replace grindstone wheels or new bench grinder?

[long ironer]

Opinions please.

Subject: Sealey 1/2hp 150mm bench grinder, vintage late 80s, with fine & coarse wheels, both 19mm wide x 12mm bore. The coarse wheel appears to have almost worn down to a bare steel core. It is only lightly used & mainly for refreshing tools, but sometimes for rougher work on steel.

The few replacement wheels I've found on the web seem to be in the price range GBP5 to 15, but none are the exact size. However new bench grinders appear to be available from GBP25 up to several 100s.

What's the best option?

A. New 150mm machine: advantages are new bearings (I'd hate to be working on a grinder when the bearings fail), and at the lower cost end price looks much the same as 2 new wheels. Any suggestions as to make/model/power/speed rating for reasonable quality please?

B. New 200mm machine? Q - are 200mm bench grinders significantly better than 150mm ones? Ditto as to make etc

C. Find source for replacement wheels - anyone know of a source for bench grinder wheels please?

TIA

[The3rd Earl Of Derby]

You could try your local Aldi first as they where selling grinder wheels for 3.99GBP awhile back,two different sizes but cannot be sure of the size.

They still have a couple of boxes in my Aldi. Course&Fine

[The3rd Earl Of Derby]

Just checked my two spare Aldi ones, they are 150mm x 12 bore, so it looks like todays grinder wheels are the same size.

If you cant get them at Aldi try

[Phil L]

They are for handheld angle grinders, the diameter of the centre hole is totally different and the disks themselves are no more than 6mm thick...bench grinder disks are about an inch thick or thereabouts.

[The3rd Earl Of Derby]

Phillip they're for bench grinders that Aldi sold also awhile back I know I bought the bench grinder along with 2 spare wheels.

p.s are angle grinder disc half inch thick. :-P

[Guy King]

The message from "long ironer" contains these words:

Aldi round here (Telford) still have stacks of unsold 6"and 8" wheels. £3/pair.

[kevin foote]

Depends what you mean by better. Must admit i have a 200mm one.

Draper do a range of 150mm wheels i think.

Try Draper.co.uk

Kev

[Chris Bacon]

My spare grinding wheels (6"/150mm) from the same source are:

Fine 60 grit width 3/4" (20mm) bore 3/4" (1/2" with reducer supplied); Caorse 36 --------------------------- do. ----------------------------.

Just nipped over the road to the workshop to check!

[Dave]

I would think that you have a wheel size of 3/4 of an inch wide with a bore of 1/2 an inch and a diameter of 6 inches. I am guessing that the imperial sizes are still with us on this subject.

If you are not experienced at fitting a grind stone wheel, then buy a new machine. The fitting of a new wheel to an old machine requires some skill and training. Better to let some one else do the dangerous bit. If the wheel bursts when you are stood in front of it, it can take out your eye sight.

I can't really comment about the quality, other than to say that any manufacturer of a grindstone is not going to sell something where the wheel will explode and take out your eyes. It is just not worth it for them to cut corners on this.

I have a buy and spew grind stone. I have had no problems with it, but I do not push it. If you need to use it for rough work, then I would suggest an angle grinder, one of the cheaper ones will do you for this work. Look on it as a consumable and throw it away when you have a problem with it. They can be bought for about 15 pounds for a 4 inch disk type, a little more for a larger one.

By the way, replacement wheels for an angle grinder are designed for morons to change, where as a grindstone wheel is designed for an expert to change.

I'll let others answer that, it is not my field.

I would advise against this. See above.

Dave

[Dave Liquorice]

Hum, not sure I'd trust a grinder wheel that may have been mistreated whilst stacked up in a shop with punters picking them over and dropping =

them etc. You don't want a grinder wheel exploding(*). I think a normal =

sort of wear related bearing failure would be minor in comparison...

[robgraham]

Oh dear, sweet naivity strikes again ! I changed the the wheels on my

6" machine some years ago and never thought about it any more than being a standard maintenance task. What skill is required of an 'expert' and what should I have attempted to do ?

And what is a 'buy and spew grind stone '?

Rob

[andrewd909]

You are probably right, 99 times out of 100 you can get away with just bolting on a new disc, however in industry it is law that anyone changing a grinding wheel disc must first complete a 'safety in the use of abrasive wheels course', every firm using grinding wheels requires a list of personnel deemed competent to change discs and carry out maintenance on the grinding machine. The main areas of concern are disc design speed, cracked or damaged discs, blotters and spacers and balancing. i would suspect that when buying a new bench grinder the discs will be fitted to match the machines caracteristics, although personally i would still check the discs for cracks caused in transit. By far the biggest cause of 'bursting' of grinding wheels is misuse i.e grinding the wrong material, forcing the work, incorrectly adjusted tool rests or grinding on the wheel edge. As already mentioned a grinding wheel can totaly ruin your weekend if something goes wrong, i seem to remember that,depending on the machine, grit particles can leave the wheel at 200 mph, so the correct eye protection should always be used, never just rely on the guards fitted to the machine

[Guy King]

The message from "robgraham" contains these words:

Well, this is rapidly turning into uk.get-a-little-man-in, isn't it.

[Dave]

First, a grind stone is on a mission to re-model your face if not installed correctly. As Andrew mentions below, it is a skilled job to mount a new stone.

