Sourcing very long countersunk m8 bolt/setscrew

[chibb]

Hi,

We're fitting a pair of rope clutches for our running backstays. Unfortunately the clutches are going to have to be mounted on a block to get the rope to go smoothly through them. This means that we need to get hold of an m8 stainless fitting that is around 140mm long!! I haven't had any luck finding anything suitable. Anyone got any ideas? Thanks.

ps. It has to be countersunk otherwise the head would stick up into the clutch mechanism.

 

[boatbuilder]

Weld a bit of 8mm studding to a csk bolt so that the joint is inside the block.

 

[Norman_E]

If you cannot weld studding to a bolt, then use countersunk bolts (available up to 100mm) to fit the clutch to the block, with the nuts and washers well countersunk. Use hex head bolts similarly countersunk to hold the blocks to the boat. Ideally the bolts holding the block should be spaced further apart than the clutch fixing bolts. If your blocks are good hardwood and you ensure that the nuts holding the clutches are well below the level of the bolt heads holding the blocks to the deck this arrangement will be satisfactory, however if you mount clutches that take a heavy load high above the deck, be aware of the leverage imposed at deck level, and put a substantial backing piece below the deck.

 

[Appleyard]

Just an idea..get a security shear nut and remove the hex section..(to do this lock it on to a bolt ,using another nut ,and twist off the hex .) You will then be left with a cone with an internal thread,use this as the "head" on a length of stainless studding ,fix it in place with loctite. You will now have made a screw with a countersunk head as long as necessary. Page 58 of the screwfix catalogue has security shear nuts in A2 Stainless steel M8... 10 for £3.99. Job done.

 

[Achilles]

Suggest you try Seascrew in Eastbourne. They do a lot of stainless stuff and I know they have M8. They have a website and do mail order.
Good Luck.

 

[simonfraser]

i assume you checked out the awsome service post, it's still on the page ?

 

[chibb]

Yes, rang seascrew and tried the other website mentioned, but both only go up to 100mm long. Got a couple of workable ideas with the welding to rod and using a security shear nut.. not sure my arc welding skills with stainless rods are quite good enough for that detailed a work yet... but I might just have a go !

 

[Graham_Wright]

I enquired of my fixing and fasteners supplier who tells me that they can only obtain up 100mm long. But you could try A2A4 (on the web).

 

[Poignard]

Please let me know if you do find a supplier because I need something similar to bolt down a pair of replacement sheet winches that are to be mounted on thick wooden chocks.

 

[chibb]

Darn, thought A2A4 had what I needed, then I realised it needs to be an M6 fitting !!!! dow... may get practicing with the welder...

 

[TheBoatman]

You might try these people as they manufacture "specials", could be pricey but worth a go.

http://www.rapoole.com/fasteners/item.asp?Product=370

Peter.