• April 2025 Turning Challenge: Turn an Egg! (click here for details)
  • Congratulations to Kelly Shaw winner of the March 2025 Turning Challenge (click here for details)
  • Congratulations to Ellen Starr for "Lotus Temple" being selected as Turning of the Week for 21 April, 2025 (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.

Turning unbalanced wood

D

Dianne Looker

Joined
Oct 24, 2014
Messages
4
Likes
2
Location
Nova Scotia Canada
I have a lovely piece of black walnut - 12" diameter, 3" thick. It is more or less round and I managed to cut a inset in one face so it is mounted on a chuck. However, when I turn on my jet 1236 lathe (which is weighted down and bolted to the floor) it vibrates so violently it's impossible to turn. My thought is the wood is denser on one side and so throws everything off.

How can I stabilize it?

I want to turn a bowl and don't want to lose much of the height if I can avoid it.
 
Dianne Looker said:
I have a lovely piece of black walnut - 12" diameter, 3" thick. It is more or less round and I managed to cut a inset in one face so it is mounted on a chuck. However, when I turn on my jet 1236 lathe (which is weighted down and bolted to the floor) it vibrates so violently it's impossible to turn. My thought is the wood is denser on one side and so throws everything off.

How can I stabilize it?

I want to turn a bowl and don't want to lose much of the height if I can avoid it.
Click to expand...


Dianne......first you have to bring it to round....."more or less" isn't good enough. This may require you to reduce rpm until you can get a perfect round.

Once you achieve that, you can further assess the available information.

-----odie-----
 
Hello Dianne,
I choose to not turn with vibration.....
I always start my pieces between centers to avoid this exact problem.

I start on a "balance" point so I can get the speed of the lathe up, without vibration.
With the lathe off and the piece between centers, using the very tip of the drive center (not the teeth) the weight is always going to shift to the bottom. You can adjust the tail and head stock contact points to "balance" the piece so it doesn't shift or rotate, when released. Once you find the balance point you tighten up the piece on the lathe and are able to rough out the piece at high speed, without vibration. The next step, while between centers, would be to prepare for your holding method. I choose to use a glue block for my bowls.
If you want more details you can see my YouTube channel, there are numerous videos showing my process, or give me a call.

Regards,
Lyle
 
I do what Lyle said.
After I turn off some wood going for a bowl shape I will often readjust the tail center to balance the grain.
This puts the weight off center and the rough turning out of round but the end result will be more to my liking.
With walnut I like to have equal sapwood on on each side.
 
Not uncommon for things to be a bit off balance even when you get them round and both faces flat, especially green wet wood. Not sure if your piece is dry or green. The faces need to be flat as well. Can be more mass than you realize on one side if a face is not trued up. You didn't mention how fast you're trying to spin it. I keep my rpm low enough to keep things stable and work up to a higher speed as I can.
 
If that Jet 1236 is the one with the Reeves drive, it may not go much below 500 RPM's. If that is the case, getting balance on a 12" diameter might be near impossible. On my 12" Rikon (70-220), anything beyond 7" or 8" had to be pretty true to start with or i'd be dancing a jig, even at its minimum 250 RPM. I have turned 10" dry on it, but that was after truing on the 16" in the garage (no heat there, and the Rikon is in my heated basement!!)
earl
 
I’m guessing that is a reeves drive lathe, with a low speed of ~600-650 rpm. Off setting the geometric center for rotating balance is an option, but likely results in a smaller dia finished piece. I prefer to trim such a blank, with the lathe off, to get it more balanced. The best tool I’ve found is a chainsaw wheel on a 4” hand grinder. Chuck or face plate mounted or between centers, find the heavy area by letting gravity do its thing, then rotate the heavy area to where it is accessible. Lock the spindle and go to trimming, checking balance along the way. Wear eye and breathing ppe as a lot of small bits get thrown everywhere.

I think that lathe has stamped steel legs. Be sure the bolts from legs to lathe bed are tight. You can gain a lot of stiffness by boxing in the ends of the legs with plywood or hardboard, screwing it firmly to the legs. With the stand bolted down, the vibration comes from the bolted joints and the stamped steel flexing - creating a torsional box will greatly reduce the movement. My old HF lathe was a copy of this lathe and boxing the ends in was a dramatic improvement.
 
Dianne Looker said:
I have a lovely piece of black walnut - 12" diameter, 3" thick. It is more or less round and I managed to cut a inset in one face so it is mounted on a chuck. However, when I turn on my jet 1236 lathe (which is weighted down and bolted to the floor) it vibrates so violently it's impossible to turn. My thought is the wood is denser on one side and so throws everything off.

How can I stabilize it?

I want to turn a bowl and don't want to lose much of the height if I can avoid it.
Click to expand...
Some more specifics might be helpful. Some pics of the blank and how it's mounted would be useful. How fast/slow are you turning? Particulars on your lathe? Etc.
 
