My lathe is a low end Taiwan made with 3/4 HP and 1” 8 tpi.

The other day I was finishing a 9” OD maple bowl with a 3/8 X 1” scrapper at
about 800-1000 RPM.
It worked well. Until I reached the 9” OD lip where the wall thickness
was about 3/8 thick. Then what seem to be the Headstock started to hum at
low decibels.
I stopped and sharpen the scraper and checked the mounting. I then
continued with very gentle touch on the scraper removing minimum wood.
Still, the Headstock was humming. I changed the RPM with negative result..
I am puzzled by this humming. I would appreciate comments as to what can
cause that humming sound.
-
Denis
Sprucewood, Rothesay, N.B

It doesn't know the words.
Sorry, I couldn't resist

"Denis Marier" wrote in message
...
My lathe is a low end Taiwan made with 3/4 HP and 1" 8 tpi.

The other day I was finishing a 9" OD maple bowl with a 3/8 X 1" scrapper
at
about 800-1000 RPM.
It worked well. Until I reached the 9" OD lip where the wall thickness
was about 3/8 thick. Then what seem to be the Headstock started to hum
at
low decibels.
I stopped and sharpen the scraper and checked the mounting. I then
continued with very gentle touch on the scraper removing minimum wood.
Still, the Headstock was humming. I changed the RPM with negative
result..
I am puzzled by this humming. I would appreciate comments as to what can
cause that humming sound.
-
Denis
Sprucewood, Rothesay, N.B

Man! You should put up a spew warning next time.... I got iced tea all over
the monitor that time!

"rdspivey" wrote in message
...
It doesn't know the words.
Sorry, I couldn't resist

"Denis Marier" wrote in message
...
My lathe is a low end Taiwan made with 3/4 HP and 1" 8 tpi.

The other day I was finishing a 9" OD maple bowl with a 3/8 X 1"
scrapper
at
about 800-1000 RPM.
It worked well. Until I reached the 9" OD lip where the wall
thickness
was about 3/8 thick. Then what seem to be the Headstock started to
hum
at
low decibels.
I stopped and sharpen the scraper and checked the mounting. I then
continued with very gentle touch on the scraper removing minimum wood.
Still, the Headstock was humming. I changed the RPM with negative
result..
I am puzzled by this humming. I would appreciate comments as to what
can
cause that humming sound.
-
Denis
Sprucewood, Rothesay, N.B

Check the belt cover. I've had the same prob on 2 different lathes. If
tightening the screws doesn't fix it, try putting thin neoprene or fiber
washers between the cover and the lathe.

"Denis Marier" wrote in message
...
My lathe is a low end Taiwan made with 3/4 HP and 1" 8 tpi.

The other day I was finishing a 9" OD maple bowl with a 3/8 X 1" scrapper
at
about 800-1000 RPM.
It worked well. Until I reached the 9" OD lip where the wall thickness
was about 3/8 thick. Then what seem to be the Headstock started to hum
at
low decibels.
I stopped and sharpen the scraper and checked the mounting. I then
continued with very gentle touch on the scraper removing minimum wood.
Still, the Headstock was humming. I changed the RPM with negative
result..
I am puzzled by this humming. I would appreciate comments as to what can
cause that humming sound.
-
Denis
Sprucewood, Rothesay, N.B

Denis Marier wrote:
My lathe is a low end Taiwan made with 3/4 HP and 1” 8 tpi.

The other day I was finishing a 9” OD maple bowl with a 3/8 X 1” scrapper at
about 800-1000 RPM.
It worked well. Until I reached the 9” OD lip where the wall thickness
was about 3/8 thick. Then what seem to be the Headstock started to hum at
low decibels.

I was going to say maybe your headstock bearings are just a tad too
loose. When your tool gets to the outer diameter of a piece, even if you
are using the same amount of force as you did towards center, that force
is amplified by leverage and putting more sideways pressure on the
spindle causing the bearings to vibrate.
But then I thought some more, and figured it could be the wood itself
humming. Probably due to the thinness of the wood, it's hardness, and
the broad-edged scraper.
If you heard the humming while turning the outside (before hollowing)
my first theory makes more sense. If you find a way to adust your
bearings, do so very carefully--a bit too tight can overheat and wear
them prematurely.
I could be wrong on both points, it may be just the quality of the
lathe--but with those cheap imports, you can usually tweak them for
better performance if you have some mechanical know-how.


