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Thread: tear-out frustrations....
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15th August 2020, 04:14 PM #1Senior Member
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tear-out frustrations....
Hi everyone,
finally had a go at turning a WA she-oak blank....the end grain sections are tearing out no matter what i do......
I've tried sharpening the gouge and presenting it with the flute side on (or 3 oclock) - what i understand to generally be the correct entry positioning for cutting the inside of the bowl starting at the rim..
and I've tried to shear-scrape with a rounded scraping tilted to a shearscraping angle....
Blank is bone dry.
I figure that some woods are more prone to this issue than others....but I've had some issues with this on my bowls over the last few months and figure technique must be a factor....
any advice greatly approeciated.
I reckon i have scope for a few more attempts before it gets way too thin.....
argghhh!!
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15th August 2020 04:14 PM # ADSGoogle Adsense Advertisement
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15th August 2020, 06:11 PM #2
Hi faulko, have you tried a swept back grind on your gouge , present the tool almost upright
Handle down low and very light cuts , you may have to lower your toolrest so you are on centre
Line , Hope this helps .........or just get some 20grit sandpaperCheers smiife
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15th August 2020, 07:15 PM #3
Other than sharp tools and presentation to the wood. Whenever I have tear-out problems especially with punky type woods and those that are too dry I find that either a mist spray with water on the surface helps to swell the fibres so that they support each other better allowing for a clean cut. By using water it still leaves you open to apply the finish of choice.
If the finish is one that is compatible with a sander sealer then a coat of that can also be used.
With both methods, you may need to reapply as you cut down. With water, it dries out and sander sealer it only penetrates so deep.
I do send to turn some quite punky wood at times especially spalted wood which have only just gone a little far.
Trying to sand out the torn grain can be a right pain as it may take some time to get below it as well as having to resort to coarse grits which you then have to work through more grits to get rid of scratches from the very coarse grits
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15th August 2020, 07:33 PM #4SENIOR MEMBER
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I wipe down with a wet cloth then either shear scrape or negative rake scrape. Light cuts and re-wet frequently. Cut down to dry wood and it will start tearing again.
When it comes to shear scraping I subscribe to Robo Hippy's technique. Start the scraper by rubbing the bevel and tilt it into the wood until it just starts to cut. That gives a slicing cut.You can't use up creativity. The more you use, the more you have. ~Oscar Wilde
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15th August 2020, 08:09 PM #5Senior Member
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Thanks all.
..i have another good sized blank of the same stuff so I assume it'll be the same...will give these suggestions a go...although i dont have a negative rake scraper.....
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15th August 2020, 08:12 PM #6Senior Member
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thanks - i thinki understand....does this method have the scraper tilted at an angle too?? I might see if Robo Hippy has this on youtube...
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thanks - i thinki understand....does this method have the scraper tilted at an angle too?? I might see if Robo Hippy has this on youtube...
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yep. i hav had a gutful of sandy..this has been my exact expeirnce.
def gonna try the water option next time
thanks
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15th August 2020, 08:15 PM #7Senior Member
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15th August 2020, 08:25 PM #8SENIOR MEMBER
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his is the Rob Hippy vid.
SHEAR SCRAPING by Reed Gray aka Robo Hippy - YouTubeYou can't use up creativity. The more you use, the more you have. ~Oscar Wilde
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15th August 2020, 08:52 PM #9SENIOR MEMBER
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On a convex surface (outside of a bowl) a skew chisel works as a NRS. That will at least let you try it. I have a slight preference for NRS over shear, I get a smoother finish off the NRS compared to shear although practice will likely fix that.
What ever way you go, NRS or shear, they need to be sharp and re-sharpened frequently. Try to push on for a little too long before re-sharpening and it will start tearing.You can't use up creativity. The more you use, the more you have. ~Oscar Wilde
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15th August 2020, 09:38 PM #10
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15th August 2020, 09:56 PM #11Senior Member
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15th August 2020, 09:57 PM #12Senior Member
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15th August 2020, 10:23 PM #13SENIOR MEMBER
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16th August 2020, 07:12 AM #14GOLD MEMBER
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A regular scraper pointed down is a negative rake scraper. I sharpen my scrapers upside down at about an 80 degree angle, which raises a slight burr. I take a VERY light cut pointing down. The burr lasts about 15 seconds. My grinder is at the right end of the lathe and a flat rest is at the left wheel. I take a cut, put the scraper on the rest, hold down with a finger give a sweep of the curved scraper against the wheel, make a cut.
A slightly swept back grind on a bowl gouge also works. I sharpen using a jig, then using a piece of rolled up 320 or 400 grit paper hone the inside. I present the gouge to the middle of the bottom of the bowl, top of gouge facing facing 9 o'clock, and sweep up to the rim.
Having the bowl rotating as fast as you are comfortable with helps. Resharpening and honing frequently helps. All of the above advice is good. We all have to figure out our own best practice and keep doing it. For me, it takes about 20 hours in short sessions in front of the lathe to get good at a technique.So much timber, so little time.
Paul
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1st September 2020, 10:14 PM #15Senior Member
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Thanks to everyone for the advice. This is a great community.
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