Thread: 9" Angle grinders - Safety problems ?

If they are doing the same rpm as the smaller ones then they'd be nearly double the circumferential speed - 9" runs at 9/5 the speed of a 5".

They could cut twice as deep into you too!

I have had to use 9" grinders since I was 15 when I started my trade and have seen my share of mishaps from them, HOWEVER, when the accidents were analyzed, it nearly always came down to the way it was used: the guard removed or loose, being used for the wrong job, being used in an unstable environment etc. I have also seen a man who almost cut his hand off with a 4" grinder.
I have also had the opportunity to use a 7" grinder and as they are the same weight and the surface speed of the disc is roughly the same, I really can't see how they could be any less dangerous.

These are my experiences and opinions, they may not agree with others on the subject, so please don't take offence.

Rob

Originally Posted by FenceFurniture

If they are doing the same rpm as the smaller ones then they'd be nearly double the circumferential speed - 9" runs at 9/5 the speed of a 5".
They could cut twice as deep into you too!

They don't do the same RPM as the smaller ones but they do end up doing about the same linear speed.

Grinders of all sizes have considerable potential for injury especially in the DIY domain.
The following is extracted from this document http://www.monash.edu.au/miri/resear...zard/haz41.pdf which is a report of an extensive DIY injury survey done in Victoria in the 1990s.

There was no death recorded due to grinders during the period 4 year period 1992 to 1995 but there were 1179 injuries recorded during a 3 year period - from 1996 to 1998.

Injuries sustained while using a grinders represented 15% of all DIY injuries and are the most likely tool being used by an injured DIYer requiring medical attention, being about double the next most commonly used tool which is a welder.
In both cases the most common injury (78%) is the to the eyes while 7% are cuts or wounds.
Only 2.5% of injuries were due to loss of control by operator (slips, snag jump), 1.4% are due to wheel disintegration or wheel coming off grinder and a small fraction were from people setting themselves on fire.

Im terms of hospital admission following injury, grinders are the 4th most commonly used DIY tool, first is ladder, second is power saw, third is lawn mower!

Nowhere in the survey do they mention the size of the grinder and I'm sure they probably did not record the grinder size

In 89% of cases involving grinders no or incorrect PPE was being used - well say no more I reckon!

Back to 9" grinders, I don't think they are as dangerous as they are made out to be if you follow the instructions to the letter.

You know Bob, in many ways I'm kinda glad I had a very minor run-in with a table saw blade. I've always treated power tools with great respect, but now I treat them with extreme caution - and there are still warnings freely given out.

Originally Posted by steamingbill

When I was working I remember seeing several email alerts and various safety alerts advising people not to use 9" angle grinders unless they had undergone special training.

From the emails it seemed they have a terrible potential to injure the user.

Ordinary small angle grinders were not considered to be death machines in the same way as the 9" ones were.

I wasn't interested in tools at the time and they did not directly impact upon my job so I did not pay much attention - why do they have this horrible reputation ?

Bill

Hi Bill

4 inch grinders can be used one handed. Note I wrote "can be" -- one handed use is not recommended.

9 inch grinders can't -- they're too heavy and have too much torque -- if a person tries to use a 9 inch one handed, an injury is sure follow.

Originally Posted by FenceFurniture

You know Bob, in many ways I'm kinda glad I had a very minor run-in with a table saw blade. I've always treated power tools with great respect, but now I treat them with extreme caution - and there are still warnings freely given out.

May all your run-ins be minor ones Brett.

Originally Posted by ian

Hi Bill

4 inch grinders can be used one handed. Note I wrote "can be" -- one handed use is not recommended.

9 inch grinders can't -- they're too heavy and have too much torque -- if a person tries to use a 9 inch one handed, an injury is sure follow.

The Ryobi 9" angle grinder user manual has 4 A4 pages of safety instructions. i.e. this is WAY too long and my takes on this is the "Yobbo attention span summary" should be in less than one page. Sure, more detail can be provided but the guts of it has to be kept short and sweet.

Have a guess where the instruction to use two hands is located in those 4 pages and how many times this is mentioned.

For reference Eye injury/protection is mention 3 times.

BobL you have one of the problems with a lot of tools, the safety instructions and warnings are covered in pages of the manual. After reading the first few lines, I say bugger this, how do we assemble it and lets start using the new tool.
Yes the manufacturers must have the instructions but they must also be presented in a manner where they actually get read.

As with any tool, 9" angle grinders can be used safely, a risk assessment should be done before commencing the job and consideration of the position of the operators body and other persons considered. Appropriate PPE used.

