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!!

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 sandpaper :U:U:U:U:oo::U:U:U:U:U:U:U:U

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

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.

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.....

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...

Quote:

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Originally Posted by tony_A

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.

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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

Quote:

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Originally Posted by Dalboy

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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Thanks Smife.....i susoect i dont understand what u mean properly....almost upright presentation sounds a bit scary..i wouldve thought it would easily catch on the wing - hence me thinking i dont understand...

cheers

Quote:

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Originally Posted by smiife

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 sandpaper :U:U:U:U:oo::U:U:U:U:U:U:U:U

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his is the Rob Hippy vid.

SHEAR SCRAPING by Reed Gray aka Robo Hippy - YouTube

Quote:

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Originally Posted by Faulko

....although i dont have a negative rake scraper.....

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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.

Quote:

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Originally Posted by Faulko

Thanks Smife.....i susoect i dont understand what u mean properly....almost upright presentation sounds a bit scary..i wouldve thought it would easily catch on the wing - hence me thinking i dont understand...

cheers

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No it,s not scary , I mean pointing the gouge tip at half way between 1and 2 o,clock , and just use the
Left side of the wing very lightly start in the centre and work your way to the outside

thanks - i use a skew like negative rake on outside of bowls regularly..but never have on inside....dont have one rounded enough to do that.........i assume u use negative rakes on inside of bowls too??

Quote:

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Originally Posted by tony_A

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.

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so start at the bottom or half way along the inside wall and then work my wat back to the rim??

Quote:

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Originally Posted by smiife

No it,s not scary , I mean pointing the gouge tip at half way between 1and 2 o,clock , and just use the
Left side of the wing very lightly start in the centre and work your way to the outside

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Quote:

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Originally Posted by Faulko

i assume u use negative rakes on inside of bowls too??

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Yes and i have 2 that I use inside bowls, a larger woodcut NRS with more gentle curves and one I ground from a 12mm skew with a tighter radius.

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.

Thanks to everyone for the advice. This is a great community.