Newbie turning question - Chatter while turning spindles

[underdog]

I'm a beginning turner and have turned a few things while learning to use a skew.

After becoming fairly comfortable with it, besides still having it catch once in a while, my biggest trouble is chatter. I'm mostly turning spindle type work between centers.

At first I thought that it was the lathe. But after selling my old $99 Big Lots stamped sheet metal lathe and graduating to a cast iron lathe (made by Central Machinery I think) I find that I still have the problem.

So I'm wondering what I'm doing wrong. It seems to be related to riding the bevel too hard. If I make a light cut (not a scrape) that doesn't ride the bevel too hard it seems like it doesn't chatter so much and even cuts a tad better. (Well, maybe not "better", so much as "easier") Is it the angle that I'm holding the tool? Or what?

Thanks for any advice.

Jim

 

[Bill Boehme]

By any chance, would these spindles be long and slender?

Since you mentioned riding the bevel rather firmly, it sounds like the spindles are flexing from the pressure that you are applying. A common new turner mistake is having a "white-knuckle" grip on the tools, especially a skew, for fear of losing control and getting a skate or dig-in. When turning spindles, especially very thin ones, a very light touch is what you need. Almost no pressure should be applied along the shaft of the tool into the wood. Use a very light touch with the forward hand, applying mostly downward pressure to keep the tool against the rest. The rearward hand should very gently control the movement of the tool, but don't ever jam it into the wood -- just gently position it so that it meets the wood and let the wood come to it.

It is also possible that your tools have gotten dull. If you are not familiar with the proper techniques for sharpening, there are several good videos available -- AND -- if you happen to be an AAW member, you will be receiving a great sharpening video next spring. That's a long time to wait, so I would recommend Alan Lacer's introductory woodturning video in the meantime. Also, I really personally like Del Stubb's video.

Bill

 

[bbrussell]

Bill pretty much covered the subject. Sharp skew is a must. The tool rest must be close to the work, as you are turning the tool rest position to the work changes, reposition the tool rest often. I like bill expect that you are holding the skew too tight to the wood. As an exercise start a planing cut and as the cut progresses take your hand away from the blade of skew. The skew will on its on contnue down the spindle without any help from you. This is not as scary as it sounds and it will teach you a lot about gripping the tool.

 

[MichaelMouse]

So I'm wondering what I'm doing wrong. It seems to be related to riding the bevel too hard. If I make a light cut (not a scrape) that doesn't ride the bevel too hard it seems like it doesn't chatter so much and even cuts a tad better. (Well, maybe not "better", so much as "easier") Is it the angle that I'm holding the tool? Or what?

You nailed it. It's differential friction. The way to make things round is to rotate against a fixed cutter. If you ride versus guide the bevel, you leave yourself vulnerable to tool or spindle bounce. Face grain gives a different resistance than quarter grain.

The folks who used to turn chair spindles for a few pennies each back in the old days helped their cause by incorporating their own steady. Their own hand. Thumb on chisel, fingers loosely around the piece, they'd get the cut going at 11:00 to 11:30. Most turners tend to plane too low on the spindle, which is why they can hook that forward part of the skew if they lift the handle a touch.

Try the A-B-C approach. Anchor the tool to the rest, touch the Bevel to the piece, Cut(curly). Helps if you make the initial penetration with your gross muscles - lock your fingers, wrists and arms, swing in with your knees or hips to start the cut. Once you have the bevel guiding on the fresh surface, you can use your small muscles to continue. They have better proprioceptive sense, and can maintain the angle best.

 

[Ken Grunke]

Take a good look at Alan Lacer's site:
http://www.woodturninglearn.net/
His articles and handouts have a lot of info on the skew (it's use, and sharpening).
The most valuable technique I learned from him was power honing--an MDF wheel charged with white diamond compound, which polishes the edge and bevel making a huge difference in the cut.
While Alan uses the edge of an MDF wheel, like a grindstone (with the edge rotating AWAY FROM THE EDGE), I use the flat face of an MDF disk held in a cheap tabletop drill press dedicated to the operation.

 

[Mort]

The others nailed the main problem areas except for speed. You may be turning to slow or too fast. I suggest checking out Brian Clifford's website. He has videos available for download - FREE - on most of the common spindle cuts with a skew. Also has written 'how to's' for download. Any spindle over 18" and under 1.75" in diameter will "whip" and deflect at turning speeds. You may wish to check out Oneway's spindle steady.

