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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 3rd Mar 2005, 7:11 pm   #1
Lowemission
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Default Removing Bush Circular Plastic Tuning Dials.

Here's a tip which should help you remove those stubborn Bush dials, photo's below.


First get yourself some Plusgas, which i find works better than other penetrating oil.
It's best to get a "tin of Plusgas" rather than the "aerosol" which i used, as you can very easily end up with a face full of the stuff !

Then get a suitable syringe (5cm long needle), preferably not from the local park . I've found the syringes which are used to refill printer cartridges are ideal due to the thicker diameter needle which can easily be bent.
Bend the needle (without stabbing yourself ) to roughly the same angle as the one in the photo.

Then VERY CAREFULLY spray a small amount of Plusgas into the lid (make sure it doesn't spray up into your face ). If you've been sensible (unlike myself ) and bought yourself a tin of Plusgas you won't have this problem.

Suck a small amount of Plusgas up into the syringe, then very gently ease the top part of the tuning dial just far enough out so that you can slide the needle between the plastic dial and tuning scale, then deposit a few drops of Plusgas onto the collar of the tuning dial and the shaft of the tuning condenser,take care not to scratch the tuning scale !

REMEMBER to get the syringe into place you only need to put a very small amount of gentle force on to the tuning dial as these plastic dials are VERY FRAGILE and can BREAK very easily.


I then recommend that you leave the Plusgas to do it's job for a few hours before attempting to pull the tuning dial off.
If like me you can't wait more than a couple of minutes (not really recommended !) the next step is to grip the tuning dial with both hands and VERY CAREFULLY pries the dial off (i find a gentle rocking motion is best ).

DO NOT even think about using a screwdriver or similar item as you'll just crack the dial .

I've used this method on several Bush radios and it's worked fine each time with no damage to the tuning dial, your finger tips might hurt a little afterwards but it's better than a cracked dial.
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Old 3rd Mar 2005, 7:46 pm   #2
Nickthedentist
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Cunning stuff! Thanks to those pictures, I'll remember that one.
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Old 3rd Mar 2005, 9:03 pm   #3
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Default Re: Removing Bush Circular Plastic Tuning Dials.

You can also ease them off by sliding a loop of strong cord behind the perspex and pulling gently.
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Old 3rd Mar 2005, 9:04 pm   #4
Paul Stenning
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Default Re: Removing Bush Circular Plastic Tuning Dials.

The official method was to use a sink plunger. I have never tried it though.
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Old 3rd Mar 2005, 9:30 pm   #5
Lowemission
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Default Re: Removing Bush Circular Plastic Tuning Dials.

The cord method i've used plenty of times for control knobs etc (which it works well on), i have tried it with these dials but prefer to use my hands as you can normally feel if the dial is going to "give" or snap.
Haven't tried the plunger method but again i doubt if you'd get much "feedback" through the plunger.

Sometimes the dials are already cracked in the middle (which can't be seen easily) due to a failed attempt to remove them which makes them even weaker.

Whichever way you decided i think the most important thing is to give it a drop of Plusgas to help free it from the shaft of the tuning condenser before trying to remove it.

I know my eyesight isn't too good but the text came out larger than i'd anticipated
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Old 4th Mar 2005, 12:57 pm   #6
newlite4
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Remember also to put some grease on the tuning capacitor spindle upon reassembly to facilitate removal of the dial at a later date.
Neil
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Old 4th Mar 2005, 4:04 pm   #7
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Hi,

I did a Bush DAC 70 last week and found it easier to pull the chassis away from the dial, that way the dial is supported by the cabinet.

Tony.
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Old 4th Mar 2005, 8:15 pm   #8
Lowemission
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Quote:
Remember also to put some grease on the tuning capacitor spindle upon reassembly to facilitate removal of the dial at a later date.
Neil
Thanks Neil, new i forgot something!

I normally use a small amount of silicon grease as it dosen't tend to harden with age like other types of grease.
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Old 7th Mar 2005, 7:22 pm   #9
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Quote:
Originally Posted by Paul Stenning
The official method was to use a sink plunger. I have never tried it though.
I have, and it doesn't work that well I have to say! I prefer using a loop of cord.
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Old 4th Aug 2006, 10:40 pm   #10
Eric_Harvie
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Just found this thread. The Plusgas idea sounds like a good idea. Thing is, where do I find Plusgas?
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Old 5th Aug 2006, 1:48 am   #11
ALANS ANITAS
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Hi

Plusgas is available from most car accessory shops, such as Halfords. It is widwly used as a penetrating fluid to enable you to undo rusty nuts and bolts.
The tins of fluid may be harder tp find than the aerosol, but are available.

|Regards

ALAN
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Old 5th Aug 2006, 9:41 am   #12
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Hello

Sounds a bit messy using PlusGas. I have removed scores of these dials, and here's the tool I use, £3.99 from Robert Dyas ..... dials are off in around 10 seconds It is a good idea to put a little grease or WD40 etc on the spindle before replacing these dials.

