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Old 26-03-2015, 10:08   #16
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Re: How To Replace These Screws?

One suggestion I have read about is to try to cut a "slice" into the head of the screw with a dremel tool and then use that slot to back it out with a flat blade screwdriver.

Good luck.
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Old 26-03-2015, 10:08   #17
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Re: How To Replace These Screws?

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Originally Posted by atoll View Post
a big hammer,and just bang them through then replace with a bolt would be the quickest method!

however looks like you need to do some major surgery,using an" easy- out" will be very difficult .

if you can get behind the inner window frame I would suggest using small diameter hole cutter to cut away the fiberglass around the screw then remove the rested screw,fill hole with epoxy and redrill with new self tappers
This.

As noted the screws, if there are only four or six, were basically to hold the acrylic in place while the adhesive set. The windows aren't leaking, and the absence of the screws is not going to lead them to leak any sooner.

I would just fill the hole with life calk and be done with it, or if you want a nicer finished look, put plastic button covers on all the screw heads. If and when the port light starts leaking or it's time to replace the glazing, take out the rest of the screws (if the heads don't break off) and then the acrylic will come off fairly easily with a putty knife or similar tools to break the seal. Then you can get at the screws with vise grips.

Going through gymnastics to replace a screw that is not doing anything, at the risk of screwing up the glazing and/or fiberglass, does not make a lot of sense to me.
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Old 26-03-2015, 10:34   #18
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Re: How To Replace These Screws?

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Originally Posted by Hawkeye View Post
What has actually happened to the SS screws that were installed is the three metals that combine to make stainless steel, which I think are iron, chromium, and a third I forget (could be manganese?) anyway, over time the elements making up the molecules migrate back to elements (there are several theories why, all are 'iffy' and boring) and the iron then rusts away, leaving crystallized chromium. It is brittle difficult to get a drill bit started. However, just below that troublesome layer is plain, undamaged stainless, which will drill if you can hold the bit centered in the hole.

Failure to hold the drill perfectly will result in it running off and damaging, maybe ever cracking, the plastic. A bummer. Possible leak, and more problems. Do not go at this without preparing properly. More on that in a moment.

It is common for only a few of the screws to have gone south, while many others are fine. get at least one good screw out and replace it with quality screws and a good caulk, like Boatlife. Avoid straight silicone if you can.

Once you have completed all the ones you can and have only the rotted shanks left, you can prepare for them. Find a way to see if you can get at the screw tips from inside the boat, where a careful bit of work with a small pair of vice grips might simplify get the dead shanks out. If not, or, if only a few can be cured that way, and you still have to get at the others with a drill bit, you need to get clever.

You say the screws are in oversize holes, which is a blessing. Carefully clean out the hole between the dead shank and the plastic with a sharp scribe or dental pick and measure the hole diameter. go to the local auto parts store and see if the have some steel brake line that will fit into the hole. Once you find some, cut off an inch of it, deburr it, and press it into a drilled hole in a small block of wood so that about 1/16 of an inch of the tubing is poking through the bottom and the wooden block can sit flat on the plastic with the tube sticking down into the hole. Now you have a jig to prevent damaging the plastic.

Select the largest drill you can that will fit through the tub without binding and carefully, at slow drill speed, clean up the top of the broken screw. It will feel and sound 'crunchy' at first, then smooth out. Stop there.

You should have a clean divot, dead center in the dead shank, which will guide your smaller drill right where you want it. Complete this action on all the broken screws before going to the next step.

Now, stainless steel is tough to drill and gets hot fast, but with sharp, new buts and a little lube, and care, it drills just fine. Too big a drill will leave nothing in the hole but the threads, and that's no good. Too small a drill will either snap off, or not allow the easy-out (screw extractor) in far enough to get a grip. You have to examine the screws you were able to safely remove and select a drill size of exactly the right size.

When you begin drilling into the screws, go slow and keep pulling the drill back to clear the chips. It is possible during this that any old sealer holding the shank will heat up, break loose, and the screw may start sinking. Stop immediately. Have the easy out ready, and quickly try to withdraw the screw. If it sticks partway out, that may just be the old sealer cooling due to the heatsink effect of the easy out, but the extractor should still overpower it and get the screws out.

