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Thread: Methods for handling large blanks

  1. #1
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    Methods for handling large blanks

    I recently came across some really large pieces of free cottonwood and I was able to get 4 chunks that I made 8 bowl blanks out of, 20-24” in diameter, plus 8 quarter sawn blanks for spindles/small facework. This is the largest I’ve ever worked with and am curious how others handle large blanks as some of the things I’ve done could probably be done better.

    I started by cutting out the pith sections and then making octagonal shapes from the outer pieces. Every time I’ve tried to cut rounds on my bandsaw it messes up my blade (3/8” 3tpi highland Woodturners blades) so I’ve stopped doing that but then it makes mounting the large irregular pieces difficult and then the first 30 minutes of turning pretty slow going.

    I was able to get about 19” rough bowls from the first couple pieces but am wondering if there is a faster/simpler way to do this. It is a lot of fun turning something this large but takes more time up front than I’m used to. Any recommendations from more experienced turners would be appreciated.

    Here’s a few pics of the initial cut logs after hauling home and filling my tiny shop (4 of the bowl blanks are kind of blocked by my bandsaw in the picture):

    IMG_9217.jpgIMG_9218.jpg

    Here is an unturned mounted piece nearly maxing out my Laguna 2436 - I used an air hammer with my compressor to remove most of the bark and then once mounted I had to use an electric hand planer to trim a couple corners because it was >24” and was hitting my ways (first time I’ve tried this and it worked great and was really quick and easy to do):

    IMG_9239.jpg

    Here are the first sets of rough bowls:

    IMG_9248.jpegIMG_9242.jpg

    Any comments or suggestions are welcome (sorry about the sideways pics…..not sure why it did that). Thanks,
    Tom
    Last edited by Thomas Wilson80; 11-25-2023 at 2:22 AM.

  2. #2
    What do you mean, messes up the blade?
    I might use a 1/2" blade but apart from that, you shouldn't have a problem.
    Are you using any kind of circle cutting jig or centering pin, or are you trying to cut freehand?

    Also, I don't recommend the shirt & tie when prepping blanks but you managed to pull it off and stay clean.

  3. #3
    That works. You might try tensioning your blade more and/or use a 1/2" blade but full rounding doesn't save that much time over trimming the corners. If you get the blanks into static balance between centers that allows for roughing at a reasonably high rpm. There is a small market for bowls that big so perhaps you won't find yourself cutting such large blanks so often. I have a 100 kg material lift as well as a chain hoist on tracks over the lathe, but maybe your back is stronger than mine. For pieces that max out your lathe swing an extra banjo on the inboard side can be helpful.

    Long ago there was a letter in Fine Woodworking about a fellow who went to turn a baseball bat after church and got his tie wrapped around the spinning blank. After a few cycles of near strangulation and entanglement he managed to sever the tie with his skew chisel and fell backward into the woodpile.

  4. #4
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    Haha, Thanks for the comments - I stayed up late Saturday turning and then wanted to send a pic to a friend just before church….the smell of cottonwood would be enough to clear the entire congregation!

    Several times when trying to cut rounds on the bandsaw with large-ish blanks I have had the blade either break or bend. I try to go slow and not do too tight of circles….maybe it’s a tension issue but I’ve watched numerous bandsaw tutorials and adjusted the tension multiple times, (but to be honest, I don’t have any bandsaw experience aside from using it for turning so it is totally possible I’m doing something I shouldn’t).

    I know the market for large bowls is small but the couple 15-16” bowls I’ve done in the past have gone fast (I’m guessing these will be around 17” when finish turned). Plus it’s just fun to make something this big.

    Thanks for the comments,
    Tom

  5. #5
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    I consider cutting turning blanks on a bandsaw like mine (14" with riser block) to be hard on blades and won't use a good blade on it. For smaller blanks I do minimal corner removal with the bandsaw or just put it on my VS lathe and cut from the tailstock center end out. Larger blanks, I trim to a very, very rough circle with an electric chainsaw first.

  6. #6
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    I stopped cutting blanks into rounds myself a very long time ago. Too hard on the smaller bandsaw blades and especially with deeper cuts and on the tougher woods we have down our way. If I didn't cut enough corners off with the chainsaw I just use straight cuts with the 1" blade on the bandsaw and do 8 straight cuts on smaller blanks and 16 on larger ones.

    I found that there wasn't much difference for me between taking the extra time to pre-cut the blanks into rounds vs tuning to round on the lathe after 8 or 16 siding them with the chain or bandsaw. With green wood I will often just turn the half log billet to round on the lathe. One of the downsides with that is the extra volume of shavings to be dealt with.

    I can confirm from my experience that larger bowls and patters are slow sellers, but a few larger speccy pieces in your display attracts potential buyers who once you have their attention might settle on one of your smaller and more affordable pieces. Don't discount your larger pieces because they are slow sellers; putting an appropriate higher price on them adds value to your smaller pieces. And, the larger more expensive pieces will eventually sell to those for whom the price is not a consideration. For some of those buyers the higher the price the more attractive the piece is to them...
    Neil

    About the same distance from most of you heading East or West.

    It's easy to see the Dunning-Kruger Effect in others, but a bit of a conundrum when it comes to yourself...



