When rivets wont hold

[ifoxwell]

So I'm replacing the jib halyard sheave box in the mast and find that galvanic corrosion has enlarged the holes in which the rivets go to such an extent that they wont hold

They are already 1/4" rivets and I don't want to go any larger so what alternatives to I have?

Thanks

Ian

 

[vyv_cox]

Install Rivnuts in the mast and use 6 mm bolts

 

[ifoxwell]

Install Rivnuts in the mast and use 6 mm bolts

Sounds like a great solution but Ive no experience of these. Do they come in stainless and how are they installed... do you need any special equipment?

 

[PaulRainbow]

https://www.google.co.uk/search?q=i...firefox-b&gfe_rd=cr&ei=JqXPWNHaJabS8AfJ0a-QAw

http://www.rivetwise.co.uk/rivets/rivet-nuts.asp

 

[PetiteFleur]

I've just watched the you tube video - you don't need to use the 'special' tool. As you are drilling into aluminium. just make the hole smaller so the rivnut taps in, held by the splines, then just screw in a LUBRICATED hex head screw which will set the rivnut.
Use stainless rivnuts with Duralac or similar anticorrosion paste. These are some on ebay - http://www.ebay.co.uk/itm/Stainless...hash=item3a7cc90d9d:m:mk_q_uZP7O1WBrOWcsugmZQ

Sounds like a great solution but Ive no experience of these. Do they come in stainless and how are they installed... do you need any special equipment?

 

[Kylora]

I've set Rivnuts without a tool. Use a long hex head machine screw, 2 washers, and a hex nut. Fit screw into Rivnut, hold it to prevent rotation, and then tighten nut down on to head of Rivnut with 2 lubricated washers taking the pressure. It does need a bit of " engineering fitter feel " to judge the force required to set the Rivnut without damage.

Ash

 

[Norman_E]

I like rivnuts, but how will putting them into the mast help? The sheave box is presumably a casting that fits inside the mast. If so drill the holes in it 6.5mm and tap them M8. Open the holes in the mast to 8mm and use 8mm button head set screws like these http://www.ebay.co.uk/itm/BUTTON-HE...hash=item2a40ee3c70:m:mFxOJXs93Jk7gZGaCM57Grg

 

[ifoxwell]

I like rivnuts, but how will putting them into the mast help? The sheave box is presumably a casting that fits inside the mast. If so drill the holes in it 6.5mm and tap them M8. Open the holes in the mast to 8mm and use 8mm button head set screws like these http://www.ebay.co.uk/itm/BUTTON-HE...hash=item2a40ee3c70:m:mFxOJXs93Jk7gZGaCM57Grg

Thanks for the input but Rivnuts will work for me. In this instance its a Selden box that sits on top of the mast rather than hook inside as some do. And as you say in an instance like that drilling and tapping to a larger size would be the best course of action

 

[Norman_E]

In that case you might need countersunk rivnuts like these. http://www.ebay.co.uk/itm/STAINLESS...hash=item25b8ef64e9:m:mGTNwabPpEB6ZPeD_orSG_Q

Note that the 6mm rivnuts have an outside diameter of 8.9mm. You will not have a drill that size! Just using a 9mm drill will leave them slack in the hole and hard to set properly. Drill 8mm or 5/16ths, and open the hole out with an 11/32 inch drill which is about 9.73mm. then use a countersink bit so that the rivets sit flush. If the rivets wont go in then gently ream out the hole with a tapered broach or hole reamer, but be very careful as you want the rivets to be a tight fit gripped by their serrations. Put a bolt into the rivnut and tap it in by the bolt head, do not just hit the rivnut as it may distort instead of going in. These rivnuts are only suitable if the mast section is 4mm or less.