Windsor Chair Resources

Windsor chairmaking tips-tools

__________________________________________________

 || Tip Index ||
__________________________________________________

QUESTION: I am having trouble with lathe chatter when turning green maple for my double baluster legs. All goes well until I taper down to 7/8 inch above the baluster in the middle of the leg. I start to get a swirling ripple effect when I use a gouge. I get the same effect when I use a planing cut with a skew to clean up after the initial shaping. I've tried different speeds and making sure my tools are sharp but I still get the same effect. I usually turn at 1000 RPM, but 1650 doesn't help. The leg I turn is at the minimum 20 inches long. I've even tried letting the leg dry before the finishing cut. To compensate, I've resorted to using finger nail gouge and very light cut for final shaping.

I have to take the swirls out with a rasp and sand paper. Any suggestions? BG2 3/19/04

REPLY:  This sounds like either one of 2 things to me.

Possibility 1 is you have a vibration under-load. An easy way to detect the problem is to place a glass of water on the bed of the lathe below the turning and see if you get ripples of a greater effect as you increase the cut rate. Troubleshooting further(if you have variable speed) you can increase/decrease the speed and note the water and results. Most likely, you need to weigh down the lathe. You have a harmonic vibration.

Possibility 2. Your drive journal on your lathe head could be worn or the tail stock has play. Use a dial indicator to check the run out. I don't think it is this really. Don't rule it out with the logic: if it doesn't do it on the ends it should not vibrate in the middle. False logic. The little problem on the end is amplified as you go out on the arm of the trouble source. The challenge is finding which end is bad when either end will effect the middle.

My guess from out here in cyber world is your lathe is vibrating and needs to be weighed down. I just don't see how a piece 20" long can get in too much of a "whipping" oscillation at 1000rpm. Start out with the simple sandbags solution and weigh it down. Additionally, I have had some troubles with light weight lathes on metal legs resting on concrete floors. Perhaps this could be a problem area. In any case, you can get to the bottom of this with some simple tests. Good Luck DO 3/19/04

REPLY: Here is how I compensate for that. I turn the baluster, or ball and the stem above it the very first thing I do, leaving the rest of the leg in roughed out round. I find that the momentum and stiffness of the larger round prevents the chatter. The rest of the leg, being closer to each end, doesn't usually present a chatter problem. If that doesn't do it, you need to dry the hard maple a little. BG-WKG 3/19/04

REPLY: I sometimes get chatter there also. When I'm turning legs it's the bottom of the leg towards the tailstock of the lathe and I'm right handed. The chatter is usually because my body gets in the way of holding the chisel in the proper position. So I take more time, concentrate on riding the bevel and keeping the chisel at something close to a right angle to the work surface and things are better. If there is still a little chatter my small radius ground skew or sandpaper will fix it up. If your lathe is OK, it's technique and may be a similar problem to the one I have. JT 3/20/04

REPLY: Chatter is the norm rather than the exception. Usually nothing wrong with your lathe. Its a simple matter of the wood flexing. Hold your hand behind the wood to act as a steady rest. Scary when you first try it but you can't get hurt with this procedure. If friction from the spinning wood creats too much heat wear a glove. When you get down to the final cuts use very light cuts. A touch up with fine sandpaper and you're done. Also turn the center part of the leg first leaving more meat at each end. Turn the ends last where the flex isn't that much of a problem. JJ 3/26/04.

REPLY: One more note on lathe chatter that I forgot to mention. I turn green or slightly air dried wood. When I first put this on my lathe it'll seem secure and tight but after initial turning I often will have compressed wood under the centers and it needs more tightening. I usually can tell this as it will start to chatter, especially when the piece gets pressured towards the tailstock. JT 3/27/04

clear

© Copyright Windsor Chair Resources, All Rights Reserved