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

[ ... ]

I took the spindle apart without difficulty. The bearings consist of
two ball bearings, one at each end, with a fingered flat disk spring at
one end taking up axial play. The bearing races are very thin, and are
pressed into place on the spindle (one end) and a spindle housing cap
(the other end). It does not look possible to remove the pressed-in
bearings without destroying the bearings (by forcing the balls into the
races), and the races are so thin I have to believe that they are
special-order.

Somewhat as I feared.

I think one replaces the assembly, not the bearing.

Are the bearings two-part, so you can remove the spindle from
the main casting?

No, but one can nonetheless remove the spindle without difficulty.

The trick is that one bearing (including both races, balls, and ball
retainer) is pressed onto the spindle, while the other bearing (ditto)
is pressed into one spindle body cap. When one unscrews the body caps
(the ones with the holes for the spanner wrench), one can pull one cap
off the spindle axle, allowing the spindle to be pulled out of the body.

O.K. That sounds reasonable.

The good news is that the bearings are OK, but were pretty dirty.

O.K. One of the nicest ways to clean small precision bearings
that I have found is a vapor degreaser. You boil a solvent (I used
Freon TF back when it was readily available -- or 1,1,1 Trichlor), and
put a double-walled liner at the top which gets cold water run through
it so it condenses the solvent and drips it back into the reservoir.

You could probably do a pretty good job with alcohol -- except
for the risk of igniting the vapors.

[ ... ]

I thought of building a little vapor degreaser as described above that
would use some available but flammable solvent, and running it only in
the middle of the back yard. Someday.

That makes sense.

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 coeficient run.) And,
when that vapor burns, the result is very fine sand all over the place. :-)

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.

[ ... ]

Hmm ... use a feeler gauge to measure the gap, and cut a piece
of shim stock to serve as a spacer, so you can tighten it firmly without
crushing the bearings.

The lip isn't very deep. Perhaps a piece of copper wire will suffice.

Perhaps.

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?


For the record, both spindle bearing caps are right-hand threaded. I
used the tips of a pair of needle-node pliers as a spanner wrench. The
caps turned easily. I did see some faint marks left by a pipe wrench on
the caps. Anyway, disassembly and reassembly were easy.

O.K. I've got some hinged pin spanners (which I use for the hub
on my surface grinder) which should work well on it, if I need to get
into it.

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?

[ ... ]

Mine has an unthreaded nose with axial hole and grub screw.

Hmm ... "grub screw"? You're posting from the UK? I think that
is mostly a UK term. :-)

Well, the Boston area, but a Boston accent (which I don't have but my
wife does have) is really a form of London Cockney.

O.K. I guess that you picked up the term from the net, then.

FWIW My wife is from the area too -- Salem.

[ ... ]

From the current Dumore catalog, they had an assortment of spindles, and
the user was expected to change spindles as needed. So, there will be
many kinds of spindle floating around, but they should all fit the
grinder.

Except that those had the entire spindle cartridge removable
from the frame, I believe. If you can't get the bearings off the
spindle, and can't get the spindle out of the cylindrical part of the
housing, then you can't change spindles, I believe.

Yes, but I think that these spindles are removable, as described above.

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.

FWIW -- my complete model number is 11-011.

Mine is Type 11G, No 1059, 115 Volts. All other info blocks on the tag
are blank. Probably bought for the US Army to a govt spec, and later
sold as surplus to my Grandfather.

O.K. The OD drop-front cabinet suggests that you are right.

[ ... ]

While I don't have good woods for the task -- just whatever is
used to make cheap 2x4s these days -- a bit too soft, I think.

The local Home Despot carries Oak, which is what I used. Oak flooring
cutoffs are often available. Likewise, Maple.

O.K. Maple I would save for use repairing concertinas, not for
one-off tools.

Well, lots of special-purpose tools were made of maple, and it isn't all
that more costly than oak in small quantities at HD, and the grain is
very fine and uniform.

I had to go to a specialty wood shop to get my maple -- of
appropriate thickness for making replacement concertina pieces.

[ ... ]

Big vice, big hammer -- tools to live by.

Well ... not too big a vise in this case. It is a drill-press
vice from Craftsman from about 1970 or so. One with the ability to
mount it at an angle to the surface. Mostly, it had a big enough jaw
opening (barely), it was heavy enough for my task, and it was easy to
get to at the moment. :-)

I'm not impressed. Real vices weigh 100# min. Like anvils.

Agreed. Closer is the original Bridgeport vise which I have. I
*think* that is heavier than the import bench vise which is on one of
the workbenches.

[ ... ]

Does the box say Dumore? Mine does not have any indication of a maker.

It certainly does. The OD ones were government issue to the
Army, and would probably not have maker's names on them. I wonder
whether that drop-front design was part of an Army spec to make it
easier to get to under certain storage conditions? I've only seen it
(so far) on the OD cases.

Another indication that my unit was made to some generic govt spec.

Yep.

[ ... ]

I wondered about the pulleys, because current grinders from Dumore show
more than two sizes.

Right - they do.

What speeds are quoted on your grinder? Mine says nothing.

Motor first:

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.

Pulleys
Wheel size RPM Spindle Motor
=====================================
1/8" to 3/4" 30,000 #1 #2
2" 6,900 #2 #1

My pulleys are 2.165" and 0.906" in diameter, so the available ratios
are 2.39:1 and 0.418:1, for loaded speeds of 19,117 rpm and 3,348 rpm
respectively. No-load speeds are about twice that.

Hmm ... I don't have the measurement for the larger pulley, but
the smaller one has a maximum diameter of 0.9245" -- measured to make
that ring spanner wrench.

For a quick-and-dirty web page showing details of the label,
plus other features of the grinder and what I am making for it, see:

http://www2.d-and-d.com/PROJECTS/TP_GRINDER/index.html

Mine seems much more spartan.

