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27th Jan 2010, 8:59 pm | #1 |
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DAC90/A Bakelite Knob
Hi,
Just got another DAC90/A today, its nice and untouched/filthy. One problem though is one of the knobs has broken away from its shaft not by me, was loose when collected, its quite a clean break. Any tips on fixing or is it better to find a replacement, I was thinking Araldite precision. Regards OTT Last edited by oldticktock; 27th Jan 2010 at 9:24 pm. |
27th Jan 2010, 9:34 pm | #2 |
Nonode
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Re: DAC90/A Bakelite Knob
Hi
i'd use bog standard superglue (cyanoacrylate) after making sure the edges meet up nicely. it works very well on bakelite! regards, Lloyd. |
27th Jan 2010, 9:44 pm | #3 |
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Re: DAC90/A Bakelite Knob
Cheers Lloyd,
sometimes I guess its just that simple, I will give it a go. Ta OTT |
27th Jan 2010, 9:59 pm | #4 |
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Re: DAC90/A Bakelite Knob
Araldite every time. I have one here that was stuck on two years ago and still attached.
Dave |
27th Jan 2010, 10:03 pm | #5 |
Nonode
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Re: DAC90/A Bakelite Knob
I'd give a vote to Araldite too. I have more luck with that than with Cyanoacrylate adhesives. It also has the added advantage that you can fill in any missing bits and build some reinforcement around the broken bits.
__________________
Brian |
27th Jan 2010, 10:03 pm | #6 |
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Re: DAC90/A Bakelite Knob
Hi superglue it soaks into the bakelite its my first choice, Regds Mick.
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27th Jan 2010, 10:11 pm | #7 |
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Re: DAC90/A Bakelite Knob
Hee hee, that's two for two.........
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27th Jan 2010, 10:33 pm | #8 |
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Re: DAC90/A Bakelite Knob
Super glue and then reinforce it with Araldite..
Paul. |
27th Jan 2010, 10:37 pm | #9 |
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Re: DAC90/A Bakelite Knob
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27th Jan 2010, 10:54 pm | #10 |
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Re: DAC90/A Bakelite Knob
I'd go with Araldite (the slow setting stuff). Cure it in the gentle warmth of an airing cupboard.
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27th Jan 2010, 11:16 pm | #11 |
Rest in Peace
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Re: DAC90/A Bakelite Knob
I would use superglue . If it breaks again then use araldite, but it depends on the cleanness of the break
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28th Jan 2010, 12:10 am | #12 |
Octode
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Re: DAC90/A Bakelite Knob
Standard Araldite every time.
Coat each surface as thinly as possible and then warm both components to about 90 deg C. This lowers the viscosity of the adhesive thereby allowing it to soak into the bakelite and also improves wetting by lowering the surface tension. Leave to set at this temperature with the joint under moderate pressure. Araldite has to rank as being one of the most useful substances invented in recent times. Quickset Araldite is useless. Leon. |
28th Jan 2010, 2:27 pm | #13 |
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Re: DAC90/A Bakelite Knob
I agree with Leon Crampin's theory, except that I'd be a bit worried about raising the temperature to 90 deg C.
At this temperature I'd be worried that the Bakelite knob would crack, especially with its brass insert. Also, Araldite goes off very quickly at this temperature so there's not much working time to get clamped-up. Finally, if cured at 90 deg C, there's the possibility of making a stress-free assembly which then becomes stressed as it returns to room temperature, due to differing expansion/contraction rates. How about: Warm the parts to 70 deg C, coat them thinly with Araldite, put them together under light pressure, and maintain at 40 deg C for 24 hours (such as the airing cupboard I mentioned earlier)? |
28th Jan 2010, 4:47 pm | #14 |
Octode
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Re: DAC90/A Bakelite Knob
The bakelite knobs on my LeCreuset cast iron casserole pans go into a hot oven on a regular basis. 90 degC is well within working limits for a thermoset plastic. Remember distributor caps?
I don't think stress is a real problem with Araldite as it takes quite a long time to cure absolutely hard. There is a long period - several days - when it is "set" and usably strong, but not rock hard. Any residual stress could equalise during this period. Leon. |
28th Jan 2010, 5:29 pm | #15 |
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Re: DAC90/A Bakelite Knob
Ok Guys thanks for the advice.
The mend is done and I await the result. I Used Araldite my first hunch, its now secured in a G-clamp and sitting in the airing cupboard. Think I will leave it there for a couple of days, then see the result. Thanks for all your advice and techniques, as usual a wealth of experience. Looking forward to the restore, I've now got another Dac90a today as well, they are like buses at the mo. Both these are untouched and have 5mm of thick dust and spiders just the way we like them Mods, you can close this down now. Regards OTT |