20mm Hole in the roof

[Keajre]

Hello,

 

I have a 20mm hole in the roof of my NB. Its 6mm thick steel. Used to be where the TV antenna was. I have no used for the hole, but seems too big to use P38, and I dont have access to a welder (although I could if that was the only way).

 

Would be interested in any advise or thoughts

 

Many Thanks

 

Stuart

Edited May 3, 2016 by Keajre

[the barnacle]

periscope? been serious how about a 25mm penny washer and rubber washer with a small button head bolt just incase you need it in the future?

[MtB]

Put a bucket under it...

[Keajre]

ye it woudl have to be an ultra thing one! I'll stick to curtain twitching :-)

 

I see your idea, could work. So penny washer, then rubber washer, then button bolt. What would the bolt screw into though?

Put a bucket under it...

I got a wine cork in it at the moment! Having the roof painted soon, so wanted to more permanent solution . .

[the barnacle]

penny washer 25mm - then rubber washer then washer with a bolt through - if you want some popping in the post i have plenty of stainless ones

[MtB]

Or for a surprisingly durable seal, put some Duck tape over it.

 

But I agree with the penny washer idea. You don't even need a rubber seal as the new paint will seal it.

 

Put a nut on the inside. Or don't you have access on the inside?

A more elaborate and secure repair would be a 3" disc of steel. Drill six holes around the perimeter then drill and tap six aligning holes in the roof. Bolt the disc down.

[johnmck]

Or for a surprisingly durable seal, put some Duck tape over it.

 

But I agree with the penny washer idea. You don't even need a rubber seal as the new paint will seal it.

 

Put a nut on the inside. Or don't you have access on the inside?

He is a boater!

The nut is already inside.

[MtB]

OR...

 

Get a 3/4" BSP tap, cut a thread in the 20mm hole and screw in a 3/4" BSP plug.

He is a boater!
The nut is already inside.

 

Ah yes, that old joke.

 

Q. What's a most dangerous nut on a boat?

A. The one steering it!

[Keajre]

OR...

 

Get a 3/4" BSP tap, cut a thread in the 20mm hole and screw in a 3/4" BSP plug.

 

Ah yes, that old joke.

 

Q. What's a most dangerous nut on a boat?

A. The one steering it!

Ah yes, I like this idea. Thanks

[the barnacle]

silicone a bit of glass over it for a roof window

[Keajre]

I dont have access to the inside no. I think the cutting a thread and then plugging it would be fine. Thanks

Thank you think tank, very helpful

[MtB]

Ah yes, I like this idea. Thanks

 

 

Where do I send the bill?

 

[Keajre]

 

 

Where do I send the bill?

 

The bill has already been recorded, and repayment is in the system. Its a special system, some call it by its tibetan name, Karma :-D

[Keajre]

Something like this:

 

http://www.ebay.co.uk/itm/3-4-BSP-2-PCE-TAP-SET-TAPER-PLUG-TAP-GAS-THREAD-BRITISH-STANDARD-PIPE-/161453183682?hash=item25975c12c2:g:KjoAAOxyQfJTfK2M

 

I cant find any taps that are 20mm in dia.

[bizzard]

Chamfer around the edge of the hole a bit with a round file then lodge a disc of card about halfway down the hole 3mm, this will then support P40 until cured.

[the barnacle]

 

 

Where do I send the bill?

 

 

pay mike in Bitcions, sorry didnt know you never had access to both sides.

 

you could aways adapt a bung - http://www.cotel.co.uk/p/229/lightweight-round-plain-insert-imperial if you ring cotel they will post a free sample, in the hope you will order alot in the future.

[magnetman]

Its quite an expensive option to tap it as you would need the tap and something to turn it with. You could quite easily end up breaking the tap as they are brittle.

 

I would just stick a metal disc of some description over the hole with sikaflex or similar pu sealant.

 

Or jigsaw it out to a suitable Size then cut out the internal lining to match and add a mushroom vent but that is a bit over the top of you just want to block the hole

 

Or fit an M16 eye bolt but then you need to nut it on the inside. Eye bolts are handy though for attaching things to.

How was the TV antenna fixed/removed if there is no access internally?

[Guest]

Metal conduit box lid from electrical wholesalers/ebay, twp m4 brass screws, sealant and paint over.

 

http://www.ebay.co.uk/itm/METAL-CONDUIT-BOX-ROUND-STEEL-LID-OR-RUBBER-GASKET-FOR-METAL-CONDUIT-ACCESSORIES-/171806163522?var=&hash=item2800720242:m:mWW_FzlmdrXlqNweKX1Y82Q

Edited May 3, 2016 by Guest

[MtB]

Something like this:

 

http://www.ebay.co.uk/itm/3-4-BSP-2-PCE-TAP-SET-TAPER-PLUG-TAP-GAS-THREAD-BRITISH-STANDARD-PIPE-/161453183682?hash=item25975c12c2:g:KjoAAOxyQfJTfK2M

 

I cant find any taps that are 20mm in dia.

 

 

Ok, it appears 19mm is the suggested drilling size when cutting a 1/2" BSP thread, and 21mm is correct for 3/4" BSP threads. Your hole is 20mm so I'd say buy a 1/2" BSP tap. The 0.5mm which will be missing from the peaks of the thread in the hole won't matter at all.

 

http://www.newmantools.com/taps/bsp.htm

 

http://www.ebay.co.uk/itm/1-2-X-14-BSP-CARBON-TAPER-TAP-THREADING-TOOL-FROM-CHRONOS-ENGINEERING-SUPPLIES-/300862879286?hash=item460cd33636:g:lQkAAOxy-1lRIA~I

Or is 20mm just approximate? In which case you'd better measure it properly!

P.S. Just turn the tap with a spanner. At that size, they really are not fragile as suggested by MM. Nor is £6 for the tap 'expensive'!

[WotEver]

Your hole is 20mm so I'd say buy a 1/2" BSP tap. The 0.5mm which will be missing from the peaks of the thread in the hole won't matter at all...

... plus the slightly oversized hole will make tapping easier.

[Mutts]

Metalset A4

https://www.smooth-on.com/tb/files/METALSET_A4_TB.pdf

[magnetman]

 

 

Ok, it appears 19mm is the suggested drilling size when cutting a 1/2" BSP thread, and 21mm is correct for 3/4" BSP threads. Your hole is 20mm so I'd say buy a 1/2" BSP tap. The 0.5mm which will be missing from the peaks of the thread in the hole won't matter at all.

 

http://www.newmantools.com/taps/bsp.htm

 

http://www.ebay.co.uk/itm/1-2-X-14-BSP-CARBON-TAPER-TAP-THREADING-TOOL-FROM-CHRONOS-ENGINEERING-SUPPLIES-/300862879286?hash=item460cd33636:g:lQkAAOxy-1lRIA~I

 

Or is 20mm just approximate? In which case you'd better measure it properly!

 

P.S. Just turn the tap with a spanner. At that size, they really are not fragile as suggested by MM. Nor is £6 for the tap 'expensive'!

Thanks for correcting me on that MtB

[OldGoat]

A brass plug turns a hole into a 'feature' - makes it look as if there's a purpose to it. You could polish it as well.

you can make it an 'interference fit' by using a hole saw (there must be a metric or Imperial size somewhere), you then can screw it , a fibre washer to seal plus Sikaflex / whatever to seal the threads.

Finished.

[mark99]

Send it to Blackburn.

[MtB]

I had to count them all...

 

 

Beatles fan too eh?!