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LionessRacing

Type of screws to mount clutches on AL mast

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Getting ready to mount some halyard clutches on a thickwalled (1962 vintage) Aluminum mast

Self tapping, Sheet metal or Machine screws? 

 

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Put a gasket under the clutch as well - thin plastic will do - just keep it separated from the mast.

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FWIW, I've never had Tefgel work loose if the fastener was properly torqued.

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I did, radar mount up the mast (and I checked it immediately before beginning the passage.) Once bitten, .......

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11 hours ago, Fleetwood said:

I did, radar mount up the mast (and I checked it immediately before beginning the passage.) Once bitten, .......

Ouch.

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Since we're already on this topic, is Blue loctite okay as an alternative to tefgel/duralac when tapping machine screws into alu?

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Nope. Tefgel works to prevent galvanic corrosion much better. Blue loctite helps it stay put, but with s.s. screwed into aluminum, pretty soon it won't come out anyway :)

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definitely tefgel or duralac.  Both prevent the metals from "marrying".

IMO, tefgel stays pliant and is better for things you know you'll want to remove; duralac takes a "set", will provide slightly more security against vibrating loose, but it isn't a thread-locker, per se.

I use tefgel for most mast fittings, but duralac for (for example) spreader-base bolts and antenna mounts, where I don't want them to wiggle loose when I'm not looking

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Product opportunity here! Duralac is a shit to own (tubes always leak then solidify) and use; Tefgel doesn't set up hard; and Loctite doesn't prevent corrosion. Be nice to only have one tube in my toolbox.

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Alumilastic used to be the standard. Don't know if it's sold any more.

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I've had pretty good luck with Loctite (red) for machine screws in aluminum. Use enough to seal the threads. Anything that seals the threads permanently will work as good as anything else. Nothing prevents electrical contact (easy to prove with a DVM), the action of any of them is to seal out the electrolyte (seawater). Tefgel is good at this while not requiring heat to remove, but has no thread locking action and the anti-galling action so important for SS-SS isn't necessary in SS-aluminum. Loctite can always be easily removed, just heat the fastener to around 400 degrees (pinpoint torch or soldering iron). That kills the Loctite bond. 

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On mast fastnings Use a thread sealer,  threadlocker with PTFE 

https://www.tefgel.com/contain.php?param=tuffgel_price

TEFGEL  is without thread locker

TUFFGEL has threadlocker 

https://www.tefgel.com/contain.php?param=tuffgel_infor

in some markets Tuffgel is hard to buy .

 

 Locktight Brand also makes a sealant,  thread locker with PTFE ...i cant remember its part number 

 

Dont know your instalation ...typically a mast surface is convex, not flat ...and the hardware to be mounted has a flat base.  Bedding the flat base hardware into thickened epoxy will solve this issue 

 

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PTFE on a label is kind of like the early days of transistor radios ("10 Transistors!!"), or the more recent infatuation with "Titanium", "Aircraft Grade", or "Military Grade". It isn't clear that it does anything for anything, and it isn't clear how much is in the product. Marketing puffery. 

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15 hours ago, DDW said:

Anything that seals the threads permanently will work as good as anything else. Nothing prevents electrical contact (easy to prove with a DVM), the action of any of them is to seal out the electrolyte (seawater).

I did not know that. Is it common knowledge? I just tested and there is continuity on my mast between fasteners set in duralac. I tested between fasteners on different fittings with duralac showing. So, it's not the fitting or lack of splooge providing conductivity.

 

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I just removed a 30 year old track from my boom, sealed with...... wait for it....

lanocote! The screws came out easily no corrosion with just a whiff of greasy sheep grease

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3 hours ago, weightless said:

I did not know that. Is it common knowledge? I just tested and there is continuity on my mast between fasteners set in duralac. I tested between fasteners on different fittings with duralac showing. So, it's not the fitting or lack of splooge providing conductivity.

 

When you tighten down the fastener the threads are going to cut through the sealant somewhere, and probably a lot of somewheres. People worry about this with zincs too, like the pencil ones in the heat exchangers. You see a lot of experts saying don't use teflon tape as it will insulate the zinc and make it ineffective. Yet again, it's easy to prove that this never happens - there is always continuity on something like this that's been tightened. 

For galvanic corrosion you need an electrical path and an electrolyte. It's almost impossible to defeat the electrical path (can be done with insulating bushings on the fitting), so that leaves sealing out the electrolyte as the main defense. 

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3 hours ago, DDW said:

When you tighten down the fastener the threads are going to cut through the sealant somewhere, and probably a lot of somewheres. People worry about this with zincs too, like the pencil ones in the heat exchangers. You see a lot of experts saying don't use teflon tape as it will insulate the zinc and make it ineffective. Yet again, it's easy to prove that this never happens - there is always continuity on something like this that's been tightened. 

For galvanic corrosion you need an electrical path and an electrolyte. It's almost impossible to defeat the electrical path (can be done with insulating bushings on the fitting), so that leaves sealing out the electrolyte as the main defense. 

Makes sense now that you point it out. I had just taken the claims of insulating at face value. However, between the well bedded fasteners I tested the resistance was negligible. I feel like I learned something. Thank you!

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14 hours ago, Gutterblack said:

I just removed a 30 year old track from my boom, sealed with...... wait for it....

lanocote! The screws came out easily no corrosion with just a whiff of greasy sheep grease

We repainted a 20 yr old awlgrip painted mast(32ft ior). All of the fasteners had been tapped by my friend. He used regular lithium grease. They came out as if I had put them in the day before. Its not like the stuff magically disappears from between the threads.

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On ‎5‎/‎30‎/‎2018 at 11:19 PM, Zonker said:

Nope. Tefgel works to prevent galvanic corrosion much better. Blue loctite helps it stay put, but with s.s. screwed into aluminum, pretty soon it won't come out anyway :)

it will come out after a longer time. But then you need a bigger screws to fit in the hole.

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On 6/1/2018 at 7:26 AM, Gutterblack said:

lanocote! The screws came out easily no corrosion with just a whiff of greasy sheep grease

I've seen masthead fittings just fall off because screws were set in that stuff.

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