Thread: Bench Grinders

Originally Posted by Harryt8

I'm looking for a recommendation on a bench grinder.
It will have light use in a DIY situation particularly for sharpening drills or chisels and maybe the occasional spade.
Am I better to go with the el-cheapo Ozito from Bunnings or the Rok from Big W at around $40.00.?
Up the scale, Masters have a 909 200mm BG200 for $98.00 and Bunnings have a Makita GB602 at $126.00.

Any thoughts?

Firstly Harryt8, welcome to the forums. Lots of sensible advice out there and submitted already. As you are intending to use the grinder for multiple purposes I think you would be best advised to stick with the standard speed grinders, which are also cheaper because they are more numerous. I would suggest that a 200mm grinder is better purely for the size motor that comes with a larger wheel, but if your budget only stretches to a 150mm machine that's OK too. Just don't expect to go as enthusiastically with that.

Initial sharpening of chisels and plane blades can be achieved quite satisfactorily without overheating of the steel, but you do have to be patient, go slowly, go gently and if neccessary keep the steel cool by dipping frequently in water.

When you buy see if you can get the machine started up, but often you can't. In that case ask if it is OK to bring the grinder straight back for exchange or refund if it vibrates. They should agree to that. If not, don't deal with them.

I have five grinders in total. Only two were bought new. One of the second hand machines is an Abott and Ashby which vibrates. I use it anyway. If it wasn't bolted to the bench it would walk out the door . Probably not good practice. I always meant to set up a dial gauge on the shaft but have not got around to it.

I don't know too much about the machines you have mentioned so can't offer specific advice other than a general ook at them and make sure you can take them back if sub standard.

Regards
Paul

We have 4 grinders, all 8" models.
The 2 oldest are Skill brand, 2hp single phase. One now has a Linishall attachment on it. Brilliant!
Still as good as when new in 1988, but they cost $200 back then - no such Chinese cheapos existed.

We have one newer one with a bit of vibration, but I put a wirebrush wheel on one side, and a buffing mop or a scotchbrite mop on the other side, in each case precision isn't the necessity there.

Just do NOT grind steel, then brass, then aluminium, then steel again.
My elderly machinist engineer father-in-law nearly lost his head when someone who'd been grinding the wrong stuff on his big 3-phase grinder. Expansion coefficients due to brass fragments embedded made the big 12" wheel disintegrate-blasted the cast housing to smithereens as it launched up, made 2 holes in the roof of the shed-one on the way up & one on the way back down, and another big hole in the back wall.

Very lucky, he was that day.

Originally Posted by pmcgee

I have four grinders, but am no expert. I have read all sorts of takes on this subject ...

My observation would suggest the grey wheel cuts faster and cooler. And the white slower/smoother but generates more heat. As if, you might say, the first cuts more than rubs and the second rubs more than cuts.
Just my understanding ... my 3-phase grinder has one of each.

...l

Hi Paul

I think you have that backwards.

While wheels come in a wide range of hardness and friability, the grey wheels tend to be harder and less friable. They are used for HSS, where heat does not matter. You do not want to use these on a non-HSS blade as the heat will damage the temper. The white wheels are a good compromise for woodworkers, especially experienced grinders. A lower grit, such as 46 is less likely to create excess heat. Most new grinders come with one 60 and one 120 grit wheel. These are fine for HSS lathe chisels, but nothing else.

Harry, be aware that a cheap grinder is cheap for a reason - the build is cheap and the components are cheap. These are simple machines and a decent one will last forever.

You want stable speed (a half speed will run to less heat but technique overcomes higher speeds), minimal vibration (even good machine may still need to have the wheels balanced), 8" white 36 or 46 grit wheel and a decent blade stand (this is generally an after market purchase, but you can make your own). Get a 6" machine if funds are tight. Go for a known brand (e.g. Makita) rather than a Big W special. I have a Carba-tec half-speed 8" machine, and it is excellent.

The 46 grit 3X wheel from Tools For Working Wood (USA) (Google for this) is the best thing since sliced bread for those beginning grinding. It will not burn your blades. Very friable and cool cutting.

Regards from Perth

Derek

Originally Posted by Stewey

Just do NOT grind steel, then brass, then aluminium, then steel again.

It is OK to do this provided the wheels are dressed in between each metal although I consider this a bit of a waste of grinding wheels since ally and brass are best shapd on a linisher with a coarse belt where this is not a problem, besides belts are cheaper than grinding wheels.

Originally Posted by derekcohen

Hi Paul

I think you have that backwards.

While wheels come in a wide range of hardness and friability, the grey wheels tend to be harder and less friable. They are used for HSS, where heat does not matter. You do not want to use these on a non-HSS blade as the heat will damage the temper. The white wheels are a good compromise for woodworkers, especially experienced grinders. A lower grit, such as 46 is less likely to create excess heat. Most new grinders come with one 60 and one 120 grit wheel. These are fine for HSS lathe chisels, but nothing else.

I don't know ... for one all I have here (almost) is old O1 steel - no HSS - and I certainly prefer the grey wheel.
I use the white wheel as a 'smoother' ... last few passes. (Same machine, same width wheels)

I wrote on here semi-recently ... I forget what I was grinding ... but I was able to take about twice as many passes across the grey wheel for less heat to the fingers than across the white wheel. The grits are certainly not that different ... but there are no labels on the wheels any more, so I don't know what the answer to that is.

