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Grinding wheel runout

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Forum topic by DanM posted 08-17-2008 10:43 AM 2946 views 0 times favorited 6 replies Add to Favorites Watch
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DanM

90 posts in 3709 days


08-17-2008 10:43 AM

Bought a Woodcraft 8 inch low speed bench grinder for sharpening purposes. Comes with 60 & 120 grit white/friable wheels. 1st thing I notice is the right (fine) wheel has what seems like quite a bit of edge runout (wobble) on the broad side face of the wheel, about 3/64” from the look of it. Tried taking the wheel off & checking the arbor, the arbor seems true. Remounting/retightening the wheel made no difference. Since the wheel is not thinner at the low spot, this means the grinding surface is also oscillating back and forth by the same amount. It’s as though the wheel has a slight “bow” in it, or (more likely) the center hole is not 90 degrees to the face. Laying the wheel on the cast TS tops seems to indicate it’s flat enough, so I’m guessing it’s the hole which is off. Is this an acceptable amount of runout, and will it cause any difficulties during sharpening? The coarse wheel is much flatter.

Thanks

Dan


6 replies so far

View MrWoody's profile

MrWoody

321 posts in 3774 days


#1 posted 08-18-2008 03:13 AM

I’m just guessing, but have you tried truing up the circumference?

-- If we learn from our mistakes, I'm getting a fantastic education.

View lew's profile

lew

12061 posts in 3755 days


#2 posted 08-18-2008 04:38 AM

A machinist friend told me that every time you replace/remount a grinding wheel, you must redress the wheel. Apparently the tolerances used to cast the grinding stone are far from perfect.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

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Karson

35121 posts in 4400 days


#3 posted 08-18-2008 04:57 AM

I would think that the face should not be out of round. I’d take the stone back, and let them try it on their machine in the store.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware soon moving to Virginia karsonwm@gmail.com †

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SCOTSMAN

5849 posts in 3585 days


#4 posted 08-18-2008 10:23 PM

Also check the arbour for tight fit. In the wheels arbour hole any slackness will be magnified a thousand times at the cutting edge if this is fine then perhaps removing the wheel has not helped and as said regrinding the front edge and sometimes also the sides will help retrue the wheel.Also try pinging the wheel when removed in future with a piece of metal like a screwdriver holding it in the centre hole to see if you get an nice clear bell like sound when struck, if it is a dull like thud then the wheel is definitely damaged/cracked and must be replaced immediately hope this helps excuse my typing tonight a bit shakey.Alistair

-- excuse my typing as I have a form of parkinsons disease

View Planeman's profile

Planeman

97 posts in 3577 days


#5 posted 08-19-2008 04:56 PM

Lew is right. Every time you mount or re-mount the wheel you are going to have to true it up with a dresser. I use a single point diamond dresser. They are not as costly as the name would suggest. Some online resources are . . .

http://www.woodturnerscatalog.com/store/Sharpening___Grinders___Wheels___Diamond_Wheel_Dresser___diamond_dresser?Args=

http://www.hartvilletool.com/product/11253

http://www.diamondtool.com/sngptdre.html

Just be careful to grind only at the point of the diamond. I once saw a fellow actually grind the diamond out of its setting because he didn’t understand how to use the tool.

Rufus

-- Always remember half of the people in this country are below average.

View DanM's profile

DanM

90 posts in 3709 days


#6 posted 08-20-2008 09:50 AM

Thanks for the replies. The actual grinding edge seems reasonably true, it’s more that the stone appears to either not be flat (thought it appears to be so when placed on the TS) or more likely, the plastic center bushing is not installed true to the rest of the stone. I’ll try swapping it for another, main problem with that is the store’s about a 50 mile drive…

Dan

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