I'm a relative newbie to woodturning and I've run into a problem and don't
have my mentor handy to get the solution. Also, I've searched online and
haven't tumbled to the answer.
I'm turning a fairly small walnut bowl, ~4" diam. The turning is all done.
There are rough patches inside the bowl and on the outside separated by 180
degrees, which are clearly due to tearing of the end grain. I've gone over
them with the scraper, and I've sanded. And I've done both procedures
again, but the patches are still there.
I know this is a common problem that must be faced and dealt with, but
obviously I don't know what next to do.
Suggestions?
George
George,
I am also new to turning but have encountered this many times - I turn
mostly maple blanks that are very dry, and find there are times that
no matter the tool or the sharpness, I still see tear out in certain
areas.
Have come to the conclusion that in these cases, sandpaper is the only
viable way to fix it.
After spending time convincing myself that its not the method or the
tool, I lightly spray the piece with water and let it sit for a few
minutes in the hope it will raise the grain ( i admit this could be a
mind game I play with myself!) then with the lathe off, I sand back
and forth with the heavier grit the area in question.
One I have worked my frustration out,I turn the lathe back on and
begin the finishing process again, starting with the grit used to
remove the tear out.
Good Luck!
Sandpaper for now. Make the next bowl relatively shallow and practice your
gouge angles where you can see them clearly. You're looking to have the edge
cut across the grain all the way, without getting more than the minimum lift
where unsupported. Scraping isn't as well supported as a gouge with a bevel
guiding. I get better surfaces with the gouge.
You might try using a standard cabinet scraper in a static mode first.
Gooseneck might reach, depending on contour. Spoon type would certainly.
There are a couple of things you can try but it really just boils down
to proper tool use and good sharpening. That being said, as a
beginner, you (and I) are still working on that and with time will get
better. In the meantime, try using some sanding sealer. I'm not sure
where you are so I can't give you available brand names for your area.
I am in Canada and the best stuff I have found so far is Home
Hardware's Sanding Sealer. A good friend of mine who is way past these
little tricks and who makes bowls for a living recommended the stuff
as probably the best available here. Just put it on, wipe it off with
paper towels and let dry a few minutes. It should stiffen the fibers
up enough for you to use a well sharpened gouge and just take a small,
itty-bitty-teeny-tiny cut all the way through. It works for me. The
other solution I have heard of but have not used yet is to coat the
area with a little bit of the finish you will be using, wipe off and
let dry a few minutes (5 or 10).
You need to understand a bit why this is happening. The fibers you are
cutting have no support in that area and they are actually being
ripped out of the wood as opposed to sliced off. You need to look for
a way to strenghten them up a bit. Sealer or a little oil can often
give them that little bit of extra support.
Some areas can be a lot tougher to fix due to the contour of the bowl.
If that is the case, a different grind on the gouge or a double bevel
can help. As a tool junky myself, I have multiple gouges with
different grinds that can accomodate the contours. If you have a very
very light touch and a very steady hand, you can achieve a near
perfect finish with a scraper but remember that whatever value you
place on "very light" and "very steady" is probably about 10 times
heavier than what I mean! Practice on a scrap until you can produce
whispy whispy strings of wood. I call it angel hair when I teach.
Like everything else in woodturning, practice, practice, practice and
never give up. It will all come together.
Works for me.
Mike Courteau
snipped-for-privacy@toymakersite.com
George, the best answer to your problem is to use a sharp tool, rub
the bevel throught the cut, and cut WITH the grain. Cutting against
the grain will result in a bad, torn surface because you're cutting
unsupported wood fibers. You need to learn how to shear scrape before
sanding. Shear scraping can remove all of the torn surface making
sanding much easier.
To shear scrape with a bowl gouge, roll the gouge so the flute is
facing the wood. With the handle down a bit and cutting above center,
cut with the lower cutting edge with the upper cutting edge very close
to the wood. With the handle leading, lightly draw the tool, going
with the grain. Apply oil to the wood in the difficult areas. In a
very short time you'll have all of the damaged areas cleaned up for
easy sanding. A caution: allowing the upper cutting edge to get too
far from the wood surface will result in a dig-in.
Wally Dickerman
Or use a forged pattern gouge with the handle perpendicular to the rest so
you can get better control than methods which rely on you to support the
tool. You can cut below center, so any upward tic takes you into air rather
than a catch. Not to mention you can steady on the bevel, too!
A lot of the tips you have already gotten should help. One other
thing that I have found useful on torn grain is to rub paste wax into
the tear out area then shear scrape or sand. Principle is the same as
the sanding sealer but I like the wax better since there's no waiting
to dry and no solvent fumes. When I'm sanding and see an area where
wax would help, I apply it, sand - and if necessary, wax again- and
then continue sanding with the same grit for a bit before moving on to
finer abrasives.
Hope this helps
Kip Powers
Rogers, AR
George
One of the best things you can do is to sharpen well and often, especially
before that last cut. Make or buy a jig. Making one is a lot cheaper and not
hard. Look for the sharpening section of my web site.
I have run across this often. A tip I read a while back suggested using
regular canning wax (parafin). I always had my doubts but finally tried it
and it gave good support to the area. I melt the wax in a can on a hot
plate and then dip an old toothbrush in the melted wax and brush it into the
problem area. Allow it to cool thoroughly and re-try with your tool of
choice. I usually move the speed up a click or two and use a very light
touch.
A lot of the tips you have already gotten should help. One other
thing that I have found useful on torn grain is to rub paste wax into
the tear out area then shear scrape or sand. Principle is the same as
the sanding sealer but I like the wax better since there's no waiting
to dry and no solvent fumes. When I'm sanding and see an area where
wax would help, I apply it, sand - and if necessary, wax again- and
then continue sanding with the same grit for a bit before moving on to
finer abrasives.
Hope this helps
Kip Powers
Rogers, AR
I use a mixture of mineral oil and veg oil, then keep enough on so yo
wet sanding. I have heard that adding bees wax to the mix helps, bu
all the bees seem to be asleep at the moment :-(
Mar
I would only add that sometimes when wood has rotted a bit, it will
lose strength and grain will tear even with sandpaper, and the options
become: seal/glue then either re-turn, or move to the next grit sooner
than you would otherwise, if you risk tearing right through the wall.
I've had spalted wood where 120 grit takes out gouges bigger than the
grains on 40 grit paper. In these cases, no amount of sharpening will
help unless the wood is sealed with one of the suggested products, or
CA glue.
First solution is that you must use keenly sharpened tools. Try a bowl
scraper or a shear scraper, with a slight burr on the edge, and take very
light cuts at high rotational speed. Another trick is to lubricate the
area, try either mineral oil or something like Briwax or other turner's wax
applied to the area then scrape with a very sharp shear scraper. You can
also use the side of an Ellsworth grind gouge as a shear scraper.
InspirePoint website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.