Help With Large Out of Balance/Off Center Turnings

I have several slabs of very nice burl (12” to 23” diameter) that I would like to use for wall hangings/shields. I would like to turn some of them so that the center of the turning is not the center of the burl slab. I have tried Googling techniques and jigs that would help balance the turning so that your lathe doesn’t walk across the shop. So far, all that I can find related to the topic is off-centered spindle turning and turning small off-center blanks that don’t really require any counter balance. Looking for ideas, pictures, articles, etc that talk about the technical side of turning something like this.

Any help that anyone can provide would be GREATLY appreciated.
Steve

Steve, I have no documents to point to but I have seen things that people have constructed for this. Many years ago I saw a balancing frame one guy made to fit behind the turning, kind of like a big faceplate except not round. He mounted his heavy blanks off-axis onto the frame (with screws, I think) then used counterweights that could be positioned to balance the piece. Seems like he was turning multiple small bowls large pieces of wood.

The details are fuzzy since I never planned to make one, but I remember thinking it should work well if made strong enough.

JKJ

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Originally Posted by Steve Doerr

I have several slabs of very nice burl (12” to 23” diameter) that I would like to use for wall hangings/shields. I would like to turn some of them so that the center of the turning is not the center of the burl slab. I have tried Googling techniques and jigs that would help balance the turning so that your lathe doesn’t walk across the shop. So far, all that I can find related to the topic is off-centered spindle turning and turning small off-center blanks that don’t really require any counter balance. Looking for ideas, pictures, articles, etc that talk about the technical side of turning something like this.

Any help that anyone can provide would be GREATLY appreciated.
Steve

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Terry Scott has done some pretty amazing off center stuff. Here's a couple of images I slurped off the web:
Attachment 400458Attachment 400459

Just goes to show what you can do with a little imagination (and a whole lot of cojones!)

You can contact him here: http://www.timberlywoodturning.co.nz...ontact-Us.html

Also, if you are on WoW, look up Paul Hedman who has posted some pretty wild looking setups.

There is not a lot of documentation on this type of work for two good reasons: * No single method works for everything, * A method that is safe for one turner with his machine may be very dangerous for someone else. The solutions are specific to the lathe being used and to the work being done.
"Small off-center work that does not need counter-balance" means different things depending on the lathe. Someone with a 6000 lb pattern makers lathe has a completely different version of "small" than someone with a 16" Nova.
My suggestion is to start small and work your way up to the capabilities of your equipment. As you get more experience and skill, the capabilities of your equipment can be expanded a little bit. At some point you may reach the limit of your equipment unless your budget allows replacement with larger equipment.

Alain Mailland does some fantastic off center turnings/carvings. He has usually just barely started his projects where the rest of us have finished. Similar to what David posted above, Alain mounts a piece to some MDF or similar substrate and secures it with ropes, chains, holddowns, etc. He was featured in the book "New Masters of Woodturning." Several other turners who turn off center were featured as well, but if I remember correctly, there were pictures of Alain's mounts. Website below might help.

kirstenmuensterprojects.com

On really rough bad pieces I sometimes remove wood with a spade bit--much like metal rotating pieces are balanced--very carefully.

Thanks everyone for your input. I will be making a large face plate out of tow pieces of 3/4" plywood (so it is 1 1/2" thick). I'll be starting with with some small items and working up to some large items. The other thing is that I keep the rpms below 500, and make sure that I use counter balance weights to make sure the face plate is balanced. I'll keep everyone posted on my progress.

There is a professional woodturner, David Barkby (whose work I greatly admire). He routinely turns 6 to 8 foot wall hangings and I think that his biggest was close to 10 feet (my guess). I saw a picture of his lathe on-line where the concrete floor had been cut out to allow turnings that are larger than the spindle-to-floor distance. Also his lathe is bolted (with a BUNCH) of bolts into separate concrete footings. I recall him mentioning that his pieces may often start out around 150 to 180 pounds and when finished may weigh in around 70-80 pounds.

David does a static balance before he starts turning. That is where you rotate the piece by hand, let go of it, and see if it rotates - - indicating that one side is heavier than the other. The heavy side will rotate to the bottom. Then he screws metal weights into the back side of the piece until the piece doesn't want to rotate. When it is statically balanced it should not favor any position. But he also told me personally that as he removes wood, that the balance changes and that it is necessary to periodically re-balance it.

Because he is making wall art, he is working on the face of the piece and is out of the line-of-fire. But it is still a bit dangerous because there is so much rotational inertia. Because he works with burls, he will re-enforce the piece with metal straps on the back while he turns if he suspects that there is a risk that the piece could "blow out". Yikes!.

Brice, I have looked at David's turning and am awestruck. Not just by the size, but by the beauty of them as well. I will be using the static method to balance the turnings as I work on them.
Thanks for sharing.
Steve

I saw one video on you tube, in which the turner used a router with a half inch round bit. The router was mounted on a floor stand and the piece, mounted outboard on the lathe was being turned by hand with the router shaving off the high spots until the piece was fairly concentric and balanced. The router was also used to slightly hollow the bowl.