I have just come back from a foil session and as I was dissembling the foil the bolts that hold the fuse to the mast were really difficult to undo. They were freshly greased and clean when I put it together and not overtightened.
The water was cold today. I am wondering if the metal of the mast contracted in the cold and gripped the thread of the bolts? I ended up rounding off the socket in one of them, now the F?@Ker is stuck in there and will need drilling out!!!!!!! 
If it's a hex head that you rounded out just hammer in a torx bit to get it out
no need for a drill
Heat up the mast with a paint peeling gun then spray penetrating oil.
The Torx hint is a good one too.
Select to expand quoteGwarn said..
If it's a hex head that you rounded out just hammer in a torx bit to get it out
no need for a drill
I have tried this with no luck so far. will have another go tomorrow.
Maybe a lesson learned for all of us. If those bolts were titanium, they may have spalled. Ti is famous for that. If you have a choice, always use stainless instead of Ti.
Select to expand quotesegler said..
Maybe a lesson learned for all of us. If those bolts were titanium, they may have spalled. Ti is famous for that. If you have a choice, always use stainless instead of Ti.
Yes, i think titanium is a strange choice for this purpose. They will all be replaced with stainless from now on.......
OMG, I wouldn't use Ti bolts for any of that. If it's a brass or stainless fitting, use stainless. Good luck!
I used to replace my foil hex screws every 50-80 sessions. I haven't needed to change any since I switched to Torx screws. I'm guessing I am up to 200 sessions on the current set of screws.
I could only get tamper proof screws with the central pin. That's turned out to be a good thing. I use a T-handle wrench with the hole for the pin and I suspect it helps to keep the wrench properly aligned on the screw.
I also went for Torx tamper proof on the foot strap screws. It's much easier to change screws around. I used to change the Phillips head screws every time I moved the straps. Now I can do any maintenance I like and not worry about screws.
I could only find 304 stainless Torx screws. I got lots of panic warnings from experts on the forums but it hasn't been a problem. I disassemble after each session and blow any excess salt water out of the holes.
My understanding is that corrosion is somewhat proportional to temperature and time. I foil almost every day in Melbourne so none of that is a problem.
Torx is really good for fin screws. I don't like Philips since the screwdriver too easily punches a hole in the board if it slips.
I have switched ALL my fin screws to outside hex head 1/4-20 stainless. I then use a fixed-size nut driver to turn them. Very safe. Very solid. No slipping.
Here in USA you can find a good selection of 1/4-20 lengths in stainless with outside hex heads. M6 holes can be nicely re-tapped to 1/4-20 and still give strong results. Sailworks has been doing this for years. I have never had one pull out.
Again, titanium is subject to spalling. Yes, you can mitigate that with grease and other alloys for the holes. But the easy solution is to just use stainless. Stainless works well with aluminum, steel, other stainless, even titanium inserts, and brass/bronze without any galvanic corrosion or spalling. Avoid titanium screws. You don't need the headaches.
But do NOT use 304 stainless. It is far too soft and rubbery. I used to run a metallurgy testing lab. 304 stainless acted like rubber in the tensile test machine. You don't want that with your gear.
There are many other stainlesses out there that are nice and strong. 316, 18-8, 17-4, and 15-5 come to mind. Several others.
Select to expand quotesegler said..
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There are many other stainlesses out there that are nice and strong. 316, 18-8, 17-4, and 15-5 come to mind. Several others.
I could only find Torx heads in 316 in a very limited range of sizes and head shapes. There's loads of 304 available, and loads of 316 hex.
Select to expand quotesegler said..
But do NOT use 304 stainless. It is far too soft and rubbery. I used to run a metallurgy testing lab. 304 stainless acted like rubber in the tensile test machine. You don't want that with your gear.
There are many other stainlesses out there that are nice and strong. 316, 18-8, 17-4, and 15-5 come to mind. Several others.
Hi Segler,
What do you mean with "304 stainless acted like rubber in the tensile test"? do you mean it would stretch more than 316 stainless?
The head snapped off one of my stainless screws that holds the front wing on. Miraculously I managed to drill it out and retap the thread. I now use Tefgel on all the screws. I just ordered the new Naish wing with a full set of titanium Torx screws. Robbie says in his video they are stronger and less likely to react with aluminium. I suppose I will find out soon.
Select to expand quoteGorgo said..
I also went for Torx tamper proof on the foot strap screws. It's much easier to change screws around. I used to change the Phillips head screws every time I moved the straps. Now I can do any maintenance I like and not worry about screws.
I like this idea, tightening phillips head footstrap screws is a PITA. I've stuffed my fair share of screw heads in the process.
Are you talking about a torx bolt (e.g. M5) used as a screw or a conventional screw, that tapers towards the tip?
Select to expand quoteremery said..
The head snapped off one of my stainless screws that holds the front wing on. Miraculously I managed to drill it out and retap the thread. I now use Tefgel on all the screws. I just ordered the new Naish wing with a full set of titanium Torx screws. Robbie says in his video they are stronger and less likely to react with aluminium. I suppose I will find out soon.
I purchased a Naish 1150 foil recently and it came with Stainless phillips head screws rather than Titanium torx screws - I was told they'd stopped providing titanium torx screws due to issues with them and had replaced them with stainless.
Select to expand quoteremery said..
... I just ordered the new Naish wing with a full set of titanium Torx screws. Robbie says in his video they are stronger and less likely to react with aluminium. I suppose I will find out soon.
Robbie says you can windfoil in 8 knots with a 5.4m surf sail and foil in 10 knots with a 4m wingding. I believe everything Robbie says. 
Select to expand quoteremery said..
