• Congratulations to Alex Bradley winner of the December 2024 Turning Challenge (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to Gabriel Hoff for "Spalted Beech Round Bottom Box" being selected as Turning of the Week for January 6, 2024 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

chucking a burl

H

Hollis

Joined
Jul 25, 2004
Messages
6
Likes
0
Location
McKinney, TX
I have a three part question that I am hoping some of the extremely talented people here might help me with😉
I recently purchased 2 beautiful amboyna burl caps, and haven't a clue as to how to chuck them 😱 I want to turn a bowl in the flat or cut face, while leaving the exterior of the cap in its natural state.
The second part of my question is, how do I remove the wax sealer that was applied to it? I usually just cut it off while turning but can't since it is on a good portion of the outside of the cap.
Lastly, what is the best way to dry it prior to finishing?
I probably sound like more of a "newbie" than I am, but I have been turning for a couple of years. This is just new territory for me.
 
Suggestions on chucking only

Hey Hollis,

I hope I'm understanding your question correctly.

Chucking burls is mostly like chucking anything else. Stuff bigger than the chuck gets mounted between centers first.

The only exception to the "like chucking everything else" statement is that you want to restrict your serious chucking for what will be the base to compression-mode only. Mount between centers and cut a tenon or spigot on what will become the base of your bowl. If you can't get a spot for the spur or other drive center (Steb, Safety Drive, etc.) because you're going through bark, figure out where center is, take a traditional chisel and mallet and get down to the real wood (past the bark) and then pound your spurs into the wood. Not hard enough to split the log, but hard enough to give good bite when you mount it between centers.

If your intention is to just leave the burl as a chunk with a scoop out of the top and call that a bowl, and leave the rest of the burl showing cap characteristics, you're going to have to find a way to mount between centers, face off what will become the base and finish it, then maybe glue it to a waste block using the brown paper bag trick. I don't know how well that'll work, actually. One instructor's recommendation is to use thick CA to mount any burl to a waste block and then turn it off. Because burls often have punky wood, soft wood, diseased wood, easily damaged wood, or just less than contiguous wood in the burl pattern, regular mounting with screws or traditional wood glues are less satisfactory.

Hope it helps. YMMV. Let us know what you do and how it works.
 
A burl is chucked just like everything else. In that respect I agree with Dean. All after is more what he does than anything.

If you bought it, your burl might be well selected and fairly free of cracks, pockets and voids, but it's still not a bad idea to reinforce aggressively if you run into soft or crumbly spots, especially in the mounting areas. CA glue is my choice, bark my filler, and I stop, locate and reinforce at the first "click," before things weaken and crack more.

I use a pin chuck/jaws for initial, scroll chuck for reverse mount. No sense risking the piece and my chops starting it on a spur center. I'd rather have something which mechanically resists dismount when the piece is at its least balanced. Faceplates are favored by some, especially for larger pieces.

For reversing and turning I'm a mortise man, and it works just fine. A lot of the tenon types use jaws that don't spread the load, so they talk in terms of "grip" and "tightening" instead of just "holding," a more gentle means of doing the job. If you have smooth dovetails in your jaws, you may use them to fit snugly to your mortise or tenon, avoiding the danger of crushing and crumbling your random-grained burl with toothed types.

As for dewaxing, start with what held the wax in suspension the first time, wetted water, if the piece is entire. Nice sodium metasilicate-based wash and rinse should do a lot. Scrub brush even more. Or you could use mineral spirits from the start and keep diluting, which will cause very little swelling compared to water. Waterborne finishes and lacquer will be sensitive to residual wax. Finishes sharing a common solvent won't.

Best way to dry is let the air dilute and carry away the water. Im betting that you won't be very wet at all, so you probably won't be subject to the suspense those of us who turn green burls suffer through as the burl determines the direction and distance of shrinkage. With burls you can't really predict like you can with less random grain.
 
