Amount oversize to mill green D-F before drying milling to final dimension

Discussion in 'Materials' started by abosely, Sep 23, 2020.

  1. abosely
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    abosely Senior Member

    It looks like I might be getting back to doing a little boat building after being away from boat things for while. :)

    I'll be buying clear Douglas-Fir from a place here on Big Island HI that gets their lumber from a small mill in Oregon. Probably will be buying 4x10x16' or possibly 4x12x16' and milling them to 1" thick, (I believe is intended to be ¾” actual thickness) and widest will be 6", most will be 1", 1-½”, 2' & 3", widths.

    I'll mill it oversized and make a covered black plastic dryer with everything stickered and clamped down. Trying to remember the sequence when drying green wood, I think start out with no fan till it all dries down a ways then put a couple of small fans to gently circulate the air after dries part way.
    Am I remembering that correctly?

    The other question I have is how much over finished dimension I should mill everything?
    I can mill it down into double thickness and widths and dry them part way or mill oversized and cut to final dimensions after drying.

    Not wanting to try and rush the drying, will let it dry as it needs to for optimal results.

    Cheers, Allen
     
  2. Barry
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    Barry Senior Member

    https://www.fpl.fs.fed.us/documnts/fplrn/fplrn144.pdf

    An interesting article that shows that the dimensional change of Douglas Fir was only .38 percent. About a third of a percent.
    It that is the case then you do not have to order the lumber much more than the 3/4 inch finished size that you are looking for.

    If decide to order from the mill to close to tolerance measurements you will have to specify that both that all 4 edges are planed, so you get square corners. In some of the mills that I have been in, they use chipper/trimmer blades on the edges and planer knives for the flats. The chipper knives have a radius built in which you do not want.

    https://woodproducts.onlineexpos.com/cgi-bin/content/24/usnr_electric_planer.html
    Within this link is the edge trimmers showing the edge process.

    So normally say a 2 x 4 is cut rough at 2 x 4, and then kiln dried to around 10% moisture content, then it goes into a planer mill which gets you to a finished size, 1 1/2 x 3 1/2 inches, The extra size is to allow for the planer to get rid of the saw marks that exist when roughing out the lumber.

    As it is unlikely that you will have access to a kiln or a saw that will consistently cut 16 foot long pieces accurately, I would suggest that you order what ever rough size that you need for planing, if you are so inclined, which will enable you to plane all 4 sides, without the radius.

    You will end up with various grains though which will act differently, ie strength etc, probably nothing to worry about but the wood workers here can clarify

    Note if you order you may want to specify "clear fir" which can be expensive as it is the best cut of a tree. If you are glassing the boat over, perhaps you can get by with a tight knot or better specification. There are a bunch of craftsmen on the
    forum who build wooden boats. Shrinkage does not appear to be the big issue.
     
  3. abosely
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    abosely Senior Member

    Thanks for the link Barry, I'm going to be buying clear green D-F in 4'x10"x16' or possibly 4"x12"x16' and will mill them to sizes needed. Sawing them to size isn't a problem, will be using thickness planer to bring to final dimensions.
    Wasn't sure how much to allow for shrinkage after drying. Want to make sure I leave everything over sized enough to plane them to final dimensions. Cant find where I have that information saved now. lol

    Cheer's Allen
     
  4. fallguy
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    fallguy Senior Member

    You never want to wet plane to final.

    cut vg, or rift if possible to one inch with a band saw

    dry stickered lumber in a covered stack or open ended building; weights on the piles or ratcheted piles are recommended; you can build ratchet bolsters with a router or by nailing to support a track

    a lot depends on climate; a very arid climate can dry lumber too fast; a damp climate can result in mold

    I am surprised green lumber gets shipped to Hawaii. When you sticker; stack all the stickers atop each other and make sure to sticker near the edges to prevent face bowing

    After dry, finish plane to 3/4". You'll be glad for the allowances in planing to help deal with movement.

