What causes this

[Faust M. Ruggiero]

I'm happily turning practice pieces trying to learn to be comfortable with a spindle gouge and a skew. Oh yes, I get a little skating now and then but I'm getting better. The safe drive is wonderful and I keep it loose enough to stall if I get a dig. However, I am baffled by one problem. I am sure it is a rudimentary error and someone will help me quickly. As I round over either end of the practice piece, with either tool, I can feel the track of the tool become "bumpy" and when I look at the piece it has spiral raised sections. I scrape them away and try again and may not get them the next pass or two then get them again. I wanted to photograph an example but it is subtle and does not show up well in the pix. The piece is tight and not vibrating and the lathe, though small and old is solid. I am sure it is my poor technique. Any one have a suggestion?
fmr

[Bill Bulloch]

Hard to follow what you are describing, but if you are rounding the end of a spindle you need to keep the bevel on the blank all the way down to the end of the round. This means that if you are rounding the right end of the spindle then you will keep the bevel rubbing and move the handle of the tool out to the right causing the point of the tool to move toward the end of the cut while keeping the bevel in contact with the spindal.

I don't know if you can follow that line, so I would suggest you get a technique good book, or better yet DVD, like Keith Rowley's, "Woodturning A Fundation Course".

Keep it up, but be careful

[Nathan Hawkes]

One thing I might also suggest is making sure that your tools are really sharp. My skew technique has improved significantly after I realized how sharp they need to be. Think "shave your arm hair" sharp. Keeping the bevel on the wood is absolutely crucial. This is what causes the skew to "skate" or "back up". Alan Lacer's DVDs on skew technique; "Skew Chisel: the light side and the dark side", and "Son of Skew" are great. He has a very easy to follow and simple, yet very solid teaching format on the videos, along with several great projects that can be done with the skew alone. As far as the spindle gouge is concerned, sharpness is also very important. I don't do a huge amount of spindle turning, but use a spindle gouge for small boxes. Since I started honing, I enjoy using the spindle gouge. Start by polishing the flutes of your gouges with an MDF wheel and tripoli compound (spinning in reverse). and with slip stones after trips to the grinder. I keep a diamond cone on the magnet rack next to my lathe for touch ups between sharpenings.

[Karl Card]

When others have mentioned sharp tools, well, i had tools when I began turning and then I bought real tools. The difference was the real tools would literally cut the hair of my arm without holding it a certain way or anything.. When I started turning with sharp tools I almost had to rethink my methods because things were so difference. Knots that used to tear out now stayed in and looked great.. just outright awesome..

[Bernie Weishapl]

I suggest the same book and the companion DVD that Bill talked about. I would also suggest you find a turning club nearby. They are extremely helpful and will help a lot on the learning curve.

[Steve Schlumpf]

Faust - how hard are you rubbing the bevel? If you are pushing into the wood fairly hard when rubbing the bevel - you can cause the spiral tracks that you are experiencing.

You didn't mention what speed you were turning at or the diameter and type of wood. Within reason - higher speeds will help to eliminate the raised ridges as will sharp tools and lighter cuts. My experience - the softer the wood, the lighter the cut. Also - allow the tool to cut the wood. If you are pushing through the cut faster than the tool can effectively cut it - you can create the spiral tracks.

I agree with the suggestion of getting with your local turning club. Nothing saves you a lot of head banging when it comes to turning than having someone knowledgeable show you the correct way to use the different tools.

Also - whenever possible - photos go a long way in helping folks give you advice that will fit your questions.

[Chris Zeigler]

I have a similar problem. I can't remember where I read it but I saw an article that claimed it can actually be caused by the lathe running too fast. I think it helped me a little when I slowed it down. Has anyone had similar experience? Honestly I have not gotten my skew as sharp as you guys are suggesting so perhaps that is my problem.

Chris

[Tim Rinehart]

The comments about making sure you are using sharp tools, and following the bevel are right, no question about that.

I am still in a learning mode myself...and find I have occasionally got exactly what you described, with the spiral raised areas, as well as general 'bumps' in a turning.

I think ... and am open to rebuttal... that you have created one little bump, using a either a bad technique (not riding bevel...not keeping tool sharp)..or just found a soft/hard spot on the wood. Once you make a single bump, think of how your tool, whether riding on bevel or not, will react to that bump as it comes around. It will 'jump' off the piece, miss a fraction of the turning, and then come down and start cutting again...repeating the problem until you have no good solid contact around the piece without hitting these little raised areas.

To correct at this point, you need to start turning from a section that is round, or be a touch more aggressive in keeping the tip of the bevel definitely engaged...not forcefully...but at least visually. As soon as you let the tip of that bevel fall out of play...it's hard to pick back up where you are without restarting cut.

Most demos with a skew that I've seen emphasize making sure you start and continue the cut from the beginning, and not start halfway thru. Also, what works for me is to be sure you avoid catches by applying the skew from the lower 1/3 of the skew. Again, as mentioned...this is best with a hands on demo or help from someone comfortable with the skew to show you.

Another alternative, while nobel to use a skew, is to try riding bevel techniques with a spindle gouge to see if that helps 'trouble areas' and to be sure your technique is solid.

[Bob Bergstrom]

Most of the time when the tool starts to undulate on the surface of the wood it is a rake angle problem or in other words you have a lot of the bevel rubbing. The force we apply to keep the tool on course compounds the effect. As we practice and relax, we use only the portion of the bevel closest to the edge. Less pressure and better rake angle result in a cleaner cut and no bounce. Rippling can be cause by trying to make the movement too fast. If you have to push to keep the tool cutting it is time to sharpen.

[Matt Hutchinson]

I have found, like Steve, that if you try to rub too much of the bevel you can cause this problem. This is because most of us use a hollow grind, so as we start the cut at the cutting edge the clearance angle (pulling the bevel slightly off the wood to actually get a shaving) may actually be too small/low. As we progress deeper into the cut we engage more of the bevel, and the 'heel' of the bevel rubs and rides along any inconsistencies we have in the surface. (It also forces a change in the clearance angle.)

That may be as clear as mud, but basically if you don't rub the bevel quite as hard, and if you give it 1-2 degrees more clearance angle, you may be able to fix the problem.

Also, very hard woods, such as maple, seem to be more prone to this issue, and lighter cuts help as well.

[Reed Gray]

I know all about the ripples that form, and they are just about the opposite of the spiral dig in cut that you get when you come off the bevel. I find them in my bowls from time to time. Rubbing the bevel is a difficult thing to learn. You need a sensitive feel to what the wood is doing, and the more you fight it, the worse it gets. Like in some old movie about learning to use a sword, think of it like holding a bird. Too tight and you kill it. Too loose and it flies away. One tiny bump will start it. To get rid of it, you have to come back to before where it starts, and go from there, or ease into the cut, removing the high spots till it gets true again. Most of the time they are small and sand out easily.

robo hippy

[Paul Atkins]

That happens once and a while and I wish I could recreate it when I want. Here is a mallet I made 20 some years ago from some hard unknown wood, but I liked it and left it. It seems the heavier the tool the less it happens.

[Faust M. Ruggiero]

OK Boys,
The message sounds like, "Sharpen better, get first hand knowledge when available, keep the bevel on the wood but don't force it there". I know I would get help here. I will give it another go later this evening. You know, I don't even mind struggling a bit. Watching wood peel away in ribbons and seeing an occasional success in the form of a smooth unsanded surface is a lot of fun.
Thanks,
fmr