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316 SS machine screws - Passivated or not


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Throwing this out there to get some present day experience from the brain trust. 

I am re bedding an 80's vintage aluminum toe rail and need to purchase a bunch of flat head machine screws.  It looks like I can order standard 316 SS flat head machine screws or passivated 316 SS.  Is the incremental price increase for passivation worth it?  Salt water / ocean service.

Also - what drive do you like and why?  The originals were straight slot.  It looks like most common availability is phillips but I can also get hex drive.  Not planning on having the boat long enough to pull and re bed again but would like some insight to ease of installation and removal.  What are the cool kids using......  

Any other suggestions for toe rail?  Favorite bedding compound for aluminum / stainless, etc.

Thanks in advance for your help.

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19 minutes ago, yoyo said:

Throwing this out there to get some present day experience from the brain trust. 

I am re bedding an 80's vintage aluminum toe rail and need to purchase a bunch of flat head machine screws.  It looks like I can order standard 316 SS flat head machine screws or passivated 316 SS.  Is the incremental price increase for passivation worth it?  Salt water / ocean service.

Also - what drive do you like and why?  The originals were straight slot.  It looks like most common availability is phillips but I can also get hex drive.  Not planning on having the boat long enough to pull and re bed again but would like some insight to ease of installation and removal.  What are the cool kids using......  

Any other suggestions for toe rail?  Favorite bedding compound for aluminum / stainless, etc.

Thanks in advance for your help.

I am not a cool kid, but I have been upgrading my hardware from Phillips, to Roberts or Robertson drive (square). As long as you prevent epoxy or goo from getting into the screw head, it eases removal. I have twisted a drive-bit and had to replace it, but never fragged a screw head, so the Robertson screws seem to enjoy a longer service life. I like Bolt Depot for my hardware. 

That's all I have. Fresh water for me these days. Others WILL have opinions about bedding compound. 

Snubs

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1 hour ago, yoyo said:

Throwing this out there to get some present day experience from the brain trust. 

I am re bedding an 80's vintage aluminum toe rail and need to purchase a bunch of flat head machine screws.  It looks like I can order standard 316 SS flat head machine screws or passivated 316 SS.  Is the incremental price increase for passivation worth it?  Salt water / ocean service.

Also - what drive do you like and why?  The originals were straight slot.  It looks like most common availability is phillips but I can also get hex drive.  Not planning on having the boat long enough to pull and re bed again but would like some insight to ease of installation and removal.  What are the cool kids using......  

Any other suggestions for toe rail?  Favorite bedding compound for aluminum / stainless, etc.

Thanks in advance for your help.

Sikaflex for bedding  3m 4200 is another choice 

if your fitting accepts countersunk Allen heads ... use them

slotheads don’t like extrerior mountings 

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And always use a drill guide to keep fastener centered ,  perpendicular and to avoid eroding the anodizing

 

typically custom made by the  machinist in the yard  for each type track or toe rail

top photo is a drill guide for the last Genoa track I mounted 

It is simply an Old prop prop shaft cut and machined 

cost 75 $

 

second pic is an off the shelf drill guide 

handy for general purpose  but tedious if you must blow thru a few hundred  holes 

 

 

B037F605-F76E-4FB3-9762-E6C05D95120C.png

3A6C39E7-2B64-4E8B-8F8F-5DFE47A8610A.png

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I've seen the odd Robertson head s.s. machine screws but they are extremely rare. I'd go with the hex head too. I doubt the originals were "passivated". (Machining s.s. to form threads can make the surface more active. If you're really worried you can DIY  https://www.pemnet.com/design_info/plating-guidelines/passivation-of-stainless-steel/#:~:text=The passivation process involves submerging,to thirty minutes is typical.  But it will self-passivate to some degree as well. 

Good idea on sourcing long open time caulking. Pick a cool, dry day (polyurethanes cure by moisture in the air). Check the expiry date on the tube.

 

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Thanks for the info on passivation.  I doubt the old ones were passivated and I'm not sure they were even 316 but they appeared to be in relatively good shape.  Probably good quality stainless from days gone by.

