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Old 09-09-2017, 11:15   #16
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Re: Aluminium setscrews

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Originally Posted by roverhi View Post
Self tapping screws are terrible fasteners to use in aluminum. Not because of the dissimilar metals but the nature of the fasteners. The self tapping screws have very coarse threads which makes for very low gripping power. Put a little torque on the fastener and they move eventually pulling out. I'm just a boat owner but have seen at least 10 instances of the screws pulling out from PO installed self tapper on boats I've owned. Just had to go to oversized machine screws for a padeye that the PO had installed with self tappers on my newest to me boat.

Drilling and tapping for coarse thread machine screws is the way to go. As others have said, use an insulator like TefGel and the fastener won't corrosion weld itself in. Also using an insulator like electrical tape under dissimilar metal fitting or caulk will cut down on corrosion.

Haven't had good luck with aluminum fasteners in other applications. Even though they are nominally the same metal, the alloys differ. Corrosion still happens. The aluminum fasteners are soft and will easily twist the heads off when trying to remove if you have to overcome much corrosion welding.
Additionally, self-tapping screws (at least the sheet metal sort) have a sharp tip that is lethal to internal halyards and wires.

Course SS machine screws with an anti-seize agent.

Blind rivets are actually be stronger in thinner masts (less than 0.1 inches thick, fastener 3/16" or less), and are very easily drilled out, without damage to the hole, if hardware emplacement is needed. Much easier to deal with than a seized screw. This is why you see them on smaller boats.
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Old 09-09-2017, 11:28   #17
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Re: Aluminium setscrews

Subject already covered.

If you don't want to pay the premium for brand made products, or simply enough can't find them around your area - yes I've been in some rather remote places for years ;-D

It may be useful to know that lanoline ( grease from wool) or any animal fat ( suiffe in French) works just as well. Ditto for mast tracks and similar to reduce friction when your fancy spray bottle is emptied or no longer sprays as intended.

A similar good tip for loosening seized fasteners is a 50/50 mix of acetone and ATF oil, or other liquid penetrating oil. Apply, tap lightly and wait some more and tap.....repeat til it comes off. Once took me two weeks of a daily 15 minutes "tap session" on a boom out haul that the previous owner of the boat apparently didn't know how to use! :-D
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Old 09-09-2017, 15:14   #18
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Re: Aluminium setscrews

As a general rule, most silicone greases are not very good as anti-seize anti-corrosion compounds. What they are good for is making things slippery, waterproof and as a dielectric compound (i.e.electrically insulating). However they are mostly low pressure greases meaning they will squeeze out of a joint very easily.

Interestingly this makes them very good for using on electrical connections. While you might think a dialectic (insulating) compound is the last thing to use on an electrical connection, the low pressure aspect is the key to understanding here. Slap some silicone grease (i.e. DC-4) on the connection and tighten it up. The DC-4 squeezes out allowing the (cleaned!) metal surfaces to make a good low resistance connection and the displaced grease keeps the connection both waterproof and fairly gas tight.

Note, this applies to a general silicone greases (i.e. DC-4 etc) but I'm sure there are specialist silicone greases that have different properties.

As an aside, I have been using Duralac for the better part of 30 years and still reckon it is good stuff but as posted elsewhere, treat it carefully and keep it off your skin, it does have some cancer risk...
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Old 09-09-2017, 16:21   #19
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Re: Aluminium setscrews

Thanks everyone, there have been some very useful responses to my question.
The self tapping screws hold a sheet metal conduit to the mast ,which carries all of my electrical wires etc. I did grind the points off them. They did the job for 30 years but were hard to remove!
Rivets are not much use as the channel occasionally has to be lifted up to change wires etc.
When the conduit is refitted, I will use 316 socket head course thread machine screws, with Duralac.
It seems Duralac is also a mild locking agent, whereas TefGel is not.
In the past, blue Loctite has been my sealant of choice.

Cheers,
Richard.
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Old 09-09-2017, 16:37   #20
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Re: Alluminium setscrews

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Originally Posted by Captsteve53 View Post
You know when I see so MANY posts since joining Cruiser Forum about dissimilar metal/substances /corroding rivets/Bolts materials and scanning the previous years amounting to the same threads, I was thinking this Forum was about getting the word out as a helping hand, especially as above every one has the same issues!! That substance i shouldn't talk about is a great answer to the majority of galvanic corrosion issue's, way better than thread-lockers in nearly all corrosive mediums,

So be it if thats the consecutive decision,

I am a Marine Surveyor with the IIMS and Lloyd's Maritime(both very well established ethical organizations) and not connected with that substance,

Sorry your forum feels that way about factual posts, Indeed in the future I will refrain from POSTING all together!! (UN BELIEVABLE!)

Steve Warren (MIIMS-Lloyd's Maritime) NZ Cheif Eng 1
My apoligies for stating things in a manner which got you so riled up. That was certainly not my intent. And why it did so I'm not at all clear about. But I was simply attempting to state that your message was recieved after your mentioning the compound a couple of times. And that after that, mentioning it yet further was (for me) quite counterproductive. Could I have stated things another way & still gotten my message across, quite probably. Could your response to my post have been a bit more calm, & reasoned perhaps? Again, yes, most likely.

