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Thread: Controlling the Pith - Turning God's will help

  1. #1
    Join Date
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    Controlling the Pith - Turning God's will help

    So I have read that when you prep a blank you cut about 3" out of the center to get rid of the pitch - that would be about 1 1/2 to each side. Or some say to cut it right down the middle and don't worry about it because you will end up turning alot of the pith away when your turn on the lathe (or if you mark it you can turn it away). In either event, I do not have very large diameter pc's of wood to prep in that manner - so then the question would be how do you control the pith so you do not get cracking/checking or at least keep it very minimal.

    Option 1 - I read was you could drill out the pith in the bottom of your vessel and then plug it later on and sand it down.....naaaa not for me.

    Option 2 - is to use thinned epoxy or CA on the pith inside the vessel and let it harden up - This is the option I use alot and have good results using it. However, I do it after I have soaked and slow dried the pc in some type of oil treatment. I also treat the bottom as part of the finishing process so that way both the inside and the outside have been treated - this is prior to finishing of course.

    Option 3 - read that it just can not be done

    Picture 1-2 - is a branch that I turned today and probably the deepest turning I have done so far - 17 1/2" tall and 6 1/2" diameter - This is one of many I have made and none have cracked out yet - some I have are more than 1yr old so Option 3 is not so true.

    Picture 3-5 - is a section where the log was sliced and and a turning blank made with the pith pointing out and then turned - pith on the side - However, with this one i sprayed the inside with thinned down linseed oil and put a coat of Minwax wood prestain sealer on the outside (I had laying around and never got around to trying) - I'll treat the bottom inside and outside the same after a bit of time. I am always experimenting so ill see if it slows the drying down like the oil treatment protocol I use.

    Pictures 6-8 are for Cynthia as an update - I decided to go back and get the other wood carving...LOL. I told my wife it was the wife of the turning god.....I don't think she was amused.

    Picture 9 - When I went back to pick up the second wood carving the guy had a popcorn maker he just purchased and because he was closing the doors to his buss - he no longer wanted it. I bartered with him and because he didn't want to load it to move it - he took $150.00 and a router bit set that I had in trade. Now, the turning god's will not go hungry.......LMAO
    On top of it is another very large vessel that was turned with the pith on the bottom - treated and still not cracking or checking.

    Note - In some woods if you turn so the pith is on the outside like I mentioned the warping during the drying can be very dramatic - sometimes causing very unusual distortions that are interesting - other times I have not liked the way it warped but so goes it...............
    Attached Thumbnails Attached Thumbnails Sat-1.jpg   Sat-2.jpg   Sat-3.jpg   Sat-4.jpg   Sat-5.jpg  

    Turner-2.jpg   Turner-3.jpg   Turner-4.jpg   Turner-5.jpg  
    Last edited by Dan Mosley; 11-21-2010 at 03:32 AM.
    First you have to learn the rules - Beginner
    Then you have to learn advanced rules - Professional
    Then you disregard the rules - This takes you to the master level................

  2. #2
    Join Date
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    Stereo gods, and armed to boot! You are totally protected, but on your own re the pith. There seem to be several beliefs on this topic. I watched an Ellsworth video where he turned an orb wit the pith on both sides midline - loud and proud. Too new to have an opinion other than keep it out of the main body.

  3. #3
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    I've only turned a few pieces with the pith still in them. Two were Norfolk Island Pine, so they had to be turned that way to feature the knot ring. NIP has pretty stable pith, so I didn't do anything out of the ordinary with them. Another was a birdhouse I turned from a red eucalyptus log, and I didn't care of the pith cracked. Other than those, I've not done any full-branch turnings, mostly because I prefer the grain patterns that show up when a blank is turned in face grain orientation.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  4. #4
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    Vaughn - I agree, it depends on the wood and it depends on what I have at hand when I am working on projects I guess. But, controlling it and the warping can be interesting fun - and a bit of a chance......
    First you have to learn the rules - Beginner
    Then you have to learn advanced rules - Professional
    Then you disregard the rules - This takes you to the master level................

  5. #5
    Join Date
    Dec 2007
    Location
    Tellico Plains, Tennessee
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    I can't offer much either... the only full branch turnings I have where the pith was left in are a couple of pepper mills and in truth, the pith was drilled out since it was in the center... only left a little in the top and like you, I add a little thin CA... haven't had any problems with them cracking - Yet!.

    When I split logs for bowl blanks, I do try to go through the direct center of the log... sometimes I'm even successful... then when I turn the bowl, I'll usually cut as much away of the face grain as I can to get just below the pith.
    Chuck
    Tellico Plains, TN
    https://www.etsy.com/shop/TellicoTurnings
    My parents taught me to respect my elders, but it's getting harder and harder to find any.
    If you go looking for trouble, it will usually find you.

