How do you balance big wood?

[Mike Golka]

Last night I stuck a large chunk of green wood on the lathe. It was about 14" in dia. and about 7" thick at the widest. I was a little leary of putting something this big on the lathe as the slowest speed is about 600RPM. It seemed balanced enough that it didn't spin on it's own but when I hit the switch the lathe started doing a jig almost immediately:eek:. Needless to say it didn't take long to shut 'er down. I repossitioned the piece and tried again, a little better but still not good. Decided to seek the advice of the sages here before I do something stupid and hurt myself. Maybe I'm expecting too much spinning something that large at such a rate but that's what I'm stuck with:(. Any help is greatly appreciated.

[curtis rosche]

to bad it doesnt go slower

youll just have to either cut it down till its more balanced or you could try counter balancing it but that could be tricky

[jason lambert]

Can you cut any areas off first and get it more round?

[Steve Schlumpf]

Mike - I've played lots of games trying to get a rough blank to spin without going into orbit. Fastest thing to do is cut off anything you don't plan to have in the finished product. If it still bucks - next option is to add some weight to the lathe. The weight won't eliminate the bucking but will tame it enough for you to get it balanced by turning it. If that still doesn't work - your next option is a bigger lathe!!!

Best of luck figuring out a SAFE way to turn it!

[Jim Becker]

Mike, it's a challenge to do very large pieces without true VS and very low speeds. Sometimes varying the RPM by just a small amount will take out any resonance and reduce vibration to a minimum. As incredible as it sounds, a reasonably small out-of-balance blank spinning at the "wrong" speed can walk a 900 lb lathe across the floor...I've seen that demonstrated with a big OneWay 2436 a number of years ago!

[Steven Wilson]

x2 on what Jim Becker said. You really need to get slower. I also use an electric chainsaw to get rid of extraneous objects on large, unbalanced blanks. Even at low rpm's I have had a couple of blanks want to walk my Oneway 2436 across the floor - ye haw !

[Alex Cam]

Here's what I do:

1. Start with the blank between centers. Take an educated guess at the balance point and tighten the quill JUST ENOUGH so the point of the drive center is engaged, but not the teeth. You want it to spin freely between the points of the drive and live centers when you let it go.

2. Let it go. The heavy side will spin down.

3. Very carefully back the quill up while you're holding the blank, making sure you keep the blank pressed against the drive center point to it doesn't fall.

4. Move the tailstock-side of the blank up so the live center point engages just below the indentation that it just made. Tighten it just enough to you can let it spin again.

5. Repeat the adjustment back and forth between the drive center and live center until the blank no longer rotates when you let it go. Keep an eye on the face of the blank and make sure you're not lifting one side up too much. You want to keep it fairly parallel to the plane of the headstock. When you're done, you should be able to let it go at any orientation and not have it spin on it's own weight. That's your balance point.

6. Once you're there, tighten the quill so the drive center is engaged. You might have to lock the spindle and roll the blank back and forth a bit, tighten the quill, roll the blank, tighten the quill, and so on.

7. Make sure everything is locked down nice and tight, and spin her up!

Using this method, I spin 13" rough blanks FAST with very little vibration. 600 rpms won't be a problem. Heck, 1200 rpms won't be a problem. Once it's rounded off you can mount it on a glue block, faceplate, turn a tenon, or whatever else you need to do.

Finding the balance point is the key.

[Robert foster]

Mike: I'm far from a sage but when I had a really out of balance piece of mulberry I used a powered plan to take off the parts that stuck out. I had to take quite a bit off to get it to turn without dancing the lathe across the floor but it worked. I just turned the piece by hand and anything that stuck out I planed off. The power planer took the wood off fast.

Bob

[Judy Kingery]

Mike,

Generally, we start with logs, halve them, take the half and chain saw the corners off, then put it on the band saw and round the blank before it ever goes on the lathe. So even pretty big chunks of wood start out fairly round and balanced. Not always perfectly round, but sure, close enough to where it's not a rodeo on lathe.

Course the major key, and I'd agree with what everyone's said, is slower speeds. I can turn just about as slow as I want to with the VS on my big lathe. Little lathe I have to be a bit more careful as the slowest I can get it (manual change/pulley - limit 3 speeds) is probably about 475 rpms to highest about 1,200. You just can't beat the variable speed that you can really go slow as you'd like on anything you turn, I use it all the time.

Best to you and you've got lots of sage advice here! Jude

[Maylon Harvey]

Mike,
My solution is something like Alex's. First I band saw my blank as round as I can. Then I face plate mount it. Then I take the belt off the pulley's on the lathe so the piece will freewheel the easiest, that is the important part. It will freewheel with the heaviest side down. This is where an electric chain saw would be handy but since I don't have one I use my sawzall. I keep cutting off corners until the piece will stay put on the lathe at any position I rotate it to. This has worked on some pretty heavy blanks on a not so heavy lathe. Hope this was understandable

[Mike Golka]

Thank you all for the great advice:D. I used a combination of ideas and mostly the chainsaw gouge:D:D with the piece on the lathe between centers to find a happy medium. I got 3 large bowls roughed out last night:Dand only had minor shimmying.

[al basham]

I've turned some large pieces and always had a balance problem. At a symposiun I think in Davis, Ca, Jerry Glaser presented a dynamic balancer concept he read in an old Dutch book. I took the concept and made one for my lathe. I used an 1 1/4 CRS cross bar, a length of 5/8-11 alloy threaded rod and two 25 pound weights. It works like a charm.
Good luck .... Al Basham

[Barry Elder]

Glad you hung in there and worked it out. You were getting some great advice from some very experienced 'turners. Keep turnin' and learnin'!