3/8" Gouge Chatter??

[Lawrence Duckworth]

I've been roughing 3" spheres with a 3/4 ``gouge and when I make a final cut with a sharp 3/8" gouge in the direction of the headstock I get a chatter almost every time. Any ideas what i'm doing wrong to get the chatter?... Thanks

[Jerry Lear]

chatter can be caused by left hand putting too much pressure on bevel.Use the left only to hold tool on rest,do not press in

[John K Jordan]

Depending on the grain orientation, cutting "uphill" at certain points might cause chatter.

Jerry makes a good point about bevel pressure. Also, when I encounter unusual problems I sometimes apply a bit more down pressure against the tool rest. Reduce the overhang of course.

Another thing, I've gone to Thompson detail and shallow detail gouges for some things since the cross section of the gouge makes it much sturdier, especially if there is unavoidable overhang. A 1/2" spindle gouge might be better than the 3/8", and the detail gouge better than the usual spindle gouge. (If you look at the gouges on his web site ignore the cover photos but drill down to the descriptions - the detail and shallow detail gouges have a much shallower flute than the photos: 50% for the normal spindle gouge, 33% for the detail gouge, and 20% for the shallow detail gouge. https://thompsonlathetools.com/product/12-shallow-detail-gouge/)

Mark StLeger told me he uses a Thompson 1/2" spindle detail gouge more much of his turnings, including his spheres. I've got these on my shelf - in a demo he turns four the same, a corian disk with a groove, and the stack spins like a bearing when you spin the top sphere!

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JKJ

[Reed Gray]

A couple of solutions already mentioned, and I will add to that. Most people tend to over do the 'rub the bevel' part. If you have much bowl turning experience, especially when turning the outside, you always get a little bounce. Part of the reason is cutting from end grain to side grain, and uphill to down hill. The tools cut differently in different grain patterns. The other is from too much pressure on the bevel and/or having the death grip on your tool in an effort to control that bumping. Clamping down makes it worse, not better.

"The bevel should rub the wood, but the wood should not know it." Unknown

"When holding the sword (tool in our case), hold it as you would a bird. Too tight and you kill it, too loose and it flies away." Old black and white Hollywood movie about Cerano de Bergerac.

I haven't done any spheres in a while, but for finish cuts, I used to use a shear scrape. That was before I had started using NRSs.

robo hippy

[Lawrence Duckworth]

Thanks so much Jerry. You’re probably right I’ll try to loosen up 👍

Again, thanks John. I’m looking at the gouges now and they’re very deep. Makes cents 🤔

[Lawrence Duckworth]

Thanks Reed. Good description. The wood is hickory and looking at it closely the grain….I get it.
The death grip is a good place to start though 😜

[Lawrence Duckworth]

Quick follow up.
Though the flutes are deeper on my tools compared to the ones shown in the Thompson link, I don’t think that plays into it. My final cut with the 3/8 is small and well supported. I took my fat hand off the tool and guided it with my pinky👍

Btw for clarities sake I guess the actual final cut is with a scraper and I hate to use it cuz brings up fibers but I can’t cut without leaving little irregularities 🤷*♂️

[John K Jordan]

Quick follow up.
Though the flutes are deeper on my tools compared to the ones shown in the Thompson link, I don’t think that plays into it. My final cut with the 3/8 is small and well supported. I took my fat hand off the tool and guided it with my pinky👍

Btw for clarities sake I guess the actual final cut is with a scraper and I hate to use it cuz brings up fibers but I can’t cut without leaving little irregularities 🤷*♂️

Sometimes fibers raised from scrapers can be tamed with an application of thin sanding sealer, dried. And a sharp, sharp, sharp scraper! I use hand scrapers a lot for that, off the lathe so I can pay attention to the grain orientation.

[Reed Gray]

Well, if you are using a scraper for the final cut, then I would suggest that you hone the burr off. I saw this done with a piece of sugar/hard maple and it left a glass smooth surface. Not sure how it would work on hickory, which does like to splinter. I would use a shear scrape. I do have one video dedicated to that. With that high shear angle, you get less tear out so a cleaner surface. The cuts are 'whisper' cuts, so VERY light and the little whispies of shavings should float in the air. Can be done with scrapers, or if you are using a gouge, the swept back ones work best. A NRS will also work very well.

robo hippy

[Lawrence Duckworth]

I'm not going to say I've eliminated the chatter completely just yet. On basswood things were pretty smooth but I can still feel a small vibration....
I'll go watch your video. :D

Thanks

[John Keeton]

Don’t know if it has been mentioned, but sometimes it can simply be a bit of dullness. A slightly dull edge will cut the softer face grain, but not do so well on end grain making the piece get out of round.

[Lawrence Duckworth]

So I watched Reeds video and a couple others, good stuff! I also saw the importance of a burrrr. I noticed a little hand tool type bur Reed used in one of his videos and would love to know what it was, home made?.. My tools are M42 with 10% cobalt. Do you guys think a rotory file or end mill would be tough enough to make a bur. tool?

thanks John, I have in fact experienced some out of round wobble...:eek:

[John K Jordan]

So I watched Reeds video and a couple others, good stuff! I also saw the importance of a burrrr. I noticed a little hand tool type bur Reed used in one of his videos and would love to know what it was, home made?.. My tools are M42 with 10% cobalt. Do you guys think a rotory file or end mill would be tough enough to make a bur. tool?

thanks John, I have in fact experienced some out of round wobble...:eek:

I haven't seen the video, but a burr is usually added with a burnishing tool. They are usually carbide but any hard steel will also work in a pinch, for example, the hardened shaft of a HSS too, the smaller diameter the better.

