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Bench Grinder run-out

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MikeWi

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#1
How bad did I mess up here? I bought a Harbor freight 8" grinder, after Christmas ,and didn't open it until today since I just got my white wheel and a stand for it. Turns out there's a significant amount of sideways wobble in the wheels, and of course, the receipt is no where to be found. The shaft has about .0015 of runout ,but the shoulder for the inboard washer is too low to get a reliable reading, and I suspect that's where the trouble is as the washers appear to be flat.

Any thoughts on how to rescue it? I always keep receipts too...
 

ACHiPo

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#2
Not to worry--you did good. Those grinder's washers, shaft, and wheels are terrible, but salvageable for a lot less than a Baldor 8".

I combined a cheapo 8" grinder with the Oneway balancing kit and one good Norton grinding wheel (46 grit I think) and have a very nice set up (I still use the fine white wheel that came with the cheapo grinder--it runs ok after balancing). The Oneway kit comes with high-quality washers and a balancing set up.
https://oneway.ca/products-category/sharpening-grinding-jigs/Balancing Systems

If you don't want to drop the coin on the Oneway system, you may be able to significantly improve things by fiddling with the washers, both rotational location and sides of the wheel. You might even be able to true them up if you have a lathe (or make new ones).
 

4ssss

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#3
The only way to rescue it the correct way would be to take out the shaft and re cut the shaft faces between centers.
 

MikeWi

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#4
The only way to rescue it the correct way would be to take out the shaft and re cut the shaft faces between centers.
That's what I was thinking too, but the shoulder that the washer sits against is about the thickness of my fingernail. I'm going to try making a new shoulder with a piece of steel bored to a slip-fit over the shaft. I have the room for it, and it would give me a truer shoulder to go up against. I'll probably just make new washers too, as these stamped ones don't look very promising.

edit: DOH! I forgot I don't have a boring bar that small! If it ain't one thing...
 
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Dave Paine

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#5
If your grinder is like my Rikon grinder the issue is partly the shaft having too small a shoulder, the washer having too large a hole and the bushing on the wheel being too large.

The really shallow shoulder on my Rikon.

Grinder_shaft_shallow_registration_shoulder_6348_edited.jpg

I made custom washers which have a better fit, but still have wobble in the wheels. I found a piece of masking tape over the shaft helps with the bushing being too large.

Grinder_wheel_installed_cut_off_excess_tape_6351_small.jpg
 

T. J.

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#6
I just bought Harold Hall's book "Tool & Cutter Sharpening". In it, he describes clamping the whole grinder to the lathe bed and indicating the spindle parallel to the ways. You can then true up the spindle with the grinder under its own power.
 

ACHiPo

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#7
Have at it, but I'm tellin' you, the Oneway stuff is quick, easy, and not all that expensive. And it works.
 

machPete99

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#8
I had similar issues with a lower end Delta grinder. The shaft was straight but crappy washers and narrow shaft made for wobbly wheels. I replaced the inner washers with a combination arbor/washer machined out of one piece of aluminum, with sliding fit on the shaft, and it now takes 1" ID wheels which are typically professional. Works much better.
 

Groundhog

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#9
I had similar issues with a lower end Delta grinder. The shaft was straight but crappy washers and narrow shaft made for wobbly wheels. I replaced the inner washers with a combination arbor/washer machined out of one piece of aluminum, with sliding fit on the shaft, and it now takes 1" ID wheels which are typically professional. Works much better.
I did the same thing on a 6" grinder. I didn't make shaft bushings though. Really improved the wobble of the grinder. The stamped washers are junk.
 

chips&more

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#10
You can buy a cheap HF grinder and play around with it and spend more money and time getting it work decently (maybe). Or you can buy a Baldor or similar and be done with it, probably for your life time. My 3 cents…Dave
 

MikeWi

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#11
You can buy a cheap HF grinder and play around with it and spend more money and time getting it work decently (maybe). Or you can buy a Baldor or similar and be done with it, probably for your life time. My 3 cents…Dave
It can't possibly cost as much as a Baldor to get working properly. I'm all about good tools, but my wallet tells me to make do.
 

Wreck™Wreck

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#12
It is a grinder so dress the wheels to the spindle, do not expect vitreous grinding wheels to be true or balanced out of the box so they must be dressed before use. It is also a good practice to ring a large grinding wheel before mounting, wheel manufacturing has progressed in the last 100 years which makes ringing them a somewhat outdated practice.

