In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]


FWIW -- I can testify that silicone oil (supposedly
non-flammable) *will* ignite and burn if the vapors from a heated beaker
of it curl around into the still-hot elements of the hotplate on which
the beaker is sitting. (There was some dry ice in the beaker to hasten
it back to the starting point of a temperature coefficient run.) And,
when that vapor burns, the result is very fine sand all over the place.
:-)

I'll have to try this someday. In the backyard.

Be sure to have a CO2 fire extinguisher handy. I'm not sure
what a hose would do for that -- possibly float and spread the burning
silicone oil.

Note that this was a mix of two silicone oils -- one which was
normally used for measurement at -50C, and the other which was normally
used at +150C. The first would boil at the high temperature, and the
second would set up into a grease at the low end, making it hard to
equate the temperature at the thermometer with that in the device under
test. The low-temperature oil, when it hit the bubbles from the dry ice
in the beaker evaporated quickly, and spilled over the edge and curled
into the heating elements.

We would have been better off letting the beaker cool down on
its own -- but we had quite a few more devices to test -- ones returned
from the customer, because while they met specs at -50, +50, and +150C,
they were out of spec at some points between those temperatures.

Ahh. I have a hotplate with totally enclosed heaters, so no drama is
likely.


In the meantime, I soaked it in WD-40 plus acetone, spinning the bearing
while immersed in solvent, and blew the bearing off with compressed
air.

O.K. As long as you don't spin the bearing with the compressed
air. *That* can be disastrous.

How so?

It can spin up to a fast enough RPM so the centrifugal force (I
know -- there really is no such thing) will cause it to fly apart --
turning it into shrapnel -- and *you* into a target. I don't know
whether there is any size limit for this to happen, but it has been
known to happen and to harm or kill people nearby.

Ahh. I can see a large bearing being driven fast enough to explode,
especially as bearing races are designed to be reinforced by being
pressed into a recess in a larger housing.

However, One would think that overspeed isn't going to be an issue with
small bearings already specified for 30,000 rpm, unless one's air supply
is something else.


Or, perhaps I can press the bearing race into place.

That would be better if possible. Can you turn up a cylindrical
pusher to press only on the inner race?

Not yet, but soon. There is a cylindrical sleeve already there. I
think it is supposed to rest on the bearing inner race on one end, and
one flange of the two that hold external grinding wheels on the other.

O.K.

It strikes me that one may be able to use the flange nut to push the
race back into position.


I would just have at it, and use the opportunity to clean the crud out
of the bearings. It isn't all that tricky or hard; I've had zero
trouble.

O.K. -- Other than getting things fully back together with the
caps fully tightened. (Which I gather was a pre-existing condition. :-)
Perhaps there is some grit stuck between the inner race and the spindle?

Yes, it was pre-existing, and I bet it was that way when Grandfather got
the unit. There is lots of dirt in the way at present.

O.K. You get yours back together properly, and then I will take
mine apart -- assuming that the manual does not turn out to say *don't*
in big bold letters. :-)

It's all back together. I will have to take it apart to push the one
bearing race back into place.


O.K. But the other fellow who has jumped into the thread has a
spindle like mine, and has screw-on collet adaptors -- not replaceable
spindles.

I wonder. I think that all Series 11 grinders have removable spindles.

It may depend on what you call "removable". Certainly the ones
which started this thread were designed to screw into a hollow spindle
with a taper, based on the photos. (Hmm ... has that auction closed,
yet? :-)

I think that the hollow spindle is a later design.



15,500 RPM no load
8,000 RPM full load.

This sounds plausible, from the sound while it spins.

You don't have a strobotac? I've recently discovered that they
are on eBay for fairly reasonable prices -- except that I already got
mine at a hamfest.

Thought of it, haven't done it yet.

O.K. If you can -- try to pick up on another auction of FX-6A
flashlamps -- these darken with use, and are now *very* hard to find. I
finally won an auction for enough to keep me going for a while.

Lots of flashlamps are made, and such things are not very critical. Is
there something else that will work?

Hmm. That number rings a bell. FX-6A is an old EG&G product. The
relevant part of EG&G was sold to Perkin-Elmer
(http://optoelectronics.perkinelmer.com), but still makes flashlamps.

The FX-6A is still available:

http://opto.mondosearch.com/cgi-bin/...ge_id=1153&que
ry=FX6a&hiword=FX6a%20

No idea what they cost, but they won't be cheap.

Selected General Radio stuff is now made by IET Labs www.ietlabs.com,
and they list flashlamps for $200 to $300, which I bet is more than old
Strobotacs go for on ebay.

For ~$300, one can buy a new Extech strobe/tach:
Vhttp://www.extech.com/instrument/products/451_499/461831_461830.html.
However, this unit goes only to 10,000 flashes per minute, insufficient
for a grinder spindle.


I bet there is a patent covering the Dumore grinder. Are there any
patent numbers on anything? My unit has nothing, but then again it's
pretty spartan.

Hmm The only data source which I have is the motor label, and
all it says on the subject is "Trade Mark Reg US Pat Off" in the upper
left and right corners. :-)

Protects only the trademark "Dumore".

Yep -- but that is all the information that I have from my
grinder. And I wonder how much of it would be patentable by that time.
Perhaps not enough to make it worth while hanging patent numbers on it,
if the patents were all expired.

Companies vary in this.


He also says that they told how much oil and what grade (which
they specified as their own brand, of course. And the oil is supposed
to only be added at the center.

Yes, Dumore type 0 oil, which sounds to be pretty low viscosity.

I wonder if one can buy new wicks.

I suspect that one would need to make new wicks at this point.
You can get appropriate felt from McMaster Carr for the task.

True, but if I order the spindle oil, might as well get some pre-made
wicks. My unit did not come with a belt, and I ordered that some years
ago, just so I could try it out. At the time, I didn't really know what
a toolpost grinder was for. Grinding tool posts?


Joe Gwinn