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December 2018


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Working with Burls

by Lyle Jamieson

If you have been a woodturner for any length of time you have, or had, or will have, a burl cross your path. That’s the good news, but many have the bad news crop up in the stress of “What Now”? We get so fearful we might screw it up, that we don’t do anything with it. Over the years we look at it, in wonder, as it self-destructs before our eyes. It will both check and crack, or rot over time.

If you have control of the harvest, do not cut the “cap” off the burl. The burl grows with the color and grain deep into the tree most of the time and if you cut the cap off you leave a considerable amount of the burl behind on the tree. Cut the tree with intentional waste wood on each side of the burl. If it is going to be stored for a while it will dry out in the tree waste wood and the cracks can be trimmed back to have fresh wood near the burl that is not cracking.

Take a look at the burl. Is it like a wart sticking out of one side of the tree or is the burl wrapping all the way around the tree, or part way around?


(Pinterest image https://www.pinterest.co.uk/creanatura/warrelknoestenburls/)

 

Let’s talk about the burl that is only on one side of the tree.  When we have a wart type burl, the first cut should get rid of the tree on the opposite side of the burl. Cut down the pith with the burl on one side of the chainsaw kerf and the tree on the other. Then cut the extra wood on each end of the burl so all that is left is the burl. It should be the general shape of a sphere or a cube the size of the burl now.  See photos A, B, C, D, E.


Photo A - This burl is mostly on one side of this tree. The line is where the first chain saw cut will be. This separates the straight grained wood of the tree with the burl area. The burl color and grain character will penetrate deep into the tree, so it is advisable to keep the tree area under the burl. The chain saw cut in this kind of burl will go right down the pith. The waste area on the left will be used for a bowl or other straight grained wood creativity.

 


Photo B - Note the cut I am making is a ripping cut into the side of the tree, not on the end grain.

 


Photo C - This a burl with the waste wood removed. This gives me information to make an educated guess on where to make the next cut.

 


Photo D - Shows the grain and color revealed by the first chainsaw cut.

 


Photo E - This is a close-up of the small area shown in photo D, exposed by the first cut. It shows the grain directions with the rays of the burl fanning out from the center to the outside of the burl.

If you have the kind of burl that wraps more than halfway around the tree you need to take a chain saw cut to cut it in half usually.  See photo F, G, H. 


Photo F - Here I am taking the second cut to cut the burl in half. This will give me two very good, and still large, bowl blanks.  his will reveal more color and grain on the middle of the burl. I might find some fantastic wood or I can be disappointed with sometimes rotten wood in the center of the burl.

 


Photo G - I look for some symmetry in shape to make my cuts. I look for natural bulges of the burl and try to cut it with equal dimensions N-S and E-W

 


Photo H - When the burl wraps around the tree, it is best to cut sections or wedge-shaped pieces. I look for bark inclusions in the burl to make my chain saw cuts. Check out the color and grain this cut shows. It is easy to see where the next cuts will be to form the bowl or hollow form blank you are after.

Here is the place where I think the stress and fear comes in. Not so much in turning the burl but making that first chainsaw cut. There are many times when there is no right or wrong cut. We just have to make an educated guess and plunge in with both feet. The first chainsaw cut will give us information hidden in the burl. Where is the grain, where is the color, where are the rotten parts, where is the waste? See photo J. 


Photo J - This cut shows good news and bad news. The good news is that there is spectacular color and grain figure. The bad news is some of the burl has decayed.  But even that could be good news if the rotten spots make a void in a deliberately placed vessel.


How deep is the burl character going into the tree?

The next decision to make is the scale of the work you want to do. Will the whole burl fit on the lathe? Do you want to turn something that big? If not, cut it in half or quarters. Or cut it in 1/3-2/3 sections. Whatever.....just make a cut.  The cut will expose the inside of the burl and give you information for the next cut, and the next cut. Ideally, when you get done you have wood that is bigger than bottle stoppers.   See photo I.  


