Thread: What size grinder?

That was the big selling point of 115mm grinders when they entered the scene, the use of worn 9" discs. It works with 5" too.
I don't know if 6" was a european thing, but you used to see a few of them about, not so much anymore.
If you wanted fast metal removal, you would have killed for one of the Hilti grinders supplied some years ago. A manufacturing/assembly glitch led to a batch of 9" grinders with 7" gearboxes. Believe me, a 9" grinding disc at 133% speed, (8800RPM ), removes some serious metal.
Hilti were spoilsports though and recalled them all before someone got hurt.
As an aside, for those interested Metabo makes a variable speed 5" grinder. This is aimed at the stainless industry I believe. Top speed is only 7000RPM though so it will be a bit harder on wheels and slower to grind with. Could be useful if you were doing a lot of blending and surface finishing with flap discs and velcro pads though.

Originally Posted by Oldneweng

Depends on the individual. For me it is mainly drills and torches but I have been having a look at angle grinders again lately.

My 5 inch end handled angle grinder has a soft start and automatic overload protection. I would not get a grinder with either these features again. Slow start is an easy way to get really bored waiting for the silly thing to get going, and waste a lot of time. I guess I do lots of small cuts. The auto overload protection means that when the grinder needs that extra bit of power it stops driving and you have to ease off the pressure and wait for, yep the silly thing to get going again.

I have burnt out the motor on 2 angle grinders. One took about a week and the other took many many years.

Something I just realised. A guard on an angle grinder makes it very hard to remove the wheel without a tool.

Dean

Soft start may be less important on a 4" but anything bigger is a good feature. You get used to it. You can wait half a second fro the speed to get up, yet you can do some serious damage with the kick from a 5" a 7" or a 9" if you are not focused.
As for taking the guard off ... well ... I have seen the hand of my friend after he cut down a pencil tree with a 4" grinder, guard off and a circular saw in stead of a grinding wheel. Saw got caught in some little branches and kicked back into his hand ... you picture it.

Originally Posted by Marc

Soft start may be less important on a 4" but anything bigger is a good feature. You get used to it. You can wait half a second fro the speed to get up, yet you can do some serious damage with the kick from a 5" a 7" or a 9" if you are not focused.
As for taking the guard off ... well ... I have seen the hand of my friend after he cut down a pencil tree with a 4" grinder, guard off and a circular saw in stead of a grinding wheel. Saw got caught in some little branches and kicked back into his hand ... you picture it.

Half a second wait for soft start. You have a different one to me. From memory it takes a lot longer than that. That what you get from buying a cheapie.

I am planning on building a stand to safely position the grinder when I have finished a cut, while it is still spinning. Not because I am impatient for it to stop but because I am impatient to set up the next cut while it is stopping and then probably grab it before it comes to rest for the next cut.

yet you can do some serious damage with the kick from a 5" a 7" or a 9" if you are not focused.

I can understand that. What I cannot understand is how someone could start an angle grinder while not focused. Seems to me the problem may be an operator error not a tool error.

As for taking the guard off ... well ... I have seen the hand of my friend after he cut down a pencil tree with a 4" grinder, guard off and a circular saw in stead of a grinding wheel. Saw got caught in some little branches and kicked back into his hand ... you picture it.

This has nothing to do with not having a guard on the tool. This is a completely different matter altogether but I am going to be polite and not voice my opinion.

Dean

Originally Posted by Oldneweng

This has nothing to do with not having a guard on the tool. This is a completely different matter altogether but I am going to be polite and not voice my opinion.

