I have several maple burls that are from a freshly cut tree – what is the proper way to dry them before turning or do I have to wait?
thank you
joe clark
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Replies
If you are making bowls, rough turn to about a 1 ½” wall thickness, (or if they are big about ½” per inch of diameter. I dry mine in a cardboard box full of the shavings for the first six months, then in the shop loft for another six. Remount and finish turn, it works great.
guess I'll miss the Christmas presents for my kids then - thanks for the information
peace
joe
Local conditions may speed it up, you just don't want to lose great material trying to push it too hard.
Joe -
A recent article I read in Turning Design quarterly mentioned that burls don't seem to experience the same checking that ordinary timber pieces do. That's not to say that they don't require 'seasoning' to keep them from going oval on you, ... they do.
But what this guy did for the feature project was to alternate drying in a microwave and convection oven for specific times once the piece was rough turned. Times and cycles depend a lot on the size(s) of the piece(s) you have, of course.
Couple other things one can do to avoid checking and shrinkage cracks -
PEG ... Poly Ethylene Glycol is used by some to displace the water in the wood thus control shrinkage. I've not tried this myself since some (much more advanced turners than I) believe it affects the finish to a greater or lesser extent.
Liquid dishwasher soap .... Really. This was written up (I think) in a past FWW issue. Soak the piece in a dilute solution of this stuff for a time and it's supposed to work the same as PEG. No effect on the finish. This I *have* tried. On a piece of cherry log about 8" in diameter (in the rough). Turned a cylinder to about 6" and soaked the thing for about a week in the soap/water solution. I've got it sitting on a shelf in the shop and it's only checked to a minor degree. Mind you, this is the entire log, pith and all. So I'd say for any quarter or portion of a log without the pith, it should work great.
Now a question for you if you don't mind.
We recently felled some maple and alder trees on our lot and I salvaged a few small burls as well. The first one I 'opened up' I don't think I approached the piece correctly. The burl figure, what little there was since it was indeed a small one, seemed to only occur on the very bottom of the inside and outside of the finished bowl about 4" in diameter. How do you intend to approach yours? Parallel to the growth of the tree or perpendicular? Maybe I just didn't have enough burl to work with.
From Beautiful Skagit Co. Wa.
Dennis
I want to cut out the burl parallel to the trunk direction. I have enough material make it work - I think - will let you know.
peace
Joe Clark
washington grove, md
Joe:
I turn a lot of burls, mostly cherry but have also turned maple, oak, willow, apple and pine. I like to turn them with a natural edge and turn them slightly green. Sometimes I turn them as soon as I get them. I've had little trouble with cracking. If they do they seem to blend in with the natural look of a burl bowl. You can fill burl voids of any type with crushed turquoise for an added effect. I like to turn them green because as they dry the burl develops subtle "waves" in the surface. This is because burls have no distinct grain. I've never seen one become oval as a straight grained bowl would when turned green. I like to finish them with a combination of equal parts high gloss polyurethane varnish, boiled linseed oil and raw Tung oil (a-la Sam Maloof). Since they are not intended to be cereal bowls food safety is not a big issue. Be careful as burls are unstable by nature and frequently can hurl chunks at you. Stay to the right of the bowl!
Good Luck
Roger
Roger - that is the kind of information I was looking for - thanks so much. I'll be sure to be out of the line of fire!
thanks
joe clark
Joe:
You're welcome. Feel free to e-mail me if you have more questions.
Roger [email protected]
Joe,
When turning a natural edge burl, what method do you use to remount the bowl to r-eturn the bottom, after it has dried? Methods like the jumbo jaws of the Oneway chuck only work for smooth, flat circular bowl egdes. I have tried to use the tailstock to the bowl against a piece of wood covered with a pad, on the headstock, but this is very difficult to center. Thanks
Joe
For small burls, those 10 in or less I use an expanding Nova chuck. If you have a bigger burl I have a jig that I use to hold the burl. I'll try to take some pictures to show you how it works.
The trick to the natural edge is getting the face plate in the center of the burl and at the angle that will allow the most pleasing edge. I usualy chisel a flat surface for the face plate, mount it and then hand turn it to watch the edge profile.
Jay -
I'm not the most experienced turner on the block but the few times I've turned natural edge pieces I've used a jam chuck of one sort or another. Simply turn some scrap lumber to a shape that will fit inside your natural edge piece, place the work piece onto the jamb chuck and, if necessary bring the tail stock up for support in order to turn all but a tiny nubbin at the center of the bottom. Then after finishing the outside of the piece, pare off the nubbin with a sharp hand chisel (off the lathe) and sand and finish to match the rest.
