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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 16th Mar 2016, 10:45 pm   #1
parlourtw73vs
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Default Refurbishing Idler Wheels.

The subject of slipping idler wheels seems to come up quite often on this forum and whilst refurbishing one of mine I happened upon an article which might be of help to some of you. Probably most of you will do as I normally do which is to attempt removal of the hardened periphery of the rubber wheel with some abrasive paper.

I normally do this by finding a small nut and setscrew which is a good fit in the centre of the idler, tightening it just enough to prevent slippage and then put it in the chuck of a drill. I'm fortunate in having a small stand drill and by gluing the abrasive to a small square block of wood I can true the edge of the idler to pretty much a right angle. This normally does the trick, but just recently I've been restoring an old Philips AG4025W record player from the mid 60's and the idler wheel on its deck is positively miniscule compared to those used in Garrard, BSR and Collaro's. I had managed to get it turning at the correct speeds with no wow or flutter when playing either 33's or 45's, but as soon as I attempted to induce its automatic functions it would slow to virtually a stop both when setting down and lifting off at the end.

I was looking for some inspiration with regard to this problem, assuming that the rubber had aged to a point where its co-efficient of friction had deteriorated to a state where it would no longer provide the required grip. Somewhere in my scanning of the internet I came across an article in which the author was talking about restoring the properties of rubber and he stated that the correct substance to use was called MEK. Some of you may know that this is Methyl Ethyl Ketone, and whilst I don't know its original intended use I've come across it in the past as being used as a plastic welding solvent available in model shops.

I happened to have a small amount left in my shed and so poured some into a screwtop jar and immersed the idler wheel in it for about a minute. I then wiped it off, it evaporates quite quickly, and reinstalled the idler in the deck. Bingo!! the changer started working with virtually no slowing down or hesitation. I've been playing it off and on for the last 2 weeks to see if it deteriorated at all but up to now it has shown no change and is performing brilliantly. Just before posting this thread I removed the platter to inspect the idler to make sure it hadn't affected the composition of the rubber, I wouldn't like to be responsible for the wholesale destruction of Britains idler drive turntables, and all was well.

I think if you've got a problem with one of your idler wheels it may well be worth trying this, I've not checked availability of MEK, the Government may have curtailed its supply because it's rather pungent. Apologies if this is something already well known to you all, but it may assist some of you in returning you turntables to satisfactory operation.
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Old 16th Mar 2016, 10:55 pm   #2
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Default Re: Refurbishing Idler Wheels.

It's likely to be difficult to obtain nowadays as it is apparently a precursor for a number of illicit drugs, including heroin and methamphetamine.
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Old 16th Mar 2016, 11:22 pm   #3
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Default Re: Refurbishing Idler Wheels.

I remember using this stuff about 12 years ago when I worked for a company making water meters! It was evil stuff, we used it to clean off LCD displays where we had stuck the plastic ribbon cable to it wrong. I also found it would happily eat through polystyrene if you dribbled it on to it... Made your skin go white and crusty too!

I have an experiment of my own to carry out at some point, I discovered by accident at work recently that a certain white lithium grease (made by 3-in one) caused the rubber bung in a syringe to swell up quite a bit, enough to stop the syringe working smoothly! It still hasn't returned to normal size, so I guess the effects are permanent. I thought it may be of use on the rubber masks on old 405 line telly's, where they have started to harden and crack up. It does take quite some time to have this effect, the grease had been in the syringe for a few months or so, but had been difficult to use very shortly after filling it.

I know it's been mentioned before about boiling rubber belts to get a bit more use from them, but I had a Technics cassette deck in bits last night, and was boiling it's belts (I know, I should just get new ones!!) and whilst I was at it, I had the rewind/ffwd idler out as it had been struggling to fully wind a C90 tape, the rubber was a bit hard on the outer rim, so I removed the rubber from the wheel and chucked it in the pan with the belts! When I removed it the rubber felt a bit more supple, and once refitted and the machine back together it ran perfectly.

Maybe there is some sort of 'off the shelf' rubber restorer out there already?

Regards,
Lloyd.
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Old 17th Mar 2016, 12:10 am   #4
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Default Re: Refurbishing Idler Wheels.

Just did a quick search on eBay for MEK and there is loads of it! Must be a popular item.
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Old 17th Mar 2016, 7:44 am   #5
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Default Re: Refurbishing Idler Wheels.

A careful application of "gun cleaner" as opposed to cellulose thinners will work too. Thinners will do the job but some rubbers will swell up and keep swelling!

MEK is still used for assembling plastic models, They are made from a hard form of polystyrene as opposed to expanded polystyrene which will instantly disappear in MEK!
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Old 17th Mar 2016, 9:01 am   #6
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Default Re: Refurbishing Idler Wheels.

I can recommend belt dressing it comes in a spray can. Made by Mecro ltd you don't need much , it works for me. Mick.
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Old 17th Mar 2016, 10:52 am   #7
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Default Re: Refurbishing Idler Wheels.

I still use a can of rubber restorer from CPC bought years ago.Not sure wether or not it is stocked but very good stuff.
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Old 17th Mar 2016, 12:52 pm   #8
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Default Re: Refurbishing Idler Wheels.

