Angle Grinder Direction of Rotation

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wcndave

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When cutting steel bar for example, I have always had the disc rotating away from me and down, with the sparks going behind me.
I think this is how I always see others doing it too.

I recently found my 9" white label Axminster getting a bit heavy and my 115 Axminster a bit noisy and vibrating a lot, and so went for a Makita 125mm cordless brushless (what a difference!)

But in the manual it shows that the disc should be rotating the other way, and you cut from the back.
To my mind, this means any binding will throw the tool toward you, instead of away from you.

As someone who's not an expert on grinders, can someone out there who is clarify if this seems correct, or just a Makita specific thing, or in fact an error....

8rwPhgep_o.jpg
 

Sandyn

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Normally, I use my angle grinder the same way as you, so the angle grinder is rotated 180 degrees compared to the 'correct' picture above. I find that gives me the best control.
 

Sideways

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Likewise. I want the wheel trying to climb up the workpiece so that 'i'm pulling back on the tool not pushing it into the work. The diagram pictured is wrong to my mind and reduces control. If the wheel starts to bite, the tool will be pushed back towards you, the wheel will try to run down the front face and head for your leg !
Of course you have to pay attention to where the sparks are thrown and adjust the guard for the cut you're making. That's why guards with a tool less adjustment are so good.
 
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imageel

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I think whichever method you use depends on how comfortable you are and sometimes the size/material being cut.
To my mind pic#2 is safer, if the disc binds the force will be downward and worst case you lose grip on the grinder the safety switch will prevent serious carnage.
Also if the to-be-cut-off piece is longish then as you proceed with the cut it is more likely that the end will droop, opening up the cut face and hence minimising likelihood of pinching.

However I think those pictures are misleading in that I'd expect most debris and sparks in pic #2 to be ejected forward and downward and not all the way around the guard and out the back!
Obviously a lot will depend on how close to the guard you work, however for best visibility one would usually start a cut somewhere in the 70-80 degree arc relative to the forward guard edge, and closer to 90 degree or more invites the disc to dig in and not give good control.
 

owen

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I always use it like the picture, that's the way my dad taught me
 

--Tom--

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Worst case is disc shatters - I always try to think in terms of which way fires the fragments away from your limbs
 
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wcndave

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1651602383256.png

Just a note that in both cases above, the disc is spinning anti-clockwise. The direction of the blade at contact shown by the red arrow.

To my mind both are wrong, because the grinder is simply upside-down... Everything I've ever seen in person, or online, shows the cut being done with the disc spinning down onto the material.

1651603448541.png


I had a quick look online, just searching for images of angle grinders cutting, and 90% were with disc on left like the pic just above. However there were enough seemingly reputable pictures going the other way to make me think it's possibly a "real thing"

To my mind pic#2 is safer
With the disc spinning upwards and any binding throwing the tool at my legs, and knuckles at the bar, I don't think it looks that safe. If you think of the disc spinning the "normal" way, the angle of attack looks much safer - perhaps that's what you were looking at.
However I think those pictures are misleading in that I'd expect most debris and sparks in pic #2 to be ejected forward and downward and not all the way around the guard and out the back!
Testing like the picture game me about 50/50 front/back
however for best visibility one would usually start a cut somewhere in the 70-80 degree arc relative to the forward guard edge, and closer to 90 degree or more invites the disc to dig in and not give good control.
Yes, like the real picture above.
I always use it like the picture, that's the way my dad taught me
Which picture? In either case you're saying you were taught to use it with the disc on the right and the front edge of the disc moving in an upwards direction?
 

Dave Moore

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When cutting steel bar for example, I have always had the disc rotating away from me and down, with the sparks going behind me.
I think this is how I always see others doing it too.

I recently found my 9" white label Axminster getting a bit heavy and my 115 Axminster a bit noisy and vibrating a lot, and so went for a Makita 125mm cordless brushless (what a difference!)

But in the manual it shows that the disc should be rotating the other way, and you cut from the back.
To my mind, this means any binding will throw the tool toward you, instead of away from you.