...........
From Beautiful Skagit Co. Wa.
Dennis
Thanks.
That's pretty much the way I have done it in the past, but I had hoped you had some method that would not require the indetation of the bottom by my tailstock center. Incidentally, when you let the piece dry after initial turning, do you leave a tenon for the chuck jaws to close down onto or a recess for the jaws to expand into?
Jay
Jay
Here are pictures of the jig I use for burls with natural edges. The bowl in the picture is smaller than the jig needs but I came to realize all my nice large burl bowls have been given away as presents. Any way look at the pictures before you read further.
The jig requires a split in the lathe bed or a really big lathe with a BIG swing. The solid disc is mounted to the lathe with a face plate on the back (not shown). A padded block just taller than the bowl is deep and contoured roughly to the inside of the bowl is placed in the center pad side up. The bowl is placed over the padded block. The padded ring is placed over and the bolts passed through. Hand tighten the bolts. Mount it on the lathe and bring up the tail stock to the center of the bowl bottom (I usually put a screw in the center hole of the face plate when turning the bowl, this gives me a center point to put the tail stock drive into). manuver the bolw around to get it to set right then gradually tighten all the nuts down.....like putting on a head gasket. When it is all tightened the bowl will follow zen budhist rules and "be one with the lathe". Back off the tail stock and turn and sand your bottom.
Without the padded block this works for any bowl and is cheap to make. If your burl has little to waste on the bottom glue on a block of scrap and turn it off with the same method.
Just to impress you I included a bowl that "exploded" just as I was finishing it. Wear a face shield! Don't stand in front of the bowl when you are turning it! Words of wisdom from the ER doc.
Let me know if you have any questions.
Roger
Roger,
Thanks for the photos. Unless there's a lip on the top edge of the bowl, which there does not appear to be, I don't see how your jig holds the bowl down onto the contoured foam pad. It looks like there is a ring that is only barely touching the bowl by its foam lining, so the bowl would fall right off. Especially with a natural edge, where the bowl won't sit flat against your circular board, I don't get it. If you don't mind, perhaps you could elaborate. By the way, I'm proud of you for the safety advice. I'm a retinal surgeon who had removed more than one intraocular foreign body from woodworkers.
Jay
It's the only burl bowl I had at home. If the bowl is bigger the natural taper of the bowl will fit in the ring. Since I turn the smaller ones with a chuck I have only a large ring. Once you catch the bowl in the ring and tighten it down it works great.
I suppose I should advise people to turn without eye protection to help our business! Got to pay those tuition bills you know.
Roger
I have enough business, thanks! So, for larger bowls, when your jig is tight, there is a separation between the ring and base plate, bridged by the bolts. Is that correct? Thanks.
Jay
Jay:
You've got it. It compresses against the tapered sides of the bowl, squeezing it down on the padded block. I turned the discs on the lathe to get them perfectly round. I also made them out of plywood because it is more stable and less likely to warp. Have fun let me know when you post a picture of your burl bowl.
roger
Thanks. Now what about the issue of the irregularity of the natural edge. THis may not allow the bowl to be compressed flat against the back plate. If it tilts because one part of the natural edge is higher than the other, the base will wobble. Thanks
Jay
Jay:
Look at the pictures again. You put a padded block on the solid disc. The block is just taller than the bowl and fits into the bowl. So when you compress the whole thing together none of the irregular natural edge touches. Clever huh.... I can't take credit a professional turner showed me how to do it.
Roger
> ...do you leave a tenon for the chuck jaws to close down onto or a recess for the jaws to expand into?
The few burls I've salvaged from the timber we took down were pretty small. Thus using a spigot (expanding the jaws into a recess) was my choice. Reason being I could leave the recess as part of the bottom and not loose too much material. Although I suppose one could finish off a tenon as a small base as well.
...........
From Beautiful Skagit Co. Wa.
Dennis
I've mostly turned burls dry. I flatten the end I want to chuck up with a scrub plane and/or a 6x48 belt sander, then I use 5 minute epoxy to glue it to a piece of plywood screwed to a face plate and turned round. When I'm done, I part it most of the way off at an angle, cut it off with a handsaw, then use carving chisels and sandpaper to blend the nipple left by parting and sawing. The plywood disk goes into the burn pail.
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