  6. #6
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    I am kinda like Vaughn. I don't like doing branches because I don't like dealing with the pith. I have done several NIP and have never had a problem. I tried a maple branch to make a HF and it split badly. That was the last branch I tried except for full size birdhouses which I put a plug in the bottom so it can be removed to clean the birdhouse out for the next year. A friend of mine here in town turns a lot of branches and he will drill the pith out of the bottom and plug it. I know you can't see it but when I pick them up and see the plug it just doesn't turn my crank. You just can't match it and IMHO just doesn't look good but that is just my personal taste.
    Bernie W.

    Retirement: Thats when you return from work one day
    and say, Hi, Honey, Im home forever.

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  7. #7
    Join Date
    Feb 2008
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    The specific species, and the individual piece of wood, play a huge part in how I treat the pith. If the pith in the log shows deep and long cracks when freshly cut, I don't even attempt to include it in the piece. If it has minor cracking that it seems to be "controllable".

    I have recently gotten into making hollow forms/vessels, and so far a little glue has proven adequate. In fact, I just made a 5' cherry vase that not only had the pith running through the center of the bottom, but had at least 5 knots along its length. In all cases CA was enough to stabilize the areas. However, it wasn't a case of applying the glue and leaving it in a corner. I checked the knots/pith almost daily. If a hairline crack was forming, I applied more CA.

    That said, I can't say that I have a ton of experience in "pith control" when it comes to vases. I have more experience with knots and piths in bowl turning. Again, CA is the method I use. Additionally, if you have the patience, sealing the entire rough bowl form (inside and out), and not just the end grain portions, seems to greatly reduce the size of cracks that appear in knots or around piths. Many times this method, combined with preventative CA application to all sketchy areas, prevents the cracking completely. It just takes twice as long to dry the rough form.

    Hutch

    P.S. Here's another interesting point. The 12" diameter x 5' rough vase form had to be dried in a 2 month time frame. I sealed the outside with shellac and left the inside completely unsealed. Within 6 weeks it was getting near dry (around 12%). Yet even with drying it so quickly the pith and the knots only had small to moderately sized cracks (even none in some cases) using the CA method.

    P.P.S With all this in mind, I am moving forward with some ideas for hollow forms which include the pith right down the center of the piece, using both branch wood and trunk pieces. I'll let you know if I have any problems.
    Last edited by Matt Hutchinson; 11-21-2010 at 05:26 PM.

  8. #8
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    Matt - I agree that if the pith shows to much damage in the way of cracks/checks then i cut it out or disregard the pc entirely. I agree that certain species are better suited for keeping the pith in than others.

    On pc's that I have turned with the pith in I also use CA and keep a close eye on them. If they develop cracks during the drying process or split and I did not catch them in time, I have used epoxy with color added. It really depends on how things are going but I try to avoid having a finished vessel with a repaired crack showing.

    In regard to sealing as you mentioned - on smaller pc's I have sealed the outside of the turnings with: 50/50 Laquer thinner and Laquer or Shellac spray from Zinsser, or Minwax wood conditioner. I am trying the wood conditioner for the first time on a bowl to see how it reacts. I usually only apply one coat and let the turning dry - it does help as you mention. As for the inside I use BLO/MS and spray it fairly well after I have sealed the outside and I do not apply anything else. Add a rolled pc of paper (or nothing) in the top and call it done for the drying time....... I think this makes the form dry from the inside out more and of course more slowly than usual.
    I just stack them up somewhere inside and forget about them for awhile.

    Matt::: How are you sealing your larger turnings ? did you use only one coat of shellac on the outside or did you use several and sand in between ? Did you put anything on the inside at all? did you just leave it totally open in your shop ??

    Unfortunately I am always changing how I do things but, lately I have started to hollow deeper and bigger than I have previously. I saw your post on the 5' long vessel and think that must have taken a quit a bit of work to hollow that deep.

    Below are pictures of a large vessel that i just put the last coat of finish on and in the morning it will be done. Pictures 1-4

    Pictures 5-7 are a large blank I cut and mounted up this evening for turning tomm morning - It will have the pith in the center
    Attached Thumbnails Attached Thumbnails t-1.jpg   t-2.jpg   t-3.jpg   t-4.jpg   t-5.jpg  

    t-6.jpg   t-7.jpg  
    First you have to learn the rules - Beginner
    Then you have to learn advanced rules - Professional
    Then you disregard the rules - This takes you to the master level................

  9. #9
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    Quote Originally Posted by Dan Mosley View Post
    Matt::: How are you sealing your larger turnings ? did you use only one coat of shellac on the outside or did you use several and sand in between ? Did you put anything on the inside at all? did you just leave it totally open in your shop ??

    Unfortunately I am always changing how I do things but, lately I have started to hollow deeper and bigger than I have previously. I saw your post on the 5' long vessel and think that must have taken a quit a bit of work to hollow that deep.
    For sealing Cherry Log Vase I shellacked the outside with 3 coats, slathering it on pretty good. The inside I left completely bare. I was working on the vase fom June thru Sept., and even though it was very hot the high humidity probably helped with cracking issues....no cracks except in the middle of knots. The more annoying problem was the natural edge; the diameter shrunk so much the bark began to buckle in several places.

    Hutch

  10. #10
    I'm reading this with interest. I have a pine HF with the pith in the center bottom soaking right now.

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