Boring & Truing Hole In Grinding Wheel ?????

[JoeLee]

I have a diamond wheel like this one in the picture, 5" in dia. It's an 11V9.
The hole is slightly oversize and is a sloppy fit on my machine arbor so it runs slightly eccentric.
I tried lining the perimeter of the hole with fine line masking tape to take up the play but then it doesn't slip over the arbor.
I was thinking of boring the hole oversize and making a thin wall PVC bushing. But the problem is how can I mount and center a wheel of this shape on a lathe or mill??? The wheel runs out of center by about .006 and the hole measures about 1.254.
I have a few Triumph alox wheels that have plastic bushings in them with a slight flare so they seat firmly on the arbor with no play. That's a great idea, all wheels should use that design.

JL.....................

[duckman]

Contact Norton/St. Gobain and ask why the hole is oversize, their # 508-795-5000 .

[JoeLee]

I did, a while back. They said due to the age of the wheel and the wheel is about 20 years old even though it's unused I'm SOL.

JL................

[Toolguy]

Can you knurl the inside of the hole lightly to make the ID smaller, then bore to size (if needed)?

[Rich Carlstedt]

Joe, I would not mess with re-boring it.. Get some Starrett precision feeler gauge/shim stock in .0015 and .002 thickness and cut the length to fit the bore . Wash both the shim and the bore with lacquer thinner and then fit it between the wheel and the spindle. Leave one side of the shim high( exposed) and then add a drop of thin super glue to the joint between the shim and the wheel. Be sure to wax the spindle first so the glue will not seep into the spindle joint. also do not overdo the glue. Half a drop goes a long way.
Make a stub mandrel, if you wish out of plastic if you are un-sure !
Rich

[Tim The Grim]

We used to mount a diamond wheel on a dedicated adapter and leave it there forever. If you don't have an adapter to marry to this wheel, this method won't work.

Thoroughly clean the hub ground diameter of the adapter with brake cleaner and then evenly coat it with a light film of high quality grey epoxy like Belzona, PC7 or JB Weld.
Allow plenty of time for the epoxy cure to set. Days not hours.
Mount the adapter hub on the spindle, set your table stops, put a vise with a lathe bit on the magnet and turn down the epoxy to the fit / diameter you need.
Mount your wheel and dress it over a piece of Molybdenum.

When imported wheels started showing up more often and we had some fit issues like yours, that is what we did.

Hope this helps.

[Mark Rand]

Picture doesn't make it obvious. If it's diamond/resin on the outside of an aluminium/steel wheel, then bore the wheel out and fit a bush to correct the diameter. I had to do this on a diamond wheel that I got of EBay. Worked perfectly.

PS:- When it comes to dressing the wheel, a molybdenum bar works very well on resin bonded diamond wheels. It's 'sticky' and pulls the diamonds out as it wears the resin.

[JoeLee]

Can you knurl the inside of the hole lightly to make the ID smaller, then bore to size (if needed)?

There is no safe way to mount this in the chuck of my lathe other than clamping down on the edge of the abrasive and that will probably crumble under the force of the jaws. Knurling the ID would put way to much force against the wall of the hole, it would never hold.

The only thing I can think of doing is to make a fixture hold the wheel. My thought it a small piece of board, build a shallow box around it and pot the wheel in body filler to hold it in place, maybe with the help of some hold down clamps or something. Then mount it on the mill, center up on the OD of the wheel and bore the hole true to center and a bit larger so I can make a PVC bushing to press in. Boring lightly would put the least amount of force against the wheel and it's delicate mount.

JL...............

[JoeLee]

Joe, I would not mess with re-boring it.. Get some Starrett precision feeler gauge/shim stock in .0015 and .002 thickness and cut the length to fit the bore . Wash both the shim and the bore with lacquer thinner and then fit it between the wheel and the spindle. Leave one side of the shim high( exposed) and then add a drop of thin super glue to the joint between the shim and the wheel. Be sure to wax the spindle first so the glue will not seep into the spindle joint. also do not overdo the glue. Half a drop goes a long way.
Make a stub mandrel, if you wish out of plastic if you are un-sure !
Rich

This is what I usually do when a wheel doesn't fit firmly. I have a few different thicknesses of various tapes that I place around the inside of the hole.
The problem with the hole in this wheel is it's not quite over size enough for any of the tapes I have to work. If it were just a couple thou bigger tape wold work.
But the other issue is the hole isn't perfectly centered and if I want to use the side of the wheel to cut with it's going to be hit and miss.
Dressing one of these wheels isn't much of an option either since the abrasive is only 1/8" deep which is typical of these or thinner. When I take the wheel off and remount it I'll have the same problem again, so....... the bottom line here is the hole needs to perfectly centered.

JL....................

[JoeLee]

Picture doesn't make it obvious. If it's diamond/resin on the outside of an aluminium/steel wheel, then bore the wheel out and fit a bush to correct the diameter. I had to do this on a diamond wheel that I got of EBay. Worked perfectly.

PS:- When it comes to dressing the wheel, a molybdenum bar works very well on resin bonded diamond wheels. It's 'sticky' and pulls the diamonds out as it wears the resin.

This is exactly what it is. 11V9. How did you mount your wheel for boring the hole????

OK...........just thought of something...........maybe I can clamp it down just the way it's shown in the picture, cup side down, center it true to the OD and bore the hole.



JL...........

[ulav8r]

Clamp to face plate on lathe and bore, or clamp to bed of mill and use boring head. I bored out a similar wheel years ago, apparently it was powder metal, crumbled but bored out easy.

[JoeLee]

Yes, this is how I'm going to have to do it. But first I'll have to clamp the wheel to the mills table through the hole so I can sweep the OD of the wheel with a dial to center it. Then use hold down clamps on the wheel and remove the center bolt. Then I will be free to bore the ID to any size I want and will be sure it's dead on with the OD.

JL..............

[dian]

where do you guys get your molybdenum sticks?

[BCRider]

Yes, this is how I'm going to have to do it. But first I'll have to clamp the wheel to the mills table through the hole so I can sweep the OD of the wheel with a dial to center it. Then use hold down clamps on the wheel and remove the center bolt. Then I will be free to bore the ID to any size I want and will be sure it's dead on with the OD.

JL..............

Face plate on the lathe? Seems like that would be easier as then you can use a simpler boring bar. Not only the boring either. You could indicate and skim away any run out in the back face at the same time. The results might run true enough that no dressing would be needed.

[wierdscience]

Just chuck the wheel in the lathe,gently,and bore it out.It will bore a lot easier than you think.Most of those wheels are either cast Aluminum or pressed (sintered) Aluminum and dead soft for vibration dampening.We had a grinder at work with a 62mm bore on a 5" wheel and every time we changed it we had to bore out a standard 1-1/4" bore.The stuff was cast Aluminum and cut like Styrofoam.