Fab Shop Workhorse..........The Humble Grinder

[NewLou]

Gidday :D

The Humble right angle grinder in 4 1/2 n 9 Inch forms are the work horses of most metal working shops particularly when it comes to Weld Grinding, blending and deburring...........

OF all the tools in our shop I spend more time on griders than any other tool. In fact before I became a metal fabricator i was ignorant to how effective these precision grinding/cutting tools can be..............

I want to invite all the metal fabricators out there too share a bit about there grinding exploits n any info U think might be worthy of handing on...........

My Grinders of Choice are a Metabo 9 inch soft start (With quick change Locking Nut) N a VArilex 1600 VAriable speed RIght Angle Grinder Both German units that to date have served me well.

American made Milwakee units are by far the most popular grinders in our shop.............Will be interesting to see how my German units hold up against em.

The supplier I use is abrasives Australia that can be found here:

http://www.specialabrasives.com/index.htm

They have some awesome gear! I tend to use the plantex products to help cut down on glass fibre intake (Hate that stuff) N must admit I'm becoming a Flap Disc FAn ...................after discovering the joys of variable speed angle grinding

Regards Lou:2tsup:

[NewLou]

Hey there:D

Cutt off wheels should be quality ................. believe me u dont want a failure mid use. So is worthwhile leaning towards more well known respected brands.

For trade use the new thinner style of wheels offer a few advantages. I use a 1mm wheel with my 4 1/2 inch grinder.The thinner wheels minimise the surface area contact between the material and the wheel due to the reduced surface width of the wheel.

The reduced surface cutting area offers the following benefiits:

Improves surface finish on the cut material
Generates less heat
REduces base material loss during the cutting operation
Requires less force for cuttingWhen working with stainless steel and other high nickel alloys cut off wheels that are sulfer and chloride free should be used to prevent contamination of the stock................In a nutshell ask for an abrasive that suits the material you are working on.

For example different abrasives are used for Mild Steel, Stainless n Aluminium

Always be in control of your grinder particularly when cutting n never try to use a cutting wheel as a grinder

REgards Lou :2tsup:

[NewLou]

Gidday:D

The jurys out on this one for me................I cant honestly say yet which I prefer they both have there place n I prefer different types of wheels for different jobs..........Im hoping a few of the more experienced can give counsel on this one.............

However the recently introduced flap discs grind and finish in one step reducing both the time needed and expense of finishing a product.

When using flap discs its really important to remember that a user can extend the working life of a flap disc by 50% by keeping the angle grinders rpm between 5000 & 8000............

REgards Lou :2tsup:

[NewLou]

Generally theres around three types of abrasive coating to look out for when using flap disks..........

The type of coated abrasive you use could impact on your results depending on the job at hand and what type of material your attempting to grind

Types of coated abrasive for flap disks are as follows:

Good: Aluminium oxide is suitable to most general purpose applications. It is specified for use on wood and most metals.

Better:Zirconia alumina grains are sharp and durable providing speedy stock removal and improved service life. Zirconia Alumina based disks are used to best affect in course grits on heavy duty metalworking stock removal applications.........Usually lasts twice as long as aluminium oxide

Best: Ceramic grain abrasives are available in a variety of grits as special products for aggressive and cool grinding. They ensure faster grinding with the addition of offering better surface quality and excellent stock removal rates.

Their cool working properties ensure longer service life & minimise surface discoloration of the workpiece.

Ceramic based abrasives excell for grinding high alloyed steels, titanium, nickel alloys and all extreamly hard materials. Ceramics will usually last 50% longer than zirconia alumina abrasives

So there you have it a nice little basic guide to help you choose the right flap disk for the job.......................

