On 22 May 2007 19:59:46 -0700, CB wrote stuff
and I replied:

I have a serious concern about a machine thread in the relatrively
thin wall of an almmunium mast. Al does not takew threads well, and
then not fine threads, adn then most thin metals a happier with
coarser threads.

Use a reivet if at all possible. Ironically, even self-tappers of
reltatively coarse thread, with large flutes, are better in thin
sections.

Apart from that, use 316 and some sort of insulator. It's worked on
many boats.


I need to tap out a 1/4" hole in my mast to 5/16" 18 (no threads in
there right now) and put a machine screw in there.

I have some options in terms of metal types and there have been a
number of discussions about corrosion and so on with SS in contact
with aluminum and how really useless the isolating compounds are in a
sal****er environment etc etc

So what's the metal of choice? I'm seeing brass, SS, silicon bronze,
zinc plated steel.. what's optimal for the aluminum (non-)interaction?
These other discussions don't have a consistent conclusion. (And no
rivets, this is a small job, I really do need the machine screw).

This is a freshwater boat and has been for a long time. However I
wouldn't rule it out of taking it down the east coast one day.

Thanks for any comments,

-CB

On Fri, 25 May 2007 00:14:06 +0800, OldNick
wrote:

On 22 May 2007 19:59:46 -0700, CB wrote stuff
and I replied:

I have a serious concern about a machine thread in the relatrively
thin wall of an almmunium mast. Al does not takew threads well, and
then not fine threads, adn then most thin metals a happier with
coarser threads.

Aluminum riv-nuts are easily obtained, easily fitted, and reasonably
replaceable when the time comes. Screw a SS screw into a riv-nut

Brian Whatcott Altus OK

Brian Whatcott wrote:

Aluminum riv-nuts are easily obtained, easily fitted, and reasonably
replaceable when the time comes. Screw a SS screw into a riv-nut

Brian, do you have a link to a source for these riv-nuts? I can't seem
to find them.

Dan "dhapp-at-wmis,net" wrote:
:Brian Whatcott wrote:

: Aluminum riv-nuts are easily obtained, easily fitted, and reasonably
: replaceable when the time comes. Screw a SS screw into a riv-nut

:Brian, do you have a link to a source for these riv-nuts? I can't seem
:to find them.

Mcmaster-Carr sell them. www.mcmaster.com, look for "rivet nut" in
the fastener section.

David Scheidt wrote:
Dan "dhapp-at-wmis,net" wrote:
:Brian Whatcott wrote:

: Aluminum riv-nuts are easily obtained, easily fitted, and reasonably
: replaceable when the time comes. Screw a SS screw into a riv-nut

:Brian, do you have a link to a source for these riv-nuts? I can't seem
:to find them.

Mcmaster-Carr sell them. www.mcmaster.com, look for "rivet nut" in
the fastener section.
THANK YOU!

On Sun, 27 May 2007 20:26:14 -0400, Dan "dhapp-at-wmis,net" wrote:

Brian Whatcott wrote:

Aluminum riv-nuts are easily obtained, easily fitted, and reasonably
replaceable when the time comes. Screw a SS screw into a riv-nut

Brian, do you have a link to a source for these riv-nuts? I can't seem
to find them.

I googled "riv-nut" for 30,000 hits.
I googled "riv-nut supplier" for 3000 hits.
Here is one of them. It has a cross-section diagram to give you the
idea

http://www.cardinalcomponents.com/fasteners.htm

Brian Whatcott Altus OK

Here is a related question. My Imron-painted aluminum mast and boom has the
usual assortment of fittings and attachment methods typically found on a
twenty-year-old boat now on it's fourth or fifth owner. For the most part
the paint is in good condition, (and stainless bolts protected with TefGel
or similar) but here and there next to older stainless fittings, or around a
weld there are the usual smaller-than-a-pea pustules of corrosion. Sooner or
later I plan to have the entire mast repainted professionally but in the
meantime what is the best etch/prime/paint touchup method to minimize
continuing damage? I assume there is a more or less standard sequence and
bill of materials used by aircraft or aluminum boat maintenance shops. Any
suggestions re online or local vendors would be much appreciated.

Scott
S/V Itchen

Scott wrote:

Here is a related question. My Imron-painted aluminum mast and boom has the
usual assortment of fittings and attachment methods typically found on a
twenty-year-old boat now on it's fourth or fifth owner. For the most part
the paint is in good condition, (and stainless bolts protected with TefGel
or similar) but here and there next to older stainless fittings, or around a
weld there are the usual smaller-than-a-pea pustules of corrosion. Sooner or
later I plan to have the entire mast repainted professionally but in the
meantime what is the best etch/prime/paint touchup method to minimize
continuing damage? I assume there is a more or less standard sequence and
bill of materials used by aircraft or aluminum boat maintenance shops. Any
suggestions re online or local vendors would be much appreciated.

Scott
S/V Itchen




A moisture cured urethane - and best would be an aluminum filled
moisture cured urethane.

paul oman
progressive epoxy polymers

Brian Whatcott wrote:
On Sun, 27 May 2007 20:26:14 -0400, Dan "dhapp-at-wmis,net" wrote:

Brian Whatcott wrote:

Aluminum riv-nuts are easily obtained, easily fitted, and reasonably
replaceable when the time comes. Screw a SS screw into a riv-nut
Brian, do you have a link to a source for these riv-nuts? I can't seem
to find them.

I googled "riv-nut" for 30,000 hits.
I googled "riv-nut supplier" for 3000 hits.
Here is one of them. It has a cross-section diagram to give you the
idea

http://www.cardinalcomponents.com/fasteners.htm

Brian Whatcott Altus OK
I see that now. I must have had an blond moment. Thanks for the link,
Dan

On Tue, 29 May 2007 19:51:53 -0400, Dan "dhapp-at-wmis,net" wrote:

....
I see that now. I must have had an blond moment. Thanks for the link,
Dan


I'm so envious: wish *I* could have a blond moment,
or brown, black or gray. I specialize in pink moments. so to
speak.....

Brian Whatcott Altus OK