Slow cure sealant makes sense.   It will definitely take some time to refit the rail one screw at a time while bending it into place.  I was amazed that when removed the aluminum rail straightened out after having been curved for almost 40yrs.

Any thoughts on polysulfide?  I remember hating that stuff in the past because of the mess.  But it has a long tack time and multi-day cure cycle.

 

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The trick is not getting any sealant on the threads as the screw is pushed thru.

No fan of the Phillips design. But they (or anything) are a better choice than slotted for a toerail: appearance and seal. Be sure to clock whichever you choose.

Passivating does make a difference. Quality hardware will be polished as well. Passivating is rather pointless if the surface is rough.

 

 

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Yeah, I like polysulphide for longevity. I think it actually has a longer life than most polyurethanes like Sika 291 / 5200 etc.

Polysulphide is very "stringy" so it pulls away in long strands as you use it; the trick is keep the caulking gun on the work; release the trigger and pause, then pull it away while wiping the tip a bit.  For this job I'd look into a powered caulking gun (rental) due to the amount of sealant you'll have to pump

 

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If you don't have ooze all around, odds are high you will have leaks later. This hard part is having just enuff to slightly extrude, but not waste a lot. Tape off edges, use putty plastic putty knife for first clean up, then alcohol & 1/2 sheets of paper towels. Have a large open top box close by - swipe a section ^& toss the paper.Have sealant around the shoulders of the fastener, a dry joint here will lead to corossion later.(look at old Swan toerails -every bolt head has a circle of crud around it). Dry bolt threads will result in leaky bolts later. Ever seen a rusty nut/washer underdeck? salt water wicking down the threads.

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1 hour ago, longy said:

If you don't have ooze all around, odds are high you will have leaks later. This hard part is having just enuff to slightly extrude, but not waste a lot. Tape off edges, use putty plastic putty knife for first clean up, then alcohol & 1/2 sheets of paper towels. Have a large open top box close by - swipe a section ^& toss the paper.Have sealant around the shoulders of the fastener, a dry joint here will lead to corossion later.(look at old Swan toerails -every bolt head has a circle of crud around it). Dry bolt threads will result in leaky bolts later. Ever seen a rusty nut/washer underdeck? salt water wicking down the threads.

Yes indeed 

Bog up both the male and female threads  ...bolt threads and hole  ...both .need to be bogged up or the joint will leak .  Water must be kept out of the counter sink or corrosion will form on the shoulders 

Caulk is cheap ... use plenty of caulk 

 

Take care on the boat interior by protecting delicate furniture from bog blowout 

masking off the joint can help contain the mess on deck 

have plenty of solvent ,paper towels  and disposable gloves handy 

All those caulking  bogs  are monstrous... the black stuff gets everywhere

when finished you might even go “ black face “

be alert on your walk home  or a riot may form 

 

 

 

 

 

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Thanks for the responses.  I like the Allen hex drive. 

I'm leaning towards polysulfide for the extended working and cure time. 

Thanks for the reminder on sealing the shoulder.  That should also add some limited separation/isolation between the aluminum and SS to reduce corrosion.  

Taping off the edges sounds like it should help a bunch with preliminary cleanup.

 

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1 hour ago, Alex W said:

Butyl has an infinite working time and much less mess...

Alex,

I thought about Butyl tape and have used it in other applications.  I do like it, especially the cleanup aspect. 

The problem I see is with this toe rail application.  The rail has to be slowly and forcefully bent into a curved position one bolt at a time.   The recommendations I have seen for butyl tape is to make a ring seal around the fasteners, push in straight and then tighten nuts without rotating the machine screw then retighten 2-3 times to fully compress the excess butyl.  I wont be able to insert each machine screw until I get the rail aligned with each hole. 

Is there a different method for Butyl tape or product you would suggest? 

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I would test what I'm proposing first.  The only toe-rail that I've rebedded personally wasn't aluminum and so it wasn't as hard (wood and plastic both curve pretty easily -- my toe rail was a combo).