Originally Posted by BobL

The Ryobi 9" angle grinder user manual has 4 A4 pages of safety instructions. i.e. this is WAY too long and my takes on this is the "Yobbo attention span summary" should be in less than one page. Sure, more detail can be provided but the guts of it has to be kept short and sweet.

Have a guess where the instruction to use two hands is located in those 4 pages and how many times this is mentioned.

For reference Eye injury/protection is mention 3 times.

Yep, the instructions pertinent to the particular tool should be upfront and bold. Perhaps things like "do not use for dental work" could be either omitted or buried as well as the real instructions are.

Nobody reads anything longer than a text message these days (usually while they are driving) . You only need the reading & comprehension skills of a gnat these days because your mobile phone will access the internet and anything you need to know can be found out if you REALLY want too - just as long as what you need to know, can be written on the back of a postage stamp in size 16 font.

So safety directions should be given, in the manual, for sure but it should have a "cliff notes version" you study before the exam so you just barely get a pass mark.

You don't need a 9 inch grinder anyway these days, they are obsolete, - there's a infra red laser phaser app for your mobile phone, that will cut that sucker like butter if you just set it to stun phase!.

I thought everyone already knew this stuff?

Originally Posted by Timless Timber

Nobody reads anything longer than a text message these days (usually while they are driving) . You only need the reading & comprehension skills of a gnat these days because your mobile phone will access the internet and anything you need to know can be found out if you REALLY want too - just as long as what you need to know, can be written on the back of a postage stamp in size 16 font.

This idea that "ready access to information" = "understand" is a big and on going problem for education that has been around for many years.

Back in the 70's at Uni and then later when I was a teacher I remember students that thought that there was no need to go to the classes or actually try to understand the material as long as they got copies of the the lecture/class notes from someone. Then if the student then filed these notes away and carried the file around for long enough the notes would mysteriously transform themselves into understanding in the students' heads.

Computers/phone/tablets are no different.

Ask these jokers to apply or use something they can read on-line and they are stuffed. In the areas I used to teach it is also not just a matter of reading the material as it is too complex to understand just by reading. The material has to be cogitated over, thought and talked about, written about in their own words (i.e. NOT copied) and played with from different directions and only them might some understanding develop.

The same applies to many safety instructions, why should you do this, why shouldn't you do that, what happens if you were to do it this way? etc.

Who wants to bet how long more it takes the nannies to ban or law, giant grinders for DIY use?!

I have two 4" (13k R.P.M.), one 5/6" (9k) and one 9" (5.6k) angle grinders. I started out using my dads' 9" grinder when I was a kid so I am comfortable with them. The smaller ones were new to me on their introduction.

I rate the 4 inchers as the most dangerous because the wheel speed is so high. They seem to be much more likely to catch on the material when cutting and because of the relatively small size of the tool body they are harder for me to hold onto because of less leverage. Disks, especially metal cutting 0.045" units fail much more readily. Flap disks wear out seemingly as soon as I turn the tool on.

I use the 5/6 inch unit the most. The more moderate wheel speed results in longer lasting wheels, especially the 0.045" cutting disks. The flap wheels last far longer as well.

The 9" unit gets the least use but only because the jobs I do don't often require it. However when the job is too big for the others it is safer for me to use because it does not need to be pushed to get the job done.

I always use PPE while using any of them. Safety glasses and gloves at a minimum and if there is more that just a little bit of work to be done I use a full face shield as well. For the bigger jobs I also wear a fire resistant leather apron and a welding jacket to prevent hot particles down the neck.

Finding accessories for the 9" grinder is more difficult, I suppose because they are not as widely used as the smaller but I have managed to track down a good set of disks, flap wheels, brushes and backing pads. I certainly hope that they do not go away.

Cheers,
Rob

Originally Posted by forp

Who wants to bet how long more it takes the nannies to ban or law, giant grinders for DIY use?!

I believe that they are banned in some workplaces but the figures are a worry, in 2008, nearly 25,000 people in the US were injured nationwide while using angle grinders.

Couple of interesting articles about grinder safety I found on-line

(warning this one is a bit gory)
http://www.safequarry.com/pdf/Abrasi...lIncidents.pdf

General causes of grinder accidents
http://www.nationalnewstoday.com/ind...break-kill.php

I did a bit of a search online for deaths involving angle grinders and the last one in Australia was not been caused by a problem with the grinder.
The most recent one was in Perth when a worked was cutting a drum that contained metho.
It was quite a few years ago but i remember that someone died cutting a metal tray containing electrical cables and they cut through a high voltage cable.