--
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



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Thanks to everyone for their comments.
Maybe the situation would have been better depicted by using the "Harmonic
vibration " instead of humming noise.
After about one week I have found that all the comments are valid.
The Harmonic vibration is probably produced by the unbalance in rotating
components of my lathe. This may be further compounded by resonance caused
by shattering of the scrapper applied on the thin wall of the maple bowl. I
was told that in some instances the rotating components may be fairly
balanced but the finishing gouge or the scrapper lightly rubbing on a bowl
could produce resonance. I was told that the same thing takes place when
rubbing the lip of a glass with your finger. Some time bowl steady are
used.
Now, If only I can find a way to adjust the bearings I may reduce the
Harmonic vibration a little?



"Ken Grunke" wrote in message
...
Denis Marier wrote:
My lathe is a low end Taiwan made with 3/4 HP and 1” 8 tpi.

The other day I was finishing a 9” OD maple bowl with a 3/8 X 1”
scrapper at
about 800-1000 RPM.
It worked well. Until I reached the 9” OD lip where the wall
thickness
was about 3/8 thick. Then what seem to be the Headstock started to
hum at
low decibels.

I was going to say maybe your headstock bearings are just a tad too
loose. When your tool gets to the outer diameter of a piece, even if you
are using the same amount of force as you did towards center, that force
is amplified by leverage and putting more sideways pressure on the
spindle causing the bearings to vibrate.
But then I thought some more, and figured it could be the wood itself
humming. Probably due to the thinness of the wood, it's hardness, and
the broad-edged scraper.
If you heard the humming while turning the outside (before hollowing)
my first theory makes more sense. If you find a way to adust your
bearings, do so very carefully--a bit too tight can overheat and wear
them prematurely.
I could be wrong on both points, it may be just the quality of the
lathe--but with those cheap imports, you can usually tweak them for
better performance if you have some mechanical know-how.


--
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

If it were my problem, I'd run the lathe empty and use my stethoscope to
listen for bearing rumble. You may also do the old mechanic's trick by
placing the steel end of a screwdriver on or near the bearing cap and the
large end butted up to your ear. If there's interference at all - repeating
change in pitch - then you might consider adjusting preload in accordance
with your instruction manual.

That said, I'd bet it's just plain old flex and chatter. A cross-grain bowl
presents two mutually reinforcing problems when a scraper is used. First is
the natural deformation of the bowl as you exposed and dried the damper
interior - bowl will be narrower across the face than along the long grain.
Second is flex as the bowl tries to get away from the scraper. That bit of
tearout that you see as you pick up the unsupported ends of the fibers makes
the bowl squirm away. The combination often produces chatter marks, always
produces noise.

What to do if it's natural? Change your scraper angle to get a bit more
shear, or go back to a broad nosed gouge and cut/shear down slope not
outward . In either case, don't be anxious to get the wood off. Just take
the mild cuts and keep the speed low, and the chatter, if there, will be
minimized. A bowl steady will allow you to get much thinner, but I find
somewhere around 7mm to be the point at which chatter becomes inevitable on
a 12" piece.


"Denis Marier" wrote in message
...
Thanks to everyone for their comments.
Maybe the situation would have been better depicted by using the
"Harmonic
vibration " instead of humming noise.
After about one week I have found that all the comments are valid.
The Harmonic vibration is probably produced by the unbalance in rotating
components of my lathe. This may be further compounded by resonance
caused
by shattering of the scrapper applied on the thin wall of the maple bowl.
I
was told that in some instances the rotating components may be fairly
balanced but the finishing gouge or the scrapper lightly rubbing on a bowl
could produce resonance. I was told that the same thing takes place when
rubbing the lip of a glass with your finger. Some time bowl steady are
used.
Now, If only I can find a way to adjust the bearings I may reduce the
Harmonic vibration a little?

Thanks for the information George
I have used a screw a screwdriver near the bearing cap. The noise is
constant without any change in pitch.

Lately, the heating system in our house is working hard to cope with extreme
cold weather (-30). The blanks are stored in between the basement rafters.
When turning the blanks I noticed that they are very dry.
I only hear the low pitch noise when I take light cut/shear with the
scrapper.

