Pretty big problem

[Art Brazee]

Guys (generically including girls),

:confused:
I've got an overarching problem that I can't seem to solve. I need some good direction.

It's perplexed the hell out of me. I continually have feedback on my tool which ends up creating a wave pattern on the work. It happens on bowls, between centers, and just about everywhere in between. It's particularly evil when I'm trying to get a smoothing cut, but it happens other times too. It occurs with a skew, bowl gouge, fingernail ground gouge, soft wood, hard wood, inside, outside, ignores grain, and generally gives me huge problems. I can't seem to get rid of it - heavy cut, light cut, low pressure, heavy handed tool pressure, speed, reversing grain direction/attack, changing blade angle - you name it. Oh yes, it isn't the lathe either. HELP

I'm a medium skilled turner, self-taught, but a long time woodworker. I've got to overcome this issue. THANKS in advance!

[curtis rosche]

Sounds like your headstock spindle is loose or has runout. Or you arent holding your tool solidly.

[Art Brazee]

It's not the lathe. I've got a big powermatic and there's no runout. I've got solid tool control; handle on hip, hip moving the tool. I'd go for this answer, but I've tried to resolve things this way. It could be though...I'll try anything.

[Steve Mawson]

Art,
Any chance you have a turning club close? Might be someone with some experience that is not too far away that could see what is going on up close.

[curtis rosche]

It's not the lathe. I've got a big powermatic and there's no runout. I've got solid tool control; handle on hip, hip moving the tool. I'd go for this answer, but I've tried to resolve things this way. It could be though...I'll try anything.

hold the tool tight against the toolrest? Or maybe your wood is flexing. If Im not mistaken, the way "waves" are made is movement back and forth in relation to tool and wood, right?
got any pictures of the wood?

[robert baccus]

I'm not sure about all those tools but too much down pressure on the gouge bevel will produce waves. I rediscover this about every two years and the solution is not intuitive. Put your effort into the tool tip and very little on the bevel. Only does this to mewhile point cutting.

[Chris Studley]

A basic, top down logical approach is best before going too crazy...

I would verify the basics like your sliding headstock is secured, tailstock alignment, tool rest tight and at proper height for cut being made. If tour tools aren't sharp or have a funky bevel funny things happen.

I'm my limited experience I find that when you find the issue realize how obvious it should have been.

Good luck..

[John Keeton]

I would start with more speed and a.better/sharper grind. Quality of cut issues are normally related to edge quality and tool presentation, but too slow a speed can cause issues, as well.

[Paul Singer]

I get this very same problem at times and I always try to blame it on the wood. Normally though if I take my tool and put a fresh edge on it then work my way past the problem slowly with very fine cuts I can smooth it out. Sometimes it takes some patience but it is normally me and not the wood. It seems like once it starts it only gets worse with each pass until I do the above mentioned procedure.

[charlie knighton]

+1 on increase speed on finishing cuts per JK

[Prashun Patel]

Does it only happen when the pieces are thin? I get waves when finish turning near the ri. For me its vibration. Can u use a steady?

Also, on bowls especially green ones i get chatter because the grain direction switches play tricks on the tool. The solution there has been to sharpen afresh.

[Robert Henrickson]

I would agree with increased speed, and sharpening as possible solutions. The two places I most likely would have this problem is with plates/platters and long slender spindles -- both almost certainly due to the wood flexing. Often I can remove the waves by cutting in the opposite direction -- e.g., if I have been using a PUSH cut, I would make several very light PULL cuts in the opposite direction. I rarely use scrapers; my experience is with gouges (bowl and spindle). Contacting a local turning group is also a good idea -- an experienced turner may be able to identify something you are doing.

[Don Orr]

Is your tool rest close enough to the wood? Too much tool overhang can cause your problem.

[Jerry Marcantel]

It's not the lathe. I've got a big powermatic and there's no runout. I've got solid tool control; handle on hip, hip moving the tool. I'd go for this answer, but I've tried to resolve things this way. It could be though...I'll try anything.

Art, how new is this big Powermatic? I'm asking because if you aren't the original owner, someone could have done something to it earlier in it's life that wouldn't be detected. I had the same problem before with a Delta Homecraft I bought used in '83. It was complete with a Delta motor and step pulley. All I did was mount it to a bench, and turn it on. I had this one spot that always left tearout, was never completely balanced, and I couldn't figure it out. It wasn't until 2009 that I just happened to be looking at the motor pulley as it was winding down and saw the pulley was out of round. It turns out that the motor has a 1/2" arbor, the pulley has a 5/8" hole, and the bushing was about 1/2" x 9/16". There were no problems after I corrected things.... Jerry (in Tucson)

[Michael Stafford]

Sounds like you are pushing too hard against the wood. DAMHIKT! Lots of time people think that riding the bevel entails lots of pressure against the wood where the cutting edge and heel of the bevel both contact the wood and you can get some bouncing and resonance causing the ripples you describe. It is sort of like the process involved in using a chattering tool on end grain. Bounce and cut, bounce and cut except with the gouge you get bounce, cut and bruise as the heel burnishes the wood behind the cut.

