Wood lathe question.

[TreeWizard]

I've been gluing up 3/4" pieces of black cherry to make shafts for some cane heads I've carved out of Ceder. I cut off the corners and put them into the lathe to turn and taper but the problem I have is when I use the gouge to round them I get a lot of vibration and jumping of the shaft. This happens even after I've rounded it.

The problem is only in the middle 1/3 and I don't know what I can do to eliminate it. I'm hoping someone who has a lot of lathe experience can help me out.

By the way the shafts are between 32" and 34" long.

[AlArchie]

That is not an uncommon problem......there is just too much flex in a shaft of any length to prevent this without some method of support for the middle of the shaft.

Check at you local tool supply and ask for a support for long turnings. There are several different models but most consist of a vertical post with either two or three wheels similar to those found on in-line skates. The wheels are lined up with the stationary turning. When the lathe is turned on, the wheels support the turning and prevent that "wobble". You'll have to move the wheels along the shaft as you turn, but the wobble is stopped.

Al

[mark yundt]

Yup...pieces that long and that thin will do that to you. The pieces are flexing,,starting to whip and climb up and over the gouge. The center 1/3 is the area least stable...the outer 3rds are a bit more solid simply because the ends are fixed in the head and tail stocks. The middle is the area where it'll bow out and away from you. The ends can't.
One solution to this ,which you may not have is a steady rest which is 3 rollers that clamp on to the turned piece and hold it steady as you turn.
Another is to increase your tool rest so the center is higher relative to the center of the piece you're turning. Imagine what is happening if the chisel is hitting the turned piece near the center..it's wanting to climb up and over the chisel..if you increase the height of the tool rest,,your hitting the turning nearer the top,,it can lessen the chance for it to climb over the chisel.
Another is don't use a gouge,,use the skew. It can be a bit tricky to use but shaves the surface beautifully...but once out of control it can take quick slices out of a piece or it can tend to grab.But the reason it works well in this situation is you are pressing on the piece and not allowing it to climb. The pressure from the tool which is basically from the top keeps the piece steady. This pressure also can act as a burnishing tool because of the pressure against the turned piece.
Another thing I do,,which some might find disturbing but works very well in limited areas like this,,is with a gloved hand cradle the turning as I continue with a scraper or gouge. I had to do this with 175 ballusters that were very thin and tapered.
Another thing..turn the center first. You'll know the basic dimensions you're shooting for,,turn to those dimensions then finish the ends.
And lastly,,if you're fairly close,,use a rasp or coarse files to get the job done. I've also used angle grinders with coarse grit discs to shape long tapers with great success after at least turning off the bulk to the point they start jumping around on me. Then I like to use old belt sander paper of a variety of grits to "shoe shine" my way to a finished turning.
For the final finish when you have it sanded pretty much to perfection,,grab a handful of the chips and dust from turning and as the piece is spinning press it and hold it to the piece.. It burnishes the wood and makes it perfectly smooth and glistens. If you missed any scratches they'll show up,,resand and do the chip/dust thing again. Really neat how that works so well.

[mark yundt]

Ideally the steady rests that both Al and I suggested work well.
If you're only doing a few of these types of things the other suggestions I made will work as well.
As I said simply guiding a gloved hand along the back of the turning works well. I even do it bare handed as it doesn't take much pressure to calm the turning down.But,,if you're not comfortable doing it this way consider this.
Make a block about 4-6 inches long with a V notch along it's length. Hold this as a steady rest as you turn the piece.
For example,,I'm right handed. I'll hold the V block in my left hand ,,the block held basically with my 4 fingers,,straddling the turning and using my thumb for stability on the tool rest. My right hand "chokes up" on the chisel in an overhand grip with the handle running under my forearm. As I said it won't take much pressure from the block to keep the piece steady..and a light pass with the gouge or scraper does it. Remember,,keep the tool rest higher than in typical turning situations so you're hitting the arc of the turning at a higher spot,,it lessens the chance for it to want to climb up and over your chisel. This is true as well if you decide to use the skew chisel either left or right skews. Using this tool in it's intended way can do much to solve the problem as well.

[TreeWizard]

Thanks for the advice. My lathe is an old craftsman with a 4" diameter round pole for the bed so finding one of the fixtures for reducing the movement may not work, but I'll try the gloved hand trick. Again I thank you.

[arapsang]

Mark's advice as always is sound. Use a skew chisel and as long a rest as possible. If you don't have a long rest strap a length of stout timber along the front of the lathe and use that as a rest. Dont bother with a glove. steady the turning as it comes towards you using a bare hand to dampen the vibrations. If your hand gets too hot you are pressing too hard. Finally back off the tailstock so that the turning is held with as little compression along its length as you can get away with.

Happy New year

Peter Connor

[mark yundt]

Thank you Peter!
And you too are correct,,I forgot to mention backing off the tension from the tailstock. Too much pressure as you know can cause long thin pieces to want to compress and bow making the problem worse.
Good point.
Again,,thanks Peter.

[mark yundt]

Well Treewizard, if you can't find one to fit your lathe,,or the price is too much..it's quite simple to make one. The design is fairly straight forward and to get it to fit on the pole ( I know the one you have) could be done without taking the lathe apart. It could all be made out of ply. You might want to consider it if you plan on doing a lot of these pieces. If it's just 4-5 here,,another 4-5 later it may not be worth it. But it can be done without much fuss.I have some design possibilities in mind.
Also,,flip through some books on lathes and jigs for them. I'm sure you'll find some ideas there as well.