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Seasoning wood
for turning
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Vibration on
the lathe
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Is it
necessary to cut the corners off a blank before turning
between centres?
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What wood
would you use for a baby's rattle?
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Problems
making a mini-scraper
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Visualising
how natural edge vases are made.
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Bevel angles
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Sharpening
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Finishing tunings made from
wet wood
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Selecting, identifying,
drying, and preparing wood for turning
FAQ 1
Question
I've just had to cut down a Laburnum and a Cherry and am
thinking about seasoning the wood for turning; any hints or
tips?
Answer
This is quite a big subject, but I will try to boil it
down. Timber shrinks most around the annual rings; so when
it is drying in the log form something has to give. In a
section of any size, ie over several inches in diameter, one
or more 'V' shaped splits often open up. If you want to
reduce the splitting the best thing to do is to split the
log longitudinally down the centre. Very often I don't
bother to split it - as wood in this form should be free, ie
a gift (I wouldn't normally buy it in this form) I just take
my chance that something will be worth salvaging eventually.
When you use wood in this form you must expect some
failures, ie splitting or warping after the piece has been
turned. It's worth noting that turner's often have these
kinds of problems with wood bought from the timber
merchants.
The most important thing when storing your logs is to
keep them cool. They must be kept in the shade in the summer
in a well ventilated place. Keep the sections of log as long
as you can subject to convenient handling and storage. The
reason for this is that the ends of timber in the round will
probably split at the ends even if they are coated with
something to slow down the evaporation.
You may find that having taken these precautions even
the thinner branches may split - I find that some do and
some don't - even when they are from the same tree. I don't
believe it's possible to predict what will happen with any
certainty.
Another question: how long does it take to dry? It is
often stated that 1 year of drying should be allowed for
each inch in thickness, ie if the board is 3 inches thick
then it should be allowed to dry for 3 years. This is only a
very crude rule of thumb - much depends on factors such as
the species and the storage conditions. As far as logs or
limb wood are concerned it is no help at all - it depends on
what you want to use it for and the time of the year. As a
rough guide small branches a few inches across may be dry
enough for some purposes after, say, six months in the
warmer part of the year. Sections larger than 6 inches or so
may never get really dry.
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FAQ 2
Question
Sometimes when I am turning a piece I get a lot of
vibration. What is the cause of this and is there anything I
can do about it?
Answer
First check the headstock bearings (and the tailstock
revolving centre) to make sure there is no play. They should
revolve freely but there should be no sideways movement.
Assuming there is no problem with the bearings the following
points may be considered.
No piece of wood is perfectly homogenous and even when it is
turned down to the round a workpiece may be out of balance,
ie heavier on one side. If the workpiece is large in
relation to the lathe this can cause the lathe to shake.
This is most likely to happen with bowls but it can also
occur with spindle turning.
The most obvious immediate remedy is to run the lathe at a
slower speed. If the lathe shakes at the slowest speed
available there are two possible tactics. The first is to
add weight to the lathe stand using materials such as bricks
or sandbags. The second possible solution is to add some
counter-balancing weights. A bowl blank, for example could
be attached to a large disk - lead weights are then fixed to
the disk and adjusted until a reasonable balance is
achieved. I have used this method successfully.
In the longer term it might be a good idea to beef up the
lathe stand and add some extra weight permanently. One way
of doing this is to build in a trough which can be filled
with bricks or sand. Sand is best because it has a higher
damping effect on vibration.
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FAQ 3
Question
Is it necessary to cut the corners off a blank before
turning between centres?
Answer
Not usually. Peter Child once said "there is a machine to do
this., it is called a lathe" (or words to that effect). The
real question is which is the quickest - to set a saw up to
do the job or do it on the lathe?
There are circumstances in which I think it might be
desirable to saw the corners off of a spindle turning blank.
One is where the blank is very large in relation to the
lathe and might cause vibration. In this case any reduction
in weight might be beneficial. (See also FAQ 2 above.)
Another is where a batch of items are to be turned. In this
case the time taken to set up the saw can be spread over a
number of items.
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FAQ 4 Question
What wood would you use for a baby's rattle?
Answer
I have always used ash for my rattles but I must say that I
have not actually made a great many. I made them for sale
for a while but then decided that, with the kind of
litigious climate we have today, it was not worth taking any
kind of risk. Having said that I would be quite happy to
give one to a grandchild (were I ever to have one). But note
should be taken of what I have to say about finishes at the
end of my article.