    Btw, if your lumber is really 4" thick; an 1/8" resaw blade will make 3/8" kerfs cutting 3 times and so the lumber will be 3 5/8" divide 4 or 0.90625" thick before drying and planing...there is no reason to try to eek out another piece
     
  5. fallguy
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    fallguy Senior Member

    If, otoh, the 4" lumber is 3.5"; 3/8" in kerfs leaves you at 3.125" and you are kinda screwed unless the vertical grains are coming out the other direction.. (edited: I mean you get 3 sticks vs 4 and more planing)
     
    Last edited: Sep 25, 2020
  6. Barry
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    Barry Senior Member

    Barring the additional cost
    I would just order the fir rough sawn to full ROUGH dimension, ie 1 x 6 x 16 or whatever your target is, have them kiln dried at their locations, shipped to you, dry and rough, and then you can plane however you want
     
  7. abosely
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    abosely Senior Member

    I don't know what direction grain will be running, I can ask to have them sawn so can get vertical and rift sawn as much as possible.
    Having the lumber milled to 1x anything jacks the price way up. I'm happy to even be able to find clear D-F period.
    Buying it in 4'x10x16' green is about the only option for getting it at anything resembling affordable. Some things here on Big Island aren't available like on main land. lol

    What makes this feasible is a small lumber yard here will add the clear D-F to their regular order so I don't have to pay actual shipping cost just buying the lumber I need.
    He orders lumber from this mill anyway, so it will come in a container load for the yard.


    Milling 4x10x16' down to size isn't a problem, I just want to be sure to leave enough extra so can dry then plane to final dimension.
     
  8. fallguy
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    fallguy Senior Member

    I can tell you one thing. I'd be supervising the day they cut. No way would I allow them to cut on trust. I have seen way to many sawyers think they knew what they were doing and eff it all up. I asked a guy here once to vertical cut and he said, "no time for that". No lie. It was in the middle of the process. I should have made him stop cutting. My losses were massive. The flatsawn lumber moved so much that many of his cuts weren't worth the time! Worse is he was paid for time. But wanted to rush and get the job done in one day instead of going into a second day.

    The real reason he didn't want to vg cut is it is work to manually turn the cant. He did not want to do the work. When you get your logs, mark the grains and make sire they understand to vg/rift saw. And monitor their work. Pay extra for the headache and your lumber will be gorgeous.
     
  9. Rumars
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    Rumars Senior Member

    Best practice is to dry it at the thickness it comes and mill it to your hearts desire when dry. Yes, it will take longer to dry.
     
  10. fallguy
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    fallguy Senior Member

    It can end up pretty furry if you plane it wet; then move some and you can't flatten.

    I like to plane dry with a crayon. I run all the stock back to back with someone taking away. I mark deep/odd defects with the crayon; if the planer doesn't get them; they show up next pass. The planer I use is on wheels, so we spin the planer after the batch is common thickness. The person taking away is not allowed to flip.

    Then I flip the boards to look for defects and determine which way to run the board best on the fly. The crayon helps keep a continuous run and less snipe issues, faster, etc.

    Good luck. Sounds like plenty of work, but worth it done well.
     
  11. abosely
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    abosely Senior Member

    I'm on Big Island HI, and the mill is in Oregon over 2000 miles away. But I'll be getting the lumber from a local lumber yard.
    He has worked with this mill for number of years and the mill knows if they send lumber thats not done right, he won't pay for it because too expensive to return it.
     
  12. abosely
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    abosely Senior Member

    Interesting, just talked to a guy that has a saw mill a mile from me. He will saw the lumber into 1" slabs for me for $150. Has a couple of sizes of Woodmizer saws. So will be band sawn and save me lot of work. :)
     
  13. Rumars
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    Rumars Senior Member

    If this wood is to be used on a boat please keep in mind that boat plans do not operate with "nominal" thickness. If it says 1x1" then that is the finished dimension as installed (planed and sanded).
     
  14. abosely
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    abosely Senior Member

    DBCE391C-C9BB-4A6B-9651-2A3CFCCB52DA.jpeg It’s a Wharram Tanenui and they call out rough dimensions and spec ¼” less planed.
     

  15. abosely
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    abosely Senior Member

    Just talked with owner of lumber yard, he’s waiting for mill to locate clear D-F in 4x10x16 in small quantity.

    But he has kiln dried, clear D-F in 1x stock in 2, 3, 4, 6 & 8 widths.
    So ¾” actual thickness and 1.5”, 2.5”, 3.5” 5.5” & 7.5” actual widths.

    Going to go through lumber list by size & lengths and see about getting this lumber.

    Down side it won’t be vertical grain, but the only places VG would really be benefit for this design would be stringers.
     
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