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Sheared off screws (Mushroom vents)


LoneCruiser

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Good evening crew...

 

i’m Undertaking a spot of painting and went to remove my leaking mushrooms - now I know why they are leaking!!!

 

the screws holding them down have all sheared off bar one on two of my vents, with just the one screw and the sillicon holding them in place.. how do you get the screws out?

 

with a screw remover I guess. But I’ll ask the experts 

 

hope you all keeping well out there 

 

David 

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2 minutes ago, LoneCruiser said:

Good evening crew...

 

i’m Undertaking a spot of painting and went to remove my leaking mushrooms - now I know why they are leaking!!!

 

the screws holding them down have all sheared off bar one on two of my vents, with just the one screw and the sillicon holding them in place.. how do you get the screws out?

 

with a screw remover I guess. But I’ll ask the experts 

 

hope you all keeping well out there 

 

David 

 

On a friends boat we spun the mushroom tops off, drilled the screws out and levered the bases off. We cut what was left of the screws off with a grinder and redrilled new holes in the roof and re tapped them.

 

Yes it WAS a b@stard of a job.

 

Somebody will be along shortly with a more elegant solution.

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Bless you.. I thought of just using extra strong sillicon!!’ And hope for try best !!!

My mushrooms seem odd!! No chamber just the top unit on the roof screwed down to roof.. looking up from inside you can see the roof insulation in between decorative ceiling and outer roof!!!

Edited by LoneCruiser
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4 minutes ago, LoneCruiser said:

Bless you.. I thought of just using extra strong sillicon!!’ And hope for try best !!!

 

I suppose sikaflex might stick them down but we just went for belt and braces I guess.

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Are they brass screws?  I hope so because brass is quite soft.

 

First go is to use screw extractors ("easy outs" that's a very incorrect name) but its never easy to drill into a screw.

 

If this goes wrong and you damage the threads you might be able to drill and tap to the next size up. Use the mushroom base as a template.

If the screws are m5 then going to m6 will be good. If they are m6 then going to m8 is not so good.

 

If it all works put the mushroom vent back in with stainless screws rather than brass, brass shears off too easily.

If you want brass then use stainless or steel first to get the mushrooms nicely seated then swap for brass one at a time.

 

.............Dave

 

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1 hour ago, dmr said:

Are they brass screws?  I hope so because brass is quite soft.

 

First go is to use screw extractors ("easy outs" that's a very incorrect name) but its never easy to drill into a screw.

 

If this goes wrong and you damage the threads you might be able to drill and tap to the next size up. Use the mushroom base as a template.

If the screws are m5 then going to m6 will be good. If they are m6 then going to m8 is not so good.

 

If it all works put the mushroom vent back in with stainless screws rather than brass, brass shears off too easily.

If you want brass then use stainless or steel first to get the mushrooms nicely seated then swap for brass one at a time.

 

.............Dave

 

Whilst I prefer stainless screws, especially for fastening anything load bearing such as fairleads, sheared stainless screws are a right b'tard being harder then the surrounding stainless steel.

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Sorry for late input, but just redrill and tap 4 new holes by turning mushroom by 10 degrees, fill the old hole with sealant, and the existing filled holes. Then you know you have 4 strong points sealed how you want them sealed.

Far easier than drilling out old screws and trying to remove stuff.

  • Greenie 2
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3 minutes ago, DandV said:

Whilst I prefer stainless screws, especially for fastening anything load bearing such as fairleads, sheared stainless screws are a right b'tard being harder then the surrounding stainless steel.

 

I have yet to have a stainless screw fail. Stainless is stronger than bog standard steel but not as strong as hard steel.

But yes, drilling into stainless is a nightmare.

 

From your avatar I think you might be a salty water sailor. Mixing mild steel and stainless in salty water is risky, but on the cut here its quite safe.

 

............Dave

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Good morning

 

up on the roof today using all your advice supplied... I think they are brass... very odd because on all 3 it’s just the screwhead neatly place in the hole...two mushrooms, 3 screws sheared off on each...

 

ketchup later

 

ps.. anyone near Carnforth... lol!!!

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18 hours ago, dmr said:

 

Hi David

No not a salty sailor.. am on the Lanky!!!

 

is the avatar my pici?

 

a total technophobe!!! Maybe I slipped in an anchor ️?

 

V/best

 

David 

 

 

18 hours ago, dmr said:

 

From your avatar I think you might be a salty water sailor. Mixing mild steel and stainless in salty water is risky, but on the cut here its quite safe.

 

............Dave

 

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When using screw extractors, you are more likely to succeed if you do not rely on brute force, which is likely to result in the extractor slipping or snapping. I have successfully removed the snapped-off, rusted-in, remains of  bolts by using plenty of petrol lighter fluid around the bolt (Plus-Gas is best if you can get it, but petrol lighter fluid is almost as good, and more penetrating than WD-40).    The extractor should be see-sawed to and fro rather than attempting to turn it steadily in one direction. Steel is not infinitely stiff, and when you first start, the portion at the top of the hole should become loose while the deeper part is still fixed. When the top part becomes freed, you should see a thin ring of rusty petrol appear, which can be flushed away with clean petrol. As more of the thread becomes loose, so petrol can penetrate further down the thread and more rust get pumped out by the to-and- fro action, until (hopefully) the thread will become free and the remains of the bolt extracted.  Patience may be required! Of course, if it is really badly rusted,  re-drilling, possibly in a different place as mentioned above, may be the practical  solution. 

Edited by Ronaldo47
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3 in 1 penetrating oil is pretty good stuff for undoing stuck & rusted screws/bolts, I'm manged to undo the bolts holding together a Wey & Arun Canal paddle gear box that had been in the bottom of Malham lock for over a 100 years, we resused the bolts as well.

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4 minutes ago, Ronaldo47 said:

.........using plenty of petrol lighter fluid around the bolt (Plus-Gas is best if you can get it, but petrol lighter fluid is almost as good, and more penetrating than WD-40).   

 

Which is unsurprising as WD40 is not a penetrating oil, or even a lubricant, it is the 40th 'recipe' used in developing a 'Water Dispersant' fluid.

 

Our demonstration with BT was to fill a pole mounted junction box with water, let the water drain out, spray in WD40 and prove that there were no problems with continuity and no shorts. The water was dispersed away from the terminals / connections.

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That's useful to know. Proper penetrating oil is not always easy to find, whereas petrol lighter fluid can usually be found in shops that sell cigarettes.( It's also good for removing chewing gum!) I have used ordinary 4 star in an emergency, but lighter fluid does not have the nasty additives you get in motor spirit. 

Edited by Ronaldo47
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