MichaelMouse said:
All after is more what he does than anything.
Click to expand...
So Very True. 😉

I use a pin chuck/jaws for initial, scroll chuck for reverse mount. No sense risking the piece and my chops starting it on a spur center. I'd rather have something which mechanically resists dismount when the piece is at its least balanced. Faceplates are favored by some, especially for larger pieces.
Click to expand...
Too often I forget about the pin chuck as a possibility. My apologies. It's a good option. I had one for a while, but it was not something that I used at that point in time. Was part of a chuck set (Precision Chuck out of England) that I no longer own. I may reinvest on a dedicated pin chuck. It would indeed be more secure than a spur or steb, but...

My guess is that any risk of the piece (or one's body parts) have at least something to do with the lathe's capacity and it's speed options. Out of balance and slow starts are good things, even on a beefy lathe, yes? If one's lathe is a step-pulley system that only gets down to 750 rpm, that might just be too quick for a large, severely unbalanced chunk of anything. Following Dale Nish's recommendations, anything beyond 12" is out of the "safe range" at 750.

Good thread, IMO. :cool2:
 
Last edited:
I usually chuck burls one of three ways, depending on size and shape. For a relatively small burl (1-4lbs) I chuck it pretty much like I would with a baseball, ie. overhand or sidearm. With a larger burl, I use a modified shot-put approach so as not to injure my shoulder.

Now with flat burl caps like you're describing, I'll either frisbee them or, for the larger ones, use a discus like motion.

How's that?

Dietrich 😀
 
dkulze said:
Now with flat burl caps like you're describing, I'll either frisbee them or, for the larger ones, use a discus like motion.

How's that?

Dietrich 😀
Click to expand...

Dietrich-you failed to mention the direction at which to throw?? (ie. Bill.Mass.) !!!! 😀 Gretch
 
Burl questions

I found an Elm tree covered with burls. I have turned two and am not sure I didn't make firewood out of them. I was told after the first one distorted and cracked so bad it almost looks square that 1/2" was too thick. The next one is 3/16" and it looks worse than the first one.
Can wet Elm burls be rough turned without excessive distortion and cracking?
Is the 10% rule a good one to follow for thickness?
I have the rest of the burls in my air-conditioned shop covered with a plastic tarp which I remove daily to see if it is wet and needs to be turned over. So far it isn't wet. Is there a better way to keep them until I figure how to handle them?
Ron
 
Forrest was wrong, life is like turning a burl.

They are pretty unpredictable, aren't they? Not only are they a surprise when you cut in and find parallel bark pockets that mean all-day filling or firewood, they also move in unpredictable ways when drying. If you're looking for circular, or close to it, you have to have luck on your side. I go against my common practice and let burls dry as they are for a while. The essentially random nature of the grain makes any big disaster unlikely, and they gain a bit of stability as the wood works out some inner tension in drying.

Elm tends toward larger figure than say a cherry or maple burl, which gives it more distortion, because there are larger areas of straighter grain to contract. No ten percent will guarantee a round, because bark pockets and even found and glued-up cracks will allow segments to move on their own regardless. If you don't have glue in it that's sensitive to heat, you might want to try either of the two plasticizing methods on a reasonably thick .5-1" piece. Boil or microwave. With either, because of the wood, do it outside, and if you try the second, with a microwave that is yours alone. It will muddy the color as it redistributes some of the extractives, but it might just allow enough relaxation to get you some stability for re-turn. I'll micro birch or maple, but not cherry.
 
lop sided pieces and burls

I am sure you guys with alot of experience are familiar with this but I recently learned the technique and thought I'd share, especially with those just starting.I keep seeing references to turning out of balance pieces and thus initially to rough them and starting very slow. We had a demonstration at our club that showed us to find the center of the wood so it wasn't out of balance and thus minimized the wobbling and walking across the room that the lathe can do with an out of balance piece. You just litely contact the piece at each end with the points of the centers so it can rotate freely. Then spin it by hand and find the heavy side(it will end up on the bottom). Readjust one end at a time moving the contact point slightly towards the heavy end and repeat this process until the piece spins freely with no evidence of a heavy side. Then with just the points contacting the wood so there is no bite by the spurs, turn the lathe on slow and advance the tail stock ever so slowly, holding the piece still so the blades of the spur drive create their own flat seat with all spurs making equal contact. Turn the machine off and advance the tail stock so all the spurs make adequate contact to turn the piece. Keep this tail stock pressure on the lite side so a catch when turning won't be bad. THis has worked amazingly well for me, hope it helps others .
Frank
 
