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Removing damaged screws

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Removing damaged screws
Started at 02:52pm on the 4th November, 2018 by John R
John R Subject: Removing damaged screws
I have a couple of screws with damaged heads which i need to remove. They are the two little screws which hold on the top of the brake fluid reservoir on my Pricol type disc brake. What's the best tool to use and how do I do it?
Posted: 02:52pm 4th November, 2018
papasmurf Subject: Removing damaged screws
Worth a try:-
Posted: 05:35pm 4th November, 2018
PeteF Subject: Removing damaged screws
You can buy left handed drill bits which often back out damaged screws.
Posted: 06:17pm 4th November, 2018
John R Subject: Removing damaged screws
Thanks. I've got a ;little set of screen extractor bits somewhere. Just not sure if there is one small enough.
Posted: 06:53pm 4th November, 2018
stinkwheel Subject: Removing damaged screws
Just drill them out. 5mm bit, go slow, stop when you see the head turn. You can then remove the lid and undo the stump with mole grips. I've done this many times (it'll be into double figures) with ones someone else has partially rounded out then put back in again. The stumps have never not undone once the pressure is removed from them. It'll tanke you about a minute.

I say someone else, because I have learned the secret of undoing them without rounding. It boils down to people using the wrong screwdriver. Most of the time someone has tried to undo those screws with a posidrive screwdriver. It's the wrong sort, it doesn't fit, it WILL round out the screw head.

Even then, it's STILL a perennial problem on Japanese bikes because on those at least, it's not a phillips either. It's a JIS (Japanese Industrial Standard). A JIS screwdriver will undo a phillips screw, a phillips screwdriver will round out a JIS screw. Trouble is, you have to seek out and specifically mean to buy a set of JIS screwdrivers. They don't come provided in a set (although they DO come in the toolkit of every Japanese bike, you know that flimsy looking one with the removable black handle?).

But an Enfield isn't japanese? No, but yes, but maybe. The mikcarb is a copy Mikuni, how closely copied? Because mikunis always have burred out cross-heads for the exact same reason. Do they make their own screws in India or buy them in bulk from a factory in Taiwan? I just checked a pricol master cylinder and I'm pretty sure it's JIS, even though it isn't marked with a punch on the screw head (I tried the different screwdrivers in it, it's either a JIS or a very badly made Phillips).

That's not all though. A JIS driver will not only undo a phillips screw, it will do it better than a phillips driver... Really. A phillips is designed for machine assembly, so the angles of the bit make it cam-out of the head when it's fully tight. A JIS will not do this. It'll grip until you shear the fastener if your grip is good enough. I suspect my #2 JIS screwdriver would have removed the screw shown in the youtube video above, rounded as it is. A tap on the end with a mallet to seat it and simply unscrew.

I have phillips screwdrivers in my toolbox. I NEVER use them. I got a set of 3 vessel JIS screwdrivers a few years back and it's one of those tools you wonder how you ever did without. Amal carb tops and float bowls, rusting tail light lens self-tappers, master cylinder screws, that screw that holds the headlamp rim on, those screws that hold the switchgear together. All waltz off. If you also own a Japanese bike, you shouldn't be without them. Ask santa for a set.
Posted: 09:20pm 4th November, 2018
PeteF Subject: Removing damaged screws
Second all that stinkwheel, I got a set of jis drivers last year and wonder how I managed before😀😀
Posted: 09:28pm 4th November, 2018

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