  7. #7
    I used to turn smaller bowls, 8-10" diameter, and have boxes of them in the attic, even black cherry and walnut, oak, maple, bradford pear. Despite being much more useable, they don't sell, unless from their tree AND then want keepsakes. Even then, . . .

    People want salad mixing bowls at least 17" diameter for wedding presents.

  8. #8
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    Octangular blanks go faster if you start on the face to round them instead of the outside diameter. Just a fraction of the rough turning. If you chainsaw the blanks to 16 sides, it gets really round. An electric chainsaw in the shop is much easier to round the blanks on the lathe. I'm not a big fan of turning cottonwood, especially when it's wet. The smell can be quite offensive

  9. #9
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    I knock the corners off with the band saw and then do any further rounding on the lathe. A 40/40 gouge is much faster for hogging off the uneven exterior than my other gouges and provides lots of practice at "floating the bevel" over an uneven surface. The gouge can take a 1/4" thick shaving, making it pretty quick to get a log round.

  10. #10
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    Like Neil and the last few posters, I gave up taking the time to bandsaw blanks round. Octagonal works just fine. Getting to round is a bit of a chore but really takes no longer than getting the bandsaw setup. Since I’m starting between centers, there’s the inevitable adjustment to balance the grain. I keep a small electric chainsaw around to adjust as needed.

    Knock off the corners at an angle from the live center to rim. Adjust speed as balance gets better and enjoy the roughing process. My bandsaw is better used to process spindle blanks, resaw the quarter sawn pith sections into lumber and stock for flat work or carving…

  11. #11
    The only problems I have had with rounding out my blanks came from the slab not being flat. If you can set the slab on a table, and it rocks, then you are going to get bent and broken blades when the blank rocks as you round them out. I did one video called 'chainsaw chopsaw'. which helps get the slab very flat, and pretty close tp parallel sides. For production work, the octagon does not work as efficiently as a rounded blank. Part of this is because you can start at higher turning speeds with a round blank. I have always used a 1/2 inch 3 tpi blade for rounding my blanks. You can round out a 5 inch blank with that blade. As for bowl sizes, I sell about the same $ amount of smaller bowls as I do larger bowls. Selling bowls over about 14 inch diameter is very slow.

    A story about cottonwood. About the only commercial use for it is lumber for horse stalls. Apparently it tastes as bad as it smells, like some one barfed on it, and the horses won't chew on it.

    robo hippy

  12. #12
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    Good info - thanks to all.

    Growing up in Utah, a lot of the trees are cottonwood and I find that, while not my favorite wood scent, I find the smell nostalgic and actually enjoy it. My wife, who is from Florida, does not!! Fortunately the smell doesn’t last in turnings or I’d be stuck with a ton of bowls and other turnings forever.
    Tom

  13. #13
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    Apr 2010
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    If I had a dedicated coring lathe always setup and ready to go I might experiment with taking the first cut to part off the outer rough cut part of the blank or even do that with half billets (log cut to turning length and sawn in half along pith line).


    • Mount half billet on cut face and turn tenon on foot side.


    • Remount on tenon and part off the outer shell from the half billet with the corer. The trajectory of that first cut to be in the wood (which is the purpose of this first cut anyway) to avoid the risks from an interrupted coring cut.


    • Take second smaller diameter cut to complete larger cored blank.


    Until I tried it I don't know if that would be saving much time. Anyway, another idea to try some time.
    Neil

    About the same distance from most of you heading East or West.

    It's easy to see the Dunning-Kruger Effect in others, but a bit of a conundrum when it comes to yourself...



  14. #14
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    Quote Originally Posted by Neil Strong View Post
    If I had a dedicated coring lathe always setup and ready to go I might experiment with taking the first cut to part off the outer rough cut part of the blank or even do that with half billets (log cut to turning length and sawn in half along pith line).


    • Mount half billet on cut face and turn tenon on foot side.


    • Remount on tenon and part off the outer shell from the half billet with the corer. The trajectory of that first cut to be in the wood (which is the purpose of this first cut anyway) to avoid the risks from an interrupted coring cut.


    • Take second smaller diameter cut to complete larger cored blank.


    Until I tried it I don't know if that would be saving much time. Anyway, another idea to try some time.

    Ronald Kanne in the Netherlands built a coring machine to start with log halves but I’m too afraid to try it with my Oneway:
    https://www.youtube.com/watch?v=EHhSaFkudSQ

  15. #15
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    Quote Originally Posted by Thomas Wilson80 View Post
    Ronald Kanne in the Netherlands built a coring machine to start with log halves but I’m too afraid to try it with my Oneway:
    https://www.youtube.com/watch?v=EHhSaFkudSQ
    An interesting and entertaining video from Ronald with his coring machine that works the opposite way to Oneway, Woodcut and McNaughton by both holding and cutting the blank from the face side. That worked very well for his first shucking cut but he didn't seem to have a quick way of changing the blade to do the smaller diameter cuts while the blank was still mounted on his corer. That may not have been obvious as the time taken to change the blades over was mostly edited out of the video. No doubt he and his engineering friend will get to solve that design issue.

    Anyway, I wouldn't say no to having one of his Mastodons to at least do that first quick shucking cut...
    Neil

    About the same distance from most of you heading East or West.

    It's easy to see the Dunning-Kruger Effect in others, but a bit of a conundrum when it comes to yourself...



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