Yes, but---

Frank, Sounds like good procedure for balance. And/but sometimes/frequently, after staring at the chunk of wood for a while one realizes that the center of the bowl-to-be is not close to the chunk's center of gravity. Then it's just go SLOW, and chunkity chunkity chunk for a while. Y'all that are fixin to buy somthing, I urge you (based upon a paltry 8 months experience with it) to scrounge up the relatively few extra dollars for electronic variable speed. Just some thoughts. I think Frank has good ideas for dealing with unbalance pieces.
 
I'd like to add that the rate at which the unbalance seeks bottom is more critical than the fact it does at all. I like to remove peripheral areas which will not end up in the final turning at the bandsaw. May still have an unbalanced piece, but closer to axis of rotation, where it counts for much less.

If you've got to have that wing hanging out on one side to chase that vision, you might want to consider a few quick counterbores inside to remove some weight where you'll be hollowing anyway. Farther from center the better. I've seen others recommend counterweights, used them on a couple of occasions, but you can bet those washers were captured under nylocks. Actually, trolling weights is what they were.

I would never recommend starting an out-of-balance piece on a spur center. Remove after balance check, shave wood to the pencil line and bore for a pin chuck is my method. Keeps my face as beautiful as it'll ever be.
 
starting an out-of-balance piece on a spur center

Michael
I would previously have agreed, but once I find the place where the piece spins freely, it is no longer out of balance. Once the spur center digs a flat seat for itself, then the spur center has enough bite so the piece won't fly off. On the other hand , I have it loose enough so that I can't get a bad catch that would throw it off. I would not attempt this with "punky" wood as it likely would fly off. I have actually taken the gouge and jammed it into the spinning wood to see if it would cause the disaster I would have had before I started doing this. Just as when the demonstrator did this,when I first saw this technique, the wood just stopped turning. I first read, when I started turning, not to put anything on the lathe that you're not willing to be hit in the face with. And indeed I did just that quite a few times( luckily I was wearing full face protection each time). But this technique sure seems to have cured the problem. I must admit I also have trimmed the piece before hand with the band saw. With really bad pieces in the past I would take off the high spots with a hand held electric plane. But since using this technique , I've not had to do this extra trimming, I just turn away the high spots.
Your pen chuck idea sounds handy , I'll have to try it. I do on occasion use a single big central screw that fits in my nova chuck to initially chuck a piece but I still use the tail stock to secure it until its shaped and the botttom . This also works real well but works better for fairly well balanced pieces.
I sure enjoy this forum, I have learned a great deal in the short time I've been attending.
Frank
 
Last edited:
Frank Alvarez said:
Michael
Your pen chuck idea sounds handy , I'll have to try it. I do on occasion use a single big central screw that fits in my nova chuck to initially chuck a piece but I still use the tail stock to secure it until its shaped and the botttom . This also works real well but works better for fairly well balanced pieces.
I sure enjoy this forum, I have learned a great deal in the short time I've been attending.
Frank
Click to expand...

Pin versus pen chuck. Pen chucks are for manufacture of same. Big fan of both it and its cousin the pin jaws for easy mount and safe roughing. Also allows the roughed piece to be held in place without a tailstock to form the mortise I favor for reverse mounting. That would be after it's as close to balance as possible, though not strictly necessary. If you leave the pillar in the piece when hollowing, it is the start point for turning round after drying.

Deeper you set those fangs on the spur the safer you are against side loading cause by you or sudden departure and subsequent imbalance resulting when a chunk of bark-bordered burl you didn't quite firm up enough departs under centrifugal force. The pin chucks run in over an inch.
 
You must log in or register to reply here.
Back
Top