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  1. #1
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    Jan 2013
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    Smile Rough turning green bowl blanks.

    Since I have a ton of green "Tassie Blackwood" turning blanks from a recent suburban backyard harvest, decided that waiting around for them to season was going to be too much to bare.
    So today it was time to have a crack at rough turning some of the smaller ones.
    I have not tried this way of bowl making before, rough turning to a thicker than desired bowl, leaving to dry, then final turning at a later date.
    Have made a fair few bowls from start to finish when green, however you always get movement in them as they dry.
    Started each one as you would, holding blank on a faceplate/chuck then turned the outer shape with a foot to clamp onto.
    DSCF6960.jpg
    Blank re-held now by the foot.
    DSCF6957.jpg
    To allow for later re-chucking when dried I have turned a recess into the bottom of the bowl on the inside surface, this recess will allow my vicmarc chuck to hold on in expansion mode when it comes to the final turning. Well, that is the plan for now. Time will tell if it's a good one. You can see the recess in the next picture.
    DSCF6956.jpg
    Looks to be a reasonable fit for the chuck in expansion mode.
    DSCF6958.jpg
    That's that for the first one then. Bowl is about 340mm dia x 90mm thick. Left the wall thickness at approx 40mm.
    Made 3 of the other 4 the same way. The other one was a deeper and smaller diameter one so decided to turn an "internal foot" on the inside rather than a recess, as a recess might have made it tricky to tighten up the internally held chuck.
    DSCF6964.jpg
    Still had to ditch the vicmarc tool in favour of an allen key to tighten it up, but it would have been trickier still with a recess in stead of a foot.
    DSCF6963.jpg
    DSCF6962.jpg
    Once rough turned I weighed and dated each one for future reference.
    DSCF6969.jpg
    Then put them on the lathe for a team photo.
    DSCF6965.jpg
    Now just have to wait for them to dry before re-turning.
    Oh yeah, and clean up the mess
    I plan to just leave the bowls in a reasonably airy shed without putting any wax or glue etc on them to slow down the drying process. If I lived where it was hot and dry, reckon I might. But it is pretty mild here and I have heard of other turners within 100klm who just put the rough turned blanks on a shelf to dry. Also have heard of other folk who pack the blanks with the shavings in a box to slow down the drying a tad.
    I would be most interested to hear feedback from other turners who regularly rough turn green bowls about the above. If you have a simpler way or criticism of any of aspect of this way of doing it...I am all ears.
    Must say I really enjoyed turning the timber green! It cut in really long ribbons, the supposedly carconogenic blackwood dust was not there.Plus the tools hardly needed to be sharpened compared to turning dry stuff.
    DSCF6971.jpg

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  3. #2
    Join Date
    Oct 2008
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    Leopold, Victoria
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    Some beautiful colours in those blanks. Look forward to seeing them when finish turned.
    Dallas

  4. #3
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    Jan 2013
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    Thanks Treecycle. There is some nice colour in those blanks. There is also a bit of sapwood (the whiter bits) that can be seen in picture number two. I have read that sapwood can be a no no when rough turning however blackwood is supposed to be a reasonably stable timber when drying so "fingers crossed".

  5. #4
    Join Date
    Jun 2014
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    Tucson, Arizona, USA
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    AB, you got some good looking wood there. I know nothing about how it moves while drying, so you will get nuttin from me on that.

    As far as making recesses/tenons on the inside, I've been doing that on larger bowls and platters/plates for about 4 years now. As you quickly found out, it's tricky tightening the chuck if the bowl is too deep. It looks like you found a solution by mounting the chuck before you put it on the lathe. I never thought of doing it that way until this post......... Thanks...... Jerry (in Tucson)USA

  6. #5
    Join Date
    Oct 2009
    Location
    South Africa
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    950

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    It never occurred to me to put a recess inside the blank, I’ll give that a try next time I’m rough turning.