If you counterbore the holes I think you can put a donut around the hole in the toe rail (very close to the hole but not touching).  When you push the toe rail into position you can now push the bolt through.  When you tighten it the counterbore will squeeze butyl up tight around the bolt's shaft.

 

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I thought about that method. 

I think that by the time I get one machine screw in place and tightened (just enough to maintain alignment) the rail will be pulled down so much that the donut will be smeared away from the next hole as it is bent into place.  I'm not confident that will maintain a good seal.   

With polysulfide I can envision putting some on the deck/under track, bend into position and then add more goop in the hole and on the bolt.   Its going to be a wonderful mess.  

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Buy a bag of these, they're perfect for initial cleanup to remove the bulk of the sealant. They're soft enough that they don't scratch the surface.

First stroke on edge against the toerail to separate the extra goo away from the joint, then flat on the deck to scoop away the goo. Keep the stick clean with paper towels and do a final wipe down with cotton rags and a little citrus solvent followed with water rinse.

For fastener clean up take a 1" chip brush and cut the bristles down to about 1" long, dab brush in some citrus cleaner and use it to scour around the fastener head, then wipe up thinned out sealant and rinse.

Screenshot_20200812-165309.thumb.png.81eaa51ca17d89ad544b439a81ce9d9b.png

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12 minutes ago, See Level said:

cotton rags and a little citrus solvent followed with water rinse

Does that citrus solvent cut through the polysulfide?  Never tried that before.

I have a bunch of those west stirring sticks.  Also have plastic putty knives and plastic razor blades.

Thanks for the suggestions.

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Yes it does, but try to keep it to a minimum and follow up with  wet rag to remove solvent film.

Also clean your machine screws with acetone prior to install to remove any machining oils that will eventually break the sealant bond.

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16 hours ago, yoyo said:

Alex,

I thought about Butyl tape and have used it in other applications.  I do like it, especially the cleanup aspect. 

The problem I see is with this toe rail application.  The rail has to be slowly and forcefully bent into a curved position one bolt at a time.   The recommendations I have seen for butyl tape is to make a ring seal around the fasteners, push in straight and then tighten nuts without rotating the machine screw then retighten 2-3 times to fully compress the excess butyl.  I wont be able to insert each machine screw until I get the rail aligned with each hole. 

Is there a different method for Butyl tape or product you would suggest? 

I've recently bedded my (timber) toerails using butyl sealant and wood screws. It worked fine. You can use butyl sealant with screws that rotate (I think Compass Marine has a section on this in his on-line article), it just seeps down the screw as you tighten it.

You need to develop a bit of technique to bend the toerail enough to get a couple of screws in at a time; it helps to have it prebent as much as possible (I dry-installed mine some time before doing the final installation.) As usual the butyl seeps out over the following few days so the screws need to be retightened. (I had to get them good and tight brefore putting the wooden bungs on!)

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On 8/11/2020 at 12:27 PM, snubber said:

Ten four. I was thinking of screws. The OP asked for machine screws. More coffee might help me. 

Having removed many different styles of stainless steel screws, the allen machine screws ALWAYS strip much easier that philips. Perhaps it is that stainless is much softer than regular steel, and more likely to deform. 

Bam Miller 

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4 hours ago, Fleetwood said:

You need to develop a bit of technique to bend the toerail enough to get a couple of screws in at a time; it helps to have it prebent as much as possible

I wish it would pre-bend.  When I removed it the dang thing went totally straight after having been curved since the 80's.  

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You might consider using shims to help with the install.  To install a long curved Genoa track, I cut thin shims and taped them at right angles to the track on the deck.  They were just thick enough so that I could lay the track on them and it would not touch the sealant.  I had a couple of long screwdrivers that fit through the holes in the deck and track.  As I flexed the track I kept it in place with the screwdrivers.  I would then insert the bolts in the track in that section and pull a shim or two and tighten the nuts.  I then pulled the screwdrivers and flexed the next section,etc.. The shims helped to cut down on the track touching the caulk and spreading it around while I worked sections of the track in place

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40 minutes ago, gkny said:

