Ebb, you were able to edit a long post (#391) at 6:41 AM today?? I just edited your 7:37 AM long post (#392) with none of the problems you describe. Maybe the problem is with your computer or LAN?
Ebb, you were able to edit a long post (#391) at 6:41 AM today?? I just edited your 7:37 AM long post (#392) with none of the problems you describe. Maybe the problem is with your computer or LAN?
CABIN WINDOWS
Approached the decision of 'slabbing-on' polycarbonate windows rather piecemeal. Only now, after the four lenses are installed, is there a whole picture - and how it might have been done better and less awkward.
The pan head machine screws bother me - now that the job is done.
The 316 PHMS come from McMasterCarr. Precisely made. Big heads flat rounded. Rim around the bottom of the head is also rounded slightly. That makes them stand out like military buttons, even directly on the rubber washers. They look like they are adrift from the work & not snugged up properly. When focused on other projects around the boat these 'proud' fastenings seem to grab the eye... Annoying.
Know same RHMS size with phillips eyes are smaller in diameter and completely flat on the bearing surface. Even if they are a bit taller than the pans, they'd appear tidy - their smaller cross holes less significant than the pan's extra large. Less head diameter dictates metal washers added on top of the 5/8" rubber ones - imco they are needed anyway under turning screws to protect soft rubber from deforming. The effect would be compact, integrated and correct. Ahdono about professional - shuda done it the first time.
THUS & SO
This IS about aesthetics: Too expensive now, but 1/4" 316 HEXHEAD capscrews for the lenses would have been pretty nice. We think of hex heads as a meat and potato fastener, but when you open the white boxes from McMCarr they bling like metalic crystals. And about as pricey! Each set, nut-washer-screw, perfectly matched. The heads, especially nice, are half the height of the PHMS, much classier and have no EYES. The dodger should have been installed with these too. Faceted heads in small sizes are much less busy than cross-eyed attention grabbers.
MAST
More practical: After the experience removing #8-20 RH phillips sheet metal screws from the mast track - spinning power bits round in defiant heads with the cordless hammmerdrill ..... making it necessary to grind them off and drill them out.... came upon the great notion... that the screws being trashed were not only softer metal than the bits but also not a smart design for turning.
Potted LED blinks on in cortex: what's the point of driving one hundred hole-in-head screwpins back into the track again, when some day, for sure, they'll ruin another fool's day?
Got a better idea? S u r e .
#8-32 316 HEX machine screws. (1/4" W head, less than 1/8" H) Perfect fit in the channel of the old 7/8" s.s. T track. Including the driver socket.
Not only will they look better but use a common driver that's designed for metal work and comes in choices. Why do we insist on using a POINTY bit to remove these dreaded embedded agitators when a nut driver or wrench or socket will do a much better job with a SIX POINT HEADLOCK!
And rather than appearing SO yachtsy fartsy with knobbly jewelry, suppose we use practical hexheads wherever we can.
Saw photos on the net of a gooseneck mast plate up-grade newly mounted with cap screws. Way more macho than cross-eyed roundheads.
Goodlooking 316 1/4-28 capscrews! Come as short as 3/8". Standard head: 7/16"Wide but only 5/32"Height.
With the price of anything 316, slim hexhead capscrews will have the same practical look as jeans by RobertoCavalli.
[EDIT - correction]
The full range of STAINLESS 316 HEX HEAD CAP SCREWS is available with narrow(fine) thread: 1/4-28 - 5/16-24 - 3/8-24 - 7/16-20 -5/8-18 - 3/4-16 - McMasterCarr pgs 3145-3146. They come fully threaded and partial threaded. Partial means that the threads are stopped and a certain number of inches on the shank are not threaded.
MAST THRU-BOLTS
Imco Correct length for the 1/2" bolts for sheave and spreaders/shroud tangs makes sure that unthreaded shank rests in BOTH holes in the mast. No fine thread partials come long enough. (mast is 3 1/2" wide, OD - adding washers, plastic spacers, tangs figure 1/2" more plain = 4") Have to use 6 1/2 - 7" partial thread standard bolts, which have long enough unthreaded shanks for this app.
The shank must bear clean and threadless on the 1/8" aluminum wall in the holes on BOTH sides. That's the trick.
A HSS die will cut more thread if needed to enable torqueing the nut (when all the washers and tangs are on the bolt) to close the assembly WITHOUT SQUEEZING THE MAST WALL. Looking to wrench the nut TIGHT against the end of the thread - yet leave all hangers with a skoch wiggle room. (currently hexhead 1/2" 316-13 partials from McMCarr: nom 7" have 3 7/8" untreaded shank)
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A bit on our ALUMINUM CORROSION. Please correct me where I'm wrong ! ! !
