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

[JoeLee]

I've found that Norton has a lot of hidden documentation if you want to search for it. Thank You, didn't see this one.

I ended up boring the hole on the mill since that was the easiest set up. I clamped the wheel down through the hole first and swept the OD with a dial to get it centered. I indicated the OD as close to the abrasive as I could get. There were a few irregularities on the OD like it wasn't perfectly round, maybe it was the paint..... don't know. But I got it centered to within .0005. Clamped it down with the hold downs "gently" and bored the hole to 1.375. Then I made the PVC bushing. I allowed .002 push fit and opened up the bushing ID an extra .002 to allow for the "squeeze factor" and then tried it on the spindle. I ended up with a perfect fit and indicated it to about .002 run out. That's a hole lot better than what it originally was and it repeats when removed from the spindle and replaced, that's another important thing.

Ideally it would be nice to have every wheel mounted on a hub but for most of us it's just not reality. Those hubs aren't cheap and on my KO grinder it's a PIA to hold the spindle from behind and loosen the thing up and pop it off, and you also risk damaging the taper in doing so.


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

[john hobdeclipe]

Leave the wheel alone and follow these instructions that I copied directly from the Norton Superabrasives Catalog.

Diamond and CBN Wheel mounting, truing and dressing guide
To achieve the best results using Norton diamond and CBN products, the following steps for mounting, truing and dressing should be practiced:
mounting – putting Wheel on machine Spindle

• Examine wheel flanges and spindle carefully.
• Be sure flanges’ surfaces are clean and free of damage.
• Ensure that the mounting flanges are flat and of equal diameter, especially on wheels with rigid centers, such as vitrified bond wheels.
• Paper or plastic blotters should only be used when mounting superabrasive wheels with vitrified cores. Using paper or plastic blotters on any other core material may result in the wheel loosening during grinding.
• Inspect machine spindle for excessive runout.
– TIR (Total Indicated Runout) should be no greater than 0.0002".
• Mount wheel between hand-tightened flanges.
• Using a dial indicator, tap the wheel lightly with a rubber or wooden block to minimize runout to less than .0010".
• Tighten flange securely and recheck with indicator.
• Allow a newly mounted wheel to operate for one full minute before grinding.
• The use of one permanent mounting for the life of the wheel is recommended whenever possible:
– If the grinding machine has a tapered spindle, mount each straight, flaring cup or dish wheel on a separate collet or adapter.
– When changing wheels the entire unit is removed, keeping the wheel in running truth.
– When needed again, the entire unit can be placed directly on
the spindle or arbor, thereby eliminating the time and abrasive lost in retruing.

Every diamond or CBN wheel I've ever mounted had an oversized bore that allowed for this centering process. Aluminum oxide wheels can have a snug fitting bushing because they are much easier to dress true after mounting.

Here's the link to the catalog:

http://www.nortonabrasives.com/sites...pdf?t=25186215

[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.

[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.

[dian]

where do you guys get your molybdenum sticks?

[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..............

[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]

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...........

[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]

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...............

[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.

[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.

[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

[Toolguy]

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

[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................