stranded
Well-known member
Won’t be needing that, but thank you.
Cutting G70 chain
- Thread starter stranded
- Start date
vyv_cox
Well-known member
Hardness does not necessarily make metals more difficult to hacksaw. The most difficult hacksaw job I have ever encountered was with pure copper, just about the softest metal you will encounter. It was an extruded section for the coil of an electric holding furnace. The section was roughly 20 x 15 mm with a hole of about 8 mm for water cooling. Three people took it in turns to make a single cut, two of whom (not me) were big tough fitters. Extremely slow, tedious progress.
Mudisox
Well-known member
+1 for a cordless angle grinder. Easiest tool to cut shrouds etc or rigging screws in the event of mast calamity. I used it more often than I ever thought for lots of things. No mast falling though....................yet.
Neeves
Well-known member
There are a number of reasons to cut chain and many of them demand holding a link securely - who has a decent sized vice in their tool kit? You could hold the link in a mole wrench - but that then needs 2 people. Even with 2 people and an angle grinder (whether cordless or not) I'd be very wary of the injury you could inflict. Angle grinders are lethal, the metal 'sparks' can blind - its a nightmare in the making.
I'm sorry but the answer is a big bolt cropper, a concrete quay side, a towel wrapping the jaws of the bolt cropper and maybe a bit of wood to rest the whole lot on. When HT chain is cut it fails explosively, hence the towel, and at least one piece of the link becomes a sharp and dangerous piece of shrapnel.
If you mast has fallen down you will do all this on deck and will not be concerned about the niceties - but an angle grinder under conditions when you have lost a mast - parrot beaked bolt croppers are a safe answer.
I admit when I want a whole link I cut the links either side of my target in a big engineers vice, bolted to a concrete work bench and cut with an angle grinder, but I wear leather gloves and goggles - or I chop off the links either side with a bolt cropper on the concrete floor, the jaws wrapped in a towel. The energy released when you cut the link can be 'imagined' - the cut link is always hot - hence they fail explosively. The trouble with cutting with an angle grinder - you need to make 2 cuts. With an bolt cropper the jaws force the 2 sides of the cut apart - not so an angle grinder - you get a clean cut, link is still closed and you either need to make another cut or force the wire apart - and G100 is very difficult to bend.
My galvanising thickness meter is not sophisticated and the chains in which I am involved are coated to a 100 micron galvanised thickness (most chain is HDG to 70 microns but variable, the US Navy spec is 80 microns). I have to measure the thickness but I need to measure a flat surface. Links don't have flat surfaces. The answer has been to slice the links length ways - as you might slice a donut. This means cutting out one link, holding it in a vice with one crown sticking out the top, slicing half of the link and then turning the link upside down to slice in the other direction. The cut links, they are whole - but halved, are then wired down the length of the rode, maybe every 10m. The cut links are then measured for gal thickness. Labour intensive - but it works. Its easy for me to measure gal thickness on a flat surface, like an anchor, but not a tight curve, like a 6mm chain link. When I started I ground the cut surface flat, as in the photo, but now I don't bother
Gal thickness is important - it determines the life of the chain, more gal, more life. Gal is cheap, relatively - but the HDG spec is determined for engineering products, beams etc, that do not suffer abrasion as is found with the environment of an anchor chain. From the galvanisers point of view gal, or zinc, is expensive and if they go too thick - the gal is not robust and flakes. See Vyv's simple 'S' test for gal adhesion.
Jonathan
Rappey
Well-known member
Fein is a brand that makes powertools. Many fein owners call their multitool a fein, expecting you to know that they are reffering to a multitool rather than a jigsaw or circular saw ? (The poster did make it clear he was talking about a multi tool in this instance)
Similar with skill saw ? Some people seem to think a circular saw is called a skill saw even if its a makita. Skill is also a brand name making a range of powertools so a saw made by skill would be a skill saw but a makita saw would be a makita saw ?
Yes you can buy a metal cutting blade for your multitool but im not sure it would go through steel any better than a hacksaw.
stranded
Well-known member
I wouldn’t look further than a hacksaw for this job now - Bahco Sandflex 24tpi bi metal blade. I’ve had more trouble cutting through the skin of a ripe butternut squash.
Zing
Well-known member
I cut an 8mm chain recently with a cordless angle grinder and a 1mm blade. Maybe 7-8 secs per half link.
Rhylsailer99
Active member
I spent a few weeks scrubbing the decks with oxalic acid after sawing chain on deck, every time I went the boat there was thousands of red dots all over the top gelcoat.
Neeves
Well-known member
If you use an angle grinder to cut on deck the dust is red hot and embeds itself permanently in the gel coat - and becomes impossible to remove.
Angle grinders are good for cutting fibreglass, which is not an issue - you should not use an angle grinder to cut steel on deck - do it on shore. If you need to use an angle grinder to cut a shackle or chain - take it ashore. I appreciate taking the chain ashore, or some of it, is a bit of a faff - less of a faff than the rust marks you will get if you do it on deck
Jonathan
Rhylsailer99
Active member
I used a junior hacksaw not a grinder , the rust spots went away after a few rinses of oxalic acid.If you use an angle grinder to cut on deck the dust is red hot and embeds itself permanently in the gel coat - and becomes impossible to remove.
Angle grinders are good for cutting fibreglass, which is not an issue - you should not use an angle grinder to cut steel on deck - do it on shore. If you need to use an angle grinder to cut a shackle or chain - take it ashore. I appreciate taking the chain ashore, or some of it, is a bit of a faff - less of a faff than the rust marks you will get if you do it on deck
Jonathan
john_morris_uk
Well-known member
Or you can buy a Makita one for the same price?
Makita DGA452Z 18V Li-Ion LXT 4 1/2" Cordless Angle Grinder - Bare - Screwfix
Neither come with a battery I note so that and a charger will be extra. I gave up buying Bosch or other makes years ago and just buy what the builders/tradesmen buy. I’ve never regretted it (except when some scrotes broke into my workshop and nicked all my Makita tools!)
john_morris_uk
Well-known member
A hard lesson I learned years ago!If you use an angle grinder to cut on deck the dust is red hot and embeds itself permanently in the gel coat - and becomes impossible to remove.
Angle grinders are good for cutting fibreglass, which is not an issue - you should not use an angle grinder to cut steel on deck - do it on shore. If you need to use an angle grinder to cut a shackle or chain - take it ashore. I appreciate taking the chain ashore, or some of it, is a bit of a faff - less of a faff than the rust marks you will get if you do it on deck
Jonathan
alan_d
Well-known member
Years ago I had the sense to cut chain off the boat, but I was surprised by the little burn holes that appeared in the fleece I was wearing.
Neeves
Well-known member
That's why one should be wary of using an angle grinder to cut rigging if you lose the rig. (I don't know the trade term) but the fragments that come off an angle grinder are red hot - you should be wearing safety glasses. How many would remember safety glasses in the adrenalin fueled work of cutting a mast free in the likely conditions when a rig fails. Additionally an angle grinder can be difficult to use at the best of times - how many wield their angle grinder singled handed (with seas over the deck)? I agree a cord less angle grinder might make short work of cutting the rig free - but its fraught with new dangers (over and above losing the rig).
Jonathan