However OSHA publishes data on it as current as 2015
http://osha.oregon.gov/OSHAConstructionDepot/2015/01/how-to-ring-text-a-grinding-wheel.html
 

HBilly1022

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#13
Yesterday I happened to be playing around with my grinder, trying to get it balanced and have the wheels turning without any wobble. I have a white wheel on one side and a green one on the other side. The white wheel was a good quality wheel and was fairly well balanced, however there was a pronounced wobble. I took the green wheel off and worked with the white one for a while and managed to get it to run with only a slight wobble by using bits of masking tape under the stock washers. With the nut snug but not tight I would spin the wheel and mark the high spot on the side of the wheel. Then put some masking tape under the washer on that side. Spin it again by hand and check for the high spot again. I kept this up until I got the wheel pretty close to true (from side to side). I found that just tapping the side of the wheel with my fingers would help to nudge it a bit too.

The green wheel was not near balanced and still has a pronounced wobble too. Some time ago I made a one piece washer / arbor for the green wheel and that helped some with the wobble but it is still there. It appears to be the wheel itself. I will go through the same process with it to get it to run true. To balance it I will drill and tap holes in washer I made and then install small cap screws in these holes until I get it balanced. Similar to the Oneway system. I was going to get that but since I already have the arbor washer made I will give that a try first.

There are a few videos on youtube that address this issue. I like the Oneway balancer but it does not address the side to side issue so you would still need to deal with that.

Hope this helps and good luck.
 

whitmore

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#14
How bad did I mess up here? I bought a Harbor freight 8" grinder,...Turns out there's a significant amount of sideways wobble in the wheels, and of course, the receipt is no where to be found.
Receipts won't get you a better grinder, but some machining might.
Keith Fenner tracked down his grinder problems a lesson somewhere
and if you (1) machine washers for the grinder and (2) make the retaining nuts
good and aligned, it might improve greatly. The (left-hand on one side)
nuts can be improved by a ball turning jig, allowing them to seat even
if they have to rock sideways, without bending the shaft. Ball-end nuts
against ball-socket washer would be ideal in this regard, whether it's
the shaft that was threaded off-axis, or the nut. Or both.
 

HBilly1022

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#15
I finished balancing the grinding wheel and all I can say is WOW!! As a matter of fact that is exactly what I said out loud when I turned the grinder on the first time, with the balanced wheel installed. The difference is astounding. Now I can see why ACHiPo was recommending the Oneway system. I might get a set of those for my 6" grinder. The 8" is working great now. I've been suffering with my 8" grinder shaking like crazy ever since I got it and blamed the probelm on the grinder. I should have made this a long time ago.

I go the idea for this from a Youtube video (wish I could remember the guys name, to give him credit). Here is a pic of the wheel with the balancing disc and the face washer.
1515606937640.png
I started by having one screw on top and kept adding screws to get the wheel balanced. Even with all these screws it still wasn't balanced and I ended up putting some lead pieces under the top screw. I guess my next step would have been to add another ring of holes inside the outer ones. I initially had a clearance problem with the top of the screw heads touching the top of the screws that secure the shroud to the grinder. I put a small washer between the balancing washer and the step on the shaft and that solved that issue. I also used medium locktite on all the screws, after I had the balance right. Sure will be nice to use the grinder with it running so smoothly now.

When I first checked the grinder I thought the shaft was bent because the nut on the end of the shaft would wobble a lot. I indicated the shaft and found there was only 0.001" runout. I looked at the nut and it appeared to be off center. A check with my digital calipers confirmed it. The wall thickness varied from 0.219" to 0.252". Here's a pic of the precision nut.
1515607375328.png
 

ACHiPo

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#16
HBilly,
That's a mighty fancy balancer you built! One of the things I didn't like about the Oneway system was sliding the two bolts around to find balance was fidgety. It didn't take that long, but took more iterations than I would like. Your index approach is very slick--maybe you just needed heavier bolts?
Evan
 

HBilly1022

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#17
I found the Youtube video that gave me the idea.

I didn't use a fancy rail system to check the balance though. I figured I would use a temp system for this forst try and if it worked I would make something better. My temp setup consisted of 2 pieces of particle board balanced on edge with 2 parallels balanced on edge on top of those. Pretty hokey but it worked. Just had to be very careful, because if it fell over the wheel would fall off and probably be damaged.
 

HBilly1022

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#19
Thanks for that......I like that balancer.
-brino
Your welcome. Give it a try ...... I think you will be impressed with the difference a balanced wheel makes. I sure was.
 

KBeitz

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#20
Quote....maybe you just needed heavier bolts?

Or little washers under what you have now.
 
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