Back to wood: I think ash, sycamore, beech, holly or any of
the fruit woods should be OK; but the best of these English
woods may be beech because it splinters less than any other.
I wouldn't wish to take any chances with exotic woods. It
seems that all the information regarding toxicity is about
the effects of dust. I have never seen any information about
the toxicity of wood when it is ingested, so it's an unknown
area. Whichever wood is used I would rely on the good sense
of the parents to take one of these rattles away from a
child if there was any sign that it was chewing the wood
away. I have never had any feedback from users at all, so I
don't know if it is an issue or not.
I have always had great fun making these rattles and I feel
that they are very attractive objects in themselves - like
little sculptures. So making them can be its own reward.
When I used to have them on my stall at craft fairs people
used to pick them up and examine them carefully looking for
the joins! The last one I made was as a demonstration at our
turning club a few months ago.
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FAQ 5
Question
I have made your baby`s rattle with which I am quite pleased
, but the mini scraper I made from a masonry nail didn`t
work very well. I made the handle and glued the masonry nail
in and then ground the head but I don`t think I got it
right.Is there any chance of a diagram or photo of how it
should look when correct.
Answer
Figure 1 (above) shows three views of a mini-scraper for
cutting the left-hand side of a ring. Figure 2 shows a small
photograph. The head of the nail is ground as shown.
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FAQ 6
Question
I am having trouble visualising how some of the natural edge
vases in your gallery are made. Can you help me?
Answer
The photograph above shows one of my natural edge vases. The
photograph below shows the piece of log left after I cut off
the material for this vase.
The image on the right (in the above photo) is the view
looking straight down on the log. The cross in the middle of
the circle is where I place my lathe centre. The points on
the wood which touch the circle will be the highest points
on the turning, the places where the wood is furthest from
the circle will be the lowest points. To find the right
place to put my centres I made a polycarbonate (perspex)
disk which has a series of circles scribed on it. There is a
small hole in the middle. I lay this over the end of the log
so that one of the circles touches in as many places as
possible and then mark the centre.
So, with the centre positioned as shown, the points A, B,
and C will be peaks (high points). The places which I have
marked ‘valley’ will be low points. The one on the right
will be the lowest because the edge of the log at that point
is furthest from the circle (or, closest to the centre).
Point D will form a minor peak because the wood on either
side is farther from the circle. It will be lower than A, B,
and C.
How deep the minor peaks and the valleys are depends on: (a)
the degree of irregularity in the outline of the log; and
(b) on the slope of the side of the vase. In practice, when
the piece is mounted on the lathe, the imaginary circle is
described by the point on the rim which is furthest from the
centre point. I always try to get as many points as possible
on the circle as I can but I don't always get it right. So I
may end up with one point higher than all the others.
I always mount the piece between centres to start with. I
rough turn the bottom end and then turn a spigot on it to
fit my chuck. One way of gaining an appreciation of how the
shape comes out, without doing all the hollowing, is to
mount an irregular shaped log between centres and turn the
outside shape. When doing this you will see the peaks and
valleys forming.
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FAQ 7
Question
I have just begun turning and am at my wits end on the
angles to sharpen my tools. If you can spare a few minutes
and give me some starting angles on the basic tools I would
be grateful.
Answer I am assuming that by the angle to sharpen
your tools you mean what I call the 'bevel angle'. How the
bevel angle is measured on differrent tools is illustrated
in the diagram below. The bevel itself is labelled in
diagram.
In my opinion the bevel angle is not as important as many
people seem to think. I have seen anything from 25 to 45
degrees recommended for chisels. Anything in that range will
cut effectively. I sharpen mine at around 40 degrees.
Similar considerations apply to bowl gouges. Again for
normal use I sharpen mine at around 40 degrees. When I want
to keep the bevel rubbing in the bottom of a deep bowl I use
a gouge sharpened to 55 degrees. It still cuts but not as
well. The bevel angle on spindle gouges can be smaller than
on bowl gouges - say 35 degrees.
The bevel angle on scrapers is not important. I grind mine
at 55 to 60 degrees.
What is extremely important on chisels and gouges is the
shape of the bevel. It must be either flat or
hollow ground. (Note: this does not apply to scrapers.)
There is some controversy about how tools should sharpened -
in particular about what the grit size should be on the
grinding wheel and whether the bevel should be honed. I use
a 60 grit wheel and normally I do not hone. Sometimes I use
a slip stone in the flute of a gouge to take the burr off
the top of the edge. Some pundits pour scorn on this method
of sharpening - but it works well enough for me .
