Not the first or last, but here are a few things that I assumed I knew
something about til I realized that I didn't. Wonder if y'all have a few
of your own?
**********************************************
1. The MT2 in the end of a 1" or 1.25" spindle doesn't leave much
meat. Does inserting a dummy MT2 when using a faceplate or heavy chuck
on a heavy load help significantly? Please _ignore RPM.

2. Does pounding a blank into a spur center on the lathe or driving the
tail center hard against the blank harm the bearings? I think the front
bearing race acts as the register for my N3K and pounding would hurt the
bearing. Not sure about lathes that use collars, etc. or separate
registers to prevent axial motion of the spindle? Also not sure if the
N3K's bearing race being tightened against the head casting is the cause
of the 'braking effect' of over tightening the tail center?

3. When the headstock end of a long heavy blank held with tail support
is balanced with counterweights adjusted on a steel plate, is the entire
length of the long blank now in balance. (ie. do I need to balance both
ends of a long heavy blank?)

3. Is the N3K's revolving headstock any less prone to vibration when
locked down along the bed axis than when at an angle to the bed? This
concerns the headstock _only. Please _ignore tail support or the
stability or instability of the bench & floor.

4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?

5. If it's a practical truth and not a logical myth that hi carbon steel
makes better scrapers than hi speed steel, then why wouldn't cold rolled
steel flats make even better scrapers? Probably like the three bears,
the middle is just right.

6. May not matter, but does my N3K's VS DC motor & its controls want me
to use its speed pot or the run switch or the line switch for the
frequents stops & starts during a long turning session? (please _ignore
the advantages of ramping up or down. that's not the question) Does it
hurt anything but my light bill to leave both line and run switches on
and the speed pot turned to zero?

I bet the answers are obvious to someone here, but they sure aren't to
me.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

"Arch" wrote: 3. When the headstock end of a long heavy blank held with
tail support is balanced with counterweights adjusted on a steel plate, is
the entire length of the long blank now in balance. (ie. do I need to
balance both ends of a long heavy blank?)
^^^^^^^^^^^^^^
I know this one, so I will answer. The *other* number 3, and the others as
well, will have to come from those with better info.

If you balance a long, unbalanced piece at by adding all the weights at one
end, you achieve "static balance." The piece will stay where you stop it,
and not fall/rotate to lower its center of gravity. However, if the ends
are differently out of balance, you have "dynamic unbalance." The two ends
will try to behave independently of each other when spinning, and you get a
tilting, end-to-end vibration.

(Arch) writes:

2. Does pounding a blank into a spur center on the lathe [snip]
harm the bearings?

One of the books I own suggest removing the spur center, and pounding
it into the wood, and then inserting it back into the headstock.

Certainly sounds like a safer approach.

I think it was the Tage Frid book on Shaping.

--
Sending unsolicited commercial e-mail to this account incurs a fee of
$500 per message, and acknowledges the legality of this contract.

Arch wrote:
2 (part 1). Does pounding a blank into a spur center on the lathe or driving the
tail center hard against the blank harm the bearings?

I have read that this is not a good idea and that the spur center
should be removed and tapped in off the lathe.

2. (part 2). Also not sure if the N3K's bearing race being tightened against the head casting is the cause of the 'braking effect' of over tightening the tail center?

My guess would be yes but now I have a question. Why do you tighten
the tailstock that tight?

3. (2nd one) Is the N3K's revolving headstock any less prone to vibration when
locked down along the bed axis than when at an angle to the bed? This
concerns the headstock _only. Please _ignore tail support or the
stability or instability of the bench & floor.

In my experience, no, at least I don't think so, at least I never
noticed a diference.

Hi Arch, where have you been ?? kind of missed you on the rcw.


Arch wrote:
Not the first or last, but here are a few things that I assumed I knew
something about til I realized that I didn't. Wonder if y'all have a few
of your own?
**********************************************
1. The MT2 in the end of a 1" or 1.25" spindle doesn't leave much
meat. Does inserting a dummy MT2 when using a faceplate or heavy chuck
on a heavy load help significantly? Please _ignore RPM.