"Denis Marier" wrote in message
...
Thanks to everyone for their comments.
Maybe the situation would have been better depicted by using the
"Harmonic
vibration " instead of humming noise.
After about one week I have found that all the comments are valid.
The Harmonic vibration is probably produced by the unbalance in rotating
components of my lathe. This may be further compounded by resonance
caused
by shattering of the scrapper applied on the thin wall of the maple bowl.
I
was told that in some instances the rotating components may be fairly
balanced but the finishing gouge or the scrapper lightly rubbing on a bowl
could produce resonance. I was told that the same thing takes place when
rubbing the lip of a glass with your finger. Some time bowl steady are
used.
Now, If only I can find a way to adjust the bearings I may reduce the
Harmonic vibration a little?



"Ken Grunke" wrote in message
...
Denis Marier wrote:
My lathe is a low end Taiwan made with 3/4 HP and 1” 8 tpi.

The other day I was finishing a 9” OD maple bowl with a 3/8 X 1”
scrapper at
about 800-1000 RPM.
It worked well. Until I reached the 9” OD lip where the wall
thickness
was about 3/8 thick. Then what seem to be the Headstock started to
hum at
low decibels.

I was going to say maybe your headstock bearings are just a tad too
loose. When your tool gets to the outer diameter of a piece, even if you
are using the same amount of force as you did towards center, that force
is amplified by leverage and putting more sideways pressure on the
spindle causing the bearings to vibrate.
But then I thought some more, and figured it could be the wood itself
humming. Probably due to the thinness of the wood, it's hardness, and
the broad-edged scraper.
If you heard the humming while turning the outside (before hollowing)
my first theory makes more sense. If you find a way to adust your
bearings, do so very carefully--a bit too tight can overheat and wear
them prematurely.
I could be wrong on both points, it may be just the quality of the
lathe--but with those cheap imports, you can usually tweak them for
better performance if you have some mechanical know-how.


--
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Sounds like it's the natural result of increased friction and a grain lift
or two. Are you getting chatter marks on the surface?

Couple things I've done in the past, before a steady, is to turn slow and
ride the left hand outside the bowl, or take two or three rounds of duct
tape to the outside to dampen vibration.

I burn wood, myself, and I've been obliged to stoke four times a day with
what our temps have been - negative 20's Celsius. Of course the wind blows,
the lake snows, and I've had to plow pretty much every day for the last week
and a half. My frozen wood supply is under a hard-packed 66 cm of snow,
which is what two meters of light stuff compacts to.

I swear the road commission has a sensor at the end of my drive. Every time
I remove the snow, they come by with the plow and fill in!

"Denis Marier" wrote in message
...
Thanks for the information George
I have used a screw a screwdriver near the bearing cap. The noise is
constant without any change in pitch.

Lately, the heating system in our house is working hard to cope with
extreme
cold weather (-30). The blanks are stored in between the basement rafters.
When turning the blanks I noticed that they are very dry.
I only hear the low pitch noise when I take light cut/shear with the
scrapper.

"Denis Marier" wrote in message
...
Thanks to everyone for their comments.
Maybe the situation would have been better depicted by using the
"Harmonic
vibration " instead of humming noise.
After about one week I have found that all the comments are valid.
The Harmonic vibration is probably produced by the unbalance in rotating
components of my lathe. This may be further compounded by resonance
caused
by shattering of the scrapper applied on the thin wall of the maple
bowl.
I
was told that in some instances the rotating components may be fairly
balanced but the finishing gouge or the scrapper lightly rubbing on a
bowl
could produce resonance. I was told that the same thing takes place
when
rubbing the lip of a glass with your finger. Some time bowl steady are
used.
Now, If only I can find a way to adjust the bearings I may reduce the
Harmonic vibration a little?



"Ken Grunke" wrote in message
...
Denis Marier wrote:
My lathe is a low end Taiwan made with 3/4 HP and 1" 8 tpi.

The other day I was finishing a 9" OD maple bowl with a 3/8 X 1"
scrapper at
about 800-1000 RPM.
It worked well. Until I reached the 9" OD lip where the wall
thickness
was about 3/8 thick. Then what seem to be the Headstock started
to
hum at
low decibels.

I was going to say maybe your headstock bearings are just a tad too
loose. When your tool gets to the outer diameter of a piece, even if
you
are using the same amount of force as you did towards center, that
force
is amplified by leverage and putting more sideways pressure on the
spindle causing the bearings to vibrate.
But then I thought some more, and figured it could be the wood itself
humming. Probably due to the thinness of the wood, it's hardness, and
the broad-edged scraper.
If you heard the humming while turning the outside (before hollowing)
my first theory makes more sense. If you find a way to adust your
bearings, do so very carefully--a bit too tight can overheat and wear
them prematurely.
I could be wrong on both points, it may be just the quality of the
lathe--but with those cheap imports, you can usually tweak them for
better performance if you have some mechanical know-how.


