Bench Grinder wheel balancing.

[banjaxed]

Are there any bench grinder wheel balancing experts here ? I bought a bench grinder but had to return it as it was impossible to balance the wheels. Thought I would spend a bit more and bought a better one, same problem. It was replaced and I spent a few hours trying to balance the wheels but still no success. I have tried two methods of balancing and scoured YouTube for tips but still no luck. I consider myself to be very practical and have built and fixed all sorts of things over the years but this has got me stumped. If anyone can suggest any tips or methods to stop me from scratching my head it would be greatly appreciated.

[teoria_del_big_bang]

I have spent a lifetime balancing grinding wheels, but ones a meter or two in diameter not on a bench grinder. And these have weights in the wheel hub to balance them, in later days weights that can be moved automatically whilst wheels running using sensors and a wheel balancer unit.

But from experience one main issue might be the bore in the wheel is a fair bit bigger than the hub on the wheel spindle so it is off center so it may pay to shim the bore a little with paper off-cuts. The bore must be slightly bigger than the hub otherwise you may crack the wheel but not too much. Then you would need to dress the outer edge of the wheel so it was also running true.

I would have thought that would be plenty for balancing a wheel on a bench grinder.
You can get heavy and light spots in Aluminium Oxide wheels that can effect balance slightly but these really only show significantly on larger diameter wheels that are running fast at 40M/S and above peripheral wheel speed, smaller wheels running slower will not be affected enough to vibrate badly.

I do not know if any of that helps 🙂 

Steve

Edited July 30, 2021 by teoria_del_big_bang

[CraigT82]

My own grinder is a bit wobbly but it is usable, just about. 

First thing I did was use chalk on the slowly rotating wheel to mark the 'high' points of the outside of each wheel, and then rotated the wheels on the arbor so that the high points were opposite each other. 

Then I checked the outer securing flanges holding each wheel on. The hole in the flange was quite a bit bigger than the shaft and so they tended to sit off centre after tightening up and creating some inbalance. A few wraps of electrical tape on the shaft helped to centre the flanges. 

Finally I dressed the wheels using a draper tool which took a good while but again made a bit of a difference. It's not great buts it's fine for my needs and is much better then it was out of the box. 

[teoria_del_big_bang]

Oh also when you have balanced best you can and there is still a bit of vibration if you can bolt the grinder down to a bench it will dampen the vibrations further.

Steve

[banjaxed]

Thank you for your replies. I have tried all the points made here till I am pulling my hair out. Dressed the wheel, turned the wheel in small increments, turned the arbour washer in small increments, used tape as spacers and bolted it down to the bench so that everything on the bench rattles. There does not seem to be a lot of side movement in either wheel (barely noticeable) and dressing the wheels has made them perfectly round. I have even removed both wheels to be sure the shaft is true and it runs perfectly which is why I am completely at a loss at what to try next. 😕

[teoria_del_big_bang]

Is the motor and spindle in balance if you run it without the wheels ?

All sounds very odd.
 

Its a bit drastic but as you probably can work out to get good balance the wheels need to be balanced themselves and also the spindle and motor need to be in balance before putting the wheels on.
Normally in my work we would have a machine that determines what angle the out of balance is and how much it is out of balance. So on the flange we would then either drill holes at that angle to lighten the point that is out of balance or more often than not there would be a series of tapped holes around the flange we would add grub screws of varying lengths opposite the out of balance.

Now obviously you do not have a machine or the tapped holes but you could do it my trial and error and drill a hole and see if it gets better. If it gets worse you can always tap it and add a grub screw if you use the right size drill, and then drill opposite.

If you can balance the spindle then you can try the wheels on, buying some good quality replacement wheels could help if the wheels are badly out of balance.

I have no idea how the spindle is driven but I am guessing unless an expensive grinder it is a separate motor and belt. In that case if its the motor itself vibrating then you would have to get the motor balanced.

Steve

[banjaxed]

Hi Steve,

The thing that bothers me is that this grinder has over 255 star reviews and how good it’s performance is and how easy it is to set up and balance. Thinking about it the first one had some rust on one side of the shaft and on inspection the second one has some rust also which I lightly sanded. Maybe this has some bearing on the balancing. I thought about drilling holes in the wheel but if it didn’t work it would be a problem to return it.

[teoria_del_big_bang]

which one is it ?

[banjaxed]

It is the Titan 400 watt  8” model from Screwfix.

[teoria_del_big_bang]

After watching these two videos I would be tempted to return it if you still can.

Out of the box it seems they are not brilliant, the 2nd video shows how to get the best out of it but even at the end it is not great.
In a way I think this will be true for all grinders certainly under £50, I think all will vibrate to a reasonable extent, even the same grinders some will be better than others it will just be pot luck how good yours is, but some models will be better and generally the more you pay the better.

Anyway see if the 2nd video helps at all or just persuades you to take it back. The 3rd video is for a different make but goes a bit deeper into the pitfalls of these cheap grinders and how to get best out of them.

1st Video         2nd video           3rd video

Hope they help

Steve

[banjaxed]

Thanks for your input Steve, I think you are right about sending it back. I only wanted one to do small jobs like sharpening tools, drill bits and the like so it does not warrant spending a lot more.

[teoria_del_big_bang]

I actually found these better and easier to use for sharpening drill bits, chisels, knives etc.

Sharpener

They are practically useless for constant use sharpening loads of stuff as it is a slow process to use, but for but for the odd chisel or drill it does a really good job and so easy to get the correct angles.
All that is left to do is a bit of a rub on a strop and they are as sharp as can be.

Steve

 

Edited July 30, 2021 by teoria_del_big_bang

[fwm891]

Last time I bought a grinding wheel for my bench grinder it came with a few different plastic spacers to fit the wheel to different shaft sizes. Failing that measure your shaft size and get a wheel to match it.

[banjaxed]

Thanks again for all your input and suggestions. I have decided not to waste any more time on this grinder and I am going to return it. That sharpener looks like a good idea Steve, might be more suitable for what I want.

Edited July 31, 2021 by banjaxed

[teoria_del_big_bang]

1 minute ago, banjaxed said:

Thans again for all your input and suggestions. I have decided not to waste any more time on this grinder and I am going to return it. That sharpener looks like a good idea Steve, might be more suitable for what I want.

I like it for the few times I do any sharpening.
Don't expect miracles it is quite easy to push too hard and stop the wheel so you will struggle to take out big gouges in your chisels if you have hit a nail or something (talking wood chisels here not bolster or masonry ones) but to put a real nice sharp edge on wood chisels, knives, scissors etc with a bit of patience they are great (in my opinion), I have had one for years.

Steve

[Dr_Ju_ju]

I've had one of those linked sharpeners for a number of years, and as Steve says, don't expect to get accurate results, but for quick jobs, especially a quick drill bit honing etc., they are ideal.

For super accuracy, angles & square cutting surfaces etc., I have an oil-stone with accurate jigs, which takes a little longer to use, but for plane blades, which require dual angles, will always produce the best results.