grinder wobble!

[Aaron Wingert]

A couple years back I purchased a Delta variable speed 8" grinder. It always ran very true after the initial truing of the wheel and periodic "cleanup" truing thereafter. A few months ago I removed the factory friable aluminum wheel and replaced with with a Norton 3X. Using the little nested plastic bushings on the new wheel I installed it and turned it on, only to find that it has about 1/8" of wobble (visible left to right as you stand at the grinder). It can be trued round, but the wobble persists no matter how many times I try re-mounting the Norton wheel. Blaming the wheel I replaced the factory wheel only to experience the exact same wobble on it, whereas there was no wobble with it until it was first removed.

The shaft runs true. I took the grinder to a Delta service center and they looked it over while I waited. They were unable to solve the problem, and the machine is out of warranty.

Anyone have any ideas? I thought about trying to either make or buy a bushing that would fit the wheel and shaft tighter but I'm not sure it would help. You see, it seems that the thick washer and cup-shaped washer compress to the flat faces of the wheel, so once they're mounted up tight the bushing isn't doing anything to hold the wheel true.

I'm stumped and would take any advice I can get on how to remedy this. Might end up with a new grinder!

[Tim Rinehart]

Search for threads with words "bushing AND grinder"....alot of discussions on this. The recommendations typically involve getting a metal 1" to 5/8" (from memory) bushing from either McMaster Carr or Grainger to replace the cheap plastic bushing.

[Aaron Wingert]

Thank you Tim, will do.

[Roger Chandler]

http://www.mcmaster.com/#8491a562/=dj8qpg

Check out this link for the drill bushing that will help cure that wobble...........those plastic bushings are the problem!

[Jamie Donaldson]

Aaron- I have encountered this wobble problem many times with the Woodcraft 8" grinders, and here is the usual solution. Loosen the nut just enough to rotate the wheel, and mark the wheel with a pencil. Rotate the wheel about an inch or two, then hand spin the wheel to see if the wobble is better or worse. Continue this procedure, rotating in the same direction until the wheel runs as true as possible, tighten the nut, and this will most often take care of the wobble. The flanges on the Woodcraft are stamped metal and are not as true running as machine turned discs on other grinders, and these flanges are the usual wobble culprits on most grinders.

[Faust M. Ruggiero]

Aaron,
I just bought a Jet 8" grinder. It is the third grinder in my shop. Yea, I know, Nuts! Anyway, I am a nut for smooth running grinders. I buy the Oneway wheel balancing system for the two grinders set up for sharpening. When I received the grinder I checked the shafts for run out and found none. I bought two Norton 3X wheels, tossed the plastic bushings and installed steel bushings. I had some wheel wobble. Then I installed the Oneway balancing fixtures on both wheels, balanced them and trued them and guess what? They still wobble. However, the sideways wobble bothers me very little since after truing the grinding surface the wheels grind smooth and true. I suppose I am telling you a bit of wobble is annoying but may not hurt as long as the grinding surface is true.
faust

[Jim Leslie]

Found exactly the same thing with mine and I have the same setup. Balanced the wheels, trued the surface and while I still have a bit of wobble it has not been an issue for me. There is no tool bounce while sharpening.
I think vibration due to the wheel due to not being perfectly balanced and the wheel not trued are the two biggest problems.

[Don Geiger]

If you have a grinder with a 5/8" diameter shaft, 1" wide wheels with a 1" hole, you can replace the plastic bushings with steel bushings from www.mcmaster.com (http://www.mcmaster.com), part # 8491A562. They are $9.60 ea. plus shipping. McMaster-Carr usually has their parts delivered within one day to the customer.

1) Install the bushings and tighten the wheel nuts.
2) Start the grinder and if you see side-to-side wobble; use a pencil create tick marks on either side of each wheel to inidcate where the apex of the wabble is. Stop the grinder.
3) One wheel at a time: loosen the nut and slide the wheel and outside cup washer outward WITHOUT rotating the wheel or cupwasher on the axle.
4)Place a small stack of about four 3/4" diameter sticky paper price marking dots (available from Wal Mart and similar stores) between the inside cup washer and the side of the wheel on the radius line between the tick mark you made and the axle.
4) Push the wheel against the inside cup washer and add sticky paper dots between the outside the the wheel and the cup washer on the raidus line on that side. Tighten the nut. Repeat for the other wheel.
5) Tighten the nuts and rotate the wheels and observe how much, if any wobble remains. If there is any appreciable woobble, repeat the process. I can usually correct the wheel wobble in one or two tries. Hopefully, this will be your experience too.

Once you've corrected the side-to-side wheel wobble, use a WHEEL TRUING device- not just a hand held wheel dresser and true the wheels so they are concentric to the axle.

Following the recommendations above should solve vibration of the grinder and your tools should not bounce whenn they are applied to the surfaces of the wheels.

Let me know if I can be of further assistance.


Don Geiger

6)

[Aaron Wingert]

Thank you guys for helping me find some good direction on how to solve this little irritation! I'm going to get started on getting this fixed tonight. Stay tuned....

[Aaron Wingert]

Being too impatient to wait on a bushing via mail order I got a little creative in the shop. I make acrylic duck calls so I made a very tight fitting bushing from cast acrylic rod and installed it in the wheel. It helped. The wheel still has about 1/16" of left/right wobble....Actually both wheels have it.

So, took the wheel off and used some parts and pieces to mount the cup washer on the shaft and tighten it down like it would be when the wheel is pressed against it. It wobbles. So based on that I think the root cause is the grinder, and the lousy plastic bushings on the Norton wheel were just making it worse. The Delta friable wheel has a rubbery bushing built in and it fits tight, yet it still wobbles.

Pretty much convinced that I just have a lousy grinder. The good news is that it is better than it was and I can live with it. Thanks for the help everybody!

[Ken Fitzgerald]

Aaron,

I have a Woodcraft Slowspeed grinder that had a wobble in one wheel when I got it. What I discovered on the wheel that wobbled....the nut that held the wheel on....it's hole was not drilled adn threaded perfectly perpendicular to the threaded shaft. When you looked at the nut installed and tightened, only about 1/8 to 1/4 of the face of the washer made contat with the cupwasher. The nut on the other wheel mated fine with the entire face of the nut contacting the cupwasher. I get a replacement nut at a local Ace Hardware and I'm still using that grinder 5 years later.