Theres a great little primer on abrasive types from the Australian Industrial Abrasives webpage here:

http://www.australianabrasives.com/belts.htm


Regards Lou :2tsup:

[NewLou]

Gidday :2tsup:

Heres a List of my Fav suppliers in regards to Grinding gear to date:

Abrasives Australia
http://www.specialabrasives.com/index.htm

Australian Idustrial Abrasives
http://www.australianabrasives.com/flexiblegrinding.htm

Abrasive Products
http://www.abrasiveproducts.com.au/index.html

Hermes Abrasives
http://www.hermes.com.au/

Saint Cobain Abrasives Australia
http://www.saint-gobain.com.au/

REgards Lou :D

[peter_sm]

I find my 5" variable speed Bosch suits my needs. I am a auto body fabricator. I use the fast speeds for grinding and cutting, and the slower speeds using the old fashioned flap discs for weld blending.

I also have a 4" Makita for tight spots. Smaller and much less power, so not as dangerous, and useable with one hand operation when safe to do so.

As for abrasives, it depends what I am building. Regular automotive sheetmetal panels, polished aluminium panels, stainless steel covers, copper radiator housings etc. To do things right I have ended up with no less than 30 different sizes, grits and base material built sanding products to suit my grinders.

[Brickie]

Gidday :D

The Humble right angle grinder in 4 1/2 n 9 Inch forms are the work horses of most metal working shops particularly when it comes to Weld Grinding,


Which of course you wont have to do once you get good at it..:roll::2tsup:

[Grahame Collins]

Brickie,
I agree!
Lou knows my attitude to weld grinding.I am quite sure he meant to say weld preparation grinding.

For those individuals still learning the craft, I do urge you to learn the cause of welding defects and how they are avoided. It's all out there on the net if you choose to look.


Sadly, many less well skilled welding operators display their lack of basic welding ability by taking the grinder to almost every bit of weld they lay.

Defect removal is not nearly as effective as defect avoidance.

It costs :


A time loss

Consumable waste

Energy (as in electric power) loss.


When I taught certification welding welding, I saw those who barely need the grinder had little trouble in achieving a pass where as those that used the grinder as a crutch to attempt the test, fail time and again.

Grahame

[Brickie]

Its been a while, but when I was welding the weld looked soooo nice, with stick I used to get the slag pealing off in one long line all by itself..:cool:

[Brickie]

I find my 5" variable speed Bosch suits my needs.

The good thing with the 5" grinders is that they have the same size bore as the 9" grinder, so when the 9" wheel has worn down it can be used in the 5"..:2tsup:

If I was to have the opportunity to buy a new smaller grinder I would buy the 5" one..

[Grahame Collins]

Thanks Lou,
You have done an excellent job in adding to the groups knowledge of abrasives.

When teaching the senior cherubs I am on their backs about the hazards of angle grinders.
Ignorance and laziness are terrible companions to work with if you are a senior engineering student with a poor safety attitude.
Some don't care about how they get the job done and that includes use of the angle grinder.
I often need to stop the classes and point out hazards

like this:

No handle on the grinder-one handed grinding

Guard removed to get better job access

Input cable cut to core wire by grinder wheel - no control-see No 1

The wrong type backing plate fitted to the grinder-dished and flat types.

The wrong diameter wheel (ie 115mm fitted to a grinder say 100mm ) -extreme vibration.

Cracked or damaged wheels left on a grinder


and thats just the angle grinders

Of course none of us would ever do that.

Grahame

[DJ’s Timber]

The good thing with the 5" grinders is that they have the same size bore as the 9" grinder, so when the 9" wheel has worn down it can be used in the 5"..:2tsup:

If I was to have the opportunity to buy a new smaller grinder I would buy the 5" one..

If you do this, check that the rpm rating of the 9" wheel is suitable for the 5" rating as well. The 5" rpm is a lot higher then the 9" so check first or you might have an exploding disc :o due to the extra speed.

I have both these sizes and will not use the 9" on my 5" as I have seen them explode and have also been hit by bits as well. The person responsible for this got his behind severely kicked by a few of us that were in the firing line.

[journeyman Mick]

..................American made Milwakee units are by far the most popular grinders in our shop.............Will be interesting to see how my German units hold up against em........................