Just depending here as always, shaft thickness between bearings and
length, length of overhang, but filling the shaft with a fitting taper
will certainly increase the stiffness of that shaft, MO

2. Does pounding a blank into a spur center on the lathe or driving the
tail center hard against the blank harm the bearings? I think the front
bearing race acts as the register for my N3K and pounding would hurt the
bearing. Not sure about lathes that use collars, etc. or separate
registers to prevent axial motion of the spindle? Also not sure if the
N3K's bearing race being tightened against the head casting is the cause
of the 'braking effect' of over tightening the tail center?

Bearings and bearings are like wood and wood, all kinds and not the
same, there are many configurations and/or combinations of bearings,
not to mention qualities.
However if the right kind of bearing of good quality is used I wouldn't
be afraid to wallop a chunk of wood onto a spur center wood, the steel
will win that handily.
Now running the lathe while HEAVY pressure is put upon them is another
story, we have now steel wearing against steel, and the lubrication
film could very well be insufficient and overheating and damage could
then occur, so yes you can use pressure, but if the bearings heat up a
lot, take some pressure off and/or slow down. MO

3. When the headstock end of a long heavy blank held with tail support
is balanced with counterweights adjusted on a steel plate, is the entire
length of the long blank now in balance. (ie. do I need to balance both
ends of a long heavy blank?)

Like Leo L said, you might have static balance, but that's not dynamic
balance, to which I would like to add, that if you have rigged up a
piece of wood and got it statically balanced and you now think you can
rev. it up, the dynamics are there in full force, and you better be
aware of that, it can do a lot of damage in a hurry, so keep it down.


3. Is the N3K's revolving headstock any less prone to vibration when
locked down along the bed axis than when at an angle to the bed? This
concerns the headstock _only. Please _ignore tail support or the
stability or instability of the bench & floor.

I'm not to sure about this one Arch, vibration is more like a
resonance, and probably a dynamically induced imbalance, changing with
speeds used, I don't think rotating the headstock will, but could make
a difference, like I said I'm not sure.


4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?

This is more a thing of who got the upper hand in making drill bits
and the drill chucks, with their own proprietary taper, best way to
prevent slippage is a clean and precise fit, MO


5. If it's a practical truth and not a logical myth that hi carbon steel
makes better scrapers than hi speed steel, then why wouldn't cold rolled
steel flats make even better scrapers? Probably like the three bears,
the middle is just right.

I don't follow you here Arch, the metal crystal structure and the kind
of other alloys/metals in there make for the carbon steel to generally
be able to be sharpened to a finer/narrow edge, This to the best of my
knowledge. I worked with it, never made it.

6. May not matter, but does my N3K's VS DC motor & its controls want me
to use its speed pot or the run switch or the line switch for the
frequents stops & starts during a long turning session? (please _ignore
the advantages of ramping up or down. that's not the question) Does it
hurt anything but my light bill to leave both line and run switches on
and the speed pot turned to zero?

Haven't got a clue Arch, maybe it's something like what hurts most, I
hit it or it hits me.


I bet the answers are obvious to someone here, but they sure aren't to
me.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

1 I believe that a tubular shaft is about 80% as strong as a solid
shaft.

2 hammering on bearing is a bad practice unless you plan on replacing
the bearing.

3.2 The Nova head stock sits on a ring about 8 inches across the pin
you tighten lock down the head stock pulls down in the center of this
ring so it does not care how you turn it.

5 How often do you want to sharpen? The softer the steel the more you
will sharpen.


6 When you suddenly kill the power to the control unit it will cut the
current to the motor. DC motors make good generators the energy stored
in the rotating shaft and the magnetic field around the motor will be
returned to the motor controller. the current running the motor had
built a large magnetic field around the motor if the current should
suddenly stop the magnetic field will collapse the energy from this
field will be collected by the coils of the motor. There is a lot of
energy stored in that field, this energy will find away to complete
its circuit throw the path of least resistance. The higher the
resistance the higher the voltage will go, should the voltage become
high enough it will break throw the insulation in the motors coils and
damage them. The designer of the motor control made some plan for this
catastrophic event, testing this plan is about as smart as testing the
air bags in your car.