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FAQ 8
Question
I purchased a cheap lathe a few years ago, along with some
decent quality tools and made pens, and some small trinkets
to amuse myself. All I had to teach myself was whatever
books I could get my hands on, and from there it was pass
and fail as I felt I slowly improved. Then I found your
videos and they hepled tremendously. Now, one of my main
concerns is how to keep an ultra sharp edge on my tools. Is
it possible to do without getting into expensive equipment?
Answer
It really isn't necessary to spend a lot of money on
equipment for sharpening. A cheap grinder with good quality
wheels is sufficient. There are instructions on how to make
a jig elsewhere on this web-site but I think it worth trying
to learn how to do most of one's sharpening freehand. I
taught myself how to do this when I first started turning
and I find it saves a lot of time. The only thing I need a
jig for is the Ellsworth type of grind.
For high speed steel tools I use a 60 grit 'white wheel' (ie,
aluminium oxide). For a conventional gouge shape I put the
heel of the bevel on the wheel first and then raise the
handle until the sparks just come over the cutting edge and
then rotate the handle. Remember the bevel must be either
flat or concave (see FAQ 7 above). It is true that many
beginners find freehand sharpening difficult - but it should
be accepted that it is a skill which needs practice.
You may wonder why I made a jig if I don't need to use it!
The answer is that when I was teaching I found students were
spending a lot of money on elaborate and expensive
commercial jigs - so I designed my jig for them.
I have looked at sharpening in a lot more detail in my
'Introduction To Woodturning'.
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FAQ 9
Finishing tunings made from wet wet wood
Question:
I have been turning or a few years but mostly seasoned wood.
I have just recently just started using green wood. My
question is about the applying the finish - I like to use
tung oil. When is it a good time, while it is still wet or
dried out? I have been told I can use a microwave oven to
speed up the drying process. Any insight you can provide
will be greatly appreciated.
Answer:
The short answer is that I think it is usually OK to sand
and finish unseasoned (wet) wood whilst it is still on the
lathe, just as you would with dry wood. I oftend do that.
This is particularly true if you are using oil. Later, if
you are not happy with the finish you can apply more oil and
buff it up. In any case some turners like to apply several
coats of oil.
There have been occasions on which I have made a goblet from
wood from a newly felled tree and the wood has been so wet
it has been difficult to sand. In such cases I have either
put the piece aside for a day or two or applied heat gently
with a hot air gun.
You also raised the question of the use of a microwave oven.
This requires a longer answer because it raises a number of
issues that I think are worth looking at.
But before considering the use of the microwave it may be a
good idea to look at another way in which wet wood can be
dealt with. Many turners use a three-stage method for
turning bowls from wet wood. They partially turn the bowl
and then store it for a time to let it dry. It is weighed at
intervals until it loses no more weight. The work-piece is
then remounted on the lathe and the turning, sanding and
finishing is completed. The reason for partially turning the
bowl is that it will dry out far more quickly then an
unturned blank. Nevertheless, it will still take several
months to dry (depending on the environment) so the wall
should turned down as much as practically possible. However,
it will probably distort to an oval shape as it dries so
sufficient material must be left in the wall so that it can
be restored to the circular state when re-turned.
A microwave oven can be used to dry out a piece of wood
before it is turned. There are three points to consider
here: (1) there is a limit to the size of the piece that can
be dried, (2) the time it takes to dry out the wood, and (3)
the cost of the electricity. Some years ago a made a few
trials and decided that it was only worth using the
microwave for very small pieces of wood. However, that
should not deter others from carrying out experiments. If
that is done the following points should be born in mind.
Whether microwaving a blank or a finished piece the oven
should be used on the defrost setting for only a few minutes
at a time. Exactly how long will depend on the size of the
piece. The aim should be to warm the wood, not to cook it.
After a spell in the oven some water will appear on the
surface of the piece. When this has dried the process is
repeated until sufficient moisture has been removed. The
piece should be weighed from time to time to check progress.
Some words of warning are required here. I have seen this
method described a number of times both on the Internet and
in print. These descriptions often state that process should
be continued until the piece ceases to lose weight. But if
that is done then there will be no moisture at all left in
the piece and this is not usually desirable. (This is known
as the 'oven dry' weight - for more about this see also
'How dry is my wood?')
There are reports of the use of the microwave by turners on
the Internet that are worth looking at - try entering 'wood
+ microwave' into Google. But do remember what I said,
above, about over- drying the wood.