If "getting the word out" about Duralac is that important to you, why not put it in your siggy line. That way in any & every post you make, your message grows. Though as with anything, if people are understand why something works so well, then they're much more apt to try it, as opposed to if they're just told "use t, it's the best"! Period.

Or for that matter, some guys would even go on to start a seperate thread about the various compounds that can be used to prevent dissimilar metal corrosion. Including which ones work better, in what specific applications, & why. Duralac included.

Heck, in the post which I made casual reference to, by Evans Starzinger, he ranked, in order of efficacy, about 7 different methods of preventing this kind of corrosion, & fastener seizing. Which was quite helpful, & definitely an eye opener. I learned a good bit from his explanations in that post, including his correcting an error on my part.

In my post in this thread, above, I endeavored to give folks a multiplicity of choices as to what they might do to mitigate problems of dissimilar corrosion causing fasteners to freeze. Along with more avenues which they could pursue in order to find yet more opinions (including from other marine professionals) as to what works in preventing this, & if so, how well (& hopefully why).

After which I also suggested that folks get smart on how to free up frozen fasteners. As regardless of how diligent about maintenance & construction on a boat, there will be frozen fasteners, it's just a fact of life. Ergo my comments there on.


I certainly wasn't trying to defame you, or malign a product.
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Old 09-09-2017, 19:46   #21
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Re: Aluminium setscrews

Adelie,

I welcome your input, how ever i Feel a PM in this situation would have been a more professional manor to approach this issue rather than publicly or at least places me in a position to prove my claims, even though you say my credentials are personally accepted (in between the lines I sense some how they are not!) so suggest for any one in doubt just go to the International Institute of Marine Surveyors website ,direct link below which gives a brief outline of specialty such as Pasted from the site)

Qualifications: Marine Engineering
Types of surveys undertaken: Classification Societies, Commercial Hull Condition, GRP and FRP, Hydrographic Surveys, Inland Waterway Craft, Machinery (condition and damage), Marine Insurance Claims (machinery), P and I Club Surveys (hull), P and I Club Surveys (machinery), State or Government Surveys, Steel and Alloy, Superintendency

:https://www.iims.org.uk/iims-members...steven-warren/

Below again are my actual Captains (Commercial) Engineering and Lloyd's Diploma's for all to view and put to rest, heaven for bid I am not whom i say I am !!

Cheers Steve (MIIMS) Lloyd's Maritime-NZ Chief Eng 1
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Old 09-09-2017, 21:28   #22
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Re: Aluminium setscrews

Captsteve53:

Several issues here.

1. I did believe you have the credential you claimed. I just don't care. And I don't believe most people here care much either. With a light touch references to your credentials will bolster positions you take here. Beat people over the head with them and they won't pay much attention to the rest of what you write. Your credentials garner you respect in your professional setting but that doesn't carry over here hardly at all. If your attitude is "Believe me because I have the credentials", people don't look much past that.

2. My previous post was not just aimed at you but at a larger group of people who need to hear the same thing. I'm not going to PM them individually, I don't have the time.

3. You have been posting a lot of anger. As with credentials, most people don't look much past the anger. The only people looking past the anger are the people who you are angry with. They look at what you've written and respond to both the content and the anger and then the mods wind up having to clean up threads of the bickering the ensues.
If you don't believe you are angry go back and look at your posting; you've used a lot of bold as if your were shouting and you've threatened to stop posting.

4. All we know here is what you write. If you write well, consistently get credible outside citations and can mostly not let differing opinions rile you up people will start to believe you a lot more and your reputation will start to carry some of your writing without outside citations. All we know is what your write.

5. I think you have a lot of expertise. I'm trying to help you to fit in because I think you can help people. You could be a boon to this forum. If I didn't think that I wouldn't have bothered, the frustration will drive you away before long, I've seen it plenty of times in the 7.5yr I've been on this forum.

6. The only thing we know is what you write.

Regards,
Adelie


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Originally Posted by Captsteve53 View Post
Adelie,

I welcome your input, how ever i Feel a PM in this situation would have been a more professional manor to approach this issue rather than publicly or at least places me in a position to prove my claims, even though you say my credentials are personally accepted (in between the lines I sense some how they are not!). . .
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Old 09-09-2017, 23:05   #23
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Re: Aluminium setscrews

Im a professional. All that means is that I get paid for the work I do under the licences I hold.

I have found on C.F. that in general, other peoples opinions are accepted only if they agree with the poster

It also is my experience that EVERYONE knows better than me in my speciality subject. Some of what I read makes me howl with laughter and some I just grit my teeth and ignore.

Perhaps that is why I never post anything regarding my subject unless a dire potential life threatening mistake is to be made and I usually do so in a PM. (Rarely.)

I will say that one of the errors people make is to think a chat board can give answers to an expensive question. In the end, all advice should be taken and discussed with the professional people who will be relieving you of several thousands of dollars to do a needed job. Sometimes the dear members of CF can give alternative methods to consider... and sometimes they can talk tosh. After being here a while, it becomes apparent whom to consider as a good source on information....even those we do not agree with but are experienced.

