Yellow eBay 5 tonne lug crimpers as emergency shroud cutters?

[Daydream believer]

No it's an offcut which can be used for another component

But it is effectively the swarf , which is the point I am making

 

[Daydream believer]

(you cannot shear brittle materials like brick and tiles)

Are you sure about that?

 

[Daydream believer]

There is some truth in the high lighted statement.

The issue is that with the mast up and the is some tension in the rigging that is true but once the mast has fallen some /most of the tension in the rigging will be quite slack and the rigging fittings movable.

When mine went over the side, it was pulling on the rigging & the fittings were quite taught. But each situation will be different. A boat rolling will probably result in a tugging moment

 

[rotrax]

You could look at it another way---The piece the guillotine cut off WAS the swarf. It was only one tooth in the blade, albeit a big one. It was just a big piece of swarf rather than lots of pieces.

Interesting comment about Sifbronze.The stuff I have is what i use for silver soldering/brazing & it does not melt the metal itself. It is a brazing flux. I have had it for many years. I just use small quants for copper model boilers. I tend to use more modern fluxes these days with lower temperature requirements. If one looks at posh bike frame the "weld" does seem to sit ON the metal rather than IN it as a stick weld does. So perhaps there is leaway in both sides of the debate.
But as I get more failures than successes my opinion is worth very little

I dont know exactly what you are using, or what heat source you are using.

You are right, the posh handmade bike frame may well have a lovely 'fillets' of Sifbronze joining the tubes. If, however, a fillet is made molten and subsequently removed, there is clear evidence of it adhereing chemicaly to the surface of the lightweight tubes. The rods can be covered in a special flux, can be cored with a special flux, can be used by heating the end of the filler rod and dipping into a powdered flux or, my prefered method, used by the Pro's, by using a 'Gasfluxer'. The Gasfluxer contains Methanol as a carrier and contains 10% borax in solution. The Acetylene gas passes through the solution and the flame burns with a green tinge.

This type of welding is a 'black art' more than a science as it is imperitive for the work to be bought to EXACTLY the correct tempreture for the Sifbronze to adhere correctly. Too cool, dry, weak joint, too hot, work becomes overheated and the Sifbronze enters the structure of the work, substantially weakening the tubes.

I can give you a lesson if you have the kit.........................................

 

[penberth3]

......"Origonal Sifbronze low tempreture rod for Brazing and Bronze Welding".

Despite this evidence he still insisted there was no such technique, coming back to the Scientific definition of welding.

So there's "bronze welding" and there's fusion welding, I don't have a problem with that terminology.

 

[penberth3]

......Yes it is a method of cutting mainly metals (you cannot shear brittle materials like brick and tiles)

You've never heard of reinforced concrete? Is all that steel to take the Shear Forces a waste of money?

 

[rogerthebodger]

You've never heard of reinforced concrete? Is all that steel to take the Shear Forces a waste of money?

The steel reinforcing is to help the concrete to resist tensile loads a you get in beams in bending.

When beams are supported at its ends and load vertically in the middle or along its length the top surface f the beam is in compression and the bottom of the beam is in tension.

concrete is good in compression but not good in tension. hence the inclusion of steel mainly in the lower section of the beam to resist the tensile stresses in the lower section of the beam

shear forces is mainly concerned in the end connections id the ends are fixed which will effect the bending moment of the beam and thus the stresses in the beam

I used to have a ferrocement boat and as the hull can be subject to forces in bh direction the steel armature is on both sides the concrete resists the compression nd the steel resists the tension, in a similar to the fibreglass an the resin in a GRP boat hull

 

[Daydream believer]

I dont know exactly what you are using, or what heat source you are using.

You are right, the posh handmade bike frame may well have a lovely 'fillets' of Sifbronze joining the tubes. If, however, a fillet is made molten and subsequently removed, there is clear evidence of it adhereing chemicaly to the surface of the lightweight tubes. The rods can be covered in a special flux, can be cored with a special flux, can be used by heating the end of the filler rod and dipping into a powdered flux or, my prefered method, used by the Pro's, by using a 'Gasfluxer'. The Gasfluxer contains Methanol as a carrier and contains 10% borax in solution. The Acetylene gas passes through the solution and the flame burns with a green tinge.

This type of welding is a 'black art' more than a science as it is imperitive for the work to be bought to EXACTLY the correct tempreture for the Sifbronze to adhere correctly. Too cool, dry, weak joint, too hot, work becomes overheated and the Sifbronze enters the structure of the work, substantially weakening the tubes.

I can give you a lesson if you have the kit.........................................

You are now adding a different process to the discussion. I would have to stick with the original. I was only making a comment, not asking to go into detailed alternatives to silver soldering techniques.

 

[Daydream believer]

You've never heard of reinforced concrete? Is all that steel to take the Shear Forces a waste of money?

Different situation altogether whereby 2 materials are combined to act in their own optimum to give greatest strength to a product.
We have already discussed shearing metal. So I do not think that there is any dispute about that part of the equation. As it is there to reduce shear in concrete, that would suggest that concrete will shear as well , Would it not?.

 

[Refueler]

IMHO - cutting away a mast / shrouds etc. - is more about saving the boat in a panic situation that just reducing damage ... and given such dire situation - how many are going to stay cool enough to get it done quickly and efficiently ??