Using gentle heat a microwave oven could possibly be used
for drying out a turning in order to prepare it for
finishing. But it is possible that this would distort the
work-piece and make sanding and polishing difficult.
However, I have never tried this and I don't know of anyone
who has, so this is another opportunity to experiment.
I have rarely made bowls from wet wood but I have made a
number of goblets and vases (see my gallery). I usually make
these from smallish lengths of limb-wood (roundwood) which
are held on the lathe with the grain parallel to the bed of
the lathe. I always sand the piece and finish before
removing it from the lathe. And often I sand and finish in
stages (see 'Natural Edge Goblets Revisited' on my site.)
Splits in roundwood caused by shrinking as the wood dries
When roundwood in its natural state dries the shrinkage
often causes wedge shaped splits. The stresses which cause
this splitting are also created in items turned from wet
roundwood as they dry. To prevent splitting I turn the wall
of a vase or the bowl of a goblet relatively thin so that it
will distort instead of splitting. The problem is that the
base of such a turning cannot be turned as thin as the wall
and there is a risk that it will split. I have experimented
with drying them in the microwave. The hope is that, as the
oven works by directly heating the water in the wood, it
will make it more pliable and so relieve the stresses that
cause splitting. I have to say that this is a very imprecise
'science'. I have microwaved quite a number of goblets -
sometimes the bases have split and sometimes they have not.
I am still undecided about the efficacy of this treatment.
I think it may be better to use a totally different approach
and slow down the rate of drying by putting the turning in a
paper or plastic bag. It should be stored in an unheated
environment. If a plastic bag is used then it should be
opened at regular intervals to allow the moisture to escape.
By slowing down the rate at which the piece this procedure
may allow the stresses to readjust without ill affects. One
thing I am sure about is that in winter a wet turning should
not be taken from a cold workshop into a warm house as soon
as it comes off the lathe.
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FAQ 10
Question:
I was wondering if you had any info. on selecting,
identifying, drying, prepping various kinds of wood suitable
to turning? Any advice or info. would be greatly
appreciated.
Answer
This question raises some big issuess.
To begin with I can say that the great majority of hardwoods
from the northern hemisphre will turn readily. Most have an
attractive appearance but some can be rather bland.
Hardwoods from tropical countries can be extremely hard but
they too can be turned and many have very nice
characteristics. As far as I am aware all soft woods (ie
those tchnically known as Gymnosperms) can be turned but
most of them will be rather bland and uninteresting. Strange
as it may seem softwoods tend to be more difficult to turn
than hardwoods. This is largely because they do not cut as
cleanly. The major exception to this is Yew; although it is
a Gymnosperm it is very hard, has a lovely colour and turns
very well. For those who have to buy their wood softwoods
tend to be cheaper (particularly in the UK) and are fine for
practising the basic cuts, ie those described in my
Introduction to Woodturning.
The question of how to prepare your wood for turning raises
a lot of issues. If you are mainly thinking of turning bowls
it is not a major problem. Bowls can be partially turned
from unseasonedwoodm and left to dry naturally for a few
months - the turning is then completed and the bowl sanded
and finished. If the the bowl is turned completely from
unseasoned wood it will probably crack or distort badly. But
if it is just a practice piece then that may not matter.
Incidentally, 'wet' wood is usually easier to turn than
seasoned wood.
For many other turned objects the wood should be fully
seasoned. Some notes on this are provided in FAQ 1 above.
The identification of wood, and its selection for various
projests are questions that need long answers that I cannot
deal with here. However, I can suggest some books which you
should find useful.
The bible for all woodworkers is Bruce Hoadley's
"Understanding Wood" published by the Taunton Press (from
the Fine Woodworking series). A little book I have found
useful is by William H Brown: "The Conversion and Seaoning
of Wood" published by Stobart and Son Ltd (London). "The
Encyclopedia of Wood" by U.S. Department of Agriculture is
useful for reference and is very cheap from Amazon. Bruce
Hoadly also has a book "Identifying Wood: Accurate Results
with Simple Tools" but I have never seen that. I would
suggest, however, that if you can can identiy the most
common hardwood trees in Canada you will, with a little
experience, be able to identity the wood from these just by
using your eyes. Another book from the Fine Woodworking
series is "Wood and How to Dry It". At the time of writing
all of these are available from Amazon.
You might also look at
"How dry is my wood?".
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© Brian Clifford
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