Hello,
I have a radio where the tuning capacitor is hard to turn. It will rotate from open to close but is stiff. I used some WD40 on the front of the shaft bearing but it did not seem to help. I don't want to get anything on the cap plates. Is there something i can use that won't cause interference after cleaning it up?
Mitch

The aluminum frame seems to oxidize where the bearings ride. Try using sink cleanser with a few drops of water making a paste. Put that in the bearings and turn back and forth a bunch of times. Keep adding more paste and keep rotating the tuner. Wash all that out after. Don't use WD-40 use some dielectric grease. This most times frees up the tuner. If not get inventive and more aggressive with something more abrasive. ( valve grinding compound )

:The aluminum frame seems to oxidize where the bearings ride. Try using sink cleanser with a few drops of water making a paste. Put that in the bearings and turn back and forth a bunch of times. Keep adding more paste and keep rotating the tuner. Wash all that out after. Don't use WD-40 use some dielectric grease. This most times frees up the tuner. If not get inventive and more aggressive with something more abrasive. ( valve grinding compound )
:
W,
used a dremmel to grind the tuner into grit. works fine now.

::The aluminum frame seems to oxidize where the bearings ride. Try using sink cleanser with a few drops of water making a paste. Put that in the bearings and turn back and forth a bunch of times. Keep adding more paste and keep rotating the tuner. Wash all that out after. Don't use WD-40 use some dielectric grease. This most times frees up the tuner. If not get inventive and more aggressive with something more abrasive. ( valve grinding compound )
::
:W,
:used a dremmel to grind the tuner into grit. works fine now.
:
'Used a Dremel to grind the tuner into grit' ?????

Uh, OK. Will C-4 work just as well?

Johnnysan-

:::The aluminum frame seems to oxidize where the bearings ride. Try using sink cleanser with a few drops of water making a paste. Put that in the bearings and turn back and forth a bunch of times. Keep adding more paste and keep rotating the tuner. Wash all that out after. Don't use WD-40 use some dielectric grease. This most times frees up the tuner. If not get inventive and more aggressive with something more abrasive. ( valve grinding compound )
:::
::W,
::used a dremmel to grind the tuner into grit. works fine now.
::
:
:
:'Used a Dremel to grind the tuner into grit' ?????
:
:Uh, OK. Will C-4 work just as well?
:
:Johnnysan-
:
:
:
:
The bearing race is frozen and turns with the shaft. Will i have to take the assembly apart and free the bearings?

::::The aluminum frame seems to oxidize where the bearings ride. Try using sink cleanser with a few drops of water making a paste. Put that in the bearings and turn back and forth a bunch of times. Keep adding more paste and keep rotating the tuner. Wash all that out after. Don't use WD-40 use some dielectric grease. This most times frees up the tuner. If not get inventive and more aggressive with something more abrasive. ( valve grinding compound )
::::
:::W,
:::used a dremmel to grind the tuner into grit. works fine now.
:::
::
::
::'Used a Dremel to grind the tuner into grit' ?????
::
::Uh, OK. Will C-4 work just as well?
::
::Johnnysan-
::
::
::
::
:The bearing race is frozen and turns with the shaft. Will i have to take the assembly apart and free the bearings?
:
The bearings in the race are frozen and the shaft turns around the bearings, that is what is stiff.

If the bearings are that badly stuck, try using a little jewelers screw driver. Get in between the bearings to push them around free. Then try the sink cleanser paste. Trying to take it apart may damage it beyond repair.

Hi Mitch,
Being patient with the berrings may bring them around. Lubricate with your favorite lubrcant and let them set before trying to loosen them.

Often there is an adjustment on these capacitors, too, in the form of a screw at the back. If it has become too tight it can cause this problem, along with slipping and broken dial strings.
After adjustment make sure your plates do not scrape at any point on the rotation. It isn't enough to test with them fully meshed. I had one that was OK at the bottom of the dial but shorted at around 950 Kc onlt to open again around 1000 Kc.

Best Regards,

Bill Grimm

Best Regards,

Bill Grimm

:Hi Mitch,
: Being patient with the berrings may bring them around. Lubricate with your favorite lubrcant and let them set before trying to loosen them.
:
: Often there is an adjustment on these capacitors, too, in the form of a screw at the back. If it has become too tight it can cause this problem, along with slipping and broken dial strings.
: After adjustment make sure your plates do not scrape at any point on the rotation. It isn't enough to test with them fully meshed. I had one that was OK at the bottom of the dial but shorted at around 950 Kc onlt to open again around 1000 Kc.
:
:Best Regards,
:
:Bill Grimm
:
:
:Best Regards,
:
:Bill Grimm
:
Mitch

If your still having problems with those bearings. Mix in a little fine dirt with the sink cleanser paste. A little more abrasion to wear in a path for the bearings to ride in. Rotate full turns back and forth. Crunchy Crunchy.

Tuning capacitors are usually housed in a steel frame that is cadmium plated. The steel can rust, but not usually at the bearings, as they are greased. The grease will dry out with age. If the condenser is dirty or if the grease is just dry, you can soak in mineral spirits or gasoline to remove all gunk and grime. Work condenser back and forth to work things loose. You can also just soak the bearing in penetrating oil or PB Blaster.

The screw on the other end, if any, usually stays set from the factory. Adjustment moves the plates around and changes their alignment. If necessary, however, it can be aligned.

Keep abrasives out of the bearings.

T.

Hello again Thomas. Have had a few tuners that would not turn with the dial cord. Or would bind so bad the cord would overlap itself. The bearings I had cleaned, but had worn through the cadmium plating. This is where some rust and pitting had occurred. I tried tooth paste at first. Then the sink cleanser paste. All that was needed was to wear down the bearing area. Clean well after then grease. Worked well.

:Hello again Thomas. Have had a few tuners that would not turn with the dial cord. Or would bind so bad the cord would overlap itself. The bearings I had cleaned, but had worn through the cadmium plating. This is where some rust and pitting had occurred. I tried tooth paste at first. Then the sink cleanser paste. All that was needed was to wear down the bearing area. Clean well after then grease. Worked well.
:
All,
I still have the patience to get this tuner working. Too much time on the radio to get it working to quit now. I will try the tooth paste.
Thanks
Mitch

If the bearings have rusted, I am guessing that these fine abrasives will probably do the trick, or even just the rust in penetrating oil, to polish everything. Normally you do not want abrasives anywhere near a ball bearing, but since they are already rusty and this isn't an auto wheel bearing we're talking about, fine abrasives will probably be fine.

You might also consider disassembling the condenser and polishing the bearings and their raceway with a fine metal polish. However, you must then perform the tedious reassembly and alignment of the condenser.

T.

:If the bearings have rusted, I am guessing that these fine abrasives will probably do the trick, or even just the rust in penetrating oil, to polish everything. Normally you do not want abrasives anywhere near a ball bearing, but since they are already rusty and this isn't an auto wheel bearing we're talking about, fine abrasives will probably be fine.
:
:You might also consider disassembling the condenser and polishing the bearings and their raceway with a fine metal polish. However, you must then perform the tedious reassembly and alignment of the condenser.
:
:T.
:
I want to thank everyone on this one as i used all combinations of solutions to free up the bearings.
The bearings are in an air dry state.

What should i use to lubricate the bearings for long term use?
Thanks
Mitch

Hello Again Mitch. Good you got that tuner working. I use the green dielectric grease on the bearings. And just a touch on the center contact point. This grease does not seem to dry out.