You might consider using shims to help with the install.  To install a long curved Genoa track, I cut thin shims and taped them at right angles to the track on the deck.  They were just thick enough so that I could lay the track on them and it would not touch the sealant.  I had a couple of long screwdrivers that fit through the holes in the deck and track.  As I flexed the track I kept it in place with the screwdrivers.  I would then insert the bolts in the track in that section and pull a shim or two and tighten the nuts.  I then pulled the screwdrivers and flexed the next section,etc.. The shims helped to cut down on the track touching the caulk and spreading it around while I worked sections of the track in place

I might be impossible to align  the old deck holes with the new track holes 

Plugging the old holes with epoxy bog then  shifting the new track clear of the old filled holes is very common 

the use of several tall studs , three inches tall  taped into the substrate are  commonly used as alignment pins     

Placement of the caulked track , using these alignment pins is s time , mess saver 

many workers ... perhaps   three or four are needed 

Dont use butyl rubber 

 

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1 minute ago, slug zitski said:

many workers ... perhaps   three or four are needed 

Confirms my thoughts - water, then beer and sandwiches, advil and cocktails, probably a gift card.

Thankfully its the same rail going back in so it should fit.  

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If you Are working outside be alert to temp

aluminum changes shape like crazy with temperature 

The main sheet track pictured took a full day to install

the  first attempt was at 0800 on a cold  winter day ... during the dry fit the holes would not align. Temperature too cold 

the track needed to be brought outside , wrapped in black plastic , then sun heated till Noon before it changed back to the original shape 

Be alert 

225602B2-5EE5-497F-9FB5-C871BE868379.jpeg

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1 hour ago, slug zitski said:

I might be impossible to align  the old deck holes with the new track holes 

Plugging the old holes with epoxy bog then  shifting the new track clear of the old filled holes is very common 

the use of several tall studs , three inches tall  taped into the substrate are  commonly used as alignment pins     

Placement of the caulked track , using these alignment pins is s time , mess saver 

many workers ... perhaps   three or four are needed 

Dont use butyl rubber 

 

Whether you use new or old holes (assuming original track), they need to be drilled before caulking.  I had epoxied and then redrilled the original holes and dry fit the track before I tried to caulk it. When I dry fit it, I masked the desk at the edges of the track.  I used the screwdrivers as levers and they allowed me to shift the track very small amounts in very specific locations to be able to line up the bolt that I was inserting.   Same idea as the studs but I found that I needed to tweak the adjustment in more than a couple of locations to get all of the bolts located in their holes. 

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43 minutes ago, slug zitski said:

If you Are working outside be alert to temp

aluminum changes shape like crazy with temperature 

The main sheet track pictured took a full day to install

the  first attempt was at 0800 on a cold  winter day ... during the dry fit the holes would not align. Temperature too cold 

the track needed to be brought outside , wrapped in black plastic , then sun heated till Noon before it changed back to the original shape 

Be alert 

225602B2-5EE5-497F-9FB5-C871BE868379.jpeg

Nice job and thanks for the heads up.  Its going to be a PITA.  I wanted to ignore it since it didn't appear to be leaking - but knowing my luck as soon as it went offshore it would start to leak.    

That's a beautiful work station that obviously took some serious planning.  The grab bars behind the winches look like a great idea.    

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1 minute ago, gkny said:

Whether you use new or old holes (assuming original track), they need to be drilled before caulking.  I had epoxied and then redrilled the original holes and dry fit the track before I tried to caulk it. When I dry fit it, I masked the desk at the edges of the track.  I used the screwdrivers as levers and they allowed me to shift the track very small amounts in very specific locations to be able to line up the bolt that I was inserting.   Same idea as the studs but I found that I needed to tweak the adjustment in more than a couple of locations to get all of the bolts located in their holes. 

I ran a drill followed by a small diameter stainless rotary wire brush to clean out old sealant.  The holes cleaned up nice. 

After the suggestions I am going to make sure I have multiple screwdrivers of the correct size to use just like iron worker spud wrenches.

I'm keeping fingers crossed that very few holes will need adjustment. 

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