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Author Topic: Loosening a thight screw  (Read 470 times)
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sirisobhakya
ThaiJin BassTrom
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« on: Jan 24, 2018, 08:35PM »

My horn has an asjustable thumb plate on the trigger. 1 year has passed but I have not yet made use of it, due to very tight screw. It is tightened from the factory. I cannot (or haven't yet been able) to turn it by hand, and I haven't dare using plier on it due to fear of deforming it or the trigger stem. The screw is made of nickel silver, has plain head and serrated rim, kind of like watch's adjusting knob.

How should I try turning it? One way that just pops inside my brain is applying cold things to the head so that the metal will contract, but I don't have much confidence in that.

Thank you for your answer.
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Chaichan Wiriyaswat

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BGuttman
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« Reply #1 on: Jan 24, 2018, 08:41PM »

If you have one of those jar openers that's a sheet of rubber, put it over the knurled knob and then use pliers.  You won't mar the finish that way.

Take a look to see if they used some thread locking lacquer (usually a red dot somewhere in the place the screw contacts the plate it's screwed in.  If there's lacquer, you can loosen it with some nail polish remover or lacquer thinner.

If all this sounds like Greek, take it to a tech, who will take about 30 seconds to do the job.
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Bruce Guttman
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sirisobhakya
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« Reply #2 on: Jan 24, 2018, 09:01PM »

Thank you! I will try it.
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Chaichan Wiriyaswat

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« Reply #3 on: Jan 25, 2018, 08:12PM »

Corrosion Cracker from Ferree's. I understand it will get into a space as small as a millionth of an inch. I used it all the time to loosen stuck screws at school and in my wood shop.

Jerry Walker
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« Reply #4 on: Jan 26, 2018, 06:16AM »

I would try penetrating oil like Liquid Wrench or WD-40, I would avoid pliers I've twisted the head right off screws that way and had to drill them out an tap the hole, not something you want to do on a musical instrument.  Use the grippy rubber pad thing to get a better grip on it but avoid pliers. 
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chatterbox272
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« Reply #5 on: Feb 05, 2018, 01:58AM »

Soft jaw pliers. Ones with rubber or plastic instead of metal teeth. I bought a set of normal parallel jaw pliers from my local hardware store that came with plastic covers for the teeth and simply use those without removing the cover. Just hold the lever close to the plate so that you don't deform it. This is quite likely what your local tech will do, and it's really not a difficult job.
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timothy42b
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« Reply #6 on: Feb 05, 2018, 05:17AM »

Also, look at it very closely.

Sometimes those serrated finger screws have a second nut that serves as a locking nut and must be loosened first.  Or a set screw somewhere.  You don't want to force it.
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Tim Richardson
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« Reply #7 on: Feb 05, 2018, 03:06PM »

Something like this is easy if you have the touch. Sadly, you get the touch by breaking a few things. Might be best to fix your kids bike first. Or just go to a tech.
I like my tech. He can make anything if he breaks it.
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See my profile for my horns. To long to put on each post.
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