This all seems elaborate and tedious. but when you are done, without damage to the plastic or the boat, it will be well worth it, and you'll have a great tale to bore others with during sundown cocktails.
Most common grades of SS alloys contain primarily chromium and nickel but could also contain manganese, molybdenum, lead, aluminum, titanium or others.

I am not familiar with the metals in an alloy migrating back to elements. Maybe this is an issue of semantics or terminology but the metals used to form an alloy are not chemically reacted so the individual components would not migrate back to elemental form, they are always in elemental form.

The one exception I know is the chromium in a SS alloy reacts with free oxygen to form an oxide layer on the SS parts which is what gives the corrosion resisting properties. If SS sits in an oxygen depleted environment (like stagnant water) then the protective oxide layer is lost and the iron in the alloy will rust. This is commonly called crevice corrosion and is very likely what caused the problem with the OP's screws.

Regardless, the remaining screw shanks are so small I think the likelihood of drilling them out is very low no matter what method is tried.
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Old 26-03-2015, 11:00   #19
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Re: How To Replace These Screws?

Oh, perhaps I should have said, the method I described in the post above was not a hair-brained theory. I wrote it because I've done it. Any of you who think it can't be done, surely can't do it. I call you people 'customers', who call me to fix what they've screwed up.

Many of the other solutions are what we ignorant farm boys call 'scotch tape and bailing wire', and if that is the way you maintain your boat, you will find yourself revisiting those very same issues again and again. If something goes belly-up and you don't restore or improve it, you are going downhill. I've been offshore alone many times in my boat and have weathered some serious conditions. For those of you who putt around the harbor on sunny days and use the boat for hanging out on and socializing, then fine, easy cover-ups are fine for you. If you think this fix is a 'mountain out of a mole hill', just wait until you try the 'pull off the windscreen and start over' method. That is going backwards.

Oh, and 316 is significantly better than 303/304 alloys. It is closer to 18-8. The alloys found in hardware stores are considerably cheaper than those sold in West Marine and Jamestown Distributors. The Marine grade stainless does not make the the stains on the acrylic shown in the pictures. I've used both and learned the hard way, but never on anything important - dock boxes.

By the way, elements DO NOT remain elemental - once they are molecular their properties are altered. Spinach is rich in iron - try and pick it up with a magnet. Same with stainless steel. Why is 400 series magnetic and 300 series not? The problem with expounding great knowledge is people are watching. Your explanation of the reason 'iron rusts in stainless' is horse crap. A molecule of stainless does NOT rust - an atom of iron does. Rust is iron oxide, not crevice crap. The ways in which stainless molecules are 'cracked', releasing the bonded iron from the molecule so it can oxidize are thought to be electrolysis, work hardening, stress, and chemical. I have found 1 out of 5 bolts on both shroud chainplates of a pretty good Sloop, rusted to brown oatmeal, just like the screws above. Checking every other bolt on the rigging showed no others. New bolts slid right in, so they weren't under special stress. No bonding wires were attached. Perhaps a manufacturing problem? No answers. This problem is as full of abstract theories as the Great Bonding Debacle of the eighties. To bond or not to bond. Guess who's boat has never had a bit of bonding or electrolysis trouble for 30 years and counting? The one I built from scratch, that I am sitting on right now.
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Old 26-03-2015, 11:06   #20
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Re: How To Replace These Screws?

Quote:
Originally Posted by Stu Jackson View Post
One suggestion I have read about is to try to cut a "slice" into the head of the screw with a dremel tool and then use that slot to back it out with a flat blade screwdriver.

Good luck.
Yes. One of the few suggestions that has a reasonable chance of working with the small diameter screw shank that's remaining. I've had this work for me several times in the past.
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Old 26-03-2015, 11:09   #21
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Re: How To Replace These Screws?