  7. #6
    Join Date
    Sep 2008
    Location
    North Carolina, USA
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    2,327

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    Artful,

    The figure in the first blank is beautiful. I too never thought of putting a recess on the inside. Anything round on a wet blank will be oval when it is time to finish turn.

    I usually start with a log split down the middle, length about the diameter, corners cut off. I roughly center the blank on the face plate and bring the tail stock up and squeeze the blank between face plate or big chuck and tail center. I spin it around a few times and adjust position so the blank is roughly balanced. I tighten the tail center, which has a ring and a point, and flatten the area around the center, take the blank out, cut off the knob and remount, make a nice big spigot, remove and grab the spigot in the chuck, rough the outside, again using the tail center, and inside, leaving the wall thickness 10 - 15 % of the diameter.

    I let the rough blank lounge around the shed 6 months or a year and then put the inside of the bowl against a chuck with big jaws about half way open and again bring up tail center sticking the point in the hole left from the first mounting in the center of the now oval spigot. I make the spigot round, and if it will be the base of the bowl mostly finish it and work up the sides of the bowl gently to bring it round. I mount the bowl in the chuck using the spigot bringing it close to the finished size and shape, remove and let it set around the shed for a week to a month so that it may move around if it wants, then remount and finish.

    If you want to hurry the process and / or have timber that is prone to cracking, starting with a soppy wet blank, rough and boil in water for 2 hours and let dry. The guy who advocates this claims it eliminates cracking. I have put roughed out bowls in a slow cooker overnight, then wrapped in a couple layers of newspaper, into a microwave until it steamed, let sit a couple hours, microwave again, repeat, etc. I have also taken the roughed out bowl and microwaved, water pours out of the end grain.

    I understand the theory behind the microwaving and boiling breaks open the cells and lets moisture come out easier. It does seem to hasten drying and lessen cracking. I have made vases from whole round timber and done the boiling, microwaving, steaming, bit that when dry did not crack or check. Another method I have used to keep from cracking is to rough out and then submerge in a solution of 1/2 water and 1/2 hand dishwashing liquid. That does seem to prevent cracking, but extends drying time forever. i have hastened the drying after the soaking by microwaving with good results.

    You can do a Google search about boiling, microwaving, soaking in dishwashing liquid, and get more information. There are many paths to the same place.

    With all of the above, Richard Raffan says, "some crack and some don't".

    What is the name of your wonderful big lathe, what is the swing?
    So much timber, so little time.

    Paul

  8. #7
    Join Date
    Sep 2010
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    Port Sorell, Tasmania
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    Looking forward to seeing the finished articles here AB. I have only done a couple of green bowls and have kept them in a plastic garbage bag for the first couple of weeks to slow down the rate of drying. Turn the bag inside out every day or two to get rid on the moisture buildup on the inside. I turned the bowls to final thickness when green and then let them move. Adds a bit of character to the bowl.
    I did this in the summer when the air is a lot dryer than now. One bowl didn't crack and the second larger bowl did crack a bit.
    If you see any cracks starting you can put some CA glue in the crack to try and stop them growing.

    Tony
    You can't use up creativity. The more you use, the more you have. ~Oscar Wilde

  9. #8
    Join Date
    Apr 2007
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    Adelaide Hills, South Australia
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    Quote Originally Posted by artful bodger View Post
    I have read that sapwood can be a no no when rough turning however blackwood is supposed to be a reasonably stable timber when drying so "fingers crossed".
    I pre-turn a lot of green blackwood and of all the different woods I have turned it is the most stable going from green to dry. Where I live in the Adelaide Hills they do need to be boxed during our hot dry summers. Not such an issue during our cool wet winters, but I invariably don't get back to them under 12 months so I box them up as standard procedure. The Tassy climate might be more forgiving.