--
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



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"George" wrote in message
...

I burn wood, myself, and I've been obliged to stoke four times a day with
what our temps have been - negative 20's Celsius. Of course the wind
blows,
the lake snows, and I've had to plow pretty much every day for the last
week
and a half. My frozen wood supply is under a hard-packed 66 cm of snow,
which is what two meters of light stuff compacts to.

I swear the road commission has a sensor at the end of my drive. Every
time
I remove the snow, they come by with the plow and fill in!
================================================== ==
You need to come on down to central or south Texas for the winter. Here
(near Austin) the low so far this winter was this week at +21 degrees F.
Tomorrow is supposed to be about 60 and sunny. Down near the border, it's
even warmer.

Ken Moon
Webberville, TX

Are you getting chatter marks on the surface?
Before the dried blank gets trued. If I am not careful with the scrapper
and use too much pressure I do get chatter marks. When I use a gouge to
true the bowl I do not get charter marks. Once the bowl is trued. Using the
scrapper again removing less than paper thin wood. I get a finish of about
120 grit.
I'll try the duct tape next time.

"George" wrote in message
...
Sounds like it's the natural result of increased friction and a grain lift
or two. Are you getting chatter marks on the surface?

Couple things I've done in the past, before a steady, is to turn slow and
ride the left hand outside the bowl, or take two or three rounds of duct
tape to the outside to dampen vibration.

I burn wood, myself, and I've been obliged to stoke four times a day with
what our temps have been - negative 20's Celsius. Of course the wind
blows,
the lake snows, and I've had to plow pretty much every day for the last
week
and a half. My frozen wood supply is under a hard-packed 66 cm of snow,
which is what two meters of light stuff compacts to.

I swear the road commission has a sensor at the end of my drive. Every
time
I remove the snow, they come by with the plow and fill in!

"Denis Marier" wrote in message
...
Thanks for the information George
I have used a screw a screwdriver near the bearing cap. The noise is
constant without any change in pitch.

Lately, the heating system in our house is working hard to cope with
extreme
cold weather (-30). The blanks are stored in between the basement
rafters.
When turning the blanks I noticed that they are very dry.
I only hear the low pitch noise when I take light cut/shear with the
scrapper.

"Denis Marier" wrote in message
...
Thanks to everyone for their comments.
Maybe the situation would have been better depicted by using the
"Harmonic
vibration " instead of humming noise.
After about one week I have found that all the comments are valid.
The Harmonic vibration is probably produced by the unbalance in
rotating
components of my lathe. This may be further compounded by resonance
caused
by shattering of the scrapper applied on the thin wall of the maple
bowl.
I
was told that in some instances the rotating components may be fairly
balanced but the finishing gouge or the scrapper lightly rubbing on a
bowl
could produce resonance. I was told that the same thing takes place
when
rubbing the lip of a glass with your finger. Some time bowl steady
are
used.
Now, If only I can find a way to adjust the bearings I may reduce the
Harmonic vibration a little?



"Ken Grunke" wrote in message
...
Denis Marier wrote:
My lathe is a low end Taiwan made with 3/4 HP and 1" 8 tpi.

The other day I was finishing a 9" OD maple bowl with a 3/8 X 1"
scrapper at
about 800-1000 RPM.
It worked well. Until I reached the 9" OD lip where the wall
thickness
was about 3/8 thick. Then what seem to be the Headstock started
to
hum at
low decibels.

I was going to say maybe your headstock bearings are just a tad
too
loose. When your tool gets to the outer diameter of a piece, even if
you
are using the same amount of force as you did towards center, that
force
is amplified by leverage and putting more sideways pressure on the
spindle causing the bearings to vibrate.
But then I thought some more, and figured it could be the wood
itself
humming. Probably due to the thinness of the wood, it's hardness,
and
the broad-edged scraper.
If you heard the humming while turning the outside (before
hollowing)
my first theory makes more sense. If you find a way to adust your
bearings, do so very carefully--a bit too tight can overheat and
wear
them prematurely.
I could be wrong on both points, it may be just the quality of the
lathe--but with those cheap imports, you can usually tweak them for
better performance if you have some mechanical know-how.


--
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

"George" wrote in message
...

SNIP
Are you getting chatter marks on the surface?
SNIP
what our temps have been - negative 20's Celsius. Of course the wind
blows,

With those temperatures I would think you would get chatter marks. G

Martin