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Thread: A bit of practice
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21st September 2010, 03:59 PM #1
A bit of practice
I've been practicing turning thin walls lately with various degrees of success. My main problem seems to be bad approach angle resulting in a thin lip as shown on the natural edge silky oak bowl and small goblet. I got the approach better on the cyprus bowl but the damn thing shattered . Managed to get some translucence though .
The cyprus was only cut down 8 weeks ago and was sopping wet, fun to turn though. I managed to get a consistent wall thickness before the "mishap" and was happy with the way things were proceeding. I put a few drops of CA on the pieces just to put it back together to show the shape. Looking at the photos I now realise that I probably should have got rid of the pith and that's probably what caused the blowout.
Attachment 148063 Attachment 148064 Attachment 148065 Attachment 148066 Attachment 148067 Attachment 148068
The silky was also green but not as wet as the cyprus, still needs some sanding and work done to finish the foot off.
Attachment 148069 Attachment 148070 Attachment 148071
The goblet bowl is weeping cherry and bone dry. The bottom 2/3rds. is not bad, but the top is terrible due to bad approach angle and lousy sanding techniques, nowhere near thin enough either. It never would have made it to a finished goblet as the centre was rotten and I had no chance of turning a thin stem.
Attachment 148072 Attachment 148073Last edited by Grumpy John; 21st September 2010 at 04:16 PM. Reason: Typo
To grow old is inevitable.... To grow up is optional
Confidence, the feeling you have before you fully understand the situation.
What could possibly go wrong.
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21st September 2010 03:59 PM # ADSGoogle Adsense Advertisement
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21st September 2010, 09:36 PM #2GOLD MEMBER
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Bugger. That would make anyone grumpy. How spectacular was the failure - bits flying all over or do you get a bit of notice of the impending failure so that you can duck/turn off power.
I've just become an optimist . Iv'e made a 25 year plan -oopps I've had a few birthdays - better make that a 20 year plan
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21st September 2010, 10:51 PM #3
All good practice though John
With the thin walled stuff I finish from the outer edge and work my way in a bit at a time finishing as I go. Looks like you tried to go back to the outside edge and the flex in the thin wall has caused the failure.Neil____________________________________________Every day presents an opportunity to learn something new
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22nd September 2010, 12:21 AM #4John Lucas
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You may be pushing on the bevel too hard. That causes the wood to flex or makes it bounce of the summer,winter wood which causes vibration. The vibration will cause the tool to grab the wood and then you get a catch. Try to see how light you can be on the bevel. Try putting more pressure down on the tool rest with your left hand and then be really light with the cut.
another technique I've been playing with is using the bowl gouge with the flute up at 12 oclock. Rotate the tool to about 12:30 so it's not cutting and then very carefull rotate it up until it starts to cut. As you feed the tool down the bowl you may have to rotate the flute more towards 12:30. Just concentrate on keeping that side bevel flat against the bowl.
When I'm cutting with the flute at about 1:30 or 2 I'm pushing the tool more into the wood. This causes the vibration I think because the tool shaft is about 45 degrees or so in orientation to the wood. With the flute up the shaft is closer to parallel to the wood so you aren't pushing against the side as much and you get less vibration and chatter.
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22nd September 2010, 12:43 AM #5
Hey Grumpy John
That cypress bowl that would of been a nice peice to what a pain in the bum that it shattered on you but even put back together it still look awsome . The sliky bowl fantastic love it well done
Cheers Nai84
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22nd September 2010, 04:47 AM #6To grow old is inevitable.... To grow up is optional
Confidence, the feeling you have before you fully understand the situation.
What could possibly go wrong.
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23rd September 2010, 08:26 AM #7Skwair2rownd
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Well GJ, at least you have the nerve to have a go!
I am not yet so brave!
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23rd September 2010, 09:24 AM #8
Great effort and a learning curve for you. I haven't tried doing any thin stuff yet. .
Reality is no background music.
Cheers John
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24th September 2010, 12:12 PM #9
I don't know which cypress you were using GJ but I reckon you couldn't have picked a worse timber for practising thin walls. First one I turned from cypress (native White Cypress) sounded like a bowl full of rice bubbles each time I stopped the lathe
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24th September 2010, 07:17 PM #10Hewer of wood
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Nice to see you pushing the boundaries GJ
You could also try a small gouge; reduces outward pressure on the rim.Cheers, Ern
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