Quote:
Originally Posted by Hawkeye View Post
....................
Oh, and 316 is significantly better than 303/304 alloys. It is closer to 18-8. The alloys found in hardware stores are considerably cheaper than those sold in West Marine and Jamestown Distributors. The Marine grade stainless does not make the the stains on the acrylic shown in the pictures. I've used both and learned the hard way, but never on anything important - dock boxes.
Just so you know.. 18-8 is a general designation for ALL 300 series Stainless steels.
"The term 18-8″ is often used to designate products made from 300 series stainless. This 18-8″ call out is referring to the 18% chromium/8% nickel alloy mixture of the steel. 18-8″ is not an actual specification, as it only refers to two different alloys in the steel. While all 300 series stainless steels share this 18/8 mix, slight differences in chemical composition between the different grades of the 300 series do make certain grades more resistant than others against particular types of corrosion."
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Old 26-03-2015, 11:13   #22
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Re: How To Replace These Screws?

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Originally Posted by Sonosailor View Post
My Fountaine Pajot Tobago 35 has wrap-around acrylic windows on the salon held on with a combination of black foam rubber, glue and some round-head screws. The screws go through some oversized pre-drilled holes and into the sandwich of the salon wall. Please see the pictures. The rubber and glue are continuing to keep the water out and the acrylic in place, but the screws appear to be rusting in the rubber and need to be replaced. I attempted to tighten or loosen one, and the head could have been picked off with my finger. How might I replace these screws?
What you are looking at is the remains of a tube-nut (sometimes also known as a "Sex Bolt"):





French boats typically use aluminum tube nuts that are prone to failure when the water seal around the tube (through the window and bedding) fails and allows water to seep through as yours obviously has. The good news is that once the inner head is gone, you can pop them out of the window/frame from the inside of the yacht with little more than a small center punch and a rubber mallet. The bad news is that replacements tend to be quite costly, in the range of $3.50 -$ 4.00, per nut (we have 90 of the little buggers in our windows). Contact the parts department for your builder for the correct size for your boat but they are typically M4x14 to M4x17 (metric of course). Clean the holes out "gingerly" so as not to enlarge them and coat the replacement tubes with silicon before inserting them. It is also wise to use something like TefGel on the threads of the screws from the interior to minimize corrosion.

Good luck...
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Old 26-03-2015, 11:20   #23
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Re: How To Replace These Screws?

Quote:
Originally Posted by Hawkeye View Post
Oh, perhaps I should have said, the method I described in the post above was not a hair-brained theory. I wrote it because I've done it. Any of you who think it can't be done, surely can't do it. I call you people 'customers', who call me to fix what they screwed up.

Many of the other solutions are what we call 'scotch tape and bailing wire', and if that is the way you maintain your boat, you will find yourself revisiting those very same issues again and again. If something goes belly-up and you don't restore or improve it, you are going downhill. I've been offshore alone many times in my boat and have weathered some serious conditions. For those of you who putt around the harbor on sunny days and use the boat for hanging out on and socializing, then fine, easy cover-ups are fine for you. If you think this fix is a 'mountain out of a mole hill', just wait until you try the 'pull off the windscreen and start over' method. That is going backwards.

Oh, and 316 is significantly better than 303/304 alloys. It is closer to 18-8. The alloys found in hardware stores are considerably cheaper than those sold in West Marine and Jamestown Distributors. The Marine grade stainless does not make the the stains on the acrylic shown in the pictures. I've used both and learned the hard way, but never on anything important - dock boxes.
First comment. Almost any grade of SS will rust if subject to crevice corrosion. This definitely includes 316 (and see Cheechako's comments on 300 series SS alloys). A quick read on crevice corrosion here. Crevice corrosion - Wikipedia, the free encyclopedia

In the case of the OP since there appears to be surface rust on the exposed head of the SS screw then there could be more than on problem. I still think crevice corrosion a likely cause of the corrosion on the shank under the head but difficult to tell without a closer examination.

As far as 316 being better, you would have to define the application. It is more corrosion resistant than 304 but, not certain but if I recall 304 is less brittle than 316.

Finally, not saying your technique will never work but drill out something as small as a screw shank it's going to be very difficult to keep the bit from wandering, even using a guide as you describe. And it will require reaming out the area around the screw which might allow removing the shank with pliers, a much simpler, easier process.

Oh and by the way, I've gotten plenty of low grade SS stuff from West Marine. Jamestown might be a different story but I generally go to them for bronze.
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Old 26-03-2015, 11:27   #24
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Re: How To Replace These Screws?