I will partially agree. Any toothed wheel on a grinder is a pet hate of mine, technically illegal in my humble opinion, despite the fact that such wheels are still sold.
However, guards on grinders should be left on. 1mm cutting discs cut nearly as well as a circular saw where flesh is concerned. If the whole of the fabrication industry uses grinders with guards, as mandated by law, (I would really love to see anyone justify removing a guard to a workplace inspector in an investigation), then why do the weekend warriors think that the rules do not apply to them? If a grinder with a guard will not fit or do the job, then the simple answer is, you are using the wrong tool.
I do not wish to offend, but for goodness sake, would any of us accept house wiring with exposed live wires, or smoke while refuelling our car? I certainly hope not, but there seems to be a willingness to remove or disable a safety device, (highly illegal and carrying large fines). Any one here with any experience conducting risk assessments? I would be surprised if you could get an unguarded grinder to come in under a high risk rating, no matter what risk matrix you used.
Just as a little side issue, consider this. You get a mate in to help you with a project and they pick up your unguarded grinder. It kicks back and they suffer an injury. Remembering Murphy's Law, that injury is not a simple nick or graze. No, your mate just copped a 1mm disc to the finger, severed a tendon and suffered nerve damage, which of course has ruined their career as a guitarist.
Enter any one of a number of no win no fee law firms and potentially a workplace regulator investigation. At best, you are looking at negligence, but quite possibly a reckless act.
A pity really. You really did like your new house didn't you?

The good thing about working at home in relation to working at work is that at home I get to decide what is safe and what is not. I am safer at home because it is me making the decisions.

If a grinder with a guard will not fit or do the job, then the simple answer is, you are using the wrong tool.

The problem is that rhetoric never got a job done.

Risk assesments! I have done them at work. Generally a waste of time because they are only done because it is a legal requirement. Once it is done everyone can relax because they have done their job. Even if something goes wrong that they did not pick up. Maybe you have a different situation but my experience is that safety is all about covering your asre.

Reading about the aftermath from the Korean plane crash in US where the passenger was killed by an emergency vehicle driving along the runway. Any investigation about said mentioned emergency vehicle would only relate to whether the crew were following prescribed instructions. If they were and still managed to kill a live victim then they were off scott free. I accept this situation except for one issue. Someone is dead because the operation instructions did not cover running over passengers on the runway. Someone missed that one big time and nothing will happen.

I am much safer looking after myself despite not using guards because I am ultimately responsible for what happens to me and I know that.

With regards to your comment on toothed wheels, I agree completely. I would never use one because I think they are dangerous. With or without a guard.

I appreciate your concern but I am sure that there are many more dangerous activities going on that are more deserving of attention.

Dean

Originally Posted by Oldneweng

The good thing about working at home in relation to working at work is that at home I get to decide what is safe and what is not. I am safer at home because it is me making the decisions.
I will definitely agree that removing other people from the equation does improve safety.


The problem is that rhetoric never got a job done.
True, but neither did taking unnecessary risks.
I have been a Boilermaker for well over 20 years now and in nearly every case where an injury or accident has occurred, the decomposition of the incident showed that it was an unnecessary shortcut or risky practice that ultimately cost more time than it saved.
Risk assesments! I have done them at work. Generally a waste of time because they are only done because it is a legal requirement. Once it is done everyone can relax because they have done their job. Even if something goes wrong that they did not pick up. Maybe you have a different situation but my experience is that safety is all about covering your asre.
That is entirely dependent upon your safety culture. They are not the be all and end all, but if used wisely are a valuable tool. Provided you act upon the highlighted risks and eliminate or mitigate them.
To me, safety is about finishing the day in the same condition you started it, albeit somewhat more tired.
Please don't forget, the sharks, (Lawyers), are circling. What happens in a tenth of a second is often decomposed over 10 weeks and blame apportioned.

Reading about the aftermath from the Korean plane crash in US where the passenger was killed by an emergency vehicle driving along the runway. Any investigation about said mentioned emergency vehicle would only relate to whether the crew were following prescribed instructions. If they were and still managed to kill a live victim then they were off scott free. I accept this situation except for one issue. Someone is dead because the operation instructions did not cover running over passengers on the runway. Someone missed that one big time and nothing will happen.
I can't speak for the Koreans, but both in my workplace and within my Volunteer Emergency Service, such a tragedy would bring about a rewrite of the procedure to prevent a recurrence. Not much comfort for the deceased admittedly.
I am much safer looking after myself despite not using guards because I am ultimately responsible for what happens to me and I know that.

With regards to your comment on toothed wheels, I agree completely. I would never use one because I think they are dangerous. With or without a guard.

I appreciate your concern but I am sure that there are many more dangerous activities going on that are more deserving of attention.

