Best way to use Duralac?

Hi all, another question for the Seabreeze brains trust.

I have a one off application coming up, through bolting a fitting through the alloy head cap of my mast. The bolt will also pass through some carbon.

I have bought the smallest amount of Duralac I can as it won't get used again in it's lifetime.

My question is, should I:
1) coat the bolt just before I fit it so it's liquid when seating
2) coat it before hand to let the compound go off before hand
3) do both 1 & 2 to get a good coating?

This is the fitting, the bolt is 240mm and will have approx 20mm cut off.

Yeah!
I would make sure the duralac is smeared well around the alloy of the mast and under the washers, the alloy is what you are trying to protect.

Richard

Alloy, carbon & stainless.....
sounds like either a recipe for a battery, or fizz-wizz !!!
if you must do it, Tefgel would be the only stuff to use. good luck.

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rumblefish said..
Don't, seriously....have tried to pull apart fittings that were well and truly covered in that yellow crap years ago, and they were seized tight!!
For anywhere that will see load like this, Tefgel is the only answer.
For rivets, bolts etc, denso paste is cheap and works better than Duralac!!

tefgel for me also not many professionals use duralac anymore

what is current best practice when installing stainless saddles onto an aluminium boom?

i have Monel rivets and Tefgel. would you also recommend fibro washers for this?

Thanks all, so Tufgel sounds the go, I'll go and swap it.
I had considered fibre washers but the load will have a compression component on the leeward side, not just shear, so I wasn't sure they would take it.

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fishmonkey said..
what is current best practice when installing stainless saddles onto an aluminium boom?

i have Monel rivets and Tefgel. would you also recommend fibro washers for this?

When using rivets, I tend to steer away from the fibro washer simply because if loading on the component compresses and decompresses the washer in a cyclic acton, the component may become loose, I only tend to use them where I have drilled and taped. or as a gasket under the head of a bolt/ nut and even on stainless pins where the head of the pin or the split pin will contact dissimilar metal.
The stainless saddles on my boom have fibro washers and are all held on with screw threads that will allow me tighten them up unlike a rivet.
It is although, quite possible that others have used fibro washers with rivets and have no problem, I just try to think ahead of a potential problem that may occur,,, as sirgallivant says they are as tough as granite.

thanks both!

so machine screws rather than rivets is recommended (boom isn't painted though).

the saddles are for the new lazy jack system that i am making, so not high loads.

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rumblefish said..

fishmonkey said..
what is current best practice when installing stainless saddles onto an aluminium boom?

i have Monel rivets and Tefgel. would you also recommend fibro washers for this?

Doing this on Monday, drill and tap plus tefgel :)
Drill correct size hole for tap, put tap in cordless drill in fast speed, spray some inox/wd40 on hole, tap in in one go, them out in one go!!

I drill and tap everything I can, especially if it's a painted boom where you might want to take it out for repainting at a later

Tapping a soft metal like aluminium with a drill on fast speed sounds pretty courageous to me. Very easy to strip it.

Kero works great, its old school in the machine shop . Any of the "toolbox in a can" products (CRC, WD40 etc) seem to work well as a cutting lubricant for aluminum. I quite often use WD40 or RP7 when parting off or screw cutting small aluminum components in the lathe.
With regard to tapping a thread under power, there is less chance of stripping the thread because of the way the tap starts the thread under a steady pressure and in an uninterrupted rotation. Apply a little pressure to start then back off and let the tap feed itself through .

If you were going to buy a tap and die set for the boat would it be imperial or metric ?.

Probably a combo set Sam
But I just buy individual taps that I need

eg: M4 M5 M6 M8
3/16w ,1/4w, 5/16w, 3/8w,
They will cover most small sail boat requirements.