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

[ ... ]

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.

As you probably have seen already -- there was a followup posted
which strongly supports my warning.

[ ... ]

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.

Even if it does not precisely cover your version. How do the
model numbers compare? (The first four digits of the serial number).
Mine are an exact match.

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.

Right -- but that should not make any difference. Perhaps the
difference in the motor bearings is because only the pulley end of the
motor experiences side loads, while both ends of the spindle do.

Or -- the bearings *may* be identical. :-)

[ ... ]

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.

Right -- but you can change the business end with the screw-on
"chuck" just as easily.

After reading the manual, I now have to bold mine up on my
lathe, and see whether the spindle height can be set high enough (mine
is a 12" swing lathe, and they are specifying this toolpost grinder for
up to 11" swing). But if not, I can probably make a new center post for
the toolpost to allow it to be mounted a bit higher.

And -- I think that I'll also make a support collar so it will
be easy to restore to the proper height each time, since this is the
only lathe which I expect to use it on. It seems a bit too big for the
little Emco-Maier Compact-5/CNC -- a 5" swing machine. :-)

[ ... ]

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.)

The thing is that most flashlamps use external trigger -- a wire
wrapped around the outside of the envelope. This one, however, has
internal trigger electrodes, and may operate with a much lower trigger
voltage.

[ ... ]

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. :-)

[ ... ]

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.

You mean "aren't too dear"? Agreed. And if they are -- just
keep buying Strobotacs from eBay. :-)

Hmm -- auction # 7607110774 is up to $83.68 with 44 minutes to
go -- but it is one of the newer ones with the light gray smooth front
panel. Model 1538-A. A connector for an external flash head, but
otherwise quite similar.

Another auction (actually only "buy-it-now") is being offered
by a vendor with delusions of grandeur. This is auction # 7405976193
and has a *starting* price of $2,955.06 (actually it is priced in Euros,
at EUR 2,444.02).

The only other current auction is # 7607451350 -- one of the
older ones, with a less bright flash lamp, and (IIRC) a much lower speed
limit. None of the photos are from an orientation to show the
"soupbowl" reflector -- which may suggest problems with it. Normally, I
would expect, even from the views show, the bulge of the large crystal
to be visible. Since it is not -- it may be broken. And while it
*looks* like a GR unit from the views given -- it may not be by GR --
they say "Electric Brazing" -- which may have been a secondary
contract manufacturer during wartime or something similar.

Auction # 7607782129 looks interesting -- a much later digital
Strobotac -- but the vendor is in love with that one too -- $1,295.00
starting bid and $1,345.00 for buy-it-now.

FWIW -- The speed ranges a

Range Flashes Per Minute Flash Duration (approx.)
1 (LOW) 100 to 700 2sssss
2 (MED) 1600 to4,200 2sssss
3 (HIGH) 3,600 to 25,000 1.2

(I got a long phone call just before this point above -- just after the
auction number was entered. It will be interesting to see whether the
article has timed out while I was talking.

[ ... ]

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.

They used to make them available -- for free. (At least the one
for the drill grinder was free.) They seem to have tossed all of the
old parts and manuals now.


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:

[ ... ]

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.

If he can snail-mail a CD-ROM to me, I can put them on my web
site at full resolution. I can't receive e-mails over 30K in size -- to
keep viruses out of the mailing lists which I host. (And to keep me
from being flooded with each new issue -- to the tune of 200-300 per
day. :-)


Just checked .. I have 20Meg or so left on my FTP space so I will scan it in
high res suitable for framing and post it there. I will post a link when it
is in place.

Glenn