Dean

Ultimately, I have no desire to argue with you, (I don't consider we have by the way, more a discussion with alternate views).
We cannot cover every eventuality, only act upon known hazards and outcomes. That is why we have seat belts, chain brakes and earth leakage protection. We do agree though that safety is compromised when outside persons access a workplace where there are hazards known and accepted by the usual operator, but not by the outsider. Interestingly, this has been compounded by the relative affordability of industrial power tools these days. Once, the weekend warrior would not access such tools as 9" grinders, nail guns and the like. Now every man and his dog has such tools, but not necessarily the grounding in their safe use. Remind me to tell you one day about the man with 3 Degrees that I saw turn a pneumatic nail gun around and fire it into a piece of timber facing and directly in line with his head while up a ladder. He came very close to a ventilated cranium, the nail stopped about 25mm shy of his nose

Originally Posted by Karl Robbers

Ultimately, I have no desire to argue with you, (I don't consider we have by the way, more a discussion with alternate views).
We cannot cover every eventuality, only act upon known hazards and outcomes. That is why we have seat belts, chain brakes and earth leakage protection. We do agree though that safety is compromised when outside persons access a workplace where there are hazards known and accepted by the usual operator, but not by the outsider. Interestingly, this has been compounded by the relative affordability of industrial power tools these days. Once, the weekend warrior would not access such tools as 9" grinders, nail guns and the like. Now every man and his dog has such tools, but not necessarily the grounding in their safe use. Remind me to tell you one day about the man with 3 Degrees that I saw turn a pneumatic nail gun around and fire it into a piece of timber facing and directly in line with his head while up a ladder. He came very close to a ventilated cranium, the nail stopped about 25mm shy of his nose

I also agree about having a discussion.

I do recognise what you are saying about outside persons accessing my workshop. I live quite a way from anywhere. The only people in recent years who have done any work in my shed are my brother and my step son. Both of these are very aware that they need to protect themselves and they know how I operate. Either of them uncomfortable with a tool would not hesitate to ask for a guard for instance. Both very responsible operators. I am very fussy who I let use my tools and nearly everyone knows this. My wife also knows this and would not let anyone use my tools if I wasn't there.

Dean

Not sure if we are helping the OP to narrow his choice of grinders, but a couple of safety matters that I have encountered are worth a mention.
I am still trying to imagine any situation where a well designed guard would hinder proper use during cutting or grinding. Have seen small machines with fixed guards, but I hope these are a thing of the past. My adjustable guards are clamped just firm enough that they can be re-set on the run just by bumping them firmly on the edge of a bench or similar, They are thus no hindrance to safe use, and allow me to put the machine down before it stops spinning, without hazard.
My other concern is switch design. It shold be possible to ensure "dead man" operation, so if the machine leaves my hand it will switch off. Some switches have the lock button where a normal hold engages it, and a conscious effort is needed to disengage it, with potential for disaster. Toggle switches on the rear are another bad idea for the same reason. It should be possible to hold a switch on without undue fatigue, but without need to use the lock in most situations.
Have an earlier 9" Bosch which I rarely use now. The switch was thumb operated and stayed on unless positively pulled off. Was cutting off a steel piece in a vise when it moved and jammed the disc, pulling it from my hands. The machine hit the floor with the switch still on, breaking the rear handle and switch off, but still connected by its internal wiring it raced 4 meters across the shop floor on the extension lead, somersaulted against he wall and came straight back towards me. Just managed to sidestep it and pull the plug from the wall as it powered past my feet instead of slicing them. I look at switches a little differently now.
Recall racing driver Stirling Moss being asked about the thrill of driving such great powerful machines. "No" he said. "I just look at a car and ask what it can do to stop me from winning the race and coming home in one piece." Tend now to regard my power tools in a similar light. Combustor.