 

[penberth3]

Different situation altogether whereby 2 materials are combined to act in their own optimum to give greatest strength to a product.
We have already discussed shearing metal. So I do not think that there is any dispute about that part of the equation. As it is there to reduce shear in concrete, that would suggest that concrete will shear as well , Would it not?.

Yes, that's exactly the point I was making to "roger the bodger" when he claimed brittle material didn't shear.

 

[wonkywinch]

After I had to cut an anchor free on a charter boat, I learned two three things. First was to add a 12" sturdy hacksaw with a 32tpi blade to the toolkit and secondly scrap any thought of ever buying a stainless steel anchor chain for my own boat.

Oh, and always allow for full fall in tide, not just your lunch stop. Saves looking at your watch while sawing away with a cheap junior hacksaw

 

[dancrane]

"...exceed the shear strength of the marital to be cut...

...My wife's garden loppers are a shearing action but her chainsaw is a cutting action."

Madame sounds alarmingly well prepared for cutting your maritals.

Sincere sympathies and best wishes.

 

[wonkywinch]

Madame sounds alarmingly well prepared for cutting your maritals.

Sincere sympathies and best wishes.

I declare rogerthebodger is really John Bobbitt

 

[rogerthebodger]

Madame sounds alarmingly well prepared for cutting your maritals.

Sincere sympathies and best wishes.

Far from it we have been happily married for over 50 years.

My pastime is Boats and Cars and SAMBO's is Gardening and Cooking for me

I have all the equipment I need to cut then materials I use

She knows the way to a man's heart is through his stomach

Please not all vital organs are still intact

It seems that posters think all cutting is shearing.

Shearing is just one of the methods of cutting using a shearing cut. Not all materials can be sheared .

Try using a shearing action on hard brittle materials


O so I misspelled Materials

 

[dancrane]

Trouble is that you have to make sure it is always charged up. Sod's law says it will not be when you need it.

DB, can this be an observation from the modern world?

How ill-organised would a skipper be, not to recharge a tool battery after use (and not to have several, or to leave all equally neglected)?

Cordless kit was once depressingly weedy with short battery life in use and in storage, but unless one defies advances in battery technology (is that even possible when the lowliest unbranded kit is Li-ion powered?), an 18v grinder must be an obvious answer to the OP's question, aside from argument for its own sake.

I like manual kit if it's a real alternative when power isn't available, but I wouldn't prepare for an improbable disaster by avoiding the obvious.

As has been mentioned in the past - cutting discs for angle grinders dissolve quickly in water. The blades disintegrate and unbalance the grinder.

Would anybody use fibre-based grinding discs in the wet?

For 20 years I used fibre-based grinder discs ashore, but they don't last long in any conditions - they even expire unused in a sealed box.

Metal discs (made of steel, and for cutting metal) are a revelation for durability and convenience.

You can even get a waterproof grinder for a measly £3,500. Underwater Angle Grinder Archives - Nemo Underwater Power Tools

Or spend £170 on a standard one, and cling-wrap the body and battery for £0.15.

 

[Martin_J]

Apologies for not answering the original post, but if you want to keep an 18v DeWalt battery charged on board, then it's not too onerous a task to place one of their in-car chargers next to the 'rig cutting' toolkit, cut the plug off and wire it up to the boat batteries.

They auto switch off once battery is charged so shouldn't be too much to worry about.

 

[Daydream believer]

You can even get a waterproof grinder for a measly £3,500. Underwater Angle Grinder Archives - Nemo Underwater Power Tools

Or spend £170 on a standard one, and cling-wrap the body and battery for £0.15.

Would one also block off the fan so that the unit overheated? Or would one think that through & let soggy shrink wrap get in the works?
But with my £3500 I did the alternative & renewed my rigging.That is a fairlygood starter for 10 (years)

 

[Daverw]

I think that the 4 seconds it would take to cut through with one hand only the motor would not overheat anyway, good battery grinders are designed to be used one handed and have brake stopped wheels, completely different beasts today

 

[boomerangben]

Far from it we have been happily married for over 50 years.

My pastime is Boats and Cars and SAMBO's is Gardening and Cooking for me

I have all the equipment I need to cut then materials I use

She knows the way to a man's heart is through his stomach

Please not all vital organs are still intact

It seems that posters think all cutting is shearing.

Shearing is just one of the methods of cutting using a shearing cut. Not all materials can be sheared .

Try using a shearing action on hard brittle materials


O so I misspelled Materials

I think there maybe a difference in the colloquial term shearing (as of sheep, garden hedges, scissors etc) and shearing within material science. I think of the cutting of material like this:

A saw blade (be it hack saw, chainsaw, disc etc) removes a piece of swarf. That tiny bit of metal was once attached at both ends and along its bottom. The saw tooth peeled that bit of swarf from the parent metal by acting as a shear on both ends and the bottom at the same time. The metal failed by being wrenched sideways away from its attachment faces in exactly the same way a shear wrenches the metal apart albeit it in a single plane. A drill works in the same way: it scraping each bit of swarf away by sliding it sideways away from the parent metal. Shearing failure is failure parallel to the face of the metal so any time you are sliding material away across its face, you are shearing it.

The other form of failure is axial, ie pulling away from the face, although metals generally still fail (at granular scale) due to shear when under tension.