Lou,
just wondering if the Milwaukee grinders are in fact US made now. They were bought out (AFAIK) by Atlas Copco (Swedish multi national) who also bought out AEG (German). They sell some seemingly similar tools with the different branding on it. Might be interesting to check the stickers on them to see of they say "made in USA" or just "Milwaukee, USA"

Mick

[Brickie]

Intersting DJ, I worked in a factory for some years welding and they only used the 5" and 9" grinders, I never once saw the wheels disintegrate, and that was over a 7 year period. :?

Mind you, that was when all the wheels were made here in Oz..:2tsup:

Moral of the story, dont buy the cheap Chinese crap.:doh:

[DJ’s Timber]

That's all good Brickie, but as I said, check the speed rating. The guy from my story use a lower speed rated one and that's why it exploded.

[Gaza]

lou, great to see you have taken your new trade. I wish all guys out of tafe have the same drive, no wonder you had bosses after you.

are you having to buy grinding wheels or do they get supplied by your company.

have you brought your own grinder's yet. if not have a look at the 9in bosch in my opion its the best. with a 4/5in try to buy one with a dead mans switch not the lock on style. we had a guy cut is entire leg open with a 4in when he dropped it start to chase him, only thing that stopped it was the lead coming out.

good luck and happy new year

[Brickie]

we had a guy cut is entire leg open with a 4in when he dropped it start to chase him, only thing that stopped it was the lead coming out.



He did a good job running with his leg cut open entirely. :roll:

Is this another of them urbun myfs? :doh:

[NewLou]

lou, are you having to buy grinding wheels or do they get supplied by your company.



Company supplies the basics including standard cutting & grinding wheels plus 'shop grinder's. I tend to lean towards supplying my own...........cant stand chasing tools n love having the right 'kit''for the job at hand.

My Varilex 1600 grinder can operate as a 100-178mm grinder (4-7inch) which as Im sure u can appreciate offers heaps of versatility.

See the link to abrasives australia to check it out .............. was recommended to me by a m8 n I consider it a top piece of kit.

I too generally prefer bosh gear but my 9 inch metabo was on sale at a great price soft start , with quick change locking nut once again handy piece a kit...................will keep forum updated on how well these puppies preform.

For the money paid I dont think I could have got a more versatile 'setup' I've also got a 4 1/2 inch 9564C 1400W Makita that I've got setup with a cutting wheel keeping disk changes to a minimum

So far this 'kit' has been working for me really well

Regards Lou

[Gaza]

the metrabo is a nice unit, very well built.

have you built a nice tool box to keep your gear in at work.

[Gaza]

He did a good job running with his leg cut open entirely. :roll:

Is this another of them urbun myfs? :doh:

This is no urban myf, the grinder was running not him. the grinder got caught in his boot laces and then went up the leg to below his knee.

[Pops]

Hi Gaza, Brickie,

No Urban Myth at all, just one of many cases. Have worked at a couple of places where this sort of thing happened.

Some years ago, read about one where a guy was in an inclined tank, he was in a harness. He dropped the 9 1/4, No Dead-Man switch, plug tied in a knot to prevent it coming apart, it ran about in the tank bouncing off the walls and the bloke until a workmate pulled the extension lead. Sadly he did not survive the encounter. A documented WorkSafe incident. I know of other cases. All gave me a new perspective, given my 'rubber thongs' safety boot type approach to safety.

For me, the safety features for angle grinders are a top buying consideration. Look after yourselves fellas. Wimpy me sticks to the 4 or 5 inch these days.

Have a Metabo 5 inch, the higher spec. motor power one. It is old but it just goes and goes and goes.

If I remember correctly, I knew a chap in the boat building industry that use the 4/5s all day every day and he said that they bought all Metabo 4/5 inch gear as they lasted longer than the others, at the time mind, which was about 10 years ago. Makita and others have made real advances in these tools since then.

Hi Lou,

I reckon that 4 1/2 inch 9564C 1400W Makita would eat my old Metabo 5 inch 900W. Sounds like a ripper little beast. Thanks for all the info.:) Realised I am out of date with some of the power tool and abrasives technology these days.

Cheers
Pops

[quercus]

The Hitachi for me have been practically indestructible, apart from a crappy 4". I hate 4" Grinders, the discs last only minutes it seems. 41/2" seem a lot more robust, and the little bit extra blade seems to last a lot longer.

