Grinding on the side of the wheel

[ChrisHParticipant @chrish]

Re bench or pedestal or off-hand grinders.

 

Many years ago when I was being taught workshop technology I was instructed to only ever use the ‘front’ or outside edge of the grinding wheel, never to grind on the side of the wheel. Now this instruction may have been for our safety as makee-learner novice engineers so we did not put heavy side pressure on the wheel, but I seem to remember something about the reason being it was about the way the wheel was made; as I said, it was many years ago, nearly 50 years or so, so the reason has been lost in time.

 

However, I see all the drill and similar tool sharpening devices advertised to make or buy seem to require one to use the side of the grinding wheel.

 

So the question for anyone with the knowledge I lack is, is grinding on the side of the wheel acceptable? I suspect it is given the very light loads imposed by tool sharpening, but it would be nice to know.

 

Chris

 

[ChrisHParticipant @chrish]

[NJHParticipant @njh]

Hi Cris

 

I seem to remember asking this before but the answer to the acceptability of the practice at that time seemed to be “maybe if you go carefully!” I admit to this way of sharpening.

I guess the safe way is a cup wheel and I really must get round to it.

Can I therefore add my voice to Chris’ – how acceptable is it to grind on the side of the wheel?

 

Norman

[David CostelloParticipant @davidcostello75947]

Everytime i use the side the word EXPLODE seems to come to mind,but i still use it??

[Tony Pratt 1Participant @tonypratt1]

Hi, I too was taught that in theory you shouldn’t grind on the side of the wheel, but in practice I and my collegues never had a problem, just don’t go mad and apply too much pressure.A decent make of wheel is very desirable as I would imagine the el cheapo wheels are not made to any particular standard but I stand to be corrected on that.

Tony

[Roderick JenkinsParticipant @roderickjenkins93242]

As usual, one size does not fit all. I’ve known of castings being fettled with the aid of a scaffold pole lever to get more pressure against the wheel and, in a car tyre fitters, a 6″ grindstone with a groove about 1/2″ in from the periphery that seemed to go right through to the other side. Bearing in mind that you can’t really dress the face of grinding wheel, using the side in commercial work is not sensible. Gentle grinding of lathe tools and twist drills in the amateur workshop though would not seem to create any great hazard.

 

Rod

[chris stephensParticipant @chrisstephens63393]

Hi Guys,

I seem to recall reading that the reason for not using the side of a wheel is to prevent excessive and unequal wear. The example given was a badly disfigured wheel and the likely hood that it would “explode”.

Now most of us are careful users of our own machines, not ham-fisted grease monkeys let loose on the communal workshop bolt shortener. If one uses the side of the wheel for

gentle things like drill sharpening and it remains more or less pristine and full thickness, then there can be little or no extra risk of catastrophic failure, indeed you are more likely to loose width by the initial truing than drill sharpening.

There is another reason for not using the side of a wheel, the bearings in the grinder are not orientated for sideways thrusts, for normal use a bit of side play matters not a jot, but for accurate use a bit of a no-no.

chriStephens

[Phil PParticipant @philp]

Tool and cutter grinders use the side of a wheel, but it is normally a cup or dish wheel that can easily be dressed with a diamond on its working face.

 

With a bit of common sense, grinding on the side of wheel should be OK, but it will be nigh on impossible to keep the flatness on the wheel as dressing it is not very practical.

 

Phil

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I believe the reason for not griding on the side of a straight-sided wheel is to do with the bond of the grinding particles. While the bond has very good strength while griding on its face, it is not sufficiently strong enough for shear forces of any great amount.

 

Below is an extract from my Abrasive Wheels Regulations 1970 booklet.

 

Misuse of the Wheel

 

Wheel breakage can occur if excessive pressure is used to apply the workpiece to the wheel. Operators may be tempted to do this if the wheel is running slower than the speed recommended by the manufacturer, or if the wrong wheel has been selected so that the wheel face has become loaded or glazed.

 

Grinding on the side of straight-sided wheels is dangerous, particularly when the wheel is appreciably worn or if sudden pressure is applied.

 

The above is from a Lloyd’s British plant and safety training course.

 

The most important thing about grinding wheels is that the peripheral speed of the wheel should NEVER be exceeded of that stated by the manufacturer. It is also important that the wheel runs as close as possible to the peripheral speed set by the manufacturer. Running a wheel significantly slower than that set by the manufacturer will tear out the grinding particles faster and will wear away the wheel quicker and also increase the risk of wheel breakage.