Electronic controls are great but they can and do sometime fail. Let's
assume you left a 40 pound blank on the lathe a few hours later a
thunder storm rolls throw and the motor control fails to a full speed
condition, how big is the hole in the wall?


Walt A



On Mon, 2 Oct 2006 15:05:53 -0400, (Arch) wrote:

Not the first or last, but here are a few things that I assumed I knew
something about til I realized that I didn't. Wonder if y'all have a few
of your own?
**********************************************
1. The MT2 in the end of a 1" or 1.25" spindle doesn't leave much
meat. Does inserting a dummy MT2 when using a faceplate or heavy chuck
on a heavy load help significantly? Please _ignore RPM.

2. Does pounding a blank into a spur center on the lathe or driving the
tail center hard against the blank harm the bearings? I think the front
bearing race acts as the register for my N3K and pounding would hurt the
bearing. Not sure about lathes that use collars, etc. or separate
registers to prevent axial motion of the spindle? Also not sure if the
N3K's bearing race being tightened against the head casting is the cause
of the 'braking effect' of over tightening the tail center?

3. When the headstock end of a long heavy blank held with tail support
is balanced with counterweights adjusted on a steel plate, is the entire
length of the long blank now in balance. (ie. do I need to balance both
ends of a long heavy blank?)

3. Is the N3K's revolving headstock any less prone to vibration when
locked down along the bed axis than when at an angle to the bed? This
concerns the headstock _only. Please _ignore tail support or the
stability or instability of the bench & floor.

4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?

5. If it's a practical truth and not a logical myth that hi carbon steel
makes better scrapers than hi speed steel, then why wouldn't cold rolled
steel flats make even better scrapers? Probably like the three bears,
the middle is just right.

6. May not matter, but does my N3K's VS DC motor & its controls want me
to use its speed pot or the run switch or the line switch for the
frequents stops & starts during a long turning session? (please _ignore
the advantages of ramping up or down. that's not the question) Does it
hurt anything but my light bill to leave both line and run switches on
and the speed pot turned to zero?

I bet the answers are obvious to someone here, but they sure aren't to
me.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

On Mon, 2 Oct 2006 15:05:53 -0400, (Arch) wrote:


4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?

Hi Arch,

I've done a little judicious snipping to skip the things I don't know
about to hit this one-

First part, I'd guess that the MT does a better job of preventing
mating parts from rotating. More surface area = more holding power.

Next, ever seen a machinist's Bohr blocks? If you haven't, they are
two blocks with perfectly flat surfaces that hold together with no
adhisive or fasteners. This is because the machined surfaces are so
precise that they allow the two pieces to sit so closely together that
the atoms in each can swap electrons (and possibly other forces, I'm
not an expert on the subject by any means)

In a perfect world, the mating surfaces between the MT or JT and it's
mating socket should work on a similar principle. Granted, most of
them have some dings and nicks, so it's not going to be quite the
same, but getting it close must be good enough. Allowing the two
parts to rust introduces a failure point that should not be there-
that doesn't mean it doesn't work in application, but the best way to
get the full performance is to make sure both the taper and the socket
are perfectly smooth and shiny. To help things stay rust-free, a
little oil goes a long way, and also adds to the bond between the two
mating parts.

As far as "tightening" goes, I've always fully opened chucks, then
inserted the JT, and put the assembly into a vise. Seems to work well
enough, and you're not pounding the guts out of your chuck.

"Arch" wrote in message
...
1.
Adequately answered.


2. Does pounding a blank into a spur center on the lathe or driving the
tail center hard against the blank harm the bearings?

The bearings are designed to work against an axial load, loading at 90
degrees is bad for them. Hammering is worse.

Also not sure if the
N3K's bearing race being tightened against the head casting is the cause
of the 'braking effect' of over tightening the tail center?


Betting the bearings at the headstock are _much_ better than the ones in the
live center. Look there for drag.

3. When the headstock end of a long heavy blank held with tail support
is balanced with counterweights adjusted on a steel plate, is the entire
length of the long blank now in balance. (ie. do I need to balance both
ends of a long heavy blank?)