Instead of riding the bevel glide on the bevel and let the cutting edge do the work. Sharp tools make this process easier.

P.S. This effect can be magnified by how far the cutting edge is over the tool rest so the closer the rest to the work the better.

[Art Brazee]

Thanks Jerry - it's a new Powermatic. I have had a few problems with new machines, but I expect it's the man - not the machine!

[Art Brazee]

Guys,
Thanks for all the feedback - There is a trend and I was thinking about the whole problem too. I don't think it's the lathe, the tools, or the speed. My lathe is new, I generally turn at about as high a speed as possible, and I've been a woodworker for a long time. My tools are very sharp. The only thing that is left is the man. Many of you have had similar problems to varying degrees and offered what works. I do think it's me. Mike offered, what sounded to me, the best explanation. I'll reply in his thread.

[Art Brazee]

Mike,
You really have offered the most plausible theory. "Instead of riding the bevel glide on the bevel" seems like good advice. I'm a bit unsure of what that means. I've tried less pressure on the tool, but I definitely ride the entire bevel on the work. My tools are not hollow ground, but flat ground - all of them. So, I have a large bevel area.

I often get a burnish behind the cut - you're suggesting (I think) that that is not a good thing. Or, at least something I want to avoid right now until I conquer this problem.

Could you elaborate a little because what you have said rings true? I so wish I had a master turner to turn to as I've found the nuances of turning move difficult than any other woodworking problem (excepting, perhaps, saw sharpening).

Thanks MUCH!

[Michael Stafford]

The best way I can describe gliding on the bevel is to tell you how I start a cut with a tool. First you place the tool on the tool rest without the tool in contact with the wood. Next gradually raise the handle of the tool until the heel is touching the wood. Slowly raise the handle until the cutting edge engages the wood and shavings start to appear. As you raise the tool more the shavings will increase in size and if you rotate the flute the curlies will be spiraling off the tool.

If the tool is sharp it will not be necessary to press the tool very hard. When you feel the necessity to press hard and the shavings change from spirals to chips it is time to sharpen. A sharp tool is one of the main secrets of woodturning and is essential to developing good tool control. Whenever the chips change in character it almost always means that the tool needs sharpening.

Burnishing the wood is not a good thing as the burnish marks can show up in your finish and they are darn near impossible to sand out.

Another dead give away to the fact that you might be pressing too hard is that the tool is too hot to hold at the bevel. If it is really hot you are pressing too hard. One other thing that can happen is that if you are pressing too hard and the wood is getting thin you will experience an almost imperceptible bounce which is the equivalent to a chatter tool flexing on the wood except in this case it is the wood flexing against the pressure of the tool. As you get thinner and thinner with your turning it becomes more essential that less pressure is exerted and sharp tools are used.

Art we all have made these mistakes as we started turning and some of us slower learners (I put myself in that category as I have much to learn) continue to make them. So give the suggestions you have received a try and I hope they help you out.

P.S. With respect to your tools being flat ground you might try rounding off the heel of the bevel a little so that you are gliding on a shorter bevel. It takes very little of the bevel for the tool to ride upon. I used to sharpen my tools on a 12" disc and found that the flat bevel made it harder to control my tool. This is not the case for all turners as many love a flat bevel. I prefer the concave bevel because it makes it easier for me to not ride on the heel. I still round off the heel of a lot of my gouges to reduce the impact and potential bruising.

[Dan Forman]

Art --- If you go to the top right corner of the web page and click on "settings", you can add your location to your profile, and it will show on your posts. There may be a creeker near you who could help you out.

Dan

[Reed Gray]

Well, on spindles, they can flex, more so if you are turning longer and thinner, and if the tailscock has a lot of pressure on it. The ratio here is in the 10 to 1 area, or 10 inch long, and 1 inch diameter will have almost no flex. On bowls, some thing else is going on.

Most likely it is too much pressure on the tool. If you have noticed that the more you clamp down on the tool to eliminate the bounce the worse it gets, this is the problem. Two comments here, neither original:

Hold the tool as you would a bird. Too tight and you kill it, too loose and it flies away.

