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Taking the woble out of a Grinder

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sbwhart:
Hi Madmodders

When I first set up my shop I needed a grinder my Dad bought me a el-cheepo grinder from B and Q that served me well until a few months ago the switch broke, rather that fix the switch I'd thought I'd buy another el-cheepo grinder from B and Q £15 squid or £13.50 with the old git discount on a Wednesday.



When I set it up and switch it on the wheels wobled like hell setting up an almighty vibration (ok girls form a line one at a time) :lol: I checked it over didn't like the look of the wheel nuts swaped them with ones off the old grinder no better swaped the wheels no better, at this point I gave up and got on with something else, but all the time it niggled me.

Decided to have a closer look at it and didn't like the look of the shaft, the dia the wheel locates on is only just smaller than the support step and with a radius on the corner the wheel washers wont sit square.



To fix the problem I would make some bushes held on with grub screws, had a look through my scrap box I don't throw out any bits a metal no matter how small.



And found these stubs of bar ends 30mm dia just the job.



Faced them off to thickness centre drilled then drilled and then bored them out to a nice fit on the shaft



Drilled and tapped them M5 for grub screw



This is what they look like on the grinder giving a nice flat face for the wheel to clamp up to.



Next job the mounting washer these are a pressed out components and I suspected the faces arn't parralel. So back to the scrap box and found an old mandrel i'd made for another job set it up in the lathe and turned it to match the bore in the washer. Tightened the washer on to the mandrel and checked the run out on the face as I suspected it was running out by about 1mm, so faced it up to correct the run out.



you can see the run out in this picture by how its cleaning up.



Washer cleaned up.

Put it all together dressed the wheel and it was a vast improvement.

OK  now a few things grinding wheel safety.

1:- Always check the speed rating on the wheel.

2:- Check the Wheel for bits missing scrap it if you find any

3:- Check the wheel for cracks by giving it a tap if its ok you'l get a clear ring if its cracked a dull thud, try it on a cracked cup.

4:- Use mounting washers of equal size giving good support to the wheel

5:- Use paper washers between wheel and mounting steel washers.

6:- Always keep the wheel guards in place.

7:- Keep the tool rest close to the wheel

8:- Use the eye sheild and wear safety glases.


Ok  How to dress the wheel'

Dressing the wheel does two things it trues the wheel up and it keeps the wheel sharp: the bits of grit can become blunt and the wheel can clog up.

To dress the wheel you need some safety kit Goggles and a face mask its a dusty job

And a dimond dresser and or a carborundum stone







Make shure the rest is up close to the face of the wheel and slowly dress the face of the wheel with the dimond followed by the carborundum stone.

Reset the rest up to the wheel and away you go job done.

Stew

bogstandard:
Nice instructive topic Stew.

You being an ex grinder man, you know how it should be done

Almost everyone has an offhand grinder, but most don't know that they are a piece of machinery that needs to be serviced regularly to keep it working as it is supposed to do, plus of course doing it safely. To a lot of people it is just a lump of filthy electical equipment stuck in a corner, with rounded over wheels, that when you stick a bit of material against the wheel it grinds the end to some sort of shape. They don't realise it is one of the major assets of a workshop, and when used and dressed correctly, the world of tool grinding opens up to them.

I would like to mention that non ferrous materials shouldn't go anywhere near an off hand grinder wheel. Not only does it clog the wheel, it can also split bits off the wheel like shrapnel, when it pentrates into the fibre of the wheel and pushes the bonded grains apart.

John

Darren:
That reminds me, I need a new grinder as mine has lost it guards.... :doh:

sbwhart:
Keeping the wheel well dressed and sharp means you won't burn the work as much:- forgot about that one  :doh:

Stew

old-biker-uk:
Thanks Stew
I was about to strip down a friends cheepo grinder & turn a decent step on the shaft, now I don't need to.
Mark :bow:

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