It's an assumption that fine thread hexheads of any size will be easier than fine thread slot or philips to back out. Don't know a soul who's using hexheads in hisorher mast track. And the next scheduled track removal maintenance for A-338 is around year 2057.
Another law of unpainted, anodize-long-gone, 45 year old mast disassembly.... is that the finer the thread the LESS corrosion is found in the aluminum, the more easy to loosen and remove.
The wide thread #8-20 sheetmetal screws Pearson used in the mast track installation created white powder and crevis corrosion* in every one of the hundred-plus holes. The track was literally 'poultice' welded to the mast - while the old s.s. screws that did move came out with sharp threads, there was no significant thread remaining in any aluminum hole. Imco the track was ready to fly off the mast.
My experience suggests that if you are the first fool to restore your mast, TAKE IT ALL OFF - INCLUDING THE TRACK!
Finer thread means less molecular-space for sea water to stagnate. BUT even a perfect threaded 316 screw in a perfect tapped aluminum hole will have spaces in the corners of the thread that need filling. Lanocoat (anhydrous lanolin) is a traditional waterproofing for threaded fasteners.
*this crevis corrosion (sometimes talked about as 'gasket' corrosion) is a lesser evil of the SAME vigorous oxygen deprived corrosion we find bubbling under painted aluminum spars.
Believe it's been shown that the real nasty can occur whether the mast is painted, anodized or conversion coated - whether the protection has been breached deliberately or by accident. The breach when moist creates an immediate anodic condition in relation to the coating which becomes cathodic. And a measurable voltage 'charge' is born that causes exchanges of electrons and there's your corrosion! Molecular moisture will stagnate, get sour, and the pH separates producing an acid/base reaction that will change Na and Cl into a more corrosive solution. Double whammy!! Visual evidence depends on unique potentials in the package of chemicals on the mast, so it's not predictable - but can possibly be horrendous. Use a barrier grease on anything deliberately piercing the mast - including pop-rivets. (S.S. pop rivets must be 100% stainless, otherwise you have to punch out the steel mandrel which then weakens the fastening.) Using aluminum pop rivets is dangerous for the same reason AND they are 1/4 the strength of s.s. Favor tapped in fine thread screws.
TEFGEL has the rep for being the most dependable corrosion block for dissimilar metals. 40% PTFE. No silicones, no petro solvents. Apply to BOTH surfaces leaving no voids for water to capillary into fastenings and bedding surfaces. Does not increase resistance used on electrical contacts. Prevents galling of s.s. screw threads driven into s.s matrix. Won't 'cold' flow like lanocote. Use on O-rings, ball & sleeve bearings as a lasting lube.
Get a 2 or 4OZ jar. You'll be using it! Cleanup with mineral spirits.
*CREVICE CORROSION, as a result, refers not only to the valley made by an accidental scratch in coated Al - and also to each fastening crater hole - but also refers to the crevis produced by two pieces of metal bearing cheek-by-jowl together. Plastic film or sheet rubber as an insulator is not enough imco, we must keep water out of the interface. Tefgel doesn't oxidize, never sets, always sticky.
[My argument against using tube synthetic rubber like polysufide under fittings applied to the mast (OR stanchion bases) is that while the material sets up and gets flexible... it's no longer sticky. Therefore if the bond fails (which happens often enough) a crevis situation is born and water is DRAWN in. However, if the rubber is a type like butyl tape: never sets, never gets hard, then water has a better chance of staying out. Will use 20milSPVC pipe wrap AND butyl (or Tefgel for tight fits) as a extra assurance barrier for metal-to-metal or non-metal fittings.]
MINI NYLON BRISTLE BRUSHES (set of five, 1/16" to 3/16", 4" long, ring mounted, $3.95 - from www.micromark.com) * will get TefGel INto the threads IN screw & bolt holes....INsuring that no hidden space is left for water to electrolyte and waste our ancient and elegant masts.
Imco, shipping prices are getting so outrageous that catalogers will put themslves out of business. Local hobby, train, toy shops, gun stores, auto paint stores for these brushes. Blisterpak brand is Hawk or KingSun. Tiniest brush will get compound into the threads of the tiniest screw hole. These are miniature bottle brushes. *(Try www.utopiatools.com/Mini-Brush-Set-Nylon-Bristle)
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Find the Tech thread 'Mast issues and renovation' for current activity on the stick.
Last edited by ebb; 10-10-2013 at 09:49 AM.
Hello Ebb. Long time no post :-) Hope all is well in your world. Can we have an update?
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