 

Having said that I have been guilty of using the side of the wheel, lightly of course, so if you must use the side, do not put undue pressure on it.

 

Don’t put so much pressure on to the face of the wheel, that it significantly slows the wheel down, as it will create more heat and cut less, let the wheel do the work.

 

Regards Nick.

Edited By Nicholas Farr on 09/01/2012 21:01:27

[BazyleParticipant @bazyle]

Going back to the start wrt specific problems with the wheel itself. As well as the tool getting hot so can the wheel when miss used by the workshop gorilla. Heat expansion in a ring behind the outer edge could generate stresses to crack the periphery. Heating under correct use causes a circumferential compression which is less problematic.

[blowlampParticipant @blowlamp]

This issue has always puzzled me too.

 

My thought is that most common bench grinders that might be used in the home workshop would have plain wheels of around 13 to 20mm wide and so fairly robust.

 

I admit to having no knowledge about the manufacture or technology behind their construction, but I do wonder just how much pressure you’d have to apply in an axial direction to have one of these burst.

 

A saucer wheel looks much more flimsy to my eye and we are told is safe under similar circumstances of use – infact lots of cup type wheels appear to be weaker to me, in many more ways than plain wheels and yet these can officially be used on their side and periphery.

 

What you don’t want is something being dragged in between the side of the wheel and its guard.

 

 

Martin.

Edited By blowlamp on 10/01/2012 14:23:16

[ChrisHParticipant @chrish]

Hello and thanks to all who have replied.

 

The general feeling I have is that the replies have confirmed what I suspected, that is, using the side of the wheel is really not to be encouraged at all, but might just be OK if just doing tool sharpening on a very gentle scale.

 

The comments on cup and saucer wheel are interesting but throw up their own queries too – as Blowlamp has suggested above.

 

So, assuming that one went down the changing to a cup and saucer type wheels on a common bench grinder, the next queries are :

What type of wheels (abrasive, grit size, bond etc) does one go for bearing in mind it would be for tool sharpening only?

Does one actually need a cup AND a saucer wheel or would just a cup wheel suffice?

What type of cup – one with tapered sides or one with straight sides? What are the differences?

And finally, where can one buy these wheels at a reasonable cost?

 

You can see I am a complete novice on this, but I suspect I am not alone!

 

Chris

Edited By ChrisH on 10/01/2012 17:32:46

[David Clark 13Participant @davidclark13]

Hi there

You can get recessed wheels for grinding on the side.

I would try and get one.

A60K5V or similar grade.

 

You could go to 80 grit but 60 would be better.

 

regards David

Edited By David Clark 1 on 10/01/2012 17:36:27

[Billy MillsParticipant @billymills]

There’s a lot to be said for diamond wheels for touching up edges, no chance of any breakage and works great on carbide without the short life and mess from green wheels.

They are also cheap and at no risk from damage in shipment or over tightening and sold by many retailers to our hobby.

Billy.

[The Merry MillerParticipant @themerrymiller]

It would be interesting to read Harold Hall’s viewpoint on this issue.

 

Len. P.

 

[Phil PParticipant @philp]

On the LHS of my bench grinder I use a fairly course grained straight wheel for roughing out shapes

I use a wheel similar to this one at the RHS for finishing off the tool.

 

http://www.abtec4abrasives.com/150mm-diameter-christen-drill-grinder-wheels-726-p.asp

 

Phil

[TerrydParticipant @terryd72465]

Posted by Billy Mills on 10/01/2012 18:29:56:

There’s a lot to be said for diamond wheels for touching up edges, no chance of any breakage and works great on carbide without the short life and mess from green wheels.

They are also cheap and at no risk from damage in shipment or over tightening and sold by many retailers to our hobby.

Billy.

 

Hi Guys,

 

I am in the process of converting an offhand grinder for use as a tool and cutter grinder, having never used modern diamond cup wheels I would like to know if they are really effective and do they last? I would prefer to use such a wheel as there is not the abrasive dust one gets with normal carborundum etc wheels.

 

Any advice from experienced uses would be really welcome.

 

Best regards

 

Terry

[BazyleParticipant @bazyle]

You might want to examine the play in the bearings before you put too much effort into your conversion.

