Grinder Vibration Question

[Richard Madison]

Is there a way, within reason, to quantitatively measure and decide if one has excessive grinder vibration that results from unbalanced wheels? I have always just dressed the wheel(s) a bit to reduce vibration, or to clean them off as needed of course.

[Gordon Seto]

Dressing and truing the wheel can only make your wheel run concentrically. If out of round was your problem, that should take care of it. Your grinder should run smoothly from then on. You will have to dress or true up the wheel to clean it up and take out the uneven wear grooving.
If the embedded metal in your wheel looks uneven in bands, most likely your tool is bouncing on the wheel.
If your vibration problem still exists, that means your wheels are unbalanced. You need to inspect the shaft and washers, or invest in the Oneway wheel balancer system.

[Andrew Derhammer]

Dress the sides too, sometimes I find a little bit of play in the tolerances of the sides and that can cause vibration too.

[Richard Madison]

Thanks guys, but my question was not about curing vibration. It was about measuring it.

[Andrew Derhammer]

Time how long it takes for it to fall off the bench from vibration:D:p

[Gordon Seto]

I don't know about dressing the sides of the wheel.
http://groups.ucanr.org/ehs/files/34447.pdf
#4 on the Operating Precautions

[Andrew Derhammer]

I don't know about dressing the sides of the wheel.
http://groups.ucanr.org/ehs/files/34447.pdf
#4 on the Operating Precautions
I forget where I heard about dressing the sides, hmm.

[David Drickhamer]

A word of caution. Grinding on the sides of the wheel can be dangerous. Side grinding can cause the wheel to crack then shatter. I've seen it happen at work and we've had training warning not to do it.
Also, Keep your wheel dressed. If you get a build up of metal in the wheel it doesn't work as well causing you to press harder. This loading of the wheel can also cause the wheel to crack and shatter.
Be safe.
Dave

[Mike Lipke]

I think it might be sorta like quantifying "smooth" scotch.

Actually, I don't know how to measure grinder smoothness. If I were deaf, and blind and touched the grinder, if I could not tell it was running, I would say it was smooth. I don't have one even close to that, but I have seen and touched them. Do they have to be that smooth to function for years? No.
Would it be lovely? yes. Can I afford one that smooth. ahh..no.

[Paul Atkins]

Where are you people getting all these off balance wheels? In my 40 some years using grinders of all sorts the only off balance ones were not dressed or chipped. The white wheels from WC have been great. I've gotten pink wheels from the saw shop that have been dressed on the sides to make the gullets for saws and have never seen one blow up. Also 3500 rpm is way too fast to sharpen anything except a lawnmower blade in my opinion.

[Richard Madison]

Thanks Mike. Good analogy.

Good question Paul. Wondered that myself. Have only been using grinders (from time to time) for about 35 years and have never met a vibration that would not vanish after a bit of wheel dressing.

[Hilel Salomon]

I think that if you have dressed the wheel properly, it can still be unbalanced and have tools skipping. The Oneway balancing kit works at reducing this. Eli Avisera, in one of his dvd's puts a coin vertically on top of the grinder when it's running and it stays up. That's balanced!!
Back in SC
Regards All,
Hilel.

[Bernie Weishapl]

Dress the sides too, sometimes I find a little bit of play in the tolerances of the sides and that can cause vibration too.

I agree with David. Where I work it is a absolute no-no to try and dress the side of a wheel. 4 yrs. ago we had a guy lose his eye and had to had his cheek bone reconstructed after he tried to dress the side so it would viberate. The stone shatter and got him.

[Richard Madison]

Well I guess that is somewhat quantitative (Eli's balancing coin), but aren't some coins are more stable than others?

Am having trouble understanding that if one buys a new grinding wheel and dresses it round and it still shakes, why would one not return it to the source and get a different wheel. Why would one buy a $64 (from their website) accessory in order to use the original defective product? Just asking. No criticism of any person or thing is intended.

[Gordon Seto]

Not every grinder is a Baldor. I think the vibration is the accumulation of multiple factors. The grinder itself, the stamped washers of the cheap grinder, loose fitting plastic adapters and uneven density of the wheel material, to loop sided center hole are all part of the problem. Sometimes we get lucky, some of the unbalanced forces evened out.
The $100 Norton SG wheel that Craft Supply carries has a 5/8" arbor hole and the 8" grinder has the same size shaft. The Oneway balanced can't be used on it. The explanation of the CSR at CSUSA was the SG wheel are better quality that we don't need to use the balancer.
I had the $80 WC grinder, no matter how much you dress or true the wheel, the possiblility of a coin standing on edge on top of the running grinder is slim to none without the help of some CA glue.
If a $80 WC special after dressing the wheels would run as steady as the Baldor that sells for more than 5 times, the Baldor would have to lower their price to compete.
The WC grinder definitely benefit from the balancer. My WC grinder died after may be couple years. I replaced with the heavy duty Delta. It was an improvement; but it is still no match to a Baldor.
BTW, Oneway recommends 3450 rpm high speed grinder for turning tools.
http://www.oneway.ca/pdf/grind_jig.pdf

[Paul Atkins]

Maybe we need a thread on grinder speed - Thanks Gordon for the Oneway link - I'm not sure why spm for grinding is critical. My grinders are belt driven with stepped pulleys so I can change speeds -hardly ever do- maybe I'll crank em up a bit. I grind all my tools on the two grinders including Japanese chisels, plane blades , jointer blades and metal lathe bits so I think slower keeps them a bit cooler and a little less frantic. The carbon steel tools need a bit more care than HSS. I turn 1/2 thick aluminum flanges for the wheels and honing pad to keep them flat which is better than the stamped ones. Another 2 cents anyway.

