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  1. #1
    Join Date
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    Default Stabilised and Cast Bush Lemon Burls then turned into Spheres

    I've made quite few spheres over the years but they seem to be "in" again at the moment. Decided to make a few using some of my Bush Lemon Burls I've collected lately as they dye stabilise well.

    First step was to soak them in a chlorine/boron mix for a while, the Boron kills any bugs and protects it while the Chlorine softens the bark and bleaches the timber. Then they were water blasted before putting them into my smoker over to dry. Started at 45C for 2 days, then increased temp by 10C every 2 days, before final drying at 110C until they stop losing weight to ensure they are 0%MC (24/7 for 2 weeks for that oven full)

    palet load of lemon burls.jpg lemon burls in the oven.jpg

    Next was to let them cool in vacuum bags before stabilising them in Cactus Juice resin (plain and coloured for dye stabilising). Because of the size it took 4.5 days under full vacuum, before soaking for another 2 weeks, then baking it to set the stabilising resin (at 100C for 4 hours).

    stabilising.jpg coloured burls.jpg

    Next I made some simple 100mm/150mm dia molds from PVC tubes and cast the burls with clear or tinted with translucent dyes Megapoxy HX Clear Casting Resin in my pressure pot. The mistake I made was not sealing the dye stabilised surface before casting, so unfortunately some of the dye leached into the resin.

    sphere blanks.jpg

    I then started to turn with TCT tipped tools the sphere blanks between steb-centres to roughly round (using offsets and dia or light shadow techniques - check out Theo's vids on Twitch)

    rough truned spheres.jpg

    Then I mounted the rough turned blanks between cup chucks I made from HDPE

    sphere cups 1.jpg sphere cups 2.jpg sphere cups 3.jpg

    They were then finished turned the spheres and sanded through to 600 grit to form perfect spheres by rotating them in the cup chucks. I got a catch on the clear cast one and a big chunk of resin went flying, so quick design change, now a smaller sphere

    Each sphere was then spray painted with car UV resistant Top Coat Clear acrylic lacquer and left to hard over a few days. As it is impossible to spray coat spheres without overspray, once hardened, each sphere was wet sanded with micromesh then polished with plastic polish all by hand.

    I also made stands for the spheres out of Blackwood and Ebonised them with my home brew (vinegar/steel wool/old tea bag) before spraying with the lacquer. Each stand was hollow to receive a LED torch to shine up on the sphere. I made 2 sizes, one for a 30mm dia torch and for 15mm torches, to maintain a base dia for the stand at 50% of the spheres.

    Here's some videos of the finished spheres
    https://www.youtube.com/watch?v=0d1XWHUUwUQ


    The larger 140mm plain burl with yellow tinted resin in sunlight, then on stand lit
    https://www.youtube.com/watch?v=hpK4ZRdFO48 https://www.youtube.com/watch?v=lD0rl62C5VM

    The 90mm red dye stabilised in red tinted resin in sunlight, then on stand lit
    https://www.youtube.com/watch?v=LV2T1OdWkjQ. https://www.youtube.com/watch?v=Dm85oCoWxqc

    The 90mm yellow dye stabilised in yellow tinted resin in sunlight, then on stand lit
    https://www.youtube.com/watch?v=lEUJ9_q2uWs. https://www.youtube.com/watch?v=NHw26XWiptc

    The 90mm green dye stabilised in green tinted resin in sunlight, then on stand lit
    https://www.youtube.com/watch?v=h-3jCYsKB90. https://www.youtube.com/watch?v=nS-PIO6824Q

    The 75mm stabilised in clear resin in sunlight, then on stand lit
    https://www.youtube.com/watch?v=vIuk3tFdEPM. https://www.youtube.com/watch?v=sFIe4_vTaHA






    Neil
    ____________________________________________
    Every day presents an opportunity to learn something new

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  3. #2
    Join Date
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    Townsville, Tropical North Qld.
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    Default

    "The mistake I made was not sealing the dye stabilised surface before casting, so unfortunately some of the dye leached into the resin."

    Hi Neil, Thanks for this post, very informative.
    I am in the process of getting together the gear to setup a cactus juice stabilising system and wonder what you would use to stop the leaching into the resin.
    I have not seen any reference to this previously and would no doubt have had the same result if not for your post.
    Cheers,
    Ian
    "The common law of business balance prohibits paying a little and getting a lot.. it can't be done.
    If you deal with the lowest bidder it is well to add something for the risk you run.
    And if you do that, you will have enough to pay for something better"

  4. #3
    Join Date
    Apr 2005
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    Nerang Queensland
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    Default

    Quote Originally Posted by Nanigai View Post
    "The mistake I made was not sealing the dye stabilised surface before casting, so unfortunately some of the dye leached into the resin."

    Hi Neil, Thanks for this post, very informative.
    I am in the process of getting together the gear to setup a cactus juice stabilising system and wonder what you would use to stop the leaching into the resin.
    I have not seen any reference to this previously and would no doubt have had the same result if not for your post.
    Cheers,
    Ian
    I use epoxy resins and maybe it doesn't happen for others as I have not heard reference to it either. On some of the experienced guys however I note the surface is a different colour sometimes. I now just precoat the burls with a thin painted casting resin coat and let set before the full cast. This helps with the air bubbles on the wood and stress cracks in the larger pours. I can't see any reason why you couldn't use an acrylic spray lacquer instead just I haven't tried it yet.

    Ive actually done some gold and silver coated burls (Cooktoen Ironwood burl and Peppercorn burl) sphere blanks ready for Q-Turn, where Theo is turning one and I am doing the other as demos. I painted on a thin coat of resin, sprinkled the powdered metal (that effectively floats on the resin giving it a solid coat), leave it to set then giving it another clear painted coat and let set again before casting. Can't wait to turn these.

    gold plated cooktown ironwood burl.jpg gold and silver casts.jpg gold ironwood from top.jpg
    Neil
    ____________________________________________
    Every day presents an opportunity to learn something new

  5. #4
    Join Date
    Oct 2006
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    Townsville, Tropical North Qld.
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    Default

    Cheers for that Neil, I thought that may have been the go, I have seen some incredible spheres on some of the casting sites and most were very clear. Looking forward to getting into the game, thanks again,
    Cheers, Ian
    "The common law of business balance prohibits paying a little and getting a lot.. it can't be done.
    If you deal with the lowest bidder it is well to add something for the risk you run.
    And if you do that, you will have enough to pay for something better"

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