unbalanced workpieces

Re: unbalanced workpieces

Stuart Johnson

I don't know it it will help you but check Lyle Jameson's videos showing how to start between centers and balancing the piece. He as several but I think this one shows the process.

https://www.youtube.com/watch?v=fAyUPce5fvY&t=5s

Re: unbalanced workpieces

john lucas

I find 50 too slow for most things. It's sort of a catch 22. Too slow and it beats you to death trying to hold the gouge steady. It takes really good control to not push that gouge into the air between the gaps of wood. When the lathe is spinning faster you hit those solid parts more frequently so it's a little easier to maintain control. Of course spinning faster means lots of lathe vibration or the lathe dancing around the room. It's also more dangerous.

The options I use are to try and turn between centers if I can to try and balance the piece safely. Use an electric chainsaw to cut off the offending protrusions. I use to use a hatchet for that which often meant dismounting the blank chop off the bad area and remount. I did that for years when I had a really light weight lathe. Now I have one of those really cheap electric chainsaws. I figure I don't use it much and if it breaks I'll just buy another one. So far it's hanging in there.

Re: unbalanced workpieces

Bill Howatt

I think you would notice a huge difference in vibration reduction dropping from 700 to 215 RPM. If you have the odd piece that is really big and bad you can tune it up as you have been doing.

50 RPM is less than a revolution per second and that is really slow for cutting unless you have an 8 ft. diameter workpiece.

My 20" General goes down to less than 50 (actually zero) but that's just the control. I don't think I've ever turned an untrimmed bowl blank which is half a trunk mounted between centers under 200.

Bill

Re: unbalanced workpieces

nick

Many thanks for the advice. I believe I know what to do now.

Re: unbalanced workpieces

Barry Irby

I have a Nova DVR and it will run very slowly. (I have forgotten how slow) At very low speeds, John is right, it will beat you to death trying to stand there and wait for the offending wood to come off and improve the balance. I have been known to mount the piece and turn the lathe on and touch it with a gouge and turn the lathe off. Then I cut off the high spots with an electric chainsaw or a power plane. and then go again. As the wood begins to balance, I increase the speed. When it gets fast enough I use the gouge.

I also use disks of plywood cut to various sizes to help me get the blanks nearly round. And I start things between centers.

Come to think of it, I think my lathe bottoms out at 250 rpm. I also rotate the blank with one hand and mark it with the gouge in the other.

Re: unbalanced workpieces

nick

Thanks Barry, Sounds like good advice.

Re: unbalanced workpieces

Jerry Maske

Barry,

That's good advice and a method I've never tried. I believe that the smoother, cleaner piece you take to the lathe, the more of this kind of trouble you avoid. So I get as much off with a chain saw, chop saw or band saw as possible. Then, if it's still way out, I get out my secret weapon. An Arbortech blade. It goes on a 4 1/2" cut off tool and will rip rough stuff off in a heart beat. It's pretty easy to lock the lathe and go at it with the Arbortech and the results are well worth the effort. Roughing under 500 will make you use words your wife won't approve of, so get things clean and round BEFORE you get to the lathe. Your lathe will be happier too.

Jerry

Re: unbalanced workpieces

Dale Miner

50 rpm's is usefully for sanding out of round objects and applying finish on the lathe.

275 is low enough for starting just about anything 15" diameter or less.

Re: unbalanced workpieces

Barry L Elder

You should turn an unbalanced piece by hand and trim with a chainsaw little by little and you will be able to tell improvements by how easy it is to spin the unbalanced piece. You should be able to remove all the "heavy" spots until you can get an even spin, even enough to apply a slow turning speed, but not 500 rpm. Think Safety! Protect yourself from your own eagerness. I spent many hours turning debris from the hurricanes of 2004 and never lost a piece. And in the turning, I learned to stop my lathe and admire the beauty that God allowed in each piece, stopping multiple times to see if the piece provided more beauty or something different. It was amazing to see what God had wrought! But I hope we don't have any more hurricanes for a while. I expect God's generosity to end in the next three or four years. Hope you can be patient enough to learn a lot!

Re: unbalanced workpieces

Lyle Jamieson

Good tips from everyone, and I have tried them all. I prefer to turn fast. TUNKA-TUNKA is not fun and not safe. For those that have not seen my videos I start between centers on the balance point. Knowing, that is not the final axis. Being balanced allows me to crank the speed up and rough it out easily and quickly. The roughing out process is an information gathering process. I am in control between centers so I will move the partially roughed out blank repeatedly in small increments taking it to the eventual desired axis. Move the axis, true the wobble, inspect it, move the axis, true the wobble, inspect it, move the axis, true the wobble, inspect it, until you position the vessel where you want it. Who is having more fun?? Me turning the tree section OR plan "B", use band saw (not safe for thick wet wood), chain saw, or using other techniques of getting it in balance?? I will even race you and see who gets it round first, I will win and I will do it safe and easy, all on the lathe with my bowl gouge.

Re: unbalanced workpieces

David Walser

Take a look at Lyle's videos. He makes a persuasive case for his methods. What's more, I've tried his approach and it works!

Re: unbalanced workpieces

john lucas

Yes I learned that technique from John Jordan and it's served me well. Once in a while I have that piece that you want mounted just the way you put it and have to find a way to get it more round. Especially when I owned smaller lathes. That is why I tried all the other methods mentioned. Ideally you do exactly as Lyle stated because it is a very good way.

In reality most new turners don't try for balanced grain, or working with the features of the wood. They struggle just to find wood for a bowl, cut it roughly round and stick it on the lathe and turn what ever is there. How many of you actually change the orientation of a bowl once you've started it. I know when I just need to make a bowl for someone I don't change the orientation often. It's just a quick and easy bowl and I live with how the grain or knots show up. For my one of kind bowls I do pay a lot of attention to all of that.

Re: unbalanced workpieces

Lyle Jamieson

Good point John. Who is in control?? Even a beginner has better instincts than a piece of wood. I stay in control or grain, color balance, and axis til it is just right. I don't let the band saw influence my shape, scale, or axis.