You could try cutting some wood off of the heavy side of the wood blank to get it more balanced on the lathe. You could also try
mounting the wood blank on a face plate and determine where the blank will be balanced before you secure the blank to the face plate.
You can place the flat surface of the wood blank on a sharp point and position the blank on the point where it comes close to being balanced
while you hold it with your hands, this will give you an idea as to wear you need to mount the faceplate, so it does not vibrate too much with
your reeves powered lathe. A VFD powered lathe can be turned down to a lower speed which is why veteran turners move up to these better
quality lathes with speed control.
 
These are all very helpful comments!

I have put a faceplate on the blank and it seems OK at a low speed so will try that.

And I will also try stabilizing the legs as Doug Freeman suggests.

Thanks again for all the feedbackl
 
For future escapades, I have two thoughts. One is that it's just about impossible to turn a 12" bowl on a 12" lathe. Usually the best you can do is about 1" less than the official throw and often less, because you have the banjo underneath the blank to deal with, too. Turning something at or over maximum size will also magnify issues such as you've had with this one.

The second thought is when you want to lose the absolute minimum thickness on a blank, a glue block is a good way to go. Using one is more than a brand new turner skill and we don't know where you are on the experience curve. It's just one modest trick for you to add to your collection one day.
 
Some pieces of wood will never balance out, and it makes no difference what you do, most likely because they wood is not balanced itself, some parts are more dense than others. The advantage of variable speed lathes is that you can use slow speeds till you get the piece rounded out, which improves balance, but like I said above, it may not 'fix' it. Take smaller bites at first, then as it gets more rounded, you can take bigger bites. My first lathe was a 4 speed Atlas, and low speed was 500 or more. I only had a chainsaw for prepping blanks. It was on 2 laminated beams, 5 foot long and 4 inches thick. I still had to brace it against the wall to start bowls, and I ain't little..... If you use a glue block, use solid wood, not plywood!

robo hippy
 
I always appreciate the information on balancing, both from this site and from classes I've taken. However, it's not as easy as it sounds and I'm sure it takes experience. Yesterday I started a relatively small piece, about 7" in diameter. It was already cut round, but it was about a 1/2" thinner on one side and still had bark on 2 ends of the top. I spent a lot of time trying to balance it and line it up properly so it wouldn't vibrate too much. I wasn't really successful and ended up just slowing the lathe enough to that it wouldn't vibrate too much until it was round and an equal thickness all the way across. I don't think I ever reduced the vibration enough to satisfy me. However, because it was only 7" in diameter and it wasn't vibrating so bad, I got the outside shaped after gradually cutting off the the wood that was causing the problem and gradually speeding it up as the vibration decreased. It just takes practice, I think, and the adjustments required to balance the piece to start with aren't always obvious, at least to me. The good thing is that it didn't come off the lathe and I was able to get it to the point I'm at. If I didn't have a lathe which allowed me to reduce the speed to around 200 rpms to start, I think I would have just given up and moved on.
 
Randy Heinemann said:
... ended up just slowing the lathe enough to that it wouldn't vibrate too much until it was round and an equal thickness all the way across. I don't think I ever reduced the vibration enough to satisfy me. ... I got the outside shaped after gradually cutting off the the wood that was causing the problem and gradually speeding it up as the vibration decreased.
Click to expand...
That's pretty much the technique we all use. More experience may get you a better starting point, but essentially it's mostly as you describe.
Starting a bowl or hollow form between centers (vs faceplate, screw chuck, etc) does allow you some freedom to mess with things. It's my preference - I have a big drive center that can handle it.
The differences between what we all experience are basically lathe (mass, sturdiness, speed control, etc), and skill of the turner (finding the balance, cutting corners efficiently, dealing with turning lots of "air", etc).
And like @robo hippy said, sometimes you're never gonna get rid of the vibration, just have to learn to deal with it / mitigate it.
 
Mike Novak said:
I wish I had known this before I bought my 12” lathe. I figured I’d never want to turn bigger than that.
Click to expand...
Yeah, I find that if you want to turn a 12 inch bowl, you'd want something with a 14 to 16 inch swing, because you gotta account for banjo clearance as well, unless your bowl blank is already perfectly round, trued and you get it mounted dead center, Otherwise after truing up , etc, you'll have something closer to an 11 incher, if lucky. Biggest bowl I have done to date on my HF 12 x 36 has been 10-1/2 inches finished , and even that, getting the blank mounted and trued up was a real struggle. not just for me, but for the motor as well.
 
@Brian Gustin I used to have that lathe. One of the advantages of a pivot HS is the piece can be rotated away from you, slide the banjo behind the work, rotate the HS back in - same thing to get the banjo out to the rim/front. Or, rotate the work to outboard. Definitely takes some fiddling with the banjo and tool rests turning outboard on that lathe. I did turn a few 14-15” bowls and platters with it. My Nova Galaxi is much easier and more fun to turn on.
 
