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Diamond wheel mounting issue

Froneck

Titanium
Joined
Dec 4, 2010
Location
McClure, PA 17059
I purchased a 6" X .40 X 1.250 1A1 Resin Bonded wheel on ebay. Actual bore Dia. 1.253 and my Darex drill grinder spindle is .6238. Made a bushing to mount the wheel, Id and OD cut while chucked so no run out. Center of the wheel is Aluminum .355 thick X Aprox. 5" ID to where the Diamond resin is bonded. About 1/8" of the Aluminum is the same thickness as the Diamond resin which is probably 10mm wide. Bushing is .350" wide. OD of the flange on the spindle is about 2" and has undercut about .01" deep X 1.5" ID. Washer is the same. Therefore bushing does not contact the sides. Wheel is tight and does not slip.
Problem wheel wobbles left/right about 1/32" Didn't measure it but it is very noticeable.Checked and cleaned the surfaces but didn't help, mounted wheel I have and no shimmy. I have to complete a job making split point drills, wheel did work good and split point is perfect. However I have 50 drills to go and worry the corner won't last. Don't have time to return the wheel and get another. I suspect the bore is not straight and thinking of chamfering both sides of the bushing.
Any thought that might help?
 
Cut a temp arbor on your lathe to just a couple tenths under the wheel bore, mount the wheel on the arbor, but not against any shoulder, and slowly spin the lathe to confirm whether the bore is off or not.

If the bore is off, and you need to use this wheel, recut the bore true after careful setup in a four-jaw, and make a new adapter. Just be sure there's no other error source before cutting the larger bore.
 
Intended to make a plug as suggested in the lathe and put the wheel on if to see where the problem is.
If I do have to re-bore the mounting hole should I use cardboard(Cereal box type) shims? Being only .4 (stated size) probably 10mm it's not very wide. What's best way to indicate so OD of the wheel is concentric with the re-bore? Even if I had enough protruding out of the chuck I don't think putting an indicator on the diamond will work, I'll probably see a spiral as the indicator point is flattened.
 
Yes, protect the bond and diamonds with either soft aluminum strips (like annealed 6061) or sure, even cereal box strips.

It sounds like you can indicate off the wheel bore, as you didn't say you had lateral runnout, just wobble. Is that correct? In that case, the very slight ellipse of the wheel bore being tilted should be quite minor and easy to true in.
 
Pictures?
Note that the wheel ID is plus .003. This is so that the ID will not locate the side to side.
This is the job of the flanges.
No way you locate off this thin bore in the side to side "wobble".
Bore should be loose sloppy.

DO NOT clamp this wheel on the OD in lathe. Seems like a good idea, add paper or something. This a very, very last resort any likely will not fix your problem.

You are very correct to be concerned as the corner rad in that notch will not hold with this runout.

What is controlling the side to side, is the as machined body body wobbling, if so why? Nuts, washers, somebody on the sides?
Stop looking at the bore as aluminum any other side force will make it move to what they want. Who clamps the sides and how true are they?

Even in a new Sopko adapter and wheel I will indicate mark the pieces, move the wheel 30 degree increments till round the world, try, try flip the washer do it again. Sand the hole open another few thou. Rinse and repeat.
Resin easy for me, just dress to the mount and if .030 worth of diamond lost no biggie but not so happy with supplier.
Plated product, .0003 off is a big deal and we will spend hours.

Your bushing is OD runout and that alone. Side to side or wobble a different problem.
Bob
 
The wheel seems fine. I made the plug and mounted the wheel, no visible shimmy.
Put an indicator on the aluminum, ran out about .003" So I bumped it until it run 0. Moved indicator near the center and no change, put the indicator on the other side .001" total! I removed spacers that are on the spindle from the maker of the grinder, took light skim cut so no run-out. Mounted the wheel again, same thing shimmy left right about 1/32" Put on other wheels I have and no shimmy or run-out. Took the bushing and tapered both sides, is loose fit now, didn't help! One thing I noticed the other wheels 1E1 and 1A1 are 1" wide 5/8" bore but have a 2" diameter hub on the wheels and are same width as the wheel 1". The washer provided is 2" OD X 5/8" bore however the 2" is about 1/4" thick, overall length is about 1", the additional 3/4" is only about 3/4" in diameter. I'm wondering if the nut 5/8-18 due to thread pitch is canting the wheel. Tomorrow I will make a flanged bushing about 2" long to see if that works.
 
Threads are OK, hold nut as I spin the shaft (easy to do since there is another wheel on the other side), nut does not wobble. But possibly when tightening will shift.
 
Up-Date

When I put the wheel on the plug a second time I made the plug slightly under size and mounted the wheel with Loctite. Wasn't yet cured due to Aluminum wheel. But I indicated the one side with the brand name out, was perfect but other side ran out. Knowing I had to face the other side I quickly removed the wheel, cleaned and replaced it brand name in with more Loctite. I indicated the brand name side and bumped it to perfect (Starrett last word .001 pointer moved slightly either side of graduation.), when I checked the outer side it seemed to only run-out .001! Was late so I went home but kicked myself for not removing the wheel when the Loctite was soft! Next day wheel was well attached, so I again indicated brand side and it remained the same, as perfect as I could get it but when I checked the other side it was now running out! so I faced a skim cut until all high spots removed to about 2.5" dia. To remove the wheel I drilled a hole in the center of the plug then bored it to little over 1", as I expected the heat softened the loctite and the wheel came off without force. Cleaned any remaining Loctite, mounted in the grinder and it runs perfect!
Thanks guys for the Help!
 








 
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