Howard
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Old 5th Aug 2006, 2:39 pm   #13
Nickthedentist
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Quote:
Originally Posted by howard
I have removed scores of these dials, and here's the tool I use, £3.99 from Robert Dyas ..... dials are off in around 10 seconds
What's this sold as? A sink unblocker, presumably? Does it still work if the centre is missing and the spindle has started to poke through (resulting in a less airtight seal, maybe)?

Quote:
Originally Posted by howard
It is a good idea to put a little grease or WD40 etc on the spindle before replacing these dials.
What type of grease though? I suspect some would be great but others would damage the plastic.

Nick.
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Old 5th Aug 2006, 3:32 pm   #14
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Default Re: Removing Bush Circular Plastic Tuning Dials.

I have always used the cord wrapped around the back of the dial and pull method. It has never failed yet (or damaged a dial). I thought I would try the plunger method though, so I bought one in Robert Dyas and had a go. Absolutely useless - never managed to get any off in the trial I did with it.

Trev
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Old 5th Aug 2006, 4:52 pm   #15
howard
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Hello Trev,

I'm sorry if you feel I've misled you, I've never had a problem with a plunger and it has worked every time. It's not a useless method at all. It needs to be trimmed around the edge before it works properly.

Howard

Last edited by howard; 5th Aug 2006 at 5:02 pm.
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Old 5th Aug 2006, 5:07 pm   #16
Nickthedentist
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Quote:
Originally Posted by howard
It needs to be trimmed around the edge before it works properly.
With what? Will a sharp "craft" knife do?

Nick.
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Old 5th Aug 2006, 5:23 pm   #17
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Hi all.

I have yet another method to add to the list.

When removing these dials, I use a square of strong of thin cloth (a handkerchief does very nicely, unused of course ).

Slide the cloth evenly underneath the dial, being very careful with the pointer (try if possible to get the cloth between the pointer and the inside of the dial).

Once the cloth is evenly under the dial, bring it up around the circumference, and gather up the excess to give you something to pull on.
You can then pull on the cloth, very gently rocking it until the knob comes loose, just mind that pointer though.

Works every time for me.

This is much harder to explain than to actually do, beleive me



Pete
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Old 5th Aug 2006, 5:27 pm   #18
Colin
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Default Re: Removing Bush Circular Plastic Tuning Dials.

I've always used the 'cloth method' too and found it to be very effective. Better than using string in my opinion as there's much more to grip and as Pete says you can hold the dial and gently wobble it from side to side as you work it free.

rgds
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Old 5th Aug 2006, 5:37 pm   #19
Brian R Pateman
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Default Re: Removing Bush Circular Plastic Tuning Dials.

The "hankie" method works fine for me on these and most other knobs too.

Never found the need for it to be clean though

Regards,
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Old 5th Aug 2006, 6:03 pm   #20
howard
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Default Re: Removing Bush Circular Plastic Tuning Dials.

Hello,

Here's a demonstration of how I use a plunger to remove large Bush dials. This TR82B has not yet been restored or cleaned so its dial has probably been on there for 40 odd years.

In the first pic you'll see that the plunger fits just inside the edge of the dial and that there is a vacuum in the plunger and it is adhering to the dial. This is a small plunger from Robert Dyas which has had a little rubber trimmed (yes with a modelling knife) from around the edge so that it fits neatly inside the rim of these dials.

In the second pic, just one tug seconds later and the dial is off.

I have used two pieces of leathercloth to lift these off and it works, but takes a lot longer that this method but the rocking motion can leave the often perished rubber VC mountings in very poor condition - mind you I always replace these anyway.

Sometimes if the dial surface is badly scratched its not so easy to get a good vacuum, but on the second or third tug they always come off. It makes no difference if the bezel is missing.

I usually put a little LM grease or WD40 on the spindle before putting a dial back on.

Howard.
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Last edited by howard; 5th Aug 2006 at 6:10 pm.
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