Thread: Bench grinder vibration

My bench grinder has a very annoying vibration, not severe, just enough to make it unpleasant to use.
Interestingly, the vibration stops as soon as the power is cut, and coasts to a perfectly smooth stop.
Bearings are not worn, and wheels are secure.
Any suggestions greatly appreciated.

Have you tried taking one wheel off at a time?

Originally Posted by ptrott

My bench grinder has a very annoying vibration, not severe, just enough to make it unpleasant to use.
Interestingly, the vibration stops as soon as the power is cut, and coasts to a perfectly smooth stop.
Bearings are not worn, and wheels are secure.
Any suggestions greatly appreciated.

Mine had the same problem. You can try buying a new grinding wheel, or I built a belt sander attachment for mine. I made a video describing exactly your problem and my solution.

https://youtu.be/-Bp_TB87PxY

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Originally Posted by A J in WA

Have you tried taking one wheel off at a time?

I have, and it doesn't matter which one I remove, it stops the vibration.

Originally Posted by Weekend.Warrior

Mine had the same problem. You can try buying a new grinding wheel, or I built a belt sander attachment for mine. I made a video describing exactly your problem and my solution.
https://youtu.be/-Bp_TB87PxY

Funny you should post that, as I recently joined a facebook page dedicated to home build belt grinders, but they seem to require a fair bit of shed realestate which put me off.
This on the other hand only requires a bit of height, which I have plenty of
Thanks for that, it is certainly an option.

Take both wheel off run machine, if it vibrates then it is the machine, bent shaft warn bearing ( crap brand ) check wheel(s) are not cracked, balance wheels and reassemble should be fine

Did dressing the wheels have any effect?

Could it be that with two wheels on you have just the right mass for the inherent vibration in the motor when powered (I presume a single phase motor) to trigger the resonant frequency of the system (= grinder + bench or stand)? If so maybe adding mass (eg. heavy plate under the grinder) or some damping to the system would help.
My little Bergin bench grinder came with soft 'grommet' style rubber feet that even after 4+ decades seem very effective as dampers, both when free standing or screwed to the bench.

This type of problem also seems to happen with grinders mounted on floor stands made of thin sheet steel.

Bill

Originally Posted by WCD

Could it be that with two wheels on you have just the right mass for the inherent vibration in the motor when powered (I presume a single phase motor) to trigger the resonant frequency of the system (= grinder + bench or stand)? If so maybe adding mass (eg. heavy plate under the grinder) or some damping to the system would help.
My little Bergin bench grinder came with soft 'grommet' style rubber feet that even after 4+ decades seem very effective as dampers, both when free standing or screwed to the bench.

This type of problem also seems to happen with grinders mounted on floor stands made of thin sheet steel.

Bill

Hello from BC.
If you have toolroom wheels with a srtipe going from centre to rim the wheels should be mounted with the stripe upwards. This is the heavy side and the slack at the hub helps to balance the system. If they are GP wheels loosen 1 at a time and turn 1/4 turn and retighten. You will find the sweet spot for each wheel like this but complete one wheel at a time. A lot of the problem is caused when the rotor is stick welded to the shaft. Usually both on the same side. Also don't dress the side of the wheels as these can be vapour blasted to balance the wheel. Good quality wheels make a difference but to find them?

Both wheels have been replaced at different times with supposedly good quality ones, and it did improve the issue, but didn't cure it.
It is mounted on a stand made of very thick walled square tube as the vertical, with a steel wheel rim as the base.
The harmonic vibtation suggestion seems to fit, because as soon as the rpms drop a fraction after powering off, it is as smooth as silk. I recon if I could run it at 50rpm less it wouldn't do it at all.
I'll try some of the suggested remedies over the next couple of days, might get lucky.
Cheers.

Originally Posted by ptrott

Funny you should post that, as I recently joined a facebook page dedicated to home build belt grinders, but they seem to require a fair bit of shed realestate which put me off.
This on the other hand only requires a bit of height, which I have plenty of
Thanks for that, it is certainly an option.

I'm most likely going to upgrade it to accept a 4" belt, which are easier to find in a variety of grits. This project is a very easy welding project and it is 1000 times more convenient than the old grinding wheel. If you do decide to make it, please comment on the video any suggestions for improvement. Thanks!!

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Originally Posted by Weekend.Warrior

I'm most likely going to upgrade it to accept a 4" belt, which are easier to find in a variety of grits. This project is a very easy welding project and it is 1000 times more convenient than the old grinding wheel. If you do decide to make it, please comment on the video any suggestions for

No probs. Definitely considering it.
Are there reasonable priced and range of belts available in Aust. or are you looking at elsewhere?
Also, most of the grinders with wide belts seem to use 2 to 4 HP motors, so how do you recon the bench grinder motor will go?

Originally Posted by ptrott

No probs. Definitely considering it.
Are there reasonable priced and range of belts available in Aust. or are you looking at elsewhere?
Also, most of the grinders with wide belts seem to use 2 to 4 HP motors, so how do you recon the bench grinder motor will go?

I never thought about the motor. That is a good point. Mostly I was thinking that I dont have problems now, and that the 4" belts are easier to find at my local supply store here in Texas.

If I have to upgrade the motor, then I would have to have an altogether much larger machine, which wouldnt fit on my small workbench. I also dont gave a lot of room in my suburban garage for a big grinder.

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Hi Weekend.Warrior,

Most small 500-750 Watt bench grinders will happily run a 100 mm abrasive belt. Problems arise when you want to do more than the motor is capable of. I have a commercial 100 mm belt grinder and it only has a 350 watt motor, as long as you don't put too much pressure on the belt, it does fine.

I also have a home brew finger sander that uses a 13 mm wide belt that I built using a 100 watt 3000 rpm pump motor. Now that one just rips metal off if you press too hard.

The bottom line is how much metal do you want to remove and how fast !

[QUOTE=ptrott;1960465]Both wheels have been replaced at different times with supposedly good quality ones, and it did improve the issue, but didn't cure it.
It is mounted on a stand made of very thick walled square tube as the vertical, with a steel wheel rim as the base.[QUOTE]
How does it run if you take it off the base? Just on a bench.

The harmonic vibration suggestion seems to fit, because as soon as the rpms drop a fraction after powering off, it is as smooth as silk. I recon if I could run it at 50rpm less it wouldn't do it at all.

Ah, . . . . one of the benefits of a 3P powered grinder on a VFD.