The head snapped off one of my stainless screws that holds the front wing on. Miraculously I managed to drill it out and retap the thread. I now use Tefgel on all the screws. I just ordered the new Naish wing with a full set of titanium Torx screws. Robbie says in his video they are stronger and less likely to react with aluminium. I suppose I will find out soon.
Was the head that snapped off your stainless screw a Phillips head or a Torx?
I too dumped the philips screws and went with stainless hex bolts. Much easier to get things tight.
Yes, for the the tensile machine we made ASTM E-8 test bars for all the alloys we processed. The bar is 1/4 inch diameter, 1 inch long, with threads on both ends.
When tested we always measured the yield as well as the ultimate tensile. All per industry and government specs.
304 stretched about 50% to get to the yield point, then finally broke in ultimate. During the stretch you could actually see the big grains moving and shaping.
316 had a normal yield and much higher ultimate. Stronger stuff. The precipitation hardening stainlesses, 17-4 and 15-5, were stronger yet.
Titanium is plenty strong with a good strong yield and very strong ultimate, but it is subject to spalling.
Keep life simple. Use stainless for fin screws, but avoid 304.
Lots of good info on bolt metallurgy and Archimedian science experiments in here
www.seabreeze.com.au/forums/Windsurfing/Foiling/Slingshot-titanium-bolt-failure?page=2
I have A4-70 SS bolts from McMaster-Carr for fuselage to mast bolts now. I think A4-70 is 316, i.e. Has molybdenum.
Might change over footstrap screws to hex, as also think Philips head has PITA characteristics.
My local Tacoma Screw has good stainless steel footstrap screws with a pan head square drive. Why, after all? Well, my foil board footstrap inserts take single screws, not double. This makes it too easy for footstraps to twist. The inserts are the tough plastic ones that take sheet metal screw threads. With a square drive tool, I can really cinch those screw down tight to prevent twisting.
Can't do that very well with philips. Could also cinch tight with torx or inside hex or outside hex.
Pan heads are low and flat enough that your feet don't notice.
Select to expand quoteDavidJohn said..remery said..
The head snapped off one of my stainless screws that holds the front wing on. Miraculously I managed to drill it out and retap the thread. I now use Tefgel on all the screws. I just ordered the new Naish wing with a full set of titanium Torx screws. Robbie says in his video they are stronger and less likely to react with aluminium. I suppose I will find out soon.
Was the head that snapped off your stainless screw a Phillips head or a Torx?
Phillips. It just would come out. So I got serious with the battery drill and it snapped.
Well I drilled the Titanium bolt out today with no big drama. tomorrow I will replace all the hardware with stainless. what a pantomime ......
A recommendation to prevent future headaches: do NOT use a power drill for ANY windsurfing gear. That is a good way to crack tapered holes and run fin screws through the board. Over the years I have seen it happen.
If ya got enough muscle to do this sport in the first place, then ya got enough muscle to turn screws safely and controllably.
Select to expand quoteoscardog said..
Lots of good info on bolt metallurgy and Archimedian science experiments in here
www.seabreeze.com.au/forums/Windsurfing/Foiling/Slingshot-titanium-bolt-failure?page=2
I have A4-70 SS bolts from McMaster-Carr for fuselage to mast bolts now. I think A4-70 is 316, i.e. Has molybdenum.
Might change over footstrap screws to hex, as also think Philips head has PITA characteristics.
you have a link for those screws on McMaster-Carr? I couldn't find them
thanks in advance!
Stainless has a habit of picking up a thread if spun in or out to fast. ie: using powerscrewdrivers.
304, as stated is bad for any marine environment and bolts. I find it harder to find 304 bolts etc. than 316, as most industrial fabrication of stainless irregardless of the product being 304, 316, 309 etc. use 316 bolts and nuts.
if you have had issues with Allen head bolts rounding out etc. it is mostly to do with the tool not the bolts. Make sure the Allen key is right size and not worn. Many can be ground back to get to unworn section ( like drill sharpening)
Select to expand quotesunsetsailboards said..oscardog said..
Lots of good info on bolt metallurgy and Archimedian science experiments in here
www.seabreeze.com.au/forums/Windsurfing/Foiling/Slingshot-titanium-bolt-failure?page=2
I have A4-70 SS bolts from McMaster-Carr for fuselage to mast bolts now. I think A4-70 is 316, i.e. Has molybdenum.
Might change over footstrap screws to hex, as also think Philips head has PITA characteristics.
you have a link for those screws on McMaster-Carr? I couldn't find them
thanks in advance!
www.mcmaster.com/screws
Hi Segler,
For footstrap screws, unable to get plastic tapping blunt end sqare, hex or torx drive 316 SS screws on mcmaster.com
Tried on Tacoma screw, seems these are all sold out, just like toilet paper for COVID19.
www.tacomascrew.com/Products/Pan-Head/14-x-1-Pan-Head-Square-Drive-Tapping-Screws-T316-Stainless-Steel-100-PKG
Were these what you bought? If not, what size?
Mcmaster.com has M6 25 or 30mm 316 Hex socket head screws, 1mm thread vs 14 threads/inch. Think these would work?
Yes, those are what I bought at Tacoma Screw. However, I don't recall mine being 316. They might be 18-8 or some other strong stainless alloy. They are definitely NOT 304. I can't look now because I am 3,500 miles from home until the CV-19 has passed.
Any decent stainless alloy, except 304, will do the job. Mine have been working well.
You might be right about the 18-8. Since I am far from home, I can't look at the receipt from Tacoma. I do know that the screws I got from them have been working well.
Here in Florida I have been getting stainless screws and bolts from Ace Hardware. Even the myriad boat shops around here recommend Ace for stainless. A Honda marine outboard motor repair shop did not have a specific screw for a Honda 130 outboard. Ace had it.
