Alternative to drilling out fittings
Printed From: Yachts and Yachting Online
Category: General
Forum Name: Repair & maintenance
Forum Discription: Questions & tips on the subject
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=10643
Printed Date: 14 May 25 at 1:09pm
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Topic: Alternative to drilling out fittings
Posted By: rb_stretch
Subject: Alternative to drilling out fittings
Date Posted: 15 Jan 13 at 7:03pm
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Back to my Albacore again. I've got a front bouyancy tank bung fitting that was fitted with steel fastenings which have rusted badly. I cannot tell if they are screws or not as there are no discernable grooves or markings. The problem is that I cannot get a drill to them because the base of the mast step is in the way, see photo.  Anyone have any ideas as to what the fastenings may be and how I could get them out?
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Replies:
Posted By: JimC
Date Posted: 15 Jan 13 at 7:09pm
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I think I'd treat 'em with a phosphoric acid based rust treatment, leave them in and and hope for the best! The only alternative I can think of is to grind the tops off with a dremel, grind them to below gel coat level, fill, and put a new fitting in with the screw holes in a different place...
If you do decide to grind them off I strongly recommend putting the boat on her side while you do the work because the access is so much less torturous if you do. |
Posted By: kevg
Date Posted: 15 Jan 13 at 7:21pm
| If you did need to drill the heads off could you use a right angled drill attachment? |
Posted By: Jack Sparrow
Date Posted: 15 Jan 13 at 7:47pm
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Posted By: Andymac
Date Posted: 15 Jan 13 at 8:42pm
| I'd think about sacrificing the (softer) bung socket, carefully chisel/score through just to the side of the fastening. Once the bulk of the socket is removed from centre. you will just be left with the fastenings x 2 through little 'washers' of plastic. Place mole grips on remnant and unscrew. |
Posted By: rb_stretch
Date Posted: 15 Jan 13 at 9:04pm
That's a good idea. There is an inspection hatch not too far away so if I can contort myself into the right position I'll try and feel what is actually behind, screw threads or otherwise..... ------------- |
Posted By: JohnW
Date Posted: 15 Jan 13 at 9:35pm
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Almost certainly self tapping screws on a Speed Alb so Andymac's suggestion is the way to go. ------------- |
Posted By: JimC
Date Posted: 15 Jan 13 at 10:04pm
Just so long as there is room to manipulate the mole grips... I was assuming there wouldn't be... |
Posted By: rb_stretch
Date Posted: 16 Jan 13 at 5:28pm
There's an unspoken rule in boating that any job will take 3 times longer than expected. Well today I went to the boat to investigate further and broke the rule. After a bit of prising with a screwdriver the whole lot came out. Not only were the screws really badly corroded, but the hole for the plug and the holes for the screws were really oversized. Obviously a bodge job on all fronts, thankfully. Expect I will need a lot of sikaflex to hold a new one in. Here is the offending plug. The chip off the bottom screw came from me poking the rust with a screwdriver to see if I could uncover the head. I reckon mole grips would have destroyed them before getting them to turn.  ------------- |
Posted By: JimC
Date Posted: 16 Jan 13 at 6:00pm
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That's a good result really. Did the screws come right out or are ends left in there? Clean all the rust off with Tcut or some other abrasive olish, fill the holes with filled epoxy and away you go:-) If the main hole is too big you could pad that with epoxy too:-)
Reckon those have to have been steel screws, very odd for stainless to go like that unless there's serious electrochemistry involved. |
Posted By: rb_stretch
Date Posted: 16 Jan 13 at 6:29pm
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The screws came out whole, so result all round. I reckon it was only the sealant and the corrosion around the threads that was holding the bung in there. Given the boat is polyester I would have thought filling the holes with epoxy would subsquently make them very difficult to drill. That and I can't actually get a drill in there, which is, I suspect, why it was a bodge job after the boat was built. Do you think Sikaflex 291 isn't going to be enough? ------------- |
Posted By: SoggyBadger
Date Posted: 16 Jan 13 at 7:01pm
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You wouldn't use pure epoxy as the filler but a mix of epoxy and micro-balloons. Mix into a thick paste which has just enough flow to go into the hole. When set it should be similar to wood to drill. ------------- Best wishes from deep in the woods SB |
Posted By: Andymac
Date Posted: 16 Jan 13 at 7:34pm
Just a tip; on one occasion, being short of any normal branded cutting paste/polish, I tried removing some rust marks from the deck of a Laser (where a ferrous padlock had been left for a loooong time) with TOOTHPASTE. The results were excellent. Don't know if the 'whitening' brands aimed at smokers would be any better still!
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