and use a boring bar to
cut the inside diameter to the same as the outside of the metal disc.

3. Glue the PVC to the metal disc with Weldwood contact adhesive.

4. Measure original thickness of drive tire and face both sides of the
PVC (centered to the disc).

5. Do a finish cut on the circumference to make sure the PVC sleeve is
concentric to the idler shaft.

6. Take a piece of 0.103" square Buna-N O-Ring stock and cut to length
to be just a bit short so it's a slightly stretch fit to the PVC.

7. Glue the ends of the cord together. Having an O-Ring cutting and
gluing fixture makes this really easy.

8. Glue the completed "tire" to the outside of the PVC sleeve.

9. Using a grinder on the tool post, grind the tire concentric to the
idler shaft.

10. Install back in phonograph.

Jeff



The PVC is only to build up the circumference of the wheel? Ken
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Old January 9th 09, 02:38 PM posted to alt.binaries.pictures.radio
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Posts: 116
Default Phono idler repair

Ken wrote:
The PVC is only to build up the circumference of the wheel?
Ken


The PVC serves two purposes. Since the idler center piece is
almost always thinner than the drive wheel the PVC serves as
a backing for rubber tire width. In this case, the original
tire thickness was about 0.150" and the center piece is only
about 0.050" thick. Secondly, the increased surface area allows
a better bond between all the materials. Metal to PVC to Rubber.

One of the problems I've seen with some "rebuilt" idler wheels was
the almost zero width of the replacement tire. Yes it works, but it
is a problem waiting to happen due to the limited contact area between
the capstan (motor shaft) and the idler, allowing for an early failure
due to dimpling when at rest.

And, as they've repeatedly stated in the entire history of auto-
motive racing, "If the rubber don't connect, nothing else matters."

A wider idler tire means better traction to the capstan and the
inside of the turntable platter with a minimum amount of slipping.
The spring tension holding the idler against the capstan and inside
of the turntable is fairly light to avoid the other issue of creating
a dimple while the system is turned off.

Jeff


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