Grinding wheel ..balancing hole?

[Martin KyteParticipant @martinkyte99762]

Posted by Neil Wyatt on 23/03/2016 12:53:36:

(I'm tempted to say I can see the face of Jesus on it too).

Stand in front of it and spin it up and you might do just that.

Martin

PS as to the 'part of the manufacturing process' means nothing. If it's bad then being part of the manufacturing process just means they are all bad rather than a one off fault. The recent fires in tumble driers were 'part of the manufacturing process' but didn't stop a recall being put in process. The issue is does it compromise the integrity of the wheel?

[Rik ShawParticipant @rikshaw]

"(I'm tempted to say I can see the face of Jesus on it too).

I suggest taking it to someone for a second opinion."

Do we really need to be drawing the clergy into this?

Rik

PS I've just noticed this is my 666th post – spooky or wot?

Edited By Rik Shaw on 23/03/2016 15:42:55

Edited By Rik Shaw on 23/03/2016 15:46:28

[Steven VineParticipant @stevenvine79904]

Thanks for posting the response from Chronos. Even though they give assurance I'm not yet totally convinced, though I should be as they know their products. I'm almost tempted to buy one and see if it has the same holes, which would confirm a dliberate act. Or, if anyone is going down there, perhaps they could cop a feel. I've seen it mentioned in a few places that grooves are sometimes introduced during manufacture to be used with flanges to assist mounting. I've look all over the internet, but all the wheels I see are plain, sans holes. This could do with an expert second opinion, is there one around?

And I don't recall ever seeing an unbranded wheel.

Steve

Edited By Steven Vine on 23/03/2016 16:52:20

Edited By Steven Vine on 23/03/2016 16:59:46

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Martin Kyte on 23/03/2016 13:36:58:

PS as to the 'part of the manufacturing process' means nothing. If it's bad then being part of the manufacturing process just means they are all bad rather than a one off fault. The recent fires in tumble driers were 'part of the manufacturing process' but didn't stop a recall being put in process. The issue is does it compromise the integrity of the wheel?

.

Exactly !

MichaelG.

[Clive HartlandParticipant @clivehartland94829]

Is it possible the makers have seen a start of a crack and to make sure it does not travel used a diamond tool to cut out the start of the crack to save the wheel? To stop cracks in metal you drill a hole at its start to stop it travelling further.

Clive

[mechman48Participant @mechman48]

Posted by Clive Hartland on 23/03/2016 17:52:05:

Is it possible the makers have seen a start of a crack and to make sure it does not travel used a diamond tool to cut out the start of the crack to save the wheel? To stop cracks in metal you drill a hole at its start to stop it travelling further.

Clive

It is possible; but that's a dangerous & sharp practice, especially where safe operation is concerned… but if as seen they're unbranded… ?

Had a play about with MS paint just to see if I could highlight the 'crack/s & it's not my eyes playing tricks

Maybe a moderator could manipulate pics better than me?

George.

[BC ProfParticipant @bcprof]

A few thoughts .

Have Chronos refused to accept a return?

Can they show similar holes in other wheels ?

Would Matt be prepared to stand in front of the wheel while it is spun up to its maximum rated rpm?

[Ian ParkinParticipant @ianparkin39383]

I'm sure that my wheel is as makers intended

I cant believe that any stone maker would risk the dangers of a stone exploding by drilling holes in it to stop cracks spreading especially on a £12 wheel

I'm sure as Chronos has said its part of the manufacturing process

are wheels moulded early in the process ? and the holes are from the mould for whichever reason

The wheel is definitately NOT cracked in any way

It rings and it runs true and works well on carbide …the reason I bought it

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, as far as standing in front of a grinding wheel of this type while it is run up to speed, is something you should not do even if you have no doubts about the soundness of the wheel. If a wheel is going to burst, the most likely time is when it is getting up to speed even if there is no reason to believe that it is not faulty.

As far as the holes in Ian's wheels is concerned, only a qualified technician would be able to give a reliable answer. I would probably be a bit reluctant to use it, but if it really has been moulded that way, it is likely to be OK, if, however it had been drilled for any reason, I would definitely not use it.

I wouldn't think that they have anything to do with balancing, as these types are balanced by the manufacturer by vibrating chalk into them in the correct places, if they need finer balancing they would be done with adjustable weights that would be incorporated into the clamping flanges either side of the wheel.

Regards Nick.

[peak4Participant @peak4]

Posted by John Pace on 23/03/2016 10:07:40:

Might be worth having a look at this video by Don Bailey
from Suburban tool in USA.

"How to dress and balance a surface grinding wheel"
In this 13 minute video the principle points of interest
are at 9 min 31 seconds and 10 min 34 sec .

There are many more interesting videos from Suburban
tool that are worth watching for people interested in grinding.

John

Did anyone look up the video that John mentioned?

Here's the link to make it a bit easier.

I've no experience of the validity of the method personally.

[MWParticipant @mw27036]

Well i've had a look around online at alot of pictures of grinding wheels and despite having seen some interesting wheels i've never seen before i can't see any with any holes on them.

Ian, what are your thoughts about the purpose of this hole? I believe you when you say it's not cracked, a cavity would not break up in such an even manner. At any rate its so far away from the periphery to be an issue at the point of contact with the tool.

Michael W

[Ian ParkinParticipant @ianparkin39383]

I have absolutely no idea what they are for …thats why I was asking never seen anything like this before

I have a total of 4 bench grinders and 1 TPG and have replaced wheels regularly as they get worn

AS I said in my OP they are moulded in and are nice round and flat bottomed

Chronos have confirmed thats how they are made..all their stock of these wheels is like that

I have brought it to their attention and they have said they are OK to use

Its a 5" small grinder I keep close to the lathe for touching up or modifying carbide bits

I know all grinders are dangerous but I would be more concerned with a 8" or larger machine

[WatfordParticipant @watford]

.
The labels on both sides of the wheel show signs of deterioration/staining, does this denote age?
It is strange that the peeeling back is adjacent to the holes.
Holes of the size shown would seriously effect the balance, so either it was balanced by unusual means OR is out of balance now because of the holes.
Manipulation of the image showing the data label shows that the label/blotter has been placed over an old label still partly stuck to the wheel.
Best practice says that this should have been removed.
The readable characters on this lower label are clearly " xxxx 32-12.x ".
This additional label seem to indicate that the wheel is second-hand.
The wheel came from Chronos.
Whilst Chronos claim that the wheel is servicable could it be that a wrong item was picked at the time of dispatch?
In the light of all the publicity that has been given I would think that Chronos would like to have it back in their possession prior to a possible accident.

 

Mike

Edited By Watford on 23/03/2016 21:25:25

[Neil WyattModerator @neilwyatt]

Posted by mechman48 on 23/03/2016 18:18:51:

Maybe a moderator could manipulate pics better than me?

George.

I had a play, but (a) I clearly think the crack is in a different place to you and (2) image enhancing was not conclusive.

I wonder if we are deluding ourselves?

Neil

[peak4Participant @peak4]

Posted by Watford on 23/03/2016 21:23:44

Holes of the size shown would seriously effect the balance, so either it was balanced by unusual means OR is out of balance now because of the holes.

Mike

Edited By Watford on 23/03/2016 21:25:25

I'm most certainly no expert on this, never having been formally trained as an engineer, (other than with telephone exchanges).

Here's a guess for you; From what I understand, wheels on a surface grinder normally have an oversized hole compared to the spindle size, such that they can be fitted to an arbour and balanced via adjustable weights.

On the other hand, wheels fitted to a small, simple, cheap, double ended bench grinder have holes the same size as the spindle to give a snug fit, and are often lead lined to further help the snug fit.

As such the balance (as opposed to side to side wobble) can't be adjusted, so perhaps it is done at the factory where the wheels are made. One method of this would be to remove a small amount of the material, as per these dimples; perhaps they are not moulded in, but are cut in, to balance the wheel. This would concur with the video that John posted earlier.

[Ian ParkinParticipant @ianparkin39383]

Posted by Watford on 23/03/2016 21:23:44:

.
The labels on both sides of the wheel show signs of deterioration/staining, does this denote age?
It is strange that the peeeling back is adjacent to the holes.
Holes of the size shown would seriously effect the balance, so either it was balanced by unusual means OR is out of balance now because of the holes.
Manipulation of the image showing the data label shows that the label/blotter has been placed over an old label still partly stuck to the wheel.
Mike

Edited By Watford on 23/03/2016 21:25:25

Theres only one label on each side

They were clean yesterday morning when it arrived

The staining is where my flange washers gripped the wheel

I pulled /peeled the blotters back to see the holes after one blotter lifted slightly it was then that I noticed these holes

[Enough!Participant @enough]

Posted by peak4 on 23/03/2016 21:45:46:

On the other hand, wheels fitted to a small, simple, cheap, double ended bench grinder have holes the same size as the spindle to give a snug fit, and are often lead lined to further help the snug fit.

Hmm never seen one like that – almost wish I had. The ones I get have a 1" dia centre hole to fit my 1/2" dia spindle and are filled with a series of plastic bushes to take up the slack. Unsurprisingly the fitted wheel needs a fair bit of balancing.

