Brackets on roof

[Kapt. Kipper.]

Hi all, I intend to fix four small brackets to the roof of my nb. A single 6mm bolt to secure each. Can anyone suggest a good method of doing this. Cheers.

[cuthound]

If the brackets are not going to be to stressed, you can just drill and tap the roof, then use stainless steel or brass machine screws.

[Kapt. Kipper.]

Thanks cuthound. So a 6 mm tap required. SS hex HD bolts. Would you use any sealant.

[X Alan W]

Thanks cuthound. So a 6 mm tap required. SS hex HD bolts. Would you use any sealant.

 

If they are not to be removed very often or not at all one of the sicaflex or similar type sealant adhesives would help to keep the brackets in the desired position

[Kapt. Kipper.]

I was thinking more of water ingress and would they need sealing. I suppose it will do no harm.

Just a thought will 4mm roof thickness give enough purchase for the bolts. Maybe some adhesive will be needed.

[cuthound]

Thanks cuthound. So a 6 mm tap required. SS hex HD bolts. Would you use any sealant.

Yes, I would put a smear of Sikaflex on the threads, immediately prior to screwing them in.

Edited June 13, 2016 by cuthound

[spadefoot]

Just a thought will 4mm roof thickness give enough purchase for the bolts. Maybe some adhesive will be needed.

It's all about the t.p.I. How thick is a 6mm nut?

[X Alan W]

I was thinking more of water ingress and would they need sealing. I suppose it will do no harm.

Just a thought will 4mm roof thickness give enough purchase for the bolts. Maybe some adhesive will be needed.

The "goo" I suggested will serve that purpose no problem if you go down the sealer route steer clear of silicone polyurethane or butyl base is best

[BargeeSpud]

Make sure you get the exact drill bit size for an M6 tap, its crucial.

[Neil Smith]

I drilled and tapped 5mm threads in my 4mm roof for the vents and sealed with sikaflex, and 4mm stainless machine screws they tightened down nice a d tight.

 

Neil.

[Slim]

5 mm tap requires 4.2 mm tapping hole (.8 mm pitch)

 

6 mm tap requires 5 mm tapping hole ( 1 mm pitch)

 

 

 

Frank

[Kapt. Kipper.]

Okay fella's thanks. So 5mm holes 6mm tapps, SS hex head screws sicaflex adhesive on threads .....jobs a good in

Cheers.

[Chewbacka]

I find the main leak problem is caused by bracket rotation, so if the four brackets are the feet for a static solar panel it might be ok, however if you are going to tilt the panel from time to time which may put a twisting load on the bolt, then I would use 2 bolts per bracket into the roof.

So in your application if there is any chance of brackets being rotated or twisted then I would use 2 bolts for each.

[the barnacle]

6 x 1mm Tap - 4.5mm drill - i tap 1.5mm tube so 4mm will have some hold - if you need any stainless bolts i have plenty - i could send you some.

[Iain_S]

6 x 1mm Tap - 4.5mm drill - i tap 1.5mm tube so 4mm will have some hold - if you need any stainless bolts i have plenty - i could send you some.

 

I'd up the drill size.

M6 core diameter is 4.77mm, so a 4.5mm hole will be REALLY hard going (and probably fatal) for the tap.

 

5mm drill at least. (I use a ¹³/₆₄", which works out at just over 5.1mm) You might get away with 4.5mm in 1.5mm thickness (and it might be better, as the metal will deform while tapping, to give a slightly longer thread length) but not in 4mm.

[the barnacle]

 

I'd up the drill size.

M6 core diameter is 4.77mm, so a 4.5mm hole will be REALLY hard going (and probably fatal) for the tap.

 

5mm drill at least. (I use a ¹³/₆₄", which works out at just over 5.1mm) You might get away with 4.5mm in 1.5mm thickness (and it might be better, as the metal will deform while tapping, to give a slightly longer thread length) but not in 4mm.

 

guess yout right as most of the stainless i tap is 2mm so i get away with a smaller drill

[Kapt. Kipper.]

Cheers barnacle, I have a supply.

[Robbo]

Hi all, I intend to fix four small brackets to the roof of my nb. A single 6mm bolt to secure each. Can anyone suggest a good method of doing this. Cheers.

Also look at magnets, you can then move the brackets easily if need be.

[Neil Smith]

Also look at magnets, you can then move the brackets easily if need be.

If he it is for solar panels I don't think magnets would hold in high wind.

 

Neil.

[Robbo]

If he it is for solar panels I don't think magnets would hold in high wind.

 

Neil.

That depends on the magnets used.

[Ssscrudddy]

36kg pull neodymium magnets, 4 per panel, hold perfectly well with the panel flat even in 90mph winds. I get a bit nervous if the panels are tilted when wind speeds are 30mph gusting to 50 mph according to weather forecasts & after storms, however they simply haven't moved. If I did it again I would get 72kg pull magnets so as not to worry about windy conditions, but with that said I leave them flat now anyway.

Edited June 20, 2016 by Ssscrudddy

[Greylady2]

Wouldn't all those powerfull magnets put a positive charge in the hull body and increase the corrosion rate overtime ?

 

I remember doing a science project when I was a kid.

 

Nothings changed much I am still dum and I still wet myself

Edited June 25, 2016 by Greylady2

[spadefoot]

Wouldn't all those powerfull magnets put a positive charge in the hull body and increase the corrosion rate overtime ?

 

I remember doing a science project when I was a kid.

 

Nothings changed much I am still dum and I still wet myself

Yes they would. If you were to accidentally put them on upside-down, your electricity would work backwards.

[Greylady2]

Yes they would. If you were to accidentally put them on upside-down, your electricity would work backwards.

Sorry if I was misleading.

 

Steel Strip 1 mm thick 1 inch wide

Add two crocodile clips 9v battery

 

Do the same without the battery same survey baseline without the battery.

 

The magnets attract negative ions a slow but positive circuit which increases rust.

 

It's a loop, remove the positives in a hull just like galvanic isolators do.

 

Magnets on hull are asking for rust.

 

Long term, it's basically electrolysis.

Edited June 25, 2016 by Greylady2