As someone who's not an expert on grinders, can someone out there who is clarify if this seems correct, or just a Makita specific thing, or in fact an error....

8rwPhgep_o.jpg
Hi,
Looking at these pics they are both wrong. Been in the engineering construction for over 50 yrs and only ever seen a crack handed person use it this way. Even I don’t use it this way and I’m left handed. Turn the grinder over and put the handle in the other side so the wheel cuts down and you are cutting in front of you. I’ve literally cut hundreds of pipes and all my fellow pipe fitters will cut it this way as you have better control and you can cut to a line easier. If you have a good wraparound you can cut a pipe with a square cut more accurately than a bandsaw.
Regards,
Dave
 

Hpps

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You can get grinders that go the other way. Years ago when I worked for a tool hire company we decided to wind the sales rep up by pretending to have a customer looking for such a grinder. To our suprise they were easy to get hold of, the joke was on us 🙄🤣
 

wcndave

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Hi,
Looking at these pics they are both wrong. Been in the engineering construction for over 50 yrs and only ever seen a crack handed person use it this way. Even I don’t use it this way and I’m left handed. Turn the grinder over and put the handle in the other side so the wheel cuts down and you are cutting in front of you. I’ve literally cut hundreds of pipes and all my fellow pipe fitters will cut it this way as you have better control and you can cut to a line easier. If you have a good wraparound you can cut a pipe with a square cut more accurately than a bandsaw.
Regards,
Dave
Hello future me.. are you saying both the two images in the Makita picture look wrong to you? I think that's what I was saying, but why did they put this in there? Must be a reason!
Thanks. Dave Moore.
 

wcndave

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You can get grinders that go the other way. Years ago when I worked for a tool hire company we decided to wind the sales rep up by pretending to have a customer looking for such a grinder. To our suprise they were easy to get hold of, the joke was on us 🙄🤣
If you turn them over, they all go the other way... which was kind of my point, why is this grinder being held this way up in the pictures to start with....
 

Phill05

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If the locking nut is Right hand thread the disk should be on the Left or you risk the disk coming loose and cut down the front of the materiel forcing sparks to go down not at you.
 

HamsterJam

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I always have the disc on the right so my left arm holding the auxiliary handle is away from the spinny part.
I also stand slightly left so if a disc did shatter, the bits will be ejected away from me.
 

ChaiLatte

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If the locking nut is Right hand thread the disk should be on the Left

What about using the disk horizontal, with the nut downwards? And horizontal with it upwards? What hand should it be in those cases? And does it vary in the southern hemisphere?

The only thing that determines the hand of the thread is the direction of rotation.
 

Phill05

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Think of using a lathe if you wind the chuck on clockwise then turn on the power the chuck rotates Towards you and lock it'self on the shaft, but if you put the lathe in reverse going Away from you, you risk the chuck flying off and giving you a good slap in the face if your not a lucky person.
 

Doug71

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If you turn your grinder upside down the direction of rotation changes relative to the material you are cutting but it doesn't change relative to the tool so the nut isn't going to be coming loose.
 

Dave Moore

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Hello future me.. are you saying both the two images in the Makita picture look wrong to you? I think that's what I was saying, but why did they put this in there? Must be a reason!
Thanks. Dave Moore.
Yes both of the pictures are incorrect. If you start cutting halfway down and working up(obviously with the grinder reorientation, not by their drawings) you will control the grinder better and it won’t run away from you and the sparks will go down to the ground.
Regards,
Dave
 

Marcusthehat

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45 years of injury free use of a 4.5"/125mm angle grinder, I always have the top of the blade rotating away from me with the sparks generally attempting to set my groin on fire. What other way would one use a small grinder/cutting disc.
 

MikeJhn

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I learnt the hard way, cutting a screed with a 225mm diamond blade, slight twist and lots of kick, seventeen stitches later, luckily the blade was hot so it part cauterised the wound, not much blood, forgot to mention I was kneeling down at the time so it was my upper leg that has the nice 150mm scar, "familiarity breeds contempt" comes to mind.
 
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