Create a pilot hole and drill them out.
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Old 26-03-2015, 11:30   #25
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Re: How To Replace These Screws?

Assuming they are in fact Sex bolts and after svHyLyte said that, I have convinced myself I can see the female portion of the bolt, then replacement is dead easy, you will in fact see another screw head inside of the boat, maybe under headliner or something possibly?
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Old 26-03-2015, 12:26   #26
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Re: How To Replace These Screws?

Some machinists will take a piece of bar stock and a cheap electric welder. Tack weld the bar onto the screw, use it as a handle and just spin it out. Then cut off the screw (with a grinder, whatever is fast & simple) and move on to the next one. There's a lot to be said for that, even if it means renting the welding gear for a day.


A manual impact hammer for about $30 is a good tool to try. You put in the closest matching screwdriver tip and whack the back end with a dead hammer or maul, which drives the bit deeper into what's left of the screw head while applying a rotating movement to it. That will encourage most screws to move, if any part of the head holds up. Using Kroil (mail order only) or PBlaster (sold at retail) are the best real options to help things get unstuck. They are not WD40 pacifiers.


Stu's mention of using the Dremel to cut in a good slot, and of course dressing up a screwdriver tip to match, is often enough. Especially if you use the impact hammer and PBlaster as well.(G)


EZ-Outs, for me, tend to break more often than work. There are different brands and types, but that's also not going to be a fast way to do many screws. Or cheap, if they keep breaking or dulling. If the screws are a soft metal, not stainless, it could be worth trying.


A lot just depends on what is handy and will not cause collateral damage. Tack welding a handle on may just be the fastest way to do them all, with no whacking required.
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Old 26-03-2015, 12:33   #27
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Re: How To Replace These Screws?

My solution, faced with a similar situation, was to remove the head from the screw (well, in my case it had already broken off), and then drill around the screw thread with this miniature hole cutter set :

Neiko 00823A Shank Heavy Duty Diamond Dust Hole Saw, 1/4-Inch, 5-Piece - - Amazon.com

Then you simply fill the resulting hole with epoxy, and drill for a new screw.
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Old 26-03-2015, 12:35   #28
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Re: How To Replace These Screws?

UnScrew-Ums - Broken Screw Extractors – T & L Tools Un Screw-ums advert in Good Old Boat

Have not tried these personally-but seem like the right idea for screws below #14 or 1/4",that would be near impossible to remove by center drilling & using any kind of easy out type tool.
This tool grabs the outside of the screw!!

I need to remove a # 12 SS WScr from a stanchion base.It is broke off just below top of SS plate.
I am going to try a roll pin, #10 equiv. internal size. I plan to heat one end of pin,expand it,(in a vise),let it cool & drive it on over the broken screw. Then use drill in reverse.


After that fails,I will buy an Unscrewum.
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Old 26-03-2015, 12:40   #29
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Re: How To Replace These Screws?

Cutting a slot with a Dremel will also have to cut into the acrylic. Not good. If you could ground the other end of the screw, it is possible to spot weld a rod to the screw by undercurrent poking it and immediately releasing the rod. Dangerous, and I wouldn't recommend it. Some things have no easy answer, no matter how hard you try to invent one. Some things are straight forward. THAT is the problem, how do you fix it. You can make believe that's the hard way, but if you want to do it right, and you don't have an EDM, that's the ONLY way. Oh, sorry, there is one more, but you won't like it.
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Old 26-03-2015, 13:16   #30
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Re: How To Replace These Screws?

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Originally Posted by a64pilot View Post
Assuming they are in fact Sex bolts and after svHyLyte said that, I have convinced myself I can see the female portion of the bolt, then replacement is dead easy, you will in fact see another screw head inside of the boat, maybe under headliner or something possibly?
I thought about sex bolts since some of my ports are installed with them but dismissed the idea. But I also looked a little closer at the second photo and looks like the remnants to me as well.

And yes I see a lot of them that are made of mild steel or mix aluminum female with steel or SS male parts, which could cause the corrosion.

So yes look on the inside of the boat to see if you find the other side of a sex bolt. All SS ones are really hard to find and expensive if you do.
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