Doug Freeman said:
@Brian Gustin I used to have that lathe. One of the advantages of a pivot HS is the piece can be rotated away from you, slide the banjo behind the work, rotate the HS back in - same thing to get the banjo out to the rim/front. Or, rotate the work to outboard. Definitely takes some fiddling with the banjo and tool rests turning outboard on that lathe. I did turn a few 14-15” bowls and platters with it. My Nova Galaxi is much easier and more fun to turn on.
Click to expand...
Yeah, I got mine used , rotating headstock was already beat up and I think bent (I suspect the original owner got a HUGE catch trying to turn a bowl with one of those el-cheapo SRG's - he gave me the gouge set he had along with the lathe (One SRG and a couple continental style gouges) were all bent in multiple places (along the flute, not just at the tang - SRG was almost L-shaped - I literally straightened it back out in my bench vise, and used it a few times on spindles) and the headstock never lined up right with tailstock - I tore it down and cleaned up, straightened and re-tightened, but I also had to shim the headstock on one corner to get it to sit flat and line up with tailstock. I can't move headstock any longer, if I do, It'll mean another couple hours just getting things lined back up :) I also finally found a Laguna banjo on here that I adapted to replace that awful, awful HF banjo....

But, I ended up with a working lathe that does allow me to produce halfway decent results (despite still having some runout on the spindle, creating vibration that is difficult but not impossible to work around) - The other thing is that motor and reeves drive, are barely strong enough to spin up a 12 inch diameter x 4 inch thick chunk of maple (I stalled the motor a few times, and it got hot enough you could smell it), so I'd say it is seriously underpowered if you are gonna do any large green wood turning, even without pivoting headstock.

However, in my view, when I do get that new Jet 1840 (or at least 1640) I have my eye on (which is best I think I'll be able to afford unless I hit the lottery) , The practice and experience turning on that HF lathe will probably make for some much nicer work coming off the new lathe.. :)
 
Dianne Looker said:
I have a lovely piece of black walnut - 12" diameter, 3" thick. It is more or less round and I managed to cut a inset in one face so it is mounted on a chuck. However, when I turn on my jet 1236 lathe (which is weighted down and bolted to the floor) it vibrates so violently it's impossible to turn. My thought is the wood is denser on one side and so throws everything off.

How can I stabilize it?

I want to turn a bowl and don't want to lose much of the height if I can avoid it.
Click to expand...
I found out that for out-of-balance pieces of wood; it's all about speed control and proper centering. I would remove any excess weight in unbalanced areas with a reciprocating saw (Sawzall) before mounting. Depending on the drive for the piece of wood, mounting and securely is, without a doubt, one of the most important safety features to start off with. I would slowly increase the speed with my variable speed controls to define the sweet spot of balance before I even approaching the piece of wood. Please be safe.
 
I never understood all the repositioning to get a piece lined up just right for turning. I do almost no natural edge pieces, and if I do, I remove the bark because it always seems to lose a piece or three either from 'natural' causes or mishandling. Also, I want my pieces to be utilitarian. I consider all design elements before the pieces go on the lathe, so it is ready to go rather than fiddle around with it when I get it on the lathe. With practice, most of the time, I can get grain centered. If it isn't perfectly centered, I don't care, in part because the people who buy my bowls don't care.

robo hippy
 
I understand the option to be able to recenter. Conditions like an unknown inclusion for one example. Matching up the amount of sapwood on both sides can benefit an equal drying situation with the bowl. So there are practical reasons to move it around
 
Just because you balance a piece before you start turning doesn't mean it will stay that way. Learning to adjust speed and tool techniques is also important-- even moreso when you begin to turn pieces that are intentionally off-center.
 
Thanks for all the suggestions. I had centered it between centers before it swirled out of balance and then the swirl marks kept moving it off center. So, anything that involved using points at both ends to find a balance point didn't work. I did, however, stabilize the ends of my lathe legs and that helped. (Later I also thought to tighten the nuts that held the lathe to the legs.) I used a face plate and slow speed to turn the outside. I then reversed it and, still keeping the speed low, carefully turned the inside. If this were an exhibition or competition piece I would have sanded it more. But I was pleased with the result - as was the family member who got the bowl as a belated Christmas gift. The lighter colour at one end shows the different density wood that caused me so much grief, but I loved the colour contrast it gave at the end.2023 bowl - off center swirl.jpg2023 bowl process -1.jpg2023 lathe reinforcement.jpg2023 bowl 2.jpg
 
Dianne Looker said:
Thanks for all the suggestions. I had centered it between centers before it swirled out of balance and then the swirl marks kept moving it off center.
Click to expand...
From first photo, looks like you used a steb center at the start - It IS one of the drawbacks to those types of centers, in cases like that it may be necessary to switch over to a 4-prong standard drive center (if you have one?) which would have a better chance of keeping your center "in place" while you prepare your blank for a scroll chuck mounting (although it appears you did switch over to faceplate afterwards?) Unless I missed something here....

Steb center can be a challenge to use for roughing out blanks, although I haven't really had any problems with it (Though I've had to remove blank and clean out the teeth when it spins out/ drills into the wood), I have had that "swirl out" happen a time or two. My solution was to take a forstner bit and drill a shallow recess for the steb center to seat into, which helped it stay on center.
 
You must log in or register to reply here.
Back
Top