Originally Posted by Combustor

Not sure if we are helping the OP to narrow his choice of grinders, but a couple of safety matters that I have encountered are worth a mention.
I am still trying to imagine any situation where a well designed guard would hinder proper use during cutting or grinding. Have seen small machines with fixed guards, but I hope these are a thing of the past. My adjustable guards are clamped just firm enough that they can be re-set on the run just by bumping them firmly on the edge of a bench or similar, They are thus no hindrance to safe use, and allow me to put the machine down before it stops spinning, without hazard.
My other concern is switch design. It shold be possible to ensure "dead man" operation, so if the machine leaves my hand it will switch off. Some switches have the lock button where a normal hold engages it, and a conscious effort is needed to disengage it, with potential for disaster. Toggle switches on the rear are another bad idea for the same reason. It should be possible to hold a switch on without undue fatigue, but without need to use the lock in most situations.
Have an earlier 9" Bosch which I rarely use now. The switch was thumb operated and stayed on unless positively pulled off. Was cutting off a steel piece in a vise when it moved and jammed the disc, pulling it from my hands. The machine hit the floor with the switch still on, breaking the rear handle and switch off, but still connected by its internal wiring it raced 4 meters across the shop floor on the extension lead, somersaulted against he wall and came straight back towards me. Just managed to sidestep it and pull the plug from the wall as it powered past my feet instead of slicing them. I look at switches a little differently now.
Recall racing driver Stirling Moss being asked about the thrill of driving such great powerful machines. "No" he said. "I just look at a car and ask what it can do to stop me from winning the race and coming home in one piece." Tend now to regard my power tools in a similar light. Combustor.

I totally agree with the comments about switches, particularly in the case of the bigger grinders. I haven't seen too many with the horrid little toggle switches lately, but I may not have been looking either.
It's actually quite interesting to look at the power tools we were using 10, 20, 30 or even 40 years ago and to see the evolution of the species so to speak.
I love the sticker that says "this tool has no brain, please use your own" live by that rule and you will have few issues.
How many people actually do a "pre start" on their tools. By this I mean, how many of us actually check their power cord, the operation of the switches and controls and the condition and operation of the guards BEFORE the use of the tool? Always better to find a fault before it finds you.

On grinders: I have 6 of the 5" size and 1 9" grinder. The 9" is my last choice and only if none of the others can do the job.

On small grinders, I like switches to lock on as sometimes I'm holding them in an odd fashion (which has its own issues as below). For big grinders, definitely a switch that turns the machine off as soon as pressure comes off it.

I prefer the paddle type handles to the 'grab the body' style. Less fatiguing on long sessions and better leverage.

ALL of my grinders have the guards installed. I can do enough damage to myself with them in place. #### happens, fact of life. I have a lovely scar right over the tendon of my right thumb, courtesy of a 1mm cutting disk that got jammed doing an overhead cut (which I shouldn't have been doing) and spat back at me. I was wearing a pair of those kevlar reinforced rigger's gloves, might be why I only needed a good chunk of surgical tape rather than a stay in the microsurgery unit.

Another guard near miss though not an angle grinder. I was helping a friend of mine do some building & using his GMC circular saw. He knew, but I didn't, that the guard return spring was weak. I'm used to my saws where that sort of thing simply isn't allowed, so my habit is to cut then put the still spinning saw down on the bench while doing whatever. HIS saw accelerated at me when the spinning blade dug into the bench, just missed my thigh and dived off of the bench. I now take my tools with me if I'm helping someone with a job. I also use my 160mm Makita circular saw if the material to be cut is less than 50mm. Far more controllable.

On variable speed - I recently bought 2 vari-speed 5" angle grinders from Aldi while I was up on the big island. $25 each, who cares, they look OK and the one I've unpacked removes metal. I planned on using one more as a sander than a grinder, didn't think about polishing stainless etc.

PDW

The OP has long gone I think.

Re dead mans switch I believe that in SA this type of grinder is required on building sites. I am recalling what my step son told me, probably when he gave me his old no longer used Makita 4 inch angle grinder which has a toggle switch at the end and did not have a guard .

I'm used to my saws where that sort of thing simply isn't allowed, so my habit is to cut then put the still spinning saw down on the bench while doing whatever. HIS saw accelerated at me when the spinning blade dug into the bench, just missed my thigh and dived off of the bench. I now take my tools with me if I'm helping someone with a job. I also use my 160mm Makita circular saw if the material to be cut is less than 50mm. Far more controllable.

Agreed. I am uncomfortable with using tools other than my own because of the unknown factor. I also put a circular saw down like that. I have a little bitty one for small cuts. I cannot remember the last time I used a big one hand held tho. We have a 10 inch and a 12 inch SCMS, a Triton with Triton brand 9 inch circ saw, a nasty little 10 inch table saw and I have a full sized table saw with sliding table. The last is still in its box waiting for shed arrangement. I rarely do hand held saw cutting.+

Dean