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

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.

The elements were not visible, but were under the plate's top,
so the curling vapors reached them underneath.

Ah. Needs an iron skirt.


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.

I think that it may be a function of the size of the air exit in
the nozzle vs the air pressure. But also -- depending on where you hit
the bearings, you can get speed multiplication -- probably the worst is
driving at the balls themselves, which could easily double the air
speed.

I'll have to think about this. One can compute the airstream velocity
at the output side of the orifice of the blowoff nozzle, and use this to
computer rpm. It would be hard for the airstream to get a purchase on
anything other than the balls - everything else is too smooth.



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. At least the manual (I presume that you downloaded it as
well) does not say to not disassemble it.

I just downloaded the manual. Quite interesting.


Interesting that there are different numbers (and different part
numbers) for the motor bearings depending on which end, but the spindle
bearings have the same number at each end.

They look the same too. The motor has a shaft coming out of one end
only, while the spindle has shafts coming out at both ends.


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.

O.K. But the manual does show that for this model at least, the
same spindle is used for both larger wheels and smaller mounted ones --
with a screw-on single-sized collet adaptor.

Yes. It appears to be the earlier design. The hollow spindle design
allows one to change the business end without disassembling the grinder.


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?

I suspect not. It has several unique features:

1) It is in a stubby 9-pin miniature tube housing.

2) aside from the two heavy-duty flash electrodes at perhaps
a 1/2" spacing, there are five internal trigger wires set up to
produce a ionized track between the two electrodes. They look
something like this from a top (end) view:

[snip]

Sorry -- it is difficult to make a nice circle using ASCII graphics. :-)

[snip]

I think that it would be difficult to adapt the typical
flashlamp to the purpose. And the diameter and base of the lamp are
needed, as it plugs into a socket on the end of the stub, and the flash
reflector slides on over the lamp once it is plugged in.

One does not have to duplicate these details. An electrical match will
generally work. Basically, one matches the flash voltage range (say 300
volts), the energy capacity (4 Joules/flash, max), trigger voltage (say
6 KV), and trigger energy (say 1 millijoule). (These are not the
correct values for the FX-6A, but give the idea.)


Hmm. That number rings a bell. FX-6A is an old EG&G product.

Yep. A friend got one at Eli's surplus at MIT, and got a data
sheet from Dr. Edgerton. He asked what we got it for, and then told us
that he wished that *he* could get them at that price. The new price
was $15.00 in 1960, IIRC. No doubt, it has not gone down since then. :-)

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

Good!

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

No bets on that. :-)

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.

It is about an order or magnitude more. I got a set of about
five or six FX-6A lamps from an ebay auction for a fairly reasonable
price, after losing an auction for a similar number which went into the
stratosphere -- at least based on what I was willing to pay. :-)

For ~$300, one can buy a new Extech strobe/tach:
http://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.

Yep. My Strobotac goes up to 25K Flashes Per Minute. It is a
model 1531-A, FWIW. The older one with the dark gray crackle panel
finish, not the later one with the light gray smooth finish.

Hmm. If the flashtubes aren't too deal, this could be a good idea, even
if the tubes cost more than the unit.


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?

O.K. Some years ago I got a Dumore drill grinder, and got a
manual from them at that time. A couple of years later, I got the
toolpost grinder, and a phone call had them not having any manuals or
parts for toolpost grinders that old.

I can understand ditching the repair parts after 50 years, but how much
trouble would it have been to scan and post the old manuals? These old
units are quite well made, and so will always be with us.


If you haven't already, download the manual and the .txt page
posted to the dropbox (http://www.metalworking.com). The files are
under the names:

Dumore_Series_11_TPG.pdf

Dumore_Series_11_TPG_Manual.txt

The .txt normally just explains what is in the image or .pdf files, but
in this case, it also gives some additional dimensions for the collet
holder which Dumore called the "chuck".

Got them, Thanks. Would have liked the photos to be legible. Perhaps
we can impose on the poster to provide a high-rez scan as well.


Joe Gwinn