Cheers,
Paul

Hi All,
Many, Many years ago, I bought a 6in. grinder, at the MTWW Show in Jeff's Shed.
Some S A Tool Co. I got it from, & happily paid $58.
Gone through 2 Wheels of 60 - 120 grits, mainly for Sharpening My Turning Tools, Drill bits, Ect.
Has not missed a beat, although it had a Push Pull Switch, that broke. Went to Jaycar, paid $2.90 for a new switch, still there, with no probs.
A Push Pull Switch was going to cost $32.

For Straightening my Wheels I use part of a Concrete Cutting Wheel. There is approx. 2 - 3mm. of Diamond Impregnated Steel left on this 12in. Wheel.
Does a Great Job, with no cost, except for cutting a piece from the Wheel.

Seen them laying in the C/C Cutters trailer, asked about them, & he gave me 2. I will never run out of them in my Life Time.

Originally Posted by pmcgee

I don't know ... for one all I have here (almost) is old O1 steel - no HSS - and I certainly prefer the grey wheel.
I use the white wheel as a 'smoother' ... last few passes. (Same machine, same width wheels)

I wrote on here semi-recently ... I forget what I was grinding ... but I was able to take about twice as many passes across the grey wheel for less heat to the fingers than across the white wheel. The grits are certainly not that different ... but there are no labels on the wheels any more, so I don't know what the answer to that is.

Cheers,
Paul

Paul

Check the ratings of the grey and the white wheels. I bet you the white is a higher grit and harder. Probably a 60 or 120 grit, an the grey is about 36. If so, you are no comparing apples with apples.

Here is a link to a specs of wheels: GRINDING WHEEL and ABRASIVES BASICS

And a short article on choosing a wheel: Choose the Right Grinding Wheel - Woodworking Tools - American Woodworker

Regards from Perth

Derek

Good links Derek, thanks.
Might be part of the puzzle right there.

My first 5" (Supertool) grinder has two "grey" wheels ... but they are marked A36P and A60P.
According to the second link ... that's Aluminium Oxide. Then checking back to the first link it says ...
"Grit type is generally either aluminum oxide (white, pink, ruby red, brown, grey, etc.) ..."
So grey doesn't mean NOT AlOx ... that's news to me might be to a lot of people.

The second grinder I got (6" Ryobi) has a grey wheel also. A60N.
I just used it to put a hollow bevel onto a very boring looking (old) "Two Cherries" 10mm plain firmer.

Judging from the other wheels, I'd say the two wheels on the 3-phase grinder are both 60 or both 46.
But I have no idea regarding the bond strength. The white wheel came from Timbecon - very vaguely recall it being 'H' or 'J'.

So ... the warnings against grey wheels is either because they are not AlOx??? or because of the bond hardness???

Cheers,
Paul

PS ... Hahaha ... first link says: "Hardness grades are typically linear: If you increase the hardness by one letter grade (An H to and I for instance) it could give you double the wheel life." Not my idea of "linear"

Are there any slow speed 8in grinders still on the market in Australia?
i haven't seen any less than 2800rpm.

The one I have does not appear to be sold any longer. This is the only one I could find at Carba-tec ..

Creusen Powerline™ 6" Low Speed Double Grinder : CARBA-TEC

Regards from Perth

Derek

Thanks but it's only a 6in grinder.
There are 10in grinders available that do 1450rpm but they are much more expensive.
Not only have Carbatec dropped the slow speed grinder they are confused about what is slow or fast.
Here they describe 2800rpm as slow speed:
Carba-Tec® Wide Stone Grinder : CARBA-TEC
Here they describe 2800rpm as high speed:
Creusen Powerline™ 8" High Speed Double Grinder : CARBA-TEC
Seems there mustn't be a market for them here.
Yet in the states there are half a dozen variable speed grinders available.
I'm guessing they come from the same factories in Taiwan and China as the ones here.
How do we influence the vendors?

Ok so as a knifemaker I have a pretty serious investment in grinders, but the ones I use most are my belt grinders, The Radius Master and TAG-101 Wilmont Grinder make bench grinders cower in submission. But for the price they would want to...

I never use a bench grinder for sharpening except with my bernoulli paper wheels (not stones, paper it sounds crazy I know) Takes about 15 seconds to get reasonably ground edge sharper than you have ever seen. really great things. I only use the fine one, as the belt grinder does a way better job than coarse one, but yeah if you have never used paper wheels I absolutely recommend them

(No affiliations, just an impressed customer)

So has anyone out there tried or have thoughts about the 909? I am referring to the wet stone grinder.

I'd try Just Tools or Total Tools for an 8" A&A utility grinder. About $100. Check their shipping costs; can be cheaper than driving down if in met. areas.

Then if on a budget, get a couple of white wheels of diff. grits.

Or then or later get a pair of the 3X wheels that Derek mentioned. Outstanding performance with a range of steels: HCS, HSS, and PM-high vanadium. Jim Davey in Aus stocks them: click They run cool, are slow to wear and slow to glaze (and I say that having spent hours with gray, white, pink and ruby wheels).

Re deglazing or retruing, the diamond T-bar tool is easy to use but in my opinion substantially reduces the effective grit of coarse wheels. Would recommend you learn to use a carborundum stick (cheap but needs replacing often) or the single point diamond dresser - with that one run it in trailing mode so as not to fracture the point.

Good luck.