Another Broken Screw Removal Question

[MainlySteam]

On the weekend I broke a small ss self tapping screw that is one of two holding a small ss coverplate over an internal pin on our aluminium boom. On examination it is clear that it had partly sheared when it was first driven when the boom was built. While I could just remove the other screw and rotate the cover plate, redrill and rescrew in the new position, I would prefer to get the old screw out, mainly to keep the cover plate in neat alignment with another just beside it.

There is no corrosion complicating things as a barrier coating was used, but it is obviously very tight through originally being driven to the point of shearing.

It has sheared flush with the aluminium it is driven into and is only about 2.5 mm dia, including the thread depth, so is not big enough to cut a slot in with a Dremel. Before I do the more mangling drill down the side approach to get some "grabbing it" room and possibly ending up with having to put a much larger screw in, does anyone know of any smart tricks for removing such small headless screws.

Thanks in advance for any suggestions.

John

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[tcm]

possible bodge option

Sorry, but with the ss in aluminium, any driling/gringing option is going to risk slipping into the soft aluminium, as i think you realise.

You could of course make additonal holes in the stainless steel cover plate, and sink new screws into those.

But what about the existing countersunk hole thru which you cannot screw anything becos of the stuck ss screw? One answer to this is that you get another stainless steel screw, chop of the threaded part and superglue the head in to cover up the existing unuseable countersunk hole, and may the Lord have mercy upon your soul.

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[peterb]

I doubt whether it will work in your case, because your screw is stainless, but I remember from my workshop days that dilute nitric acid (one part acid to one part water) will attack steel but not aluminium. A useful trick for removing broken screw taps from soft ali.

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[Avocet]

Re: possible bodge option

I don't thing there's much hope but it might just be worth trying a hot air gun on it. The ally will expand a lot quicker than the stainless. You might, with a sharp centre punch, be able to rotate the screw untill it drops into the boom...

Other than that, I think you're stuffed, I'm afraid! I take it you can't get mole grips onto the other end of the screw?

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[TheBoatman]

From your post, I didn't understand if the screw went all the way through the boom. If it does then you might try punching the old broken bit through into the boom. You will need a very flat faced punch only slightly smaller than the screw you're removing. It should work and you will end up with a reasonably clean hole to insert a larger screw.

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[oldsaltoz]

G'day John,

Had this happen some time ago an outhaul fitting, TheBoatman is on the right track, I punched the broken screw through then enlarged both the holes on the boom and the outhaul fitting.

With all the screws now the same size (And Larger) it should be good for another 20 years.

BTW Avagoodnewyear...



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[supermalc]

One way of removing metal screws from ally is to weld a bar onto the top of the screw. Of course this needs access to workshop equipment, and have space around it. As the weld only sticks to the steel, and also heats the whole lot up, and the ally expands slightly more, this usually works.

The small size may be a problem, but if you have access to someone with a small portable mig they may be able to weld the top to something that can be gripped enough to turn.

I once removed a broken cylinder stud in a Hillman Imp block that several others had tried (and failed) and it was 1/2 inch below the top of the hole using this method. Doesn't work everytime of course but may be worth a try.

Malc.

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[Guest]

One way I got a screw 'out' was with a Dremel and a needle grinder bit in it .... the needle grinder is a lot smaller than the screw and if you pick the tapered one .... it grinds a central hole to keep it guided, while it grinds into it is grinding outwards as well. As mots booms etc. are not so thick on the ally - it only requires a short way in - then a needle puch to push it into the boom. Leaving a reasonable hole.

It worked for me, took ages but.....

<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
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[Dave_Knowles]

Hi John,

Have a look at <A target="_blank" HREF=http://www.rutlands.co.uk>http://www.rutlands.co.uk</A> and do a search for screw extractor. They may work but evn if they don't they are worth knowing about.

<hr width=100% size=1>Dave
Southampton - uk

<A target="_blank" HREF=http://www.MyCleopatra.co.uk>The site for cleopatra boat owners</A>

 

[MainlySteam]

Re: possible bodge option

Tut, tut tcm. Superglue!. Not quite to the standard of some of your gems that I can remember with respect to varnishing, carpet and some others. But, I do concede, perhaps as practical /forums/images/icons/smile.gif as I think the general view is that I might be stuffed, and therefore may have to in the end heed your solution and then seek mercy for my soul from the Lord.

Regards

John

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[MainlySteam]

I had not thought of punching the screw right through. Don't know if it actually goes right through though (the other side is hidden) so might have an explore pulling the other screw out (but it is worryingly tight!).

If punching is not possible I will resort to the Dremel and needle grinder bit - perhaps first a nick out of the aluminium each side first to see if I can get some wire cutters end on to grip and rotate the screw with some heat and if not then see if can just grind the screw out.

Dave thanks for the extractor info -while not sure will help with aluminium, I had remembered those being mentioned in a thread some months ago but could not remember what they looked like. I have never seen them over here and intended looking out for some.

We leave for a 2 week or so sail mid next week so will stand and scowl at it while I am away, just to get it in a submissive frame of mind, and attack it with a vengence when I get back. I'll have my superglue ready as a last resort.

Thanks for the suggestions everyone, a great help, and for any yet to come.

Regards

John

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[Becky]

The best way to remove anything like hard steel in soft aluminium is to ask your dentist for some help. I have done such things in the past, the degree of dexterity one develops drilling people's teeth makes such things easy! If you live anywhere near Petersfield Hants. I would gladly do it for you.
Becky

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[petereff]

i had a broken screw in my aluminium engine case my bro in law(engineer)
used a tool called an easyout then re-threaded the hole try asking your local
car mechanic or maybe you have a friend who knows one

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[Dave_Knowles]

John,

I bought some the other day and they look fairly sturdy. It maybe worth trying one as they don't cost very much and the worst that will happen is that you will blunt it.

<hr width=100% size=1>Dave
Southampton - uk

<A target="_blank" HREF=http://www.MyCleopatra.co.uk>The site for cleopatra boat owners</A>

 

[Heckler]

patience, tap tap, bit of this bit of that, pin punch try and drive in?
stu

<hr width=100% size=1>http://www.beneteau-owners-association.org.uk

 

[MainlySteam]

Thanks for the suggestion Becky and the kind offer. Unfortunately, I live out in NZ - perhaps a holiday out here may be in order!

Regards

John

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[robind]

get hold of a dry ice pencil like those used on Warts in the health service and freeze the B*g*er that will loosen it, in ali, alternativley take off the cover plate and check out to see if you have a short stub end left and if so use a "sharp jawed" mole wrench to withdraw it. Also use masking tape to prevent any scratching.
Best of luck
Rob

<hr width=100% size=1><A target="_blank" HREF=http://www.rejuvanu.com>RejuVanu</A>

 

[Gunfleet]

Please have some feeling for the nervous Becky and don't mention t***h again

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[charles_reed]

I knew a NZ dentist

who was working in London, and a lovely girl she was too.

In those days (early 60s) they used to have to work for the Government for a pittance to repay their tuition fees.

I believe Oz and NZ were the first to have student loans instead of grants.

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[Omatako]

If you have to drill out and really want to preserve original appearance (and don't mind a bit of extra toil) consider an insert. Drill out to 6mm or whatever will be still be concealed by the cover plate, tap the new larger hole, insert a suitable bolt with a substance like Loctite, cut off at surface, dress down and drill and tap a new hole back to original spec in original location. Takes longer but guarantees original appearance.

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