Let me repeat again.... CF IS A CHAT BOARD. Everyone discusses the topics whether they have experience or not, everyone offers their experience and everyone has a right to do so... because it is a chat board. People will do what they want and if they follow the advice given and it goes pear shaped... well.

Its a chat board. That is the extent of the description.
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Old 10-09-2017, 03:30   #24
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Re: Aluminium setscrews

Quote:
Originally Posted by weavis View Post
Im a professional. All that means is that I get paid for the work I do under the licences I hold.

I have found on C.F. that in general, other peoples opinions are accepted only if they agree with the poster

It also is my experience that EVERYONE knows better than me in my speciality subject. Some of what I read makes me howl with laughter and some I just grit my teeth and ignore.

Perhaps that is why I never post anything regarding my subject unless a dire potential life threatening mistake is to be made and I usually do so in a PM. (Rarely.)

I will say that one of the errors people make is to think a chat board can give answers to an expensive question. In the end, all advice should be taken and discussed with the professional people who will be relieving you of several thousands of dollars to do a needed job. Sometimes the dear members of CF can give alternative methods to consider... and sometimes they can talk tosh. After being here a while, it becomes apparent whom to consider as a good source on information....even those we do not agree with but are experienced.

Let me repeat again.... CF IS A CHAT BOARD. Everyone discusses the topics whether they have experience or not, everyone offers their experience and everyone has a right to do so... because it is a chat board. People will do what they want and if they follow the advice given and it goes pear shaped... well.

Its a chat board. That is the extent of the description.
There are very knowledgeable professionals and also some that are not.
I listen to the person and make judgement based on my summary of that person.
Eg. Recently on a remote island I met a fellow cruiser who was a doctor. He was into fitness and was very sure of what he knew. My background is exercise science and I made my cruising money by building a fitness gym business. It was reasonably obvious to me that this mans knowledge was very dated (hes approaching 70), what was also obvious was he wasnt open to entertaining new information or even questioning what he knew. Sometimes what you know gets in the way of learning.

My point is there is alot of very intelligent professionals out there and others that passed the exams. This applies to all professions and industries.

In regards to surveyors....well let me just say I'm sure there's some very good ones out there, the three I've used in the past weren't from that group.

I do all my own boat work due to a lack of faith in professionals.
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Old 10-09-2017, 05:58   #25
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Re: Aluminium setscrews

Quote:
Originally Posted by Adelie View Post
Captsteve53:

Several issues here.

1. I did believe you have the credential you claimed. I just don't care. And I don't believe most people here care much either. With a light touch references to your credentials will bolster positions you take here. Beat people over the head with them and they won't pay much attention to the rest of what you write. Your credentials garner you respect in your professional setting but that doesn't carry over here hardly at all. If your attitude is "Believe me because I have the credentials", people don't look much past that.

2. My previous post was not just aimed at you but at a larger group of people who need to hear the same thing. I'm not going to PM them individually, I don't have the time.

3. You have been posting a lot of anger. As with credentials, most people don't look much past the anger. The only people looking past the anger are the people who you are angry with. They look at what you've written and respond to both the content and the anger and then the mods wind up having to clean up threads of the bickering the ensues.
If you don't believe you are angry go back and look at your posting; you've used a lot of bold as if your were shouting and you've threatened to stop posting.

4. All we know here is what you write. If you write well, consistently get credible outside citations and can mostly not let differing opinions rile you up people will start to believe you a lot more and your reputation will start to carry some of your writing without outside citations. All we know is what your write.

5. I think you have a lot of expertise. I'm trying to help you to fit in because I think you can help people. You could be a boon to this forum. If I didn't think that I wouldn't have bothered, the frustration will drive you away before long, I've seen it plenty of times in the 7.5yr I've been on this forum.

6. The only thing we know is what you write.

Regards,
Adelie
Adelie,

Hope you will allow a final note,

Highlighting in writing never conveys Anger as per the Webster dictionary
Quote
If someone or something highlights a point or problem, they emphasize it or make you think about it. END QUOTE Thats what highlighting is used for:

ANGER when writing is when vulgar/rude/threats/comments are made,

So as for your comment "so much anger" is totally incorrect as per above Webster Dictionary reference, and that is what was going on with my writing's/High lighting which nearly all my posts contain and is as I have been taught when writing , Writing is a huge part of being a Surveyor and Highlighting is very common to make the point (Not in ANGER).I believe that is your own personal interpretation.For the record I'm not angry with any individuals with in this forum(now or ever!) I was replying to a post telling me what to do!! when writing future posts.

As for beating people over the head with credentials, mostly i dont, when i sign with credentials it's in a true effort to convey a point/ post when i see clear and present danger with prior postings in that thread only, either it be personal or financial,

So thank you all for this short period of allowing me to assist the boating community at large from a professionals view point and thank you to all for the private PM's.

Bottom line for mein this Forum was passing on correct relevant information, trying not to give miss-information/theories, from my 40 odd years in the marine trade

Cheers Steve.
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