    I expect a % failure rate with any pre-turned green wood and despite blackwood's stability I still lose a few in each batch, in the order of <10%. But that is acceptable downside to such a no fuss method. Your pre-turning procedure looks sound to me. Just keep in mind that the internal recess will warp a bit and may need to be adjusted to readily fit your chuck jaw size(s) when dry. I usually go slightly oversize to compensate for warpage.

    I've never found any problems with leaving the sapwood on blackwood and try to keep some of it for the nice contrast it provides.
    Stay sharp and stay safe!

    Neil



  10. #9
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    Thanks for the feedback and kind comments.
    Neil, yes I did make the recesses and feet slightly oversize to allow for movement.
    Do you have a general "rule of thumb" about how thick you leave the wall of your green bowls?.
    Paul39, the wonderful large lathe has no name. It was built by an engineering works/foundry here in Hobart for the company's pattern shop.I managed to pick it up for a song at auction when the company closed 30 years ago. It sure is a Tonka, in many respects it is far superior to a Wadkin patternmaking lathe. About the only thing the Wadkin beats this one on is the distance between centres.
    The round window frames you can see behind the lathe were turned on the outside faceplate, larger ones are 1200mm dia. Larger ones could easily be made but I'd have to make a bigger faceplate first.

  11. #10
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    By far the easiest way to to turn and as mentioned its very stable, some warping but rarely cracking.
    Inspiration exists, but it has to find you working. — Pablo Picasso


  12. #11
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    Apr 2007
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    Adelaide Hills, South Australia
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    Quote Originally Posted by artful bodger View Post

    Do you have a general "rule of thumb" about how thick you leave the wall of your green bowls?.
    I probably did have some 'rule of thumb' in the beginning, but many hundreds of bowls later I just do it by eye.

    Eyeballing yours, they look about right. Perhaps the thickest ones (the deeper bowls) could have had a tadd more off the inside, but they should be OK as is.

    On deeper bowls, I found the Vermec Spindle Extension very useful. It provides more reach and hex key manipulation space. I got Vermec to make me up a longer one than their standard 60mm extension.
    Stay sharp and stay safe!

    Neil



  13. #12
    Join Date
    Jan 2007
    Location
    Covington, Virginia USA
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    76

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    I am SSssssooooo jealous of the species you guys get to play with on a lathe.... WOW, the grain and colors....
    Turning wet is kinda fun, you can cut an awful lot in a big hurry... post finished pics please.... so I can drool a bit more?
    "Too old to be this useful, Way too useful to be this old"

  14. #13
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    Jan 2009
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    Perth
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    Quote Originally Posted by mobjack68 View Post
    I am SSssssooooo jealous of the species you guys get to play with on a lathe.... WOW, the grain and colors....
    Turning wet is kinda fun, you can cut an awful lot in a big hurry... post finished pics please.... so I can drool a bit more?
    Ha Ha
    I have always said that when turning green wood, you feel like a professional turner. The timber slices beautifully, great swathes of ribbons of shavings, no catches, quick and easy. Mind you, the downside is you MUST remove all wet shavings and dust from the lathe bed immediately to prevent instant rusting.

    Unfortunately, in 6 months time, the reality of the timber catches up. Hard, dry, oval, and dusty

  15. #14
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    Aug 2017
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    Canberra
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    Very interesting and great wood. I struggle with drying wood, I wish it was more controllable and quicker!

  16. #15
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    Have had another crack at the pile of blackwood blanks. 10 days shy of 3 months since the last effort I was surprised by how much the blanks had dried out in that time. Of course they are no where near dry however no blackwood juice getting sprayed around anymore and not cutting in delightful ribbons to the same extent. It is a bit of a wake up call to get stuck into the rest of them sooner rather than later.
    Have started with the smaller blanks. This lot range in diameter from 360mm to 225mm and in height from 100-70mm. Thinking a bowl corer/saver might be a worthwhile investment before doing the larger ones.

    The first ones I did a few months ago seem to be behaving well as they are drying out and none have split so far, so have racked out these ones in the same manner (as one would green boards).

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