I know grit disks have a limited life but is there a significant risk with old diamond disks?
My 9" one has loads of diamonds left on it. It has never been abused (I'm too wimpish to even think of it) or used wet. And I can't think why age alone should matter with metal. But as I approached the paving blocks I realised the cutting disc was 10 years old so an excess of caution made me pause and ask. (Well, that and an excuse to put it off in this weather.)
I've not heard of grit disks having a 'shelf life' but I can imagine their 'aging' with use, due to vibration etc.
As for diamond disks, doesn't it depend on the construction?
Certainly, erring on the side of caution is wise, I've see an bench grinder wheel shatter for no, obvious, reason. It could have be 'messy'. Fortunately, it wasn't. (Other than the broken bits.)
Worst that could happen is the diamond grit fall off. Unlike a fabric type that might shatter.
+1, can't see any risk if you are wearing gloves and eye protection.
Presumably this is a metal disk?
Look at the use-by date which should be somewhere around the mounting hole. The dates are very conservative (3 years from manufacture generally). It isnt all metal, there will be some time of adhesive holding the diamonds in place.(though some are pressed into place). The danger is a piece flying off and hitting you in the eye. Wear the correct goggles, not glasses.
AIUI moisture, freezing and impacts can be problems for abrasive disks that consist mostly of grit and glue. Those shouldn't pose a problem for a mostly metal disk (other than affecting the adhesive that bonds the grit, and I think they're usually brazed not glued anyway). Suitable PPE should of course be used, I'd suggest a helmet and visor rather than (or in addition to) goggles when using any large-diameter fast-spinning thing that could throw chunks at you.
A metal disc should be fine. The better ones have the diamond fragments embedded in the metal of the rim, rather than just being stuck to the surface. So it should not wear any quicker.
Thanks for that and to all the others for their comments. I omitted to mention that it's a segmented disc so I was unsure if more than just dust might come flying off at - if me sums are right(ish) - up to 300 mph. Anyhow, I'll add helmet and visor to the usual google and gloves and see how far I get before I melt.
I helps to remember that any disc can fly to bits, and to plan accordingly. While the discs may not fly to bits all that often, this planning will also help avoid permanently embedding bits of glowing metal in nearby glass and tiles, or setting fire to anything. Not likely in cutting blocks -- but the amount of dust can be impressive!
One can practice with thin Dremel cutoff wheels, which fragment easily at the slightest provocation and come without a guard.
Thomas Prufer
Protect ones face and hands etc. I too have seen discs go, but its often as likely with new as with old and if the design of the grinder is right most bits that fly off should not be going toward you. Myself, I never use one any more for obvious reasons! Bloody noisy as well even either ear defenders. Brian
Diamond coated discs are a very different contruction. Basically a steel wheel with embedded diamond powder. So far less likely to implode than a fabric type.
grit discs yes, but rather hard for a steel disc to fly apart. I suspect you'd need to spin it up to 50k rpm for that to happen, or hit it with a hammer as it spins.
NT
I thought it was only the flexible angle grinder discs that had a shelf life because the resin deteriorated, the sintered bench grinder type do not suffer from this and steel diamond ones don't either.
Under the abrasive wheel regs the use by date should be stamped on the hole reinforcing if required
AJH
I can imagine a segment of a segmented diamond disc flying off, and the whole disc becoming unbalanced, the grinder vibrating wildy, and mayhem ensuing...
There's a scale: One end is using the grinder freehand without a guard, wearing synthetic shorts, no shirt (but a tie), flip-flops, and your dreadlocks falling into the cut line, all the while standing knee-deep in solvent-soaked rags releasing flammable and intoxicating fumes. The other end is wearing full plate armor with a jousting helmet, a diving mask, angle grinder bolted in a stand, guard, new disc, and have an ambulance standing by...
There is a range somewhere in the middle where I'd feel comfortable:-) I'd use the old disc -- but be wary of where bits could fly.
Also, you can always get a block splitter, and avoid all the above, and the dust. (Won't work for everything, though.)
Apropos of mayhem: I'll take the opportunity to post this H&S video on forklifts. It's in German, nevermind, just watch. (Warning: graphic detail!).
Thomas Prufer
Yes thanks. I'd found that there was a requirement for AFAICS all _bonded_ discs to have a limited life. (As Alan indicated, max 3 years from manufacture). I didn't know what to make of my failure to find a requirement for non-bonded discs: one of the many things I don't trust is my search ability.
Hmm. I don't think any of my grit discs are that young.
NT
Block splitters cost money - and are heavy. Hire's not cheap at the snail's pace I work. And I am really just playing, having picked up c.700 Priora blocks for £60 (plus a couple of sweaty days ferrying them in a Focus through London traffic over umpteen traffic calming measures).
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