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Going Bigger

Discussion in 'Woodturning Discussion Forum' started by John Hammonds, Feb 15, 2021.

  1. Karl Loeblein

    Karl Loeblein

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    John, Consider getting a hydraulic lift table at Harbor Freight or Northern Tools to lift heavy wood off of a truck and onto your lathe.A lift table can be very handy getting around the shop.

    As far as turning large bowls, boiling for a couple of hours can help as several have suggested, but I also suggest turning more than twice on large bowls. This way there is a smaller amount of warping to deal with each time being turned and ,thus, less bouncing tools & shaking on the lathe.
     
    Bill Boehme and John Hicks like this.
  2. John Hammonds

    John Hammonds

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    Thanks much, John T., for the detailed response. Very interesting process and beautiful work!
     
  3. John Hammonds

    John Hammonds

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    Thanks, Karl. I seem to remember an old post from Bill B. along those lines. Might be time for me to listen.:)

    So, you guys are boiling large bowls. Never would have thought of that. That's gotta be one large pot and heat source. But I could do it out back behind the shop with a 55 gal. drum and a fire underneath. I seem to recall reading about the theory behind boiling some years ago but memory fails ... do we think it ruptures the cell walls and allows all the moisture in the wood to essentially be "free", thus speeding the drying process? How much time do we think that saves? Or, more important to me, does it significantly reduce the risk of cracking? Does it obviate the need to seal or put in a controlled chamber (I assume not, based on what John T. is doing)?

    Turning more than twice is something I've done rarely but can certainly see the benefit. Good idea.

    And, oh by the way, for those looking for sources of domestic wood, I stumbled onto this website by WoodMizer: https://woodmizer.com/us/Find-a-Local-Sawyer#. It lists operators of WoodMizer saw mills by state. I had been in contact with one locally but he didn't really want to "play ball" ... was more interested in selling board feet and cutting everything 4/4. Using that website I found a guy within 30 minutes of me willing to cut whatever I want however I want. And somebody just gave him a lathe and he wants to learn to turn. Well, I said, this could be a win-win. Onward and upward.
     
  4. robo hippy

    robo hippy

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    I can't think, well, remember, an article devoted to the boiling process. What I do remember from demonstrations, and Dale Larson comes to mind, boil 1 hour per inch of thickness, let pieces come back to air temps in the pot, remove, dry the surface, seal, and then put on a shelf to finish drying. Supposedly the boiling ruptures the cell walls, and this allows the 'bound' water to release more easily. This relieves 'drying' stresses, so you get less cracking, especially on difficult woods. I think Dale used a horse trough for boiling his madrone. Steaming them can work as well, but I think most just go for the boil. To me, I didn't care for one thing about the boiling process. It seems to muddle the colors more than just letting things air dry.

    John, if you become friends with that woodmizer guy, and mentor him, you may end up with too much wood. Some of my favorite pieces to turn are the buttress parts where the tree comes out of the ground. Frequently highly figured, and a lot of the time, it is tossed or cut off because of how it flares out.

    robo hippy
     
  5. Karl Loeblein

    Karl Loeblein

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    I use a very large stainless steel bowl that I found at a flea market over a turkey fryer, but you could also a drum that’s been cut down to a reasonable height. I suspect boiling relaxes tension in the wood (vice rupturing the cells) and the heat drives out some of the internal free water. I find boiling cuts drying time in half similar to a one or two day soak in alcohol ($). I only boil for woods that are really bad at cracking, or I’m just in a hurry to get the second (or third) turning completed. If I’m in a real big hurry them I use a microwave oven. To be honest, I have enough dried rough turned bowls stacked up that I’m seldom in a hurry anymore.

    Regardless of the method you may still want to seal the end grain (or use a box or bag to help control the rate of drying) in order to avoid a steep moisture gradient that could put stress back into the wood.
     
  6. robo hippy

    robo hippy

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    I would guess that you need stainless or galvanized metal for your boiling pot. If you use a standard 55 gallon metal drum, you will get metal stains in the wood.

    robo hippy
     
  7. John Hammonds

    John Hammonds

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    I think you're right and, while I'm intrigued by the different processes we use to dry our turnings, I would only go to the boiling method (or some other) if I absolutely had to. So, unless I get into mounting an entire cross section of a tree on the lathe to make some kind of giant hollow form (and I might some day), I'll stick with my you-can't-rush-this-drying-thing process. But again, I am intrigued by the process and appreciate the input.

    Thanks to all. I enjoyed the conversation and learned from it. Now, where did I put that lathe? ....
     
  8. JeffSmith

    JeffSmith

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    Location (City & State):
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    I found a very large stock pot in the scratch and dent section of a restaurant supply place several years ago - it's heavy gauge aluminum and I can't remember how many quarts they said it was, it's 26" diameter and nearly that tall. The price was great since it had a dent in the side, but I couldn't afford the lid for it - they wanted three times what the pot was marked at...works great on a jet burner.
     
  9. John Hammonds

    John Hammonds

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    [Note: this post has been edited from the original to focus on what I think is the real problem with the lift set up. Many thanks to Karl Loeblein for helping me figure this out.]

    I went out and bought one of those Harbor Freight 1000 lb lists today but had a problem with the set up. Rather than what the owner's manual calls a "filler bolt", my lift came with a rubber plug in the fill hole. When I bled and filled the hydraulic cylinder per the "Tool Set Up" section, and then tried to operate the lift, the plug blew out and some of the hydraulic oil sprayed out. I thought the plug was the problem, but your response to my original post suggested it was an overfill condition. I think you're absolutely right and the problem is in the instructions ... and my foggy memory on hydraulic theory.

    Because the fill port cannot be accessed with the table in the down position and the hydraulic piston and push rod fully inserted (the way we would normally add oil to a fully enclosed hydraulic actuator ... one without a separate reservoir), the instructions call for the table to be raised to the full up position. With the plug out, it says to "Fill until the Housing will hold no more fluid". It then says to replace the filler bolt and tighten it ... at this point I put the plug back in and now realize that is incorrect. The filler bolt or plug (depending on the version you get) should be left out at this point. The table should then be lowered and the excess oil should be allowed to drain out. Then the table should be raised so that access can again be gained to the fill hole and THEN the fill plug or filler bolt should be reinserted. When I did it that way, the table worked as expected, the plug did not blow out, and I saw no hydraulic leakage. The reason this revised method works is because it accounts for the increase in volume of metal in the cylinder as the push rod goes in.

    Am posting this just in case someone else runs into the same problem.
     
    Last edited: Mar 1, 2021
    Al Chavez likes this.
  10. Karl Loeblein

    Karl Loeblein

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    That plug is for the return reservoir so I wouldn’t expect the plug to be under much pressure unless you overfilled the reservoir. Look at the parts diagram and you will probably find it only comes with a rubber plug on that reservoir. If you can find the plug then my suggestion would be to try again with a little less hydraulic fluid. When you lower the table all the way then there shouldn’t be any hydraulic fluid coming out the fill hole (unless you have the table on it’s side).
     

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