Photo I - This is a close-up of the cut surface. The pith of the tree is at the bottom of the photo. The burl character goes well into the middle of the tree. There is a special vessel waiting in here for sure.

 


Photo K - It is a bit hard to see the shape of the burl under the plexiglass sheet. I use the circles to show where the possible center would be. And where to trim away some waste wood to make a hollow form. The fourth circle ring would be the target size. Look for the saw kerf from the last chainsaw cut in the bottom middle of the photo. The red marker lines on the wood is where I make the next chainsaw cut.

We have to fight the frugal gene--we all have one! It might be more spectacular to make a smaller vessel with good grain and color by wasting away some wood. We need to resist the overwhelming urge to make a 10-inch bowl from a 10-inch tree.

Here are my steps for tackling a burl:

  1. Narrow down some of the endless options. Does the burl dictate what will get turned? Not in my shop, I think even a beginner’s instincts are better than a tree’s! So make some decisions before starting. What is your skill level? What are you good at, bowls or hollow forms? What do you enjoy, where is the fun? Bowl or hollow form or whatever floats your boat, pick one and plan to go with it.

  2. Decide the axis. Is the top facing the bark or is the top facing the pith? There is usually a color pattern or grain direction to burls. If your chainsaw work exposed the grain it is easier to make this decision.

  3. Visualize what will be wasted in the turning process. Will the shape of the turning take the wall through the best color and pattern of the burl or will the turning put the best parts of the burl on the floor as shavings?

  4. Put the piece on the lathe. Place it between centers on the balance point.  Place it so the cap is either parallel or perpendicular to the bed and on the balance point of weight so we can get the lathe speed up. The idea here is we are making most of the decisions before we start turning.  The more planning we do the luckier we get.  We can get lucky sometimes by just putting a piece on the lathe and see what happens, but planning ahead will yield better results. Photo below is from my video “Birch root burl with undercut shoulder using the boring bar”.  [https://www.youtube.com/watch?v=majDVtHeBmo&feature=youtu.be]
     
  5. Clean up the center points with a hand chisel so you are grabbing between centers on solid wood, not bark. I use a laser and “point” at the burl to see where the top edge of the vessel will be as I rotate the blank by hand on the lathe. The laser can get you a head start on position and show you where a cut with the tool will be over a rough surface. To see where the rim of a bowl or top of a hollow form is, place the laser pointing perpendicular to the bed with the tool rest parallel to the lathe bed. Slid the laser back and forth on the tool rest pointing at the burl as you slowly rotate the burl by hand.  If the rim has an unwanted low spot, move the axis to tilt the burl in a better position.  To see the largest diameter or circumference of the burl, place the laser pointing parallel to the bed and spin the burl by hand to make adjustments in the axis. This can help establish the outside surface. We have to decide if there is too much wood on one side and too much air on the other side, then move the blank to a new set of centers until you have it fairly balanced to the shape and balance to the weight.  Another option is to intentionally create a void by putting wood on one side and air on the other side of the blank.  With the laser’s help you can see how big the void will be and how much air you have once you turn it round.  This is only a starting point, not the final axis. There have been burls that I have had on 8-10 different axes as I rough it out before I get it to its final axis for turning.
     
  6. Now take a few cuts and cut the corners off a bit and start the roughing process. Stop and look often! Sneak up on the shape knowing you will move the axis as you go. At this early turning stage, my goal is to get information. As the wood comes into round and the weight stabilizes, I can move it incrementally to the shape I ultimately want.
     
  7. Once you find the perfect axis where the grain, color and shape will be possible, make the flat concavity for the faceplate. Once on the faceplate, then we do the final shaping and finish the surface both top and bottom, outside and inside. Do not do any final shaping between centers.

Go for it! It is the first chainsaw cut that is the hardest. After that, you have more and more information to make the necessary decisions to get something really extraordinary from your planning.

Here are some forms I have made out of burls:


Cherry Burl, 7" x 7" x7"


Maple burl, 5" x 5" x 6"


"Attraction"

 

Click here to read about the author, Lyle Jamieson.