What really causes GRINDER WOBBLE?

[fobos8]

Evening fellow woodworkers.

I've recently been looking at buying a bench grinder to sharpen my chisels - see this thread https://www.ukworkshop.co.uk/forums/viewtopic.php?t=30427.

I was about to buy a Record 8" grinder but have noted that quite a number of users have a problem with the wheel wobbling/machine vibrating. This seems to be a problem with a few other brands of grinders aswell.

Are wobbling wheels purely caused by out of true wheels. If so this can be cured dressing.... right?

...... or are wobbling wheels due to the grinders being rubbish? in which case dressing will not resolve the problem.

I hope you'll appreciate that I have no experience of grinding as yet. All my sharpening is done on diamond stones.

I don't want to end up buying a cheap grinder which wobbles if it will be better to spend a bit more money to get a decent one.

Thanks in advance, Andrew[/url]

 

[Modernist]

The problem is more likely to lie in the wheels than the grinder. I think Record can be relied upon to provide a true shaft and decent bearings but cheap wheels are likely to be out in the truth in the bore.

Decent stones from Norton etc and specialist stones for woodtools which are now widely available will be a bettter bet. Either that or buy a machine with those on already.

You can only really dress the circumference of a grinding wheel on a bench grinder so if the bore is true then that will give you a balanced wheel when dressed.

Maybe someone has experience of such machines "off the shelf"

Brian

 

[matthewwh]

Try running the grinder without a wheel on, if all is quiet and harmonious then the problem lies with the wheel.

Classic Hand Tools have the Norton grinding wheels which by all accounts sound excellent. I think Philly has one if you want a first hand opinion.

 

[Derek Cohen (Perth Oz)]

Grinder wheels - just like the wheels on your car - need to be balanced to run smoothly.

The way to balance a wheel is to make a mark (draw a line from the centre to the perimeter) and then rotate the wheel slightly (loosen it, move the wheel, tighten again). Keep doing this until you get the least amount of vibration. Do both wheels.

I once had a 10" high speed grinder that was well out of balance. It sounded like a jet taking off. It vibrated so much that it would walk off a bench top even if held down with a clamp. It scared the bejesus out of me!

Regards from Perth

Derek

 

[Philly]

Andrew
I have the 8 inch Record grinder - once its trued up it works pretty well. And, as Matthew says, I also have the Norton 3X wheel fitted - this is an excellent upgrade wheel and cuts really cool.
Hope this helps
Philly

 

[Ironballs]

I have a Scheppach Tiger and there's no wobble there

 

[Maverick.uk]

Grinder wheels - just like the wheels on your car - need to be balanced to run smoothly.

Very true!

In my day job as an Engineer all our grinding wheels fitted to our machines are balanced before mounting and sometimes again after true ing. This is enabled by the wheels being carried by a mount that has wheel weights built in. This is mounted on a leveled set of bars and is checked and weights adjusted until it runs true.

However with off hand grinders as we refer them you do not normally balance them because the finish is not critical in the work they do.

As has been suggested quality of the wheel can have an impact the density across the wheek is never uniform and hence the out of balance.

Gettinga balanced wheel on your off hand bench grinder is going to depend on how the wheel is carried, but the suggestion of finding the heavy spot and loosening and tightening to see if you can improve is a good one, but again it will depend on the design of the grinder.

Cheers

Mav

 

[Joel Moskowitz]

with a bench grinder there is enough play in the bushings and wheel bore to make any balancing attempt a waste of time. However after you mount the wheel dress the rim (never dress the sides of the wheel) and the wheel will run true and balanced.
if you have a little side to side wobble it doesn't effect much because the weight of the wheel is still balances around the axle (any play in bore is so small and near the center of axis that it doesn't effect balance).
IF you have significant side to side wobble check your axle and side mount of the wheel with a dial indicator to see if it is runout - or you just may have dirt somewhere.

machine grinding equipment works to an entirely different level of accuracy.

 

[Maverick.uk]

IF you have significant side to side wobble check your axle and side mount of the wheel with a dial indicator to see if it is runout - or you just may have dirt somewhere.

machine grinding equipment works to an entirely different level of accuracy.

Agreed, if you have side to side wobble there is something wrong, machine, spindle or wheel.

Cheers

Mav

 

[Jamesc]

Having refurbished a couple of grinders the most significant fault I found was the washers either side of the wheel. On both the machines I worked on recently they were rubbish. They were die cast items but in both cases the center hole was not true, the faces pressing against the wheel were rough (as cast) and in one case the centre hole was too big.
Fortunately I'm a metal worker with woodworking interests so I made new washers. The results were dramatic, I went from bucking broncos rumbling across the bench to almost whisper quiet.
its definitely worth checking that the washers at least look right on any prospective purchase.
I'm sure I recall seeing replacement washers for sale somewhere but not needing them myself didn't make a note.

Regards

James

 

[ivan]

Wheels are fired like bricks, and can distort in the firing, so no wheel is likely to have zero run out. Side to side wobble due to the wheel itself is something you have to live with. Dressing removes most of the vibration and should be repeated as the wheel glazes over from use. LV sells a balancing kit for offhand grinders, but you're not likely to find one in an engineering supplies catalogue (ie, bit of a gimmick)

 

[Maverick.uk]

Wheels are fired like bricks, and can distort in the firing, so no wheel is likely to have zero run out. Side to side wobble due to the wheel itself is something you have to live with.

But should be minimal.

In all the wheels i have mounted it has never caused excessive wobble on an off hand grinder, which is why i wonder if there might be something else amiss here.

Cheers

Mav