The bevel should rub the wood, but the wood shouldn't know it.

When turning the outside of the bowl, and the inside hasn't been hollowed out, there is no chance for wood movement/shrink/warp as you turn. As the wood spins, you alternate from cutting up hill/end grain/against the grain, to down hill/side grain/with the grain. This will create some bounce. When you clamp down with your hands on the tool, and the tool rest, this makes the bounce worse, kind of like a car or wagon with straight axle, and no shock absorbers. If you loosen up a bit, you can absorb a lot of the bounce to the point where it is almost gone. It is hard to teach this because it is some thing you have to learn to 'feel'. If you check out my You Tube clip on turning a bowl with gouges (type in robo hippy) you might be able to see what I am talking about. If you are getting the bounce, back off a bit, then ease the gouge in to just nibble off the high spots till it is fairly round, and start cutting again.

With the inside of the bowl, as you remove mass, the bowl/wood will 'adjust' to having mass removed. The same battle of cutting up hill vs down hill is going on. It can flex as you turn, especially if you are using heavier than needed tool pressure. This is why you generally turn the inside/do finish cuts on the inside in steps. Go down an inch or so and finish cut it. Then go down another inch or so, and finish cut that part. You may have to 'blend' the start/stop points with a shear scrape because the wood has moved.

One on One lessons are probably the best way to learn.

A burnished surface is a good thing on a finished product, but not so much so on one that needs to be sanded. The compressed surface is more difficult for finish to penetrate, and it is also difficult to sand out. If the surface is really burnished, again, this is too much tool/bevel pressure.

robo hippy

[Bob Bergstrom]

I find changing the rake angle (less of the bevel rubbing, 1/8" instead of 1/4") will help. If you can make the cut with a minimum of force holding down the tool on the tool rest or with only one hand on the handle of the tool, you are cutting properly. The more down force on the tool rest the more the tool is resisting the cut. Usually it is only a small step, lean or twist of the handle to correct it. Grinding down the heal of the bevel may help. I found the skew much less likely to leave ripples if I took lighter cuts , but also reduce the amount of bevel rubbing. Just enough to stabilize the cut.

[Jeff Moffett]

I've had this issue as well, and the solution for me was opening up the flute of the gouge a little more. I was being conservative and kept the flute closed (around the 9 or 10 o'clock position). I found that if I opened up the flute (around 11 o'clock) I got a cleaner cut with no ripples.

[Jim Burr]

Oops...Mike beat me to it. It's half speed, half bevel. If you ride the bevel with the correct angle, you will cut everytime. If your grind is sharp enough to cut on slow speed, it'll cut on a faster one so sharp is sharp. Given your sharpening skill are up to par, speed, angle and bevel are the keys

[Rodney Walker]

Joining a club is good advice. It will go a long way toward making the learning curve less steep. Nothing beats learning in person. If there's a club near you, it's well worth the time and effort to join.
Rodney

[Dennis Nagle]

I was having the same problem until an old turner who watched me turn pointed out that I was not riding the back bevel of the tool on the wood. Since them, EVERYthing is turning much smoother. I second finding a turning club in your area.

[Reed Gray]

Speed had little to do with it. Mostly it is technique, how you hold the tool as you cut the wood.

The terms 'open' and 'closed' flute always confuse me. Open flute to me is a continental style spindle gouge, and closed flute is a deep V gouge. I always roll my gouges onto the side to cut. This puts the nose of the gouge in a high shear cut angle, and the wing does more of a scraping cut, depending on how heavy of a cut you are taking. This is in part because I hold my tools more level when cutting, whether on the inside or the outside of the bowl. On the outside of the bowl, you can drop the handle, and get the higher shear angle by using the wing. With the flutes rolled more onto the sides, the risk of the wing catching and digging in is 0.

robo hippy

[Rick Markham]

Since, you are a "newer" turner there is always a significant chance that over time your grind angle on your tool has changed. Tool steels work best at specific angles if you get out of their range they really cease being sharp, or dull extremely fast. Personally, I would hollow grind all of my gouges, and make a bullet shaped grind on your skew. By trying to ride a flat bevel you are resting the tool on a single point (where this happens varies depending on your angle of attack) A hollow ground gouge rests on the cutting edge and the very back of the grind, You have two points of contact in a stable configuration and the front one is the cutting edge :) (making it intuitive to engage the cutting edge on the workpiece.) If you are white knuckling your way through this, it only makes it worse as Reed said! Most shaping cuts I make are controlled with a single finger on the gouge. Presentation of the tool (and the sharpness/proper grind angle) is everything! Good luck!

