# Bench Grinder Balance Plate



## Ray C (Dec 8, 2012)

Here's one you'll either like or hate...

One of my grinders died and I picked-up a HF grinder for 39 bucks.  Not half bad but, one wheel was way out of balance.

Took a piece of aluminum out of the drops bucket, cut a slot and welded some weight on the end.  First I found/marked the heavy end then, added the weight.   Globbed a little extra bead to make it heavier and ground down the edges.   How did I calculate the weight?  -Took a WAG!  Of course, when using the side of the wheel, I'll have be a little more careful -but I can live with that.

Had to test and adjust the radial position a couple times but, it's smooth as silk now.  And yes... the buffer pad is missing in the photo but it's installed now.

BTW:  It really helps to balance the bench grinder wheels.  Makes the bearings last a lot longer.

Ray


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## Tony Wells (Dec 9, 2012)

That strikes me as exceedingly dangerous. In the first place, if the wheel was that far out of balance, new, it is clearly defective. There is no way I would put one on a grinder like that. I've seen the results from an exploding wheel more than a few times, and once a superb tool and cutter grinder (man) lost an eye to one. 

For another, as I'm sure you know, you used a static balancing method, and wheels are dynamically balanced at the factory if there is any balancing to be done in the first place.  And as the wheel wears, your static balance is no longer correct, even as a static balance.


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## pineyfolks (Dec 9, 2012)

Spend $20 on a new wheel , get the right wheel for the material you are grinding and save someone from getting hurt when that thing flies apart:nono:


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## Ray C (Dec 9, 2012)

As mentioned, you'll either like or hate this.   But first, as everyone knows, always wear a face shield when grinding -no exceptions.  I use the wire mesh thing that HF sells.  Also, I always use buffer pads and side covers on bench grinders.  

Wheels... I'm convinced there are no more quality wheels anymore.  Last year, I purchased a half dozen 7 & 8" wheels for the surface grinder.  Only one was OK.  All of them were Norton except the one that balanced fairly well.  Last week, I replaced all the wheels on the bench grinder.  Got two of them from Lowes, a name brand that I don't remember and they were out of balance and even wobbled side-to-side.  I returned those and the replacements were poor balance but otherwise OK.  The other two were from HF and they were half decent.

Now for the interesting stuff...  After installing one of the new 8" wheels on the SG, I was letting it spin for the requisite minute or so and POP, it fractured.  No great fanfare, just a POP, the safety caught the pieces and it rattled around until I hit the power.  The other one (7") was in use for several months and it made thousands of passes and was doing a fine job.  It was a finish wheel and never made a pass more than a couple ten-thousandths.  Out of nowhere, it too fractured during the spin-in procedure.  Same thing.  Went POP and rattled around.  BTW:  I'm extremely careful when handling wheels and have individual hubs for all of them that stay with the wheel.  I also use buffer pads -religiously.

I admit to breaking a bench grinder wheel by accident.  I had a 5' long bar that I had to grind both ends a bit.  While flipping the bar around to catch the other end, I whacked it into the wheel.  Same thing, POP and the safety shield caught the pieces.

Due to this streak of bad luck, I made hubs for all my wheels and have one balance hub that's working well (PDF of design enclosed).  I've only made one so far.  (For Christmas, I want a truckload of 1040 and 4140 so I can make the other 8 hubs).

I wish I could say the gizmo I rigged-up was a novel idea but, I basically made a fixed version of product that's on the market and one that I saw on a friends (beautiful Baldor) bench grinder which had an adjustable linear weight.  Enclosed are other examples of wheel balancers -it's not a new concept.   As for balancing, all procedures start-out with a static method to get it in the ballpark then you need to install it and fine tune it (i.e. a crude form of dynamic balancing).

 Interesting to note that many advertisements I see for grinding wheels and accessories never show buffer pads.

I've only broken one technical rule with the one on the bench grinder -no one picked-up on it.  All pressure plates are supposed to cover the center 1/3 diameter of the wheel.

Everything in our shops (aka: man-caves) is dangerous!  Grinding wheels are just another example.  It's when you attempt things out of ignorance, make careless mistakes or don't wear safety equipment is when you get hurt. 



Ray

PS:  On the PDF enclosure, you can click the image and use the mouse  buttons and scroll to rotate the image in 3D.  -Only works with Acrobat  Reader; clones thereof tend not to work.  BTW:  The CAD drawing was done with Alibre.


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## pineyfolks (Dec 9, 2012)

Home Shop Machinist vol28 no3  May-June 2009 , just a thought.


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## HotAire (Dec 9, 2012)

Put me down in the "HATE" list, you know - the Much LONGER list....