Quote:
Originally Posted by parlourtw73vs View Post
I've not checked availability of MEK, the Government may have curtailed its supply because it's rather pungent.
That's not the reason, it's because it is highly carcinogenic. I still hold a licence to buy & use it but everytime I order some, I'm bombarded with reams of Health & Safety documents and that my Safe Storage cabinet is still secure.

Less restricted & less dangerous is Butanone. Also model shops sell a product called "Plastic Weld" (Methylene Chloride or Dichloromethane)
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Old 17th Mar 2016, 7:42 pm   #9
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Default Re: Refurbishing Idler Wheels.

It's a long time since I did A-level Chemistry, but I'm sure Butanone is the official scientific name for MEK. Maybe you are confusing it with something else?

Horrible stuff, I used to use it at work for removing old glue when re-coning loudspeakers.
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Old 17th Mar 2016, 8:26 pm   #10
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Default Re: Refurbishing Idler Wheels.

Dichloromethane is old type nitromors paint stripper but I think the formula has changed these days for something safer. There's a product called Rubber Renue out there as well which has some effect.
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Old 17th Mar 2016, 8:49 pm   #11
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Default Re: Refurbishing Idler Wheels.

MEK is indeed nasty stuff; whatever you do, avoid inhaling the vapour. I've used gallons of it in my time to refurbish printing machine rollers, but would treat it with great caution these days. Its effect on rubber is really only temporary, anyway. I'm out of touch now, but have no doubt that printers' suppliers would have many safer, more effective alternatives available - one that I'm aware of is Varn Super Rubber Rejuvenator. Being industrial products, these come in relatively large volumes - perhaps a forum 'group buy' would be in order (or just try asking for a sample).
If you do decide to try it, be aware that MEK quickly and effectively strips most kinds of paint (not to mention that it will penetrate skin and dissolve the fatty insulation of nerve fibres).

P.S. MEK is correctly known as butanone these days.

Last edited by dseymo1; 17th Mar 2016 at 8:58 pm.
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Old 17th Mar 2016, 10:21 pm   #12
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Default Re: Refurbishing Idler Wheels.

I never knew just how nasty that MEK stuff was! We certainly were not told any of this at work. We just had it in those little pump-top dispensers and dipped bits of rag in it to clean up the LCD displays and PCB's that we had done wrong...

Regards,
Lloyd.
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Old 18th Mar 2016, 2:58 am   #13
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Default Re: Refurbishing Idler Wheels.

Quote:
It's a long time since I did A-level Chemistry, but I'm sure Butanone is the official scientific name for MEK. Maybe you are confusing it with something else?
I should have explained more. For some reason, Butanone seems to have less restrictions buying it than product marked MEK. I use RL Slaughter as my supplier and, when I order Butanone, I don't get the 5 minute questionaire that I used to get when ordering MEK.
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Old 18th Mar 2016, 12:04 pm   #14
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Default Re: Refurbishing Idler Wheels.

Quote:
Originally Posted by camtechman View Post
For some reason, Butanone seems to have less restrictions buying it than product marked MEK. I use RL Slaughter as my supplier and, when I order Butanone, I don't get the 5 minute questionaire that I used to get when ordering MEK.
Maybe the suppliers use the name as a basic qualification filter. A casual user might ask for MEK, but if you ask for Butan-2-one (I've just looked it up), you are more likely to be a scientific or professional user. Possibly related to the panic some years ago about solvent-sniffing kids.
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Old 18th Mar 2016, 2:18 pm   #15
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Default Re: Refurbishing Idler Wheels.

Well, who knew there would be so many different chemicals available to improve the constitution of rubber. Perhaps some of the industrial chemists amongst the group can explain just how these substances work. I thought it may be a thorough degreasing of the rubber which caused the improvement but I've no expertise or insight to support this idea.
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Old 18th Mar 2016, 9:26 pm   #16
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Default Re: Refurbishing Idler Wheels.

Has anyone tried car brake-fluid? I recall that in the 1960s amateur RTTY-types would sometimes use brake fluid on the rubber pad that re-inked the printhead on some teleprinter-models.
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Old 19th Mar 2016, 4:38 pm   #17
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Default Re: Refurbishing Idler Wheels.

Dimethyl ketone (common name 'acetone') works to lesser extent, is easy to buy in small quantities (pharmacies) and is less harmful. I also remember MEK as 'blanket reviver', used to revive the surface of the rubber 'blanket' (and the rollers) of offset litho printing machines. Nasty stuff - but very effective! - Roger
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Old 19th Mar 2016, 4:51 pm   #18
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Default Re: Refurbishing Idler Wheels.

Brake fluid in the 60s was different from today's silicone based substance. It used to strip paint and rot some natural based rubbers.
This modern stuff is supposed to be better, it adsorbs less moisture, is less harmful to paint, but is a major cause of fires in car crashes, the master cylinder reservoirs, now being push on plastic, come off and the exhaust manifold heat ignites the brake fluid.
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Old 21st Mar 2016, 3:10 pm   #19
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Default Re: Refurbishing Idler Wheels.

PLATENCLENE for cleaning and reviving rubber rollers etc.

Used by the office equipment techies.

http://uk.farnell.com/af-internation...-can/dp/224315

http://www.amazon.co.uk/Automation-F.../dp/B0012IKSHO
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Old 21st Mar 2016, 5:53 pm   #20
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Default Re: Refurbishing Idler Wheels.

That is the stuff I use and first class.
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