First I would check all my tools and make sure the angle of your grind is appropriate for what tool steel it is made out of. Then, I would hollow grind my gouges, It will make it easier on you

[Mark Levitski]

Speed had little to do with it.

Maybe not speed in itself. However I am in the "speed" group for this problem based on own experience. The suggestions to up the speed of the lathe are not as important as to guard against moving the tool too fast through the cut. IME this produces what you describe. In this case it IS related to speed, but not directly. Too much tool-advancing speed through the cut can yield the same poor technique issues that arise via other faults in presentation. Slowing down the progression of the tool through the cut, or, alternatively, speeding up the lathe, should help.

[robert baccus]

It seems to me that the easiest way to remove ridges and out of rounds it to apply a tip cut with a razor sharp gouge presented head on. Like a toothpick, flute straight up at high rpm. This allows the tool to cut the high spots and not follow them. Sounds like you are at that point maybe.

[john taliaferro]

I make little Christmas trees sometimes and the pattern you talking about looks nice on my 1 1/2 x6 " trees . It was an accident at first but when i tried to do it again it turned out to be the hardest turning I have ever tried .So make some trees while you can . slow , dull, tool rest back ,hold the tool loose and let it bounce .

[Reed Gray]

Mark,
I will have to think about that for a bit, and try some more cutting in the shop. When roughing, I generally will cut as fast as the lathe will let me, and not at the speed in which the wood will cut cleanly. Can't say that I ever really noticed any bounce from that. Most of the time, well, almost all the time when roughing bowls, I am a psycho with the scrapers. The skill involved with finish cuts, for sure, means learning to feel when the wood is cutting cleanly, and when you are plowing through it with roughing cuts. I have notices, and it seems to be mostly on the inside, that some woods are just stringy, and will bounce no matter what you do.

robo hippy

[Royce Wallace]

If I had you at hand, I would have your turning technique corrected within 30 minutes. I AM DEPARTING from what others have said above. Forget riding on the bevel stuff--you cannot get a good cut "riding the bevel" period. A flat grind is the best way to cause your problem. You are a wood worker--think about how a good wood plane is presented to the wood--no bevel is on the wood--just the cutting edge-SO the cutting edge of the turning tool is presented to the wood the same way. The tool must be lifted slightly off of the bevel to make the proper cut -- a cut without the result you are getting. For this reason a turning tool is best sharpened with a bevel of the turning stone radius--not flat. For that reason turning tool sharpening jigs will present that type of edge. With your tool really sharp present it to the wood on a skew type of cut and lift the tool slightly off, or above, the bevel moving the direction you are cutting (r to l, l to r??) How much you must raise your tool will depend upon the cutting edge you have on the tool. Wish I had you here--hope this helps.

[Reed Gray]

Royce,

If I had you at hand in my shop, I could show you how to get a good, smooth, even, and clean bevel rubbing cut in 30 minutes. Sharp tool, light touch, learning how to move with the tool, and very gently rubbing the bevel. While a hand plane does not have a bevel to rub, it has a sole that it rides on to help control the cut.

robo hippy

[John Keeton]

Royce, just as a point of reference, Reed is not an amateur woodturner - actually, far from it. It sounds as though each of you may be discussing nearly the same thing, but from a different perspective.

[Art Brazee]

Terrific help!

I turned four legs this weekend to a George Nakashima Bench I'm working on. There's definitely something with bevel and speed. I amped the speed way up and that seem to help. However, not riding the bevel helped the most. I still got some feedback, sometimes. But, must less and I could control it to a degree.

As for the grind - I flat grind and that's not going to change. I'm set up for that and do it well. I think a hollow grind might help this problem, but so can lifting the tool.

Someone pointed out the speed is relative - the speed THROUGH the wood is really the key. I think they are right. However, turning a two inch blank at 2500 helped quite a bit.

The only issue I have with not riding the bevel is one of shape control. It's a bit easier (more control) riding the bevel. I think on bowls that subtle loss of control might a hard bitter pill as bowl shapes are so changed by the smallest change to radius.

[Royce Wallace]

Having just reviewed all of the foregoing, makes me wish a good club meeting was involved with all of you present with attitude.

[Reed Gray]

We just had our 'Empty Bowls' meeting where we all bought in bowls to be donated for the annual Food Bank auction. I was the one who took them in. In looking over the bowls, there were 3 universal problems:

One was sanding scratches.

Two was tear out.

Three was inside bowl bottoms that were more like washboards than smooth even curves.

The above three will make for good demonstrations for our club. As a professional, I am more persnickety than most, and a lot of what I do from years of learning/experience, can be taught. I have to learn that......

robo hippy