Chris I think the conclusion should be as you said it is fine for light cuts and that is all one should be doing. The precautionalry advice is for those who equate a bench grinder with and angle grinder and use it in the same way.

[blowlampParticipant @blowlamp]

Terry.

 

I’m not that experienced in their use, although I do have a couple of diamond wheels and they work well for finishing. They hold their shape well, but I still use a conventional stone for roughing out to form if much material needs removing.

 

I true them with a small diamond file, if and when necessary.

 

With regard to the dust. Don’t forget that much of it will be composed of tiny HSS or carbide particles from the cutters themselves, so will be an abrasive in itself.

 

 

Martin.

 

 

[Clive FosterParticipant @clivefoster55965]

Major wheel damage or break up generally needs something to get stuck between the wheel and a stationary, solid, object. This is much more dangerous when working on the side of the wheel rather than in the approved manner.

 

When grinding on the front the working plane is a narrow cylinder so the wheel surface above and below object being ground is further away. Besides reducing the depth of cut when things get out of position, thus reducing the drawing into the jam forces, it also makes it more likely that any wheel damage will be a chunk taken out rather than a full blown break up. The break-up forces tend to be somewhat on a chord of the circle which, being a weaker orientation, is less likely to take the whole wheel out.

 

On the side of the wheel the working plane is flat so, should something shift and start to jam up there is depth of cut reduction geometry to offset the draw in tendency. Rather the opposite. As the offending object is drawn the depth of cut increases adding to the draw in effect. The forces on the wheel are across a flat side so its much less likely that a chunk can be knocked out relieving the forces before they get too large. Instead positive feedback is likely to continue until either the motor stalls or a serious crack develops across the flat side leading to wheel explosion. For various reasons such a crack is likely to be more or less on a radius, clearly the most dangerous orientation.

 

Another factor working against grinding on the side of the wheel is the difficulty of dressing. If its dressed at all. So the wheel will most likely be at least somewhat glazed and won’t be working anywhere near its best. Its tempting to up the pressure on a wheel that isn’t cutting well.

 

As has been said grinding on the side of the wheel is pretty similar to using a cup wheel. So ideally the wheel should be dressed with a slight inwards taper, 5 to 10°, so that only the outer edge is doing any work. Tool and cutter grinder users will know that this shape makes a big difference to how easily and accurately a tool can be ground to a good finish. It also makes using the common swing across the wheel drill sharpener a lot less finicky.

 

Clive

 

 

 

[ChrisHParticipant @chrish]

Re the comments about diamond cup/saucer grinding wheels. They seem to be a good idea and would like to try one, but first I would like to add my voice to Terry’s query to ask do they last?

 

I ask as looking at a section through the wheel on the Arc Euro Trade website the actual abrasive bit is only 3mm thick. I realise that it would be only used for fine cuts on tool sharpening, but even so, 3mm doesn’t sound much?

 

Anyone out there with knowledge on this?

 

Chris

[KWILParticipant @kwil]

My usual industrial regrinder uses CBN wheels. They can be used on the side and edge and have, ‘ tis said “an infinite life if treated with respect”. Littlle or no pressure is required and they run very cool. Surface finish is superb.

[The Merry MillerParticipant @themerrymiller]

 

In case any readers aren’t up to speed on CBN wheels (Cubic Boron Nitride) it’s worth looking at the link below on Peter Childs (woodturning) website.

Lots of additional helpful info is also there.

Bear in mind that most woodturning tools nowadays are HSS.

 

http://www.peterchild.co.uk/grind/aboutcbn.htm

 

One drawback is the high cost of CBN wheels.

 

Len. P.

 

 

[Steve GarnettParticipant @stevegarnett62550]

There are some cheaper, and possibly more appropriate CBN wheels available from Abtec – may be worth a look?

[David LittlewoodParticipant @davidlittlewood51847]

I have used a diamond cup wheel from Arc a few times to grind small TC tools. It worked very well and hasn’t shown much sign of wear, but it is fair to say I have not really given it any hard work yet. They are cheap enough. The cup wheel is adequate for most purposes, you would only need the sharp tapered one if you need to gash something. Not sure you could do with the dish ones that can’t be done equally well with the cup one.

 

FWIW, on the original debate, I used to do some grinding of lathe tools on the side of a conventional bench grinding wheel, but since getting a proper T&C grinder I always use a cup wheel. The difference in convenience and accuracy is enormous.

 

David

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