 

[MichaelMouse]

Take a good look at Alan Lacer's site:
http://www.woodturninglearn.net/
His articles and handouts have a lot of info on the skew

Had heard that Alan was not just a turner, but a thinker. His site shows it. He points out that the convex skew is one way of getting the nose out of the way for smoothing cuts, but also shows a set of Glaser-Lacer skews which come close to an old-style beading tool, where there is no hanging nose waiting to trap the unsuspecting. I have learned to live with the long-nosed grind that came with my HSS rolled edge skew for planing, but prefer the old carbon steel tools which look more like the G-L types for convex forming. It's much easier to cut down and in on a bead with them, than with the long-nose, though I would recommend a small forged gouge for the less experienced. All the good features of the curved skew with added piece safety because the edge curves away from the point of cut in two dimensions. Looks an awful lot like an Osolnik gouge, which I guess is why Rude favored spindles with it and a rougher - me too, where it'll fit

Oh yes, Ken, give the green Chromium oxide polishing compound from Lee Valley or Woodcraft a try, if you haven't. It's more aggresive than white diamond while providing a mirror edge for the tool if you want it. Carvers love the combination of it and a hard felt wheel. Before someone jumps in with "edge rounding," I'll go on record saying don't press, just let it run off the edge. Mine's on an old Maytag motor, so as not to sacrifice a good balanced mandrel.

 

[underdog]

Wow... where to start... first thanks for sharing your expertise with me.

I've read, and re-read your responses and I think it's finally starting to sink in.

Michael, your comment about differential friction made a lot of sense after a little thought.

And yes I suppose that these are small spindles. I've been making mostly letter openers... But the eggs I made the other day had much the same problem.

As for the sharpness of the skew, I suppose that is a factor. I've been sharpening it almost every time I use it. Of course that's really unavoidable with high carbon steel. Haven't invested in any HSS steel yet. So it sounds as if it may be a combination of things. 😕

Problem is that my learning difficulties are compounded now that I broke the lathe. First the tightening handles on the tail stock and on the head stock clamp broke because of very porous castings. The next, more serious problem, was with the belt and variable speed drive. I'd been hearing a "clicking" noise in the VS since I first turned it on. This is a lightly used second hand lathe. Thinking this was normal (this lathe was a whole lot more quiet than the old stamped sheet metal lathe!) I continued with several turnings, until I heard the belt whacking the inside of the cover. At that point I decided it really needed a looksee.

After taking the cover off, I noticed that the motor pulley on the VS was not lined up with the pulley on the Spindle. I'm certain this led to the demise of the belt as it was pulling it to the side quite a bit. Thinking this was easily solved, I loosened the set screws on the inboard side of the pulley and pried it away from the motor. Unfortunately the casting in the pulleys aren't any better, and the heat from a misaligned belt had also crazed the metal. So of course the pulley snapped in half leaving me with no way to finish that nice piece of figured walnut that's between centers at the moment. 😱

Any advice how to get parts out of Harbor Freight? I've not had much luck with their technical service folks in the past. I think I'd be better off to peruse the Grainger or MSC catalog. I've got a real bias against waiting for things from Taiwan. I had a really.... no... extremely :mad: bad experience with one of the major importers of moulders from there...

I've been contemplating buying this lathe from its owner, he now says not to bother, but just buy a new one. Being frugal, and very mechanically inclined (I was an auto-mechanic in another life...) I'm not sure I want to follow that advice. If I buy it I'll probably want to junk the VS and put after market-stepped pulleys on it and after-market handles on... I've a real aversion to junky variable speed devices - that was part of my bad experience with cheap Taiwanese moulders.

 

[hcbph]

I know some people will think this is crazy but if you are in a place where there are shops that repair farm equipment, give them a call. I had a pulley for a 50+ yr old Atlas metal lathe get damaged in a move. This was before the days of Ebay and I had previously had no luck finding a replacement. Happened to be in a welding shop that fixes farm equipment, and they had one hanging on the wall. They also had some where they'd weld the proper sized hub onto a pulley to get the right sizes.

Worth a look. Good luck

Paul

 

[MichaelMouse]

Eggs could be more from tool bounce than spindle squirm, I'd say. Difference in hardness between early and late wood, and the angle at which you are cutting it can set you up for bounce unless you concentrate on holding the tool steady on the rest.

You shouldn't have to sharpen carbon steel all the time, though heat from pressing it into the work even to the point of bounce would soften a super thin edge. Reinforces the first point of analysis.