I reread the answer, and it still does not make sense to me. If I taper the
bottom of a bowl blank, it doesn't start oscillating, so any physics are
going to be so subtle as to be meaningless. It is mv squared, after all,
and for balance _Delta_ (difference) is the appropriate mass. What makes
sense is to get as much unneeded wood out of the way at the bandsaw as
possible.

3. A circle loads same-o all directions.


4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?

Keeping things short minimizes the effect of runout error. Side loads -
see above - ar not what tapers are about. Clean, unlubricated is what you
want, just as the directions have it.


5. If it's a practical truth and not a logical myth that hi carbon steel
makes better scrapers than hi speed steel, then why wouldn't cold rolled
steel flats make even better scrapers? Probably like the three bears,
the middle is just right.

Malleability counts in turning the burr. Of course, the more easily it's
turned up, the more easily it can turn down. No burr is really required
with the piece in motion, just an edge on your HSS will do.


6. May not matter, but does my N3K's VS DC motor & its controls want me
to use its speed pot or the run switch or the line switch for the
frequents stops & starts during a long turning session? (please _ignore
the advantages of ramping up or down. that's not the question) Does it
hurt anything but my light bill to leave both line and run switches on
and the speed pot turned to zero?

Betting it matters not. Probably a shunt besides the braking for the
generated DC.


I bet the answers are obvious to someone here, but they sure aren't to
me.


Always interesting to get an explanation and then test it. Hopefully these
are better than hypotheses.

"George" wrote: The bearings are designed to work against an *axial* load,
(clip)
^^^^^^^^^^^^^^^
Did you mean to say "radial?"

"Leo Lichtman" wrote in message
...

"George" wrote: The bearings are designed to work against an *axial*
load, (clip)
^^^^^^^^^^^^^^^
Did you mean to say "radial?"

Ayup, dicandpurpular to the axis of rotation.

"George" wrote: Ayup, dicandpurpular to the axis of rotation.
^^^^^^^^^^^^^^^^
Herst a wort? (Do you speak any Yiddish?)

Arch one addition here, regular ball bearings are not designed for
axial trust, but you don't have to go to spherical or tapered roll
bearings hat need preload on them, there are torrington or angular load
ball bearings, specifically designed for loading in both directions, I
put a link in here for you to peruse if you like.
They would be exactly the kind of bearings for most wood lathes. MO

http://www.timken.com/industries/tor...r/ang_cntk.pdf

Have fun and take care
Leo Van Der Loo

Arch wrote:

4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?



The JTs that the chucks mount on are Jacobs tapers, not Jarno. The
Jarno tapers are long tapers very similar to Morse tapers.

The Jarno tapers are easier to machine than the Morse as they all have
a .600" per foot taper. The Morse tapers are around the same, but vary
for each size.

A Jacobs taper will hold very well if it is installed correctly.
Perfectly clean surfaces, free from burrs, is often enough. To get
them tighter, heat the female part in an oven and then drive in the
male arbor.

Here is a link to a good table of tapers:

http://www3.telus.net/public/aschoepp/tapers.html

John Martin

Thanks John for that link, some really interesting stuff on there.

Have fun and take care
Leo Van Der Loo

John wrote:
Arch wrote:

4. Is a Jarno taper used on a Jacob's chuck arbor because it's short or
there other reasons? Which best prevents mating parts from rotating, MT
or JT? I've had both tapers slip by deliberately overstressing cheap
chucks. I let them rust to prevent slipping. Is there a better way to
'tighten' Morse & Jarno tapers?



The JTs that the chucks mount on are Jacobs tapers, not Jarno. The
Jarno tapers are long tapers very similar to Morse tapers.

The Jarno tapers are easier to machine than the Morse as they all have
a .600" per foot taper. The Morse tapers are around the same, but vary
for each size.

A Jacobs taper will hold very well if it is installed correctly.
Perfectly clean surfaces, free from burrs, is often enough. To get
them tighter, heat the female part in an oven and then drive in the
male arbor.

Here is a link to a good table of tapers:

http://www3.telus.net/public/aschoepp/tapers.html

John Martin

Thank you all for your information and insights. I learned something
from each of you and I hope some other woodturner learned something
he/she didn't know. There are many things related to our craft that we
don't know that we don't know.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings