Grinder wheel replacement

[roombacurious]

Following my only partially successful attempt to grind my index finger down (see post in General Woodworking forum...) I was at least happy to see that my finger was not the only damaged party - a chip seems to have come off the grinder's wheel as well! It's not very big but I'm not feeling very safe using it like this so I'm thinking to replace the wheel in question.

I've read elsewhere that grinder wheels should only be changed by a professional because they need balanced. Is this true?

 

[chicken_house_man]

Generally if you're being paid to use it should be fitted by a trained person. The level of training depends of the surface speed I think? If it's yours and you're using it at home there shouldn't be much of a problem with you changing it if you feel you are competant. If the chip isn't too large it may just dress out with a dressing tool.

 

[Digit]

Take the wheel off, hold with screwdriver in the hole and tap it gently with a small hammer and listen! If the wheel is cracked there will be a dead sound. If it's ok it will 'ring'.
If you have a bench grinder you should also have a dressing tool, used as needed it will keep the wheel in balance.

Roy.

 

[Harbo]

Are we talking about the common and garden grinders here - the 6" or 8" types because I have exchange a few in my time and I ain't no professional.

I would have thought as long as the holding nut was tight and it runs without too much vibration (if any) then things were OK?

Rod :?

 

[Digit]

If the wheel is 'dressed' it shouldn't vibrate at all.

Roy.

 

[PowerTool]

Oooh,I'm trained in replacing wheels on bench grinders and angle grinders!
Did it as part of the machinery lessons at agricultural college - as already mentioned,doesn't apply to home use;believe it is only relevant to workplaces coverd by the Factories Act,in which case anyone changing abrasive wheels must be A)suitably trained,and B)named on a register kept by the employer.

Andrew

 

[roombacurious]

My grinder is a pretty standard 6" one, just for DIY use.
I think changing the wheel is pretty silly person-proof, I'm only worried about the balancing in case any excessive vibration gradually weakens the wheel making it more prone to shattering.

BTW, another question: Is it safe to use the side of the wheel (not the circumference in front of the tool rest, the larger area at the side) for grinding - e.g. for wider chisels. Again with regards to weakening the wheel or other risks.

 

[Digit]

The suggestions I made earlier are the standard checks that should be made when changing any wheel, even new from the box. But all wheels should be dressed regularly, this not only helps maintain the balance but frees unclogged grits for fresh sharpening.
Diamond dressers are quite cheap and a balanced wheel is much less likely to fail or course premature wear of the grinder's bearings.

Roy.

 

[Anonymous]

BTW, another question: Is it safe to use the side of the wheel (not the circumference in front of the tool rest, the larger area at the side) for grinding - e.g. for wider chisels. Again with regards to weakening the wheel or other risks.

Generally speaking the answer is no, unless the wheel is designed for face grinding. However many people still use the sides and I've seen jigs etc that can only be used that way?
I do use the sides but only with very light pressure, never enough to wear the wheel to the point it gets undercut.

 

[lurker]

Power tool, just to bragg - I can beat that!! I'm a qualified Abrasive wheels instructor :roll: :lol:

Room',

Don't worry!! you are unlikely to have a machine thats balance -able ( these have inbuilt counter balances).

If you have a chip, don't muck around just replace the thing!! a wheel rupture is very dangerous and people have lost their eyesight as a result.

Have you seen Phillys post about those 3X wheels??


Bung in a new wheel, you can do the "ring test" beforehand:

- put a scrap of wood or pencil through the wheel hole (do not touch the wheel otherwise) an sharply tap the side of the wheel with another pencil
repeat at every 90degrees - it should "ring"

Mount up the wheel (all guards in place) and good eye protection for yourself - run up and it should be relatively vibration free.
Give a gentle dress with devil stone and away you go.

 

[pooka]

For info, according to Lee Valley even a dressed wheel can be out of balance, and they sell a specific balancing kit to sort out such wheels:

http://www.leevalley.com/wood/page.aspx?c=3&p=49226&cat=1,43072

I wonder how difficult it is though to distinguish between a wheel which can be safely balanced like this, and one which is just plain unsuitable for use due to being badly made in the first place (although you'd hope that the latter would never get as far as being sold).

 

[lurker]

I can't see how this kit would be much use. But I can see how someone could make things a whole lot worst with it.
I've never known anyone be able to understand wheel balancing from written instructions. Its one of those things you need to see demonstrated and then try yourself in the company of an expert

Although we are saying wheel balancing its really about equalsing the shaft loading.

For most of the small machines we use in woodwork any misbalance is negligable.

I'd suggest that if anyone has a badly vibrating machine to just loosen one of the wheels & rotate 90 deg on the shaft & try again.