[John Ponder]

Paul,
I think you are on to something with your ½ inch thick aluminum pads. Most of the mid-priced grinders I have seen all use stamped steel washers to retain the wheels. It does not matter how straight the wheels are if the retainers are warped. Please give us more details about your aluminum spacers, you may have a new product to market here.
Thanks,
John

[Paul Atkins]

Here are 2 different ones - one is 3/8" the other 1/2" thick. Pretty simple -reamed to fit shaft too.

[John Ponder]

Paul,
Those look great and should cure any problems with wobbling grinder wheels. I wish someone would market them. Thanks again,
John

[Randy Klein]

I wish someone would market them.


IIRC, that is the main benefit of the Oneway balancing system - machined washers.

[John Ponder]

I’ve never seen the Oneway system in person, but I’ll order one today and see if it helps. Although I do wish I had the ability to turn some like Paul’s.
John

[Gordon Seto]

You may want to consider replacing the flimsy stamped washer with the extra thick precision washer with low parallelism (page 742)

http://www.use-enco.com/CGI/INPDFF?PMPAGE=742&PARTPG=INLMK32

[John Ponder]

Those look good but I assumed that the O.D. should be approximately the same as the stamped steel retainers. Any thoughts?
John

[Gordon Seto]

The steel washers that came with the Oneway balancing system are about 1¼" OD. But they are against the machined aluminum balancing hub.

The picture shows the difference between flanges of the $80 WC special and the $200 heavy duty Delta slow speed grinder.
It clearly shows that only portion of the WC flange was making contact with the wheel.

[John Ponder]

Maybe I misunderstood, did you mean use the small washers WITH the balancer kit? I understand you don’t use the stock retainer washers with the kit. Those retainer washers from the HD Delta look good, are they straighter than the ones on the WC?
John

[Richard Madison]

Thought I had an idea for a moment there, based on Paul's post, but I was wrong. Remember saw blade "stabilizers"? But they are for 5/8" arbor, and IIRC most grinder arbors are 1/2". Never mind.

[Gordon Seto]

Maybe I misunderstood, did you mean use the small washers WITH the balancer kit? I understand you don’t use the stock retainer washers with the kit. Those retainer washers from the HD Delta look good, are they straighter than the ones on the WC?
John

See Instruction #10
http://www.oneway.ca/pdf/balance_kit.pdf

The retainer washers on the HD Delta looks like they were machined (circular milling marks on both sides), they are flat. Those from the WC were stamped from heavy sheet metal. From the uneven scratch marks, it was obvious that the washer did not have even contact with the grinding wheel.

This is from the 100 pounds 8" Delta grinder.
The Delta 8" variable speed grinder is only 48 pounds.
The Delta 8" single speed grinder is 24 pounds.:confused:

[John Ponder]

OK, now I understand. Hopefully the balancer kit will arrive this week. Thanks for all the help and information.
John

[Jerry Allen]

I got a WC 8". One of the steps on the motor shaft where the inner flange washer rides had not been completed at the factory. WC replaced it immediately.
The step that the inner washer rides on is critical. If the step is not perfectly flat and pependicular to the shaft axis, you will have problems. A small error (or even a chip of wood or dirt) will magnify the error at the edge of the wheel. The washers are a lot larger, so less magnification, but warpage or a sloppy center hole can really throw it off. The washer can be flattened using aggresive grit and a sheet of plate glass if the error is not too great, or it can be shimmed a bit with pieces of paper placed stategically at the periphery of the washer.

[Tim Thomas]

My boss has an iPhone and he recently downloaded a seismograph application for it. You can put the iPhone down on a flat surface (like a table) and then tap around it and it will measure the vibrations and produce a graph. When he showed it to me I thought "That's neat, but what the heck would you ever NEED it for?!?!". Now I know. You could use it to measure the vibrations produced by your power tools. We could use these objective measurements to solve long-standing arguments about the virtues of link belts in reducing vibration, prove the value of dressing grinder wheels, and all other manner of machine vibration connundrums.

Of course, this will only work if you have an iPhone, and I don't, so I'll have to leave it to some other woodworker to see if my crackpot idea actually has any merit... :D

(Although, I do have several friends with iPhones. Maybe they would be willing to help me experiment. But convincing them to place delicate and expensive electronics on top of my woodworking equipment might be a hard sell. Hmm....)

** edit **
link to iPhone app I am talking about: http://coneri.se/iphone