The big problem with small grinders is that you are tempted to use them one handed - a bit like small chainsaws. This has obvious follow on implications for missing fingers etc.

My worst incident apart from the usual grazes, was when I was changing a cutoff wheel on the old 9 1/4" and I duly unplugged the machine to change the disc safely. Went to use it and realised it was unplugged. Accidentally locked the trigger on at the same time. I then did the really stupid thing, and clamped it between my two legs as I plugged the lead back in. 13 stitches later I was thanking myself I hadn't lost a leg. The doctor stiching me up told me that when he used to work in casualty in the city, they were putting stiches in to people every day from small grinder accidents on building sites mainly because people were holding them one hand, and bumping the other, usually taking out a neat bit of tendon at the same time. The only good thing about a grinder cut is that it usually cauterizes and seals the wound as it cuts, so not too much blood loss, unless you hit an artery of course.


That brings up the issue of dead man switches. All big grinders seem to have them now, which is a good thing. Smaller grinders don't for some reason. Even the new bosch I bought recently didnt.

Next to chainsaws, I think they are one of the most dangerous, but also most useful tools you can buy.

[Andy Mac]

Angle grinders are not only an invaluable tool in the metal workshop, but also for woodwork. I have a small Dewalt (100mm?) and fitted with a rubber backed sanding disc its ideal for quick removal of timber, and even quite refined work as in finishing a carving. Depends on the grade of sanding disc. I have an Abortech disc for it as well.
I am bemused with people buying cheap throwaway ones, or putting up with old battered ones. A good grinder is a wonderful investment! I often advise students leaving art school, about to set up their own studio, to buy a small grinder, by a reputable maker as a first priority. Cut and shape metal, ceramic, stone, wood, etc with the correct abrasive disc.
But don't ya hate the older types that need 2 spanners to change discs!?:(( I notice though that Shinano air grinders still don't have spindle locks. In saying that, I have cracked the gearbox casting on a good B&D angle grinder with a spindle lock (made in Germany), attempting to remove a stuck Arbortech carver. It had tightened up after carving really hard wood, and I assume the spindle lock applied all that torque I gave it directly to the casing...maybe that wouldn't happen using 2 spanners? Any thoughts there?

Cheers,

[quercus]

Someone who worked in a tool shop told me a huge batch of 9 inch GMC grinders had a locknut that literally fused itself to the spindle if it was used hard, and was impossible to get off. They all were replaced.

I agree with the prior post about getting a quality grinder. For the amount of time you end up using it, the initial cost is a minor consideration

[peter_sm]

Is it better to buy a good quality German or Japanese 100mm grinder at $100 than go through 5 low quality grinders also costing a total of $100

Personally I would be annoyed when the cheap grinders let me down with breakage, early wear, low power etc.

Ultimately the buyers choice

[Fossil]

I could not agree more.

I think there should be some form of global discussion about all of the wasted resources and generated pollution from mass producing all the crap that we see these days. Think greenhouse gas reduction strategies ??????

It just doesn't take that much more more effort on the part of the manufactures to turn out quality gear, over the crap that we commonly see. Poor castings, bearings, switch-gear etc, and cheap thin windings that burn easily.

[graemet]

Although I have only used an angle grinder rarely in the past, my old Ryobi carked after 10,years of abuse and I bought a Makita 4". A huge difference in quality. Recently, I have had the need to cut steel bar and sheet up to 16mm and decided to use the 1mm disks. They seemed not to last very long, specially with the heavy stuff, so I took every opportunity to buy cheap disks on bargain prices. The local Mitre 10 was the closest outlet open last Sunday when I ran out of disks again and they only had Hitachi disks. What a difference. I reckon the Hitachis outlasted the cheapies by a factor of 3 or 4.:-
Moral : you get what you pay for.
Cheers
Graeme

[peter_sm]

1.0mm discs are for sheetmetal (they even have 0.75mm). there are 1.6mm discs for heavier bar and plate.