I still prefer my carbon steel tools for the final pass. They seem to take a smoother, effortless wispy thin cut better than HSS or PS. I don't use high speeds on the lathe, and make the pass fairly rapidly, so heat is minimized.

 

[underdog]

Michael,
From my experience with moulders, I've noticed that while solid carbide will outlast HSS for acceptable sharpness, good sharp HSS will give a much smoother finish at the outset. So I can well believe that high carbon steel will give a nicer finish than HSS.

I think I understand what you mean in terms of tool bounce when pressing it hard against the bevel. An ever alternating cutting effort or friction (as the grain changes each quarter rotation) against that bevel can cause a "bounce". Am I understanding this correctly?

As far as the spindle "squirm" I'm understanding that it will deflect if pressed hard enough, but why will that cause a spiral patterned chatter? And am I understanding you to say that this is a different cause of chatter than "tool bounce"?

What motivated me to write this post was a particularly bad session with a White Oak letter opener. ( Although I didn't like the rugged grain or color of the oak, all those mistakes gave me a form I was rather pleased with!) The Maple and Cherry letter openers gave a little chatter, but nothing I couldn't clean up with a little care and some sandpaper. The White Oak on the other hand just got me really frustrated....

So I'm wondering if you can confirm this? As White Oak is notably very porous as compared to cherry or maple, I would think the "bounce" would be worse with this wood.

 

[MichaelMouse]

Michael,

I think I understand what you mean in terms of tool bounce when pressing it hard against the bevel. An ever alternating cutting effort or friction (as the grain changes each quarter rotation) against that bevel can cause a "bounce". Am I understanding this correctly?

As far as the spindle "squirm" I'm understanding that it will deflect if pressed hard enough, but why will that cause a spiral patterned chatter? And am I understanding you to say that this is a different cause of chatter than "tool bounce"?

What motivated me to write this post was a particularly bad session with a White Oak letter opener. ( Although I didn't like the rugged grain or color of the oak, all those mistakes gave me a form I was rather pleased with!) The Maple and Cherry letter openers gave a little chatter, but nothing I couldn't clean up with a little care and some sandpaper. The White Oak on the other hand just got me really frustrated....

So I'm wondering if you can confirm this? As White Oak is notably very porous as compared to cherry or maple, I would think the "bounce" would be worse with this wood.

Well, everything is relative. It makes little difference whether the tool or the piece is moving, the effect is the piece acquires lumps and slumps in a pattern which begins with its own resonating hard/soft pattern and is modified by the direction and speed of your tooling. As you've noticed, with the huge differences in hardness between early and late wood, oak is going to be more difficult than maple or cherry, that's for sure.

That's why it's so important to do the things that minimize the tendency to bounce. First, reduce pressure on the piece, second, modify your angle of attack to minimize non-cutting friction, and third, keep your tools sharp. You can also cheat, and get a steady to help you out, or learn to use your off-hand as one to help. It can get warm if you're not careful, though, especially on bowls.

 

[underdog]

Our new club did a promo today at a local show. I got to be one of the demonstrators since I was one of four members that showed up... We had a lot of fun today and I credit some of that to you guys. See our blurb on the AAW Georgia chapters list under "Classic City Woodturners". Not much to see yet but we're cranked up and running!

Using a decent lathe (it was very smooth and very quiet) was a treat! It was our presidents older (the blue one) mini Jet. However I was still using my.... uh.... "inexpensive" Hi-carbon tools. So as slow as I am they got dull. But, I tried several of those techniques you guys mentioned on that piece of walnut. Suffice it to say that using your fingers as a steady rest will make them hot in a hurry if you push too hard at a high RPM ! But I saw a definite improvement in the chatter situation. I also used the one handed technique, but it looks like I need some practice on that...

I could see the deflection if I applied the tool too hard also, so I think ya'll nailed it on the head. Dull tools, incorrect application, and a flexy spindle will cause chatter. I had already tried backing the tailstock pressure off but that hadn't solved the problem...

And the Walnut sure turns easier than the White Oak! I'll make sure to turn Oak green or else use HSS so the tool stays sharp longer. I actually got a quite decent finish on the walnut even though it was very dry and figured. I now have a nicely shaped figured walnut letter opener on the desk. And several people even wanted to buy some of the ones I had on display! ("Sorry, not for sale today, we're just doing a club promo.... Would you like to join our club?" ) I might even pay for some tools if I keep this up.

Thanks for all your help guys. I appreciate it.