There have been threads about doing your own gas work in the past and I agree, that if you feel competent, then go ahead and do it. When it comes to mounting a new wheel on a grind stone, I would favour a lot of caution, unless you have had some training of how to do it and the dangers that can come out of this simple exercise. Over tighten the nut that holds the wheel to the shaft and you can expect an exploding wheel pretty soon and it will not leave a pretty face either.

I have been in engineering for well over 40 years and I remember seeing a grind stone wheel bursts and it went clean through a brick wall. On the gory side, I have a cousin that saw a lathe operator picked up and dashed to death by the lathe he made his money on. You takes your chances.

Second. Buy and spew is an acronyms for a well known DIY store where the folk that work there wear red or orange pinnies (dependant on the size of the store). They sell cheap tools for the DIYer. That is why I stated that if the grind stone wants a new wheel, then the best bet is to buy one of theirs. At least then, you can get compensation from them if anything goes wrong from a badly fitted wheel. (I have one of their cheap ones and it is fine for everyday use)

Dave

[Dave]

Not really. If folk that change a grind stone wheel are aware of the dangers, then just like working with gas, with guide lines, it is made that much easier and safer.

Dave

[Chris Bacon]

The rests and guards should be adjusted properly to minimise danger.

The grinding wheels I bought ad Aldi have quite good instructions in the packet, including one to run up the machine for some time after fitting a new wheel, before using it.

"Use protection". "Adjust the machine". "Use grinder properly".

I bet it wasn't a 200W 6" one from Aldi (or similar).

That's too late. One of my pet gripes is that anyone at all can buy power tools of all description without even being advised how to use them, and the dangers. If B&Q or whoever put on an evening hour of tuition, even for the price of a pint, it would be *much better*.

[long ironer]

Thanks for all the replies.

Dave wrote:

This is why I posted - I'm extremely wary of grindstones. Any fellow veterans of late BTH/AEI/early GEC Rugby Mill Road days around will remember a former machinist on the site with a large inch deep dent in his forehead.

I'm not sure about wonky bearings on grinders either. My guess is there's a high chance of a shattered wheel once a dud bearing develops.

As Andrew mentions below, it is a skilled job to

To sum up,

1. No opinions emerged on relevant merits of 150mm dia v 200mm grinders

1. No opinions on relative merits of various makes and powers

2. Care is needed fitting a new wheel. I recall seeing a video on tool sharpening 10-15 years ago by Jim Kingshott in which he went into commissioning a new bench grinder. Even with a new one out of the box he made a point that the wheels should be removed, suspended and tapped to make sure each one gives a clear ring. I can recall hearing the same thing at various oither times since Mill Rd days.

1. As the bearings appear OK & considering Jim Kingshott's advice I decided to chance it and replace the wheels.

Pursuing that it turns out there's a vast number of different, but almost the same, grinding wheel sizes. plenty of 20mm but no 19mm; ditto 12.7mm bores but not 12mm etc; none the right size at the usual internet tool depots. Some have plastic bore adapters. With my wariness of grinders I'm not going to chance a wheel unless it is exactly the right fit.

I rang Sealey who were much more helpful than their web site leads you to expect. It turns out that there's plenty of Sealey agents around, and you have to order the wheels from them @ around GBP10 each inc VAT.

Thanx again

[robgraham]

Just to add a word of caution from a different perspective on angle grinders - my father killed himself using one.

This was not an exploding wheel or anything of the likes but a circumstance that he should have foreseen (at 79 perhaps that was not unreasonable). We worked it out that he wanted to cut a piece of 6mm steel plate; he had clamped it to his workbench and had set up a guide for the angle grinder. It seemed he was making several passes over the steel and all went OK until the cutting wheel broke through and the sparks of cut metal went straight downwards. Unfortunately this was also his wood working bench with shavings and sawdust, and to compound it he had a plastic gallon container of white spirit we think under the bench at the point he was working - and it was a garage with a pull down door.

The lesson of course is not to mix wood work and metal work and to keep flammable fluids well away from both.

Rob

[Dave]

That is good news. It looks as if things have improved over the years. I have not had to replace a wheel yet and I will be 60 next month. But I am aware of the dangers.

snip

LOL no :-)

It was a big bugger though :-)

I remember my training as an apprentice on a centre grinder. I was taught to back off the grind stone three turns of the wheel before stopping the machine to take a measurement. Trouble was, I didn't do that once and when I went to advance the stone 3 turns forwards, to re-grind, I got lots of stone in my face. It taught me a lesson for life.

Sadly, yes. But if they sold a grind stone that had a badly balanced wheel, at least you would know that they would be held responsible for it.

That would be an excellent idea. I wonder if they would take it up?

Dave

[Dave]

At that size, I doubt that it matters. 150mm is about 6 inch, 200 mm is about 8 inch. if you were to go from 150 mm to 300 mm then you might like to consider water cooling and the speed that it rotates.

As far as makes go, it doesn't make that much difference if they all use the same wheel :-) See below.

Glad you have seen that. It was what I was banging on about :-)

Once you are aware of the dangers, then the dangers are pushed into the background.

Welcome to the world of metric and imperial measures :-)

Thanks, I'll take a look at their web site.

Dave