unscrewing problem

[bancho]

Maybe this is funny question but I'll ask anyway...

Today I wanted to change my SL1200 Technics' tonearm. Maybe I was uncareful or there was some preexisting damage. The problem is I destroyed the cap of the screw for the tonearm bearnig mechanism. One screw went out smoothly but I've stucked with the other one.

Now how is it possible to unscrew it? Does anybody have any idea? The drilling is not an option as there is very delicate area.
Please help!!!

This is 3mm screw for metal, cap is +. It is accessible through 5 mm hole and is 2 cm (1 inch) deep.

[bancho]

I see the only solution is the screw extractor...

I guess I'll finish tomorrow.

[mossboss]

If you can do that in a hole 1" deep you are a better man than the lot of us here
Get a screwdriver that you dont care for to fit the damaged screw and Araldite it on to the damaged screw use some plasticene or blue tack to hold it in position
Let the epoxy set and attempt to remove it afterwords
Leave it for longer than the time suggested on the tube
If you clean up both the head of the screw and the tip of the screwdriver with a little alcohol, IPA, or acetone it will ensure a good adhesion and the little screw will come off
Drilling the damaged screw so as to use of an 'easy out' down a hole you cannot see you will be hard pushed get it in the centre so as to do it right
If you have a friend that has access to a wire erroding machine it will be the best
Alternative a milling machine with a small two flute cutting bit will be able to machine out the ruined screw to the threaded size
You can than run a tap after you cleaned up the swarf and the remaining bits of metal remaining in the threaded part
Cheers

[cymbalism]

that sucks man. are you talking about one of the two screws in the bottom that hold the swivel mechanism? if so, i'm not sure how to extract it other than how chris mentioned. you can't really do anything other than that because its not like you can loosen it up enough to twist it off because of that brass rod that slides down into the table base.

i've changed at least 30 tone arms over the past 16 years and i've never had that problem. best of luck with it though man, i hated doing it because soldering those hair thin wires is always tedious.

[bancho]

so... I had to drill the screw cap off. with a drilling machine, very slowly, taking the filings wth a small magnet.
but I did it and everything is working properly now.
yeeeee!!!

[platesrecords]

Hi - I have a similar issue - I went to tighten the stylus pin that holds the shank on my Presto 1C cutterhead and it snapped in the centre. Now the middle piece is stuck inside the cutterhead and completely recessed, with nothing to grip. Also there is not + or phillips head as the bit that is stuck is the middle of the screw, rather than the end. The screw is very small about 1.7mm gauge.

I wondered if anyone has any experience in this - my options will be maybe to use some kind of miniature screw extracting tool - and to hope that it works... I suspect it won't though.

Perhaps next options are drilling into it - but this is risky and could destroy the screw. Next step, superglue something to the screw and pull it out?

Any advice much appreciated

Cheers

Nick

[opcode66]

How to extract stuck screws.

0. Insure you're using the correct size screwdriver. Get as many small drivers as you can. I have tons of little ones of many widths and my collection grows frequently. I can now also custom grind my own tips. Also, insure that you are holding the frame tightly and you exert a lot of downward pressure as you turn.

1. Place the stuck screw and item in a sonic jewelry cleaner if all can go in water. This really helps to loosen things up significantly. I've had instances of screws working themselves out with enough time in the bath. Immovable prior...

2. Try using a rubber band over the tip of the screwdriver. This helps give it more bite.

3. For flat slot screws that snap in half, a trick that sometimes works is to grind a half circle tip from a round shaft. Use that as a screwdriver. This works only if the threads at the top of the hole haven't been damaged by previous attempts to free the screw.

4. The final option is the hardest. And, naturally, the one that you mostly have to resort to. You need to use a lathe/mill or a CNC machine because a drill press has too much runout typically. But, with a proper turning machine, you can tap a 1mm hole into the stuck set screw a millimeter or two deep. Then, simply insert a small screwdriver (jewelers screwdrivers work best). The with of the screwdriver blade should be just larger than the diameter of the hole. You force it in. Then, you can turn the screw out. Pictures below.

I rebuild mono cutterheads. Close to 250 now. I also am going to be providing Neodymium Magnet Upgrades for Presto Cutterheads. I also have a Presto Clone brewing and close to ready for sale.

http://www.cutterhead.repair

http://www.prestoclone.com coming soon...

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