As fits government construction.

[ ... ]

Set it up like surgery, with a sheet of plastic covering everything
except what absolutely must poke through?

Reasonable. I've read suggestions for covering everything with
several layers of wet newspaper, so the abrasive will stick to the
newspaper.

Wet newspaper will rust things, but I suppose that's not as bad as
abrasive grit everywhere.

It will rust things *if*:

1) The surfaces are not first wiped down with Vactra No. 2.

2) The wet newspapers are left on for longer than a work day.

And -- of course -- the newspapers could be wet down with oil
instead of water. It would accomplish the same purpose, not risk rust,
and make the newspaper harder to dispose of. :-)

With the plastic covering, the classic trick is to use sheet
polyethylene at least 0.002" thick, and force the sheet down on whatever
must penetrate, allowing the punctured sheet to pull tight around
whatever sticks through it.

Reasonable.

[ ... ]

Nice work. One trick to get that kind of precision is to set
the compound at 5.7106 degrees (as close as you can get, at least), and
for every 0.001" you crank the compound feed, you move 0.0001" closer to
the axis. (If you care, that decimal degrees comes out to be:

5 degrees, 42 minutes, 38 seconds

Good luck on the typical compound angle scale. :-)

It's a nice trick, even if one cannot set this on the angle scale. I
would just set it to something, measure the effect of advancing by a set
amount, and then use a hand calculator to figure out what to do to
achieve a specified effect.

Actually -- setting it to 5-3/4 degrees by eye should get you
close enough. You are only going to be making very small reductions in
diameter, so frequent checking with a good micrometer should suffice in
addition to this. This simply lets you make adjustments in finer steps,
and it would be useless for turning, as there is often more spring than
that in even a good rigid lathe.

Right. This only works for grinding on anything other than a Hardinge.

Agreed. Though it works *sometimes* with really sharp cutters
and non work-hardening workpiece materials on the Clausing. When I want
to work to precise dimensions, I often use one of the carbide insert
tools from my Emco-Maier Compact-5/CNC. It is a very small 55 degree
diamond insert, and I lucked into a batch of inserts which are very
sharp and not TiN coated, so the edges are not rounded off. Certainly
the inserts which came with the lathe were not so sharp.

My recollection is that it was the 1957 model year Corvette, but I have
not found any documents.

O.K. That was pretty close to the start of the Corvette line,
wasn't it? And the same for the Ford Thunderbird line, for that matter.

I don't recall.

I believe that the two-seat Thunderbird started in 1956. I was
in high school then, in a small town in South Texas, and someone there
got one -- and was the focus of attention. Not too much later, 1959 I
think, Ford spoiled the T-bird by turning it into a four-seater. At
least the Vette remained two-seat all the way into the present.

It turns out that the bread and butter was fuel injection systems for
general aviation engines.

O.K. So this was not just your grandfather, but the company for
which he worked?

Both. I don't think that Grandfather was an employee, as all his
patents were his, and were not assigned to anybody.

O.K. Which explains why he had a shop at home, and could (and
did) do such precision work -- for the prototypes, so he was not
obligated to anyone else, and could license his patents to who he
wished.

[ ... ]

Too much more to do tonight. Well ... I just took a look at it,
and was reminded how difficult I've found it to follow patent
descriptions of almost anything -- including electronic circuits for
which *I* hold the patent. :-)

I certainly agree, but I've found the patent literature to be quite
useful over the years.

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. :-)

[ ... ]

Hmm ... I really think that you still want spindle oils for
this, not motor oils.

Hmm. I wonder what Dumore says about this. This spindle is pretty
fast, but then again this isn't a lathe headstock bearing either.

Another poster said that the carpet thread is original.

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.


I think that oil is wicked to the taper, and propelled towards
increasing diameters by centrifugal force, leading the oil to circulate
through the bearings enough to keep them lubricated. This will work far
above the speed at which splash lubrication fails.

Did you figure out what the central oil port does? Perhaps it
provides a reservoir to replenish the oil from the wicks, and you are
only expected to remove the caps at the ends to replace the wicks?

That's my impression, although the covers over the two wicks are stamped
"oil".

Hmm ... I don't remember any such markings on mine -- just the
screw-in caps with no markings. I at first expected them to allow me to
slide the end caps out when I loosened them. When that didn't happen, I
unscrewed one to find the wick. :-)

[ ... ]

Been there, done that. Cameras are like that too, although physical
bruises are uncommon.

Yes -- the springs are not nearly as strong. :-) I've worked on
them, too.

Did the MGA manual mention how to reassembly this little beauty?

Sure -- the same way they had to reassemble *any* part. The
last paragraph of each section would read:

"Reassembly is a reversal of the above."

:-)

It was possible to use a chunk of round steel stock (even an old bolt)
to press the bearings and springs in enough to get the rods started,
after which things were fine until you removed the rods again. :-)

I recall working on the front shocks for a MGB my then girlfriend owned.
These were the swing-arm shocks. I don't recall much about them except
that they were a bitch to install without damage to all concerned.

Hmm ... I replaced the ones on my second MGA (1600 Mk II), and I
don't remember it being particularly difficult -- unlike some other
things, including replacing the clutch plate and pressure plate. :-) For
*that*, you have to remove the engine and transmission as a unit. And
to do that as indicated by the manual, you have to remove the
transmission tunnel, and to remove *that* you first had to remove the
floorboards -- plywood floorboards secured by screws which stuck out far
enough through the floor to get dinged and rusted.

After doing it by the book *once*, I figured out how to remove
the motor and transmission without removing the trans tunnel. But it
required small hands and blind dexterity. (It still beat doing it as
intended. :-)

Enjoy,
DoN.
--
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