[Ramon WilsonParticipant @ramonwilson3]

Hi guys,

I don't visit here anywhere near what I used to but tonight I did and this took my eye immediately. I hope you won't mind this rare input but I do feel I should say something

For what it's worth I spent the best part of fourteen years at one company surface grinding on a virtually daily basis using Jones and shipman 540 and 1400 surface grinders. Much of the work was form grinding so wheels were constantly being changed throughout the day as opposed to just occasionally. Wheels varied from 6mm to 20mm wide and 150 to 200mm diameter in varying grits, bonds and hardness. In all that time I have never, ever, seen a wheel with holes formed in as shown. That does not mean to say they are not 'correct' just that it appears exceptionally unusual to me. I should perhaps point out that despite the potential for complacency due to familiarity wheels were always treated with the utmost respect

It does look as if it's 'manufactured' but as several here have iterated a flawed grinding wheel is indeed a seriously dangerous thing to be near if it 'lets go'. Personally, unless the company can give an absolute assurance that it's a manufacturing process seen on all similar wheels by the manufacturer I would hesitate to put it to use.

Several years ago there was a case here in Norfolk where a man died as a result of a grinding wheel bursting and severing an artery in his arm. That was in a home workshop, rare yes but once is one too much. The case was used as an example of what can go wrong on locally held grinding wheel courses.

I don't want to be seen as raining on someone's parade by being so safety conscious but better safe than sorry.

Regards – Ramon

 

 

Edited By Ramon Wilson on 24/03/2016 00:03:44

[TendorParticipant @tendor]

The maximum tensile stress (tangential direction) in a rotating disk with a central hole occurs at the cylindrical surface of the hole (i.e. minimum radius) and reduces as the radius increases (to about 1/4). Removing a concave dimple near the inner radius will increase local stresses further (stress raiser). If the material has a sufficiently high fracture stress compared to the peak local stress – no matter. But why unnecessarily increase maximum stress? The only possible purpose I can think of is post-manufacture balance. One then wonders whether the manufacturer knew his business. I encourage further investigation beyond the retailer.

[Clive HartlandParticipant @clivehartland94829]

In most cases where I have seen balancing adjustment the weight is removed around the periphery of the rotating mass. Why then adjust balance so close to the middle of the disc? This is where it would have the least effect.

Clive

[mechman48Participant @mechman48]

Posted by Neil Wyatt on 23/03/2016 21:41:24:

Posted by mechman48 on 23/03/2016 18:18:51:

Maybe a moderator could manipulate pics better than me?

George.

I had a play, but (a) I clearly think the crack is in a different place to you and (2) image enhancing was not conclusive.

I wonder if we are deluding ourselves?

Neil

Thanks… maybe my eyes are giving me optical 'delusions'. I think the general consensus is of the opinion not to use it albeit …' It rings and it runs true and works well on carbide …the reason I bought it '.

I reckon the only way of resolving all our queries/comments is a statement from the manufacturers ( India China ? &nbsp explaining exactly how & why the indents are there & how it has been balanced.

George.

[Russell EberhardtParticipant @russelleberhardt48058]

Just a couple of observations:

1. If the holes are moulded in as the OP states and seems to be most likely they could not possibly have anything to do with balancing. If they are symetrically positioned and the same size they will not upset the balance.

2. As has been pointed out they will be stress raisers. Whether or not the stress is raised significantly to cause a problem only the manufacturer can answer.

Why are they there? We can only speculate. They must be intentional. Could it perhaps be to suit some specific machine which has driving pegs on the flanges?

Russell.

[Neil WyattModerator @neilwyatt]

Posted by Russell Eberhardt on 24/03/2016 09:20:02:

Why are they there? We can only speculate. They must be intentional. Could it perhaps be to suit some specific machine which has driving pegs on the flanges?

You could well be right there, although such a driving arrangement sounds fraught with hazard.

Neil

[Clive HartlandParticipant @clivehartland94829]

It should be easy to look at the holes and see if they are as cast or intentionally machined in with a diamond burr.

The diamond would should a surface that has cut grains as it worked, cast in would show open pores of grains.

[Steven VineParticipant @stevenvine79904]

Posted by Ian Parkin on 23/03/2016 09:14:10:

Just had this in from Chronos

Hello

 

Thank you for the email, the hole is a result of the manufacturing process and it won't affect the performance.

 

Regards

 

Matt

 

Chronos

 

 

Hi Ian

Would it be possible to take the matter one step further with Chronos.

Could you ask Matt if he could explain what specific part of the manufacturing process has necessitated the inclusion of the holes.

Can Matt ask the manufacturer to give their reason for the holes being there.

Steve

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