Tree things;

1. All-thread rod CANNOT be used. The treads will dig into the soft lead distorting ANY balance.

2. To "Balance" a stone or most anything, it has to be FIXED to the balance shaft where your is merely Dangling from all thread rod = don't work.

3. When that sloted piece comes loose (and it WILL!) it's gonna cause you some Real Damage. Imagine how much it's gonna cost you to have it pulled out of your arm then stitched back up.  Ain't worth it...

Suggestion: Look on You Tube for the guy that bought a Tool Grinder from Harbor Freight then Rebuilt it, you'll see many good ideas and how to balance a stone. It IS very easy, even the Right Way. Oh, get you a Diamond dresser to dress them with, those stones & spinning wheels are JUNK, a diamond will cut open the little balls they are made of giving a much better cut, just go easy with it as they will cut fast, eating up a stone.

Lastly, Harbor Freight DID NOT sell that Contraption you have thru the stone or mounted to it. That balancer was intended for a Motor Cycle wheel, that came with cones to center with.

Have never met "Murphy" but he sure has visited ME several times, Learn from your mistakes.

HotAire
hotaire@sbcglobal.net

.


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## Bill Gruby (Dec 9, 2012)

I'm sorry but what you did here Ray is an absolute no-no. I have been a machinist for some time now and have never seen a stunt like this on. There is no like or hate involved. It is just plain dangerous. Have you ever seen a wheel blow? It ain't pretty. You say make sure to wear safety glasses. Well if that counterweight decides to leave or even move, you will need more than safety glasses to insure you will not be maimed or worse.

 As Tony said, wheels are balanced at the factory. If you need that much weight to balancs it return it for a new on or can it and buy a new one.

 Newbies take heed, do not try this at home.

 "Billy G" :thinking:


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## llarson (Dec 9, 2012)

A friend has a big dent in his forehead from a wheel that blew up; he was lucky, he lived.


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## bcall2043 (Dec 9, 2012)

Ray C said:


> ...........  Also, I always use buffer pads and side covers on bench grinders.
> 
> Wheels... I'm convinced there are no more quality wheels anymore....................
> 
> ...



Ray,

Thanks for bringing up this interesting topic. We have all been down the "out-of-balance grinder" road or will be in this hobby. 

Sorry I have another dumb question. I am not familiar with the term “buffer pads” which you have mentioned several time in talking about grinder wheels. What does the buffer pad look like and how is it used with a grinding wheel?

About wheel quality.......I suspect that even the "brand name" suppliers have outsourced their product to reduce labor cost and increase profits. This does not mean their product is bad. However in my opinion with the learning curve of cheaper labor it is more likely the quality control process can fail during transition and.......well you see the results.

I normally use a face shield when grinding with a hand grinder and safety glasses when using the bench grinder. A few weeks ago I was talking with my son about getting a face shield that was smaller after seeing one that fellow forum member Charley D. was using at work. My son said that was a bad idea and told me of an accident where a worker was using one of those portable cutting wheel tools and it broke severing the artery in his neck. I did not get this old by taking short cuts however I do have a few scars from making bad decisions but I am learning. Think I have decided to use the full shield more in the shop. Maybe even look for a stronger one.

Benny
The Orphanage Never Closes


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## Bill Gruby (Dec 9, 2012)

Benny;

 Buffer Pads or paper blotters are the paper circles used on both sides of the wheel when mounting.

 "Billy G" )


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## Ray C (Dec 9, 2012)

Bill / All,

Since this is a homeshop site, it's probably best to stick to  conventional methods.  And I highly recommend that for most  situations.   BTW folks, for a brief time while earning my physics  degree, I did  research in rotational destruction analysis for the railroad  institute affiliated with my college.  THAT was some spectacular stuff.   We spun the daylights out of things!

At the very least, this is a good discussion about state of quality  control in grinding wheels.  I'm seriously beginning to doubt that  wheels are balanced  at the factory -at least anymore.  I've purchased several name brands  and all ranged from slightly unbalanced to so far off, I didn't even  try.    As I said, I had a brand new 8" wheel crack on it's initial  spin-up.  When I tried to return the ones to MSC, there was no refund.  3   wheels and 180 bucks gone in thin air.  I really wish the quality  control on these things were up to snuff.  On this grinder, the first  replacement I got from Lowes was so bad, the entire grinder was spinning  in circles.  That wheel is history now -not even going to mess with  it.  A badly unbalanced wheel is  dangerous.

I totally agree not to do anything you're uncomfortable with.  I also  spent many years rebuilding antique diesel engines and all  had external flywheels in the 50-300lb range spinning from 650 to 1800  RPMs.   Since most had single throw crankshafts, counterbalances were a  necessity.  The first thing we did was get rid of any old, rusty wheels  -and we destroyed them for the sake of others.  I've made many modern  flywheels and designed/built ones with  spring force mechanisms allowing the weight to move according to RPM.

