Using stainless steel screws in wooden boats

[metin_mehel]

You can use stainless as long as it doesn't become wet.

On an epoxy wood boat all fasteners should be dry so it shouldnt be a problem.

Stainless steel Countersunk heads can be trouble if the hull skin is thin. If you feel that the head cant be permanently buried under a thick layer of epoxy , you should use bronze.

So if ss component completely covered by epoxy, there is not any problem?

 

[PAR]

Maybe I just haven't got the heads hot enough on S/S screws, partly because poor heat transfer of the material. I've certainly used heat to get a few metal items out of timber beddings before now.

Melt point of epoxy varies a lot from around 150 deg C through around 230 deg C (for West and SP epoxies) up to a little over 350 deg C. Wood chars at around the same point (225-230) as the West/SP epoxy melts though it should release a bit earlier.

Now why does this board not like it when I put in Alt248? - I thought that was Ascii, Ainsi and Unicode for degree symbol!.

Epoxy doesn't melt, but does deform and goes "plastic" starting at about 150 degrees. At 150 it loses about 50% of it's strength and starts to become soft. At 200 degrees, it's really starting to move under load, which is why the regular formulations don't pass the type 1 WBP test.

Rather then a soldering iron, which I find takes way too long, I use a torch on an extra long screw driver, heating until it's got a dull glow. I push the tip through any goo filling the slots or cross point and let it sit for a few seconds, then apply turning force. It'll release pretty quick with these temperatures.

Again, if the fastener or stainless element is "bonded" (entombed in epoxy), it will not cause trouble. This includes the head, which also must be well covered.

 

[alan white]

It's a good thing too, since stainless is a lot cheaper than titanium.

 

[SukiSolo]

Thanks Michael and PAR for sharing those tips for getting the screws out. I've just been putting a probably too low power soldering iron on the heads. Torch mode ought to work OK too, cheers.

I prefer to use slotted heads as opposed to Pozi's as it seems better for grip when you do want to remove a screw. Also had a lot of poor quality Pozis where the heads strip way to easily - cheap far eastern S/S?. I'll take the longer insertion time with the slots so at least I can get them out. Slot gasket strips are a case in point.

 

[Stumble]

I prefer squared drive, but anything is better than slotted, even Phillips.

 

[SukiSolo]

The Allen head bolts an CSK ones are fine but Philips and Pozi's (screws) have proven real nightmares to remove and still do. I rate removal of slotted ones at least 150% better even if only three years old. Still it has proven investment in S/S Ni tipped drills worthwhile....

Now why can you not get the hybrid type - Pozi/slotted in S/S?

 

[JSL]

From my experience the best common drive head (here in Canada) is the Robertson (square drive) - either the 4 point or the 8 point. A real plus is that if you ever have to use a screw extractor the pilot hole is easy to center.

 

[alan white]

The problem with slotted screws is that they are absolutely intolerant of a poorly matched screwdriver. Unlike Philips or torx or square drives, slots are not of any consistently measurable size. At least it sure seems that way after forty plus years of turning them.
However, a good complete (?) set of 20-30 screwdrivers should usually cover most sizes of slotted heads. The fit should be tight but to full depth. Some could have the tips beveled to allow for the full width of a flat head screw to be filled.
Unfortunately, modern efficiency constraints favor driver-driven fasteners, and slotted screws don't like to be driven by motors. So they have limited application these days.
So don't count out slotted screws unless you've fitted the right screwdriver to them.
You may find they drive pretty well after all.

 

[PAR]

I have to remove screws frequently, often knowing 50% of them will need to be extracted. I use the hot driver first, to see if the thing will budge, but I also have an extractor with me, knowing I'll have to drill them. Philips can be easily drilled, because of the cross point, while slotted, you have to carefully punch them before you can drill. As a last resort, I have some hollow bits I can use to cut the wood around the fastener. These make a big hole, but remove the fastener and surrounding wood in one shot.

 

[metin_mehel]

I love to use screws because the clamps are expensive. However it diminishes the strengrh of wooden components.

 

[PAR]

You must be using the wrong size screws . . .

 

[SukiSolo]

When removing old brass screws (usually with heads worn off!) if I can drill a slot that sometimes works. Otherwise I'll just lever the thing out with fitting and put in new cross grain plugs. Old brass keelbands are a favourite for this treatment

It is quite rare to see square head screws this side of the pond, but Allen (hex) and torx are common for bolts. Alan, you are quite correct a good range of drivers is needed for slotted screws but this seems to be more related to the age of the fastener and standards or lack of at time of manufacture. At least with the big ones a square shaft driver and long adjustable tends to shift'em.

 

[alan white]

When removing old brass screws (usually with heads worn off!) if I can drill a slot that sometimes works. Otherwise I'll just lever the thing out with fitting and put in new cross grain plugs. Old brass keelbands are a favourite for this treatment

It is quite rare to see square head screws this side of the pond, but Allen (hex) and torx are common for bolts. Alan, you are quite correct a good range of drivers is needed for slotted screws but this seems to be more related to the age of the fastener and standards or lack of at time of manufacture. At least with the big ones a square shaft driver and long adjustable tends to shift'em.

Slotted screwdrivers have a slight taper at the tip which causes the tip to back out when turned unless there's a lot of pressure behind the handle.
You're right that an adjustable wrench helps the screwdriver turn. With a helper, you can hit the screwdriver hard just as pressure is applied to turn.
A good device (mentally inventing here) would be a five pound buck with a pocket for the screwdriver handle end. You would hold the buck in place tight and rap the adjustable wrench handle quickly to turn the screw before the screwdriver shaft could have time to back the buck's mass out.

 

[PAR]

They make a hand held impact driver of sorts. You smack it with a hammer and it backs or drives whatever bit (or socket) you have on it. These work pretty good too.

 

[rwatson]

From my experience the best common drive head (here in Canada) is the Robertson (square drive) - either the 4 point or the 8 point. A real plus is that if you ever have to use a screw extractor the pilot hole is easy to center.

Dont forget, you can convert a phillips or square drive to slotted with a Dremel and a fine cutting wheel.

If you mess up that slot, cut at right angles again, right into the shank if needs be, to get more purchase.