Truing a small grinding wheel on the drill press
 

I inherited a little 1/4 inch shank brown unknown abrasive grinding wheel from
my father, well worn.

So I trued it.

I placed the drill press base and column on the bench and added the cross vise.
No screws yet. I put the diamond truing tool in the vise, along the steps with
the jaws removed. I added the head, stopped at the top of the column. I added
the wheel, tightening the chuck firmly. I moved the vise to the side and
screwed it two steps off center, then slid the vise over to the right. I
lowered the head to place it near the wheel. I adjusted the cross slide so the
diamond was after top dead center, that is, the closest point, to avoid a
catch. I slid the long feed by hand using the ruler to get a start.

I ran the wheel down along the diamond, removing an excessively heavy cut. I
stopped. The wheel was way out. I got a high spot touch and took a cut. Nice.

What a friggin' mess. I had particles in my hair, on the adjacent table, and
the floor. I probably breathed some. I guarded the cut with my hand and
continued to feed with the long feed. At one point the diamond glowed red.
Oops. C + O2 = C O2. Lost some expensive diamond that way. Eventually I got
that nice crisp sound and gave it up.

Soon I will mount the accessory table to the cross vise, clamp the Unimat
spindle head in the vise, clamp a bicycle crank extractor bolt in the three jaw
chuck, and tilt the table to present the work to the wheel at an angle. Then
I'll take off a little to make the bolt fit the dust cap Harris sold me, to
form a one key extractor with an 8 mm hex key fitting. The work will spin,
driven by the wheel, and stay true. Harris didn't have any extractors so they
sent me parts that were close. They are quite convenient, and are a security
risk for those parking in high risk areas.

Oh, by the way, it looks like smoochie and I are buying a house together. Maybe
out in Sterling near the airport and the bike trail.

4BR, 1B rambler, $265,000. Cookin' with gas again after 24 years.



My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter

Truing a small grinding wheel on the drill press
 

Went ahead and set up the Unimat One headstock with the Harbor Freight two inch
three jaw chuck and crank bolt about thirty degrees off vertical. Whatever the
slope of the jaws steps was...

But when the shafts face each other, things tend to unscrew! So I tightened it
all down more than I liked to, and it came out. Then I filed the bolt in the
drill press.

The stone drives the work and since it's at an angle, cuts it, too. It's easy
to build up speed. At speed, the slightest finger drag causes high deceleration
from inertia and it unscrews. So you have to modulate your finger drag very
carefully to see it never gets going real fast, just fast enough for a nice
even feed, and consequentially, concentricity and circularity.

The way they work is, the inner radius is smaller than the radius of the dust
cap, so the small torque transferred at the bolt is opposed by large torque.
Also, the bolt torque is dynamic friction and less than the static friction at
the cap.

They work great now.

I could go into business making these for Harris, who supplied the too closely
matched parts, hand selected from what appear to be stock parts.


Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter

4-1-9 Fraud
http://www.secretservice.gov/electronic_evidence.shtml