FWIW, for the bench gridner, I did exit velocity calculations first but decided  not to do KE (kinetic energy) calculations because I knew I was working  with materials under 2 oz and well below what's considered "the speed  threshold" of 200 ft/sec -the speed at which things are considered  "ballistic".  That  said, this weight would have a hard time leaving the shaft since it's  captured at both ends.  If it could come off, it's exit velocity would  be 45 ft/sec (because it's radius is 1.5 inches).  Pieces at the edge of  a wheel for example would exit at 89ft/sec.  Putting into perspective,  these are  roughly the same exit speeds (actually less) of swarf coming off a piece  turned in a lathe -albeit at higher mass.  It about 2x less than a  carbide insert coming off a mill face tool.

And as a final test, I mounted the weight at it's extreme extension  alone on the shaft and spun it up.  -And of course, this is/was done in a  controlled manner!    As I suspected, it was totally anti-climactic and  basically no different than a slightly out of balance wheel.  Used in  conjunction with a slightly OOB wheel, it spins like silk.  And when  mounted with that wheel in the 180 wrong position well... it was just  unbalanced.

Since this is a highly charged topic and specialized like rocketry  and/or firearms modifications we'll leave it alone.  I would like to  follow-up at some point in the future about balancing mechanisms -both  static and dynamic. 


Ray

And for your viewing pleasure, here's pics of nice static balancer used  on all my chucks and dozens of other things.  It cost very little to  make.


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## Ray C (Dec 9, 2012)

These are the shields I use and have them located at every piece of equipment for easy access.  The wire one is surprisingly good and comfortable.  It distorts your vision a little bit but not as bad as you might think and you get used to it.  The "chemistry goggles" are used when there's a lot of swarf flying off the lathe but I dislike how they steam-up and get scratched.

I almost made a mistake once though when doing a lot of welding (which involves a lot of grinding).  I was switching back/forth between the wire shield for grinding and the welding helmet for welding.  -Almost touched-off the rod with the wire screen on...  -That's what you call an accidental mishap.  All the other stuff is calculated and controlled.

Bill is/was right.  Don't do this at home...

Ray






bcall2043 said:


> Ray,
> 
> Thanks for bringing up this interesting topic. We have all been down the "out-of-balance grinder" road or will be in this hobby.
> 
> ...


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## macrnr (Dec 9, 2012)

If it looks dangerous, it probably is dangerous. Some things such as grinding wheels should never be modified. Accidents of this nature happen so fast, there is no time for reaction. I am the safety officer for my company, and this would never fly in a commercial setting. It only takes one accident, and you are done. My 2 cents


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## L98fiero (Dec 9, 2012)

Ray, what I've noticed as a common thread on several of the posts you've made is others saying 'run away, hide under the bed, Ray is going to kill someone' instead of making constructive critisizm. It ain't necessarily so, if you're paying attention to what you're doing and for the largest part, it seems to be the case with you.
I agree that you can't balance the wheel mounted on threaded rod _but_, you could find the rough balance on an unthreaded rod so you could get a start on placment of a balance weight. Also, as you said, you should have the proper blotters/pads under the washer but more than that, what I noticed was that you had the balance weight under the washer. The stresses in the wheel created by that are far more of a concern than anything else and that alone can cause the wheel to break.
Balancing wheels is common on larger grinders and wheel arbours are available, as on one of your posts, with the balance weights as an integral part of the arbour, and that is the proper way to balance wheels. On a surface grinder the wheels should be permanently mounted on their arbour and balanced or if there is no option for balancing, don't use the wheel. Most of the imported bench grinders have washers that are much too light and quite often not centered, it would be quite easy to make an arbour to mount the wheel and balance it. I've made new washers for mine from 1/4 steel, all that would be needed to make a balancing option would be to drill and tap equally spaced #10 holes around the rim.
As always, use the proper guarding and safety equipment, primarily, your brain!


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## macrnr (Dec 9, 2012)

Perhaps the constructive "consensus" is this is a bad idea. You don't have to run away and hide to see that. Sometimes common sense needs to be your guide.


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## Bill Gruby (Dec 9, 2012)

My warning to the newbies and all others stands. This is dangerous. 

"Billy G"


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## Tony Wells (Dec 9, 2012)

This is a bad idea. H-M cannot be responsible for recommending anything that is potentially fatal to people who may read this as perfectly safe and acceptable shop practice. If you feel you must balance your grinding wheels, buy the appropriate balancing equipment, and the balancing attachments designed and engineered, and backed by an insured supplier. This is NOT RECOMMENDED for the home shop.

Thread is closed.


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