In article ,
"Harold and Susan Vordos" wrote:

"Joseph Gwinn" wrote in message
...
snip----

I'm now trying to sharpen the split-point cobalt drill. It won't be
split-pint anymore, but that's OK.

What bamboo said. You can split the point, too, but study one well before
you try, so you understand what you're trying to accomplish. It's important
for the split point to be dead on center and have the proper angles, so it
takes a little skill. You can do it!

After some practice. I understand the split-point geometry well enough,
but first I need some practice hand-grinding, so I'll do plain points at
first.


At least one grindstone on the 6" Ryobi doesn't run true, wobbling from
side to side, making the world vibrate. What would be good replacement,
by make and model? Or, does one simply shim the wheel with cardboard?

Joe Gwinn

Never shim a wheel. You risk cracking by the uneven clamping pressure
you'd achieve by the shims. It's good to remember that you should never
run a wheel without the blotter while we're talking about the subject. The
blotter's purpose is to spread clamping forces such that minor wheel
irregularities don't cause cracking when the flanges are tightened.

The wheels do have blotters, the labels.

Following another poster's suggestion, I hand flattened the mating
surfaces by wet sanding on a granite surface plate, and broke the sharp
corners with a hand file. Stones still wobbled, but one possible cause
eliminated. The irregularities should also be much reduced, if the two
surfaces of the flanges are parallel.

The stones are 1" wide and 8" (not 6") in diameter, on a 5/8" arbor, are
gray, and claims to be made by Ryobi.


Don't over tighten. It's not necessary.

Define "over-tighten", please. The spindle nuts are now looser than
they were in the as-received machine, but still I'd like to know the
limit to be avoided.


As bamboo suggested, check the flanges that they run true. If they do,
using a long handled diamond, dress the sides of the wheel until it runs
true. It's not uncommon for wheels to not be parallel, which will make the
world vibrate, as you suggested. You should be pleasantly surprised that
your grinder runs quite smoothly when you're finished. You can follow up
with a dressing stick if the sides display some light grooving after you've
applied the diamond. You should be able to steady the diamond on the
wheel guard adequately to achieve acceptable results.

The flanges are pressed metal, and the shoulder on the shaft isn't very
large, so I'm wondering if the shoulder is setting on the uneven area
where the 5/8 hole was punched out. The flanges fit tightly upon the
5/8 shaft.

Using a dial indicator, I measured the wobble on one flange: 0.008" at
1.25" radius. This would translate to (4/1.25)(0.008)= 0.0256" at the
outer edge of the stone. This is approximately what I see by eye.
(Don't want to grind the dial indicator probe tip, so didn't indicate
against the stone.)

Originally, the wobble was much worse than above, but was reduced by
rotating the stone on the shaft and looking for minimum wobble, so
something isn't square to the shaft.

I'm wondering if the problem is the flanges. Is there a source for
machined (versus pressed) steel flanges? I haven't found such things in
MSC and like catalogs.

Another poster suggested ditching the OEM stones, which are made by
Ryobi. Is this likely to solve the problem, or at least help?

Joe Gwinn