These are some I use. Again, the smaller the diameter the better, i.e., easier to raise a burr:

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However, if buying one my new favorite is the Arno burnisher - it has a small diameter side and a triangular side, actually an extremely small diameter rounded edge which is more aggressive. This works very well on conventional scrapers, NRS, and cabinet/card hand scrapers.

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I usually remove any burr from the grinder with an extra file diamond hone or by stropping, then burnish a burr. The grinder burr is coarse and relatively weak while the burnished burr can be smooth and stronger and last longer. I used to do this with "conventional" lathe scrapers but now I almost always stick to negative rake scrapers like these. NRS are much easier to control, more forgiving in that they are difficult to cause a catch, and I think give a smoother surface. I grind these from 10V steel Thompson Tools.

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With this grind I can use the end flat or the curve on the inside or outside. I put the burr on the side needed for the piece - with several ground the same I just have left and right-handed versions.

You can also sheer scrape with a gouge with swept back wings. It would be easy to show how this is done but harder to describe. You can probably find pictures somewhere.

After using a scraper on the moving part I generally stop the lathe and even remove the piece and use a hand scraper just before sanding. This usually allows starting with fine sandpaper instead of coarser which can give a better surface.

JKJ

[Lawrence Duckworth]

Geese John, I think my info overload siren is going off :)


This is the scraper I have.
https://carterandsontoolworks.com/products/1-negative-rake-scraper?variant=41859860681


I'll snoop around in the barn this morning and see if I can find something I can make a bur tool out of. I didnt realise how important the bur is....or for that matter there was a tool for it.


I like the scraper profiles you have there, especially the left and right hand deal. no idea what the three dagger looking things are...Yikes :)


wow.. thanks again

[John K Jordan]

...
I like the scraper profiles you have there, especially the left and right hand deal. no idea what the three dagger looking things are...Yikes :)


Oh, no. Here I go on scrapers again. I can't help myself.

The "dagger" photo is just of the same three scrapers but looking at the sides to see the included angle. I think I use about 60-deg included angle.

Here is one of my three "primary" negative rake scrapers in action, first using the curve and then using the (almost) flat on the end. I've never seen anyone grind them like this but the flat is perfect for smoothing platters, gentle curves, and here, the wings of a small squarish platter. I've had people tell me you can't use a scraper when "turning air" but it's not so.

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A NRS can be any angle less than 90-deg. The first picture shows some smaller ones I use a lot - they will leave end grain on boxes, etc, smooth as glass with good wood. I grind most of my scrapers from Thompson stock, round, rectangular (scraper), skew chisel, and detail gouge. I often sharpen another shape on the other end. Some special use scrapers that don't get so much use are ground from old HSS tools. BTW, I use all these without handles.

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As mentioned, I do a lot of final smoothing with hand scrapers, mostly off the lathe, just before sanding:

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After smoothing on the lathe with the NRS then off they lathe by hand, I can often start sanding with 400 grit, occasionally finer, often by hand. Just say No to power sanding with a rotating disks!

A few of my favorite hand scrapers. I grind cabinet scrapers into various shapes with a belt sander, sharpen at 90-deg on a 600 grit CBN wheel, smooth the flat ground edge with an extra fine diamond hone (also removing any grinding burr), then burnish a smooth burr on both sides for double the use between sharpenings. This method is commonly used by furniture makers to prepare cabinet scrapers. When a burr gets dull, I usually take it off with the diamond hone then raise another one or two before I take it back to the grinder. The two in the upper left are 1/8" thick from StewMac, generally marketed to musical instrument makers.

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JKJ

[Reed Gray]

For the M2 HSS tools, you can burnish a burr using the traditional burnishing rods that are used on the card scrapers. The triangle one works better. For the M42 and V10 metals, it is more difficult to raise that burr with anything other than a carbide rod. First one I made was a carbide drill bit that had been 'resharpened' and came in a small box with a bunch of tiny ones. A small diameter router bit will work as well.

I have been going back and forth on the burnished burr thing. For some reason, experimenting is a necessity to me...... Some times, the burr from the grinder seems to work just fine. I can turn it down and back up once or twice, then go back to the grinder. I can also hone a burr on the scrapers, using a medium or fine diamond hone. Lately, while turning some figured big leaf maple that is pretty green, I have been using both shear scrapers and NRSs on it, and the burr from a 600 grit CBN wheel seems to cut as well as just about any other burr. I need to get the 1000 grit wheel up on another grinder to play with it as well.

With the NRSs, I still prefer one with a 60/25 or 60/30 grind. It seems that the burr holds up a lot better if there is some metal under it to support the burr. The 30/30 ones just don't hold up as well.

The bass wood is pretty soft, and I wouldn't expect it to cut as cleanly with a NRS as the black locust would. Still, as some one said, a NRS is a high maintenance tool. I spend more time touching up that edge than any other tool I use. Also, it is just for fine finish cuts, not any type of stock removal.

robo hippy

[Lawrence Duckworth]

All very interesting John. never ever heard of cabinet scrapers.
That fixture you're using in the banjo looks very handy too.


I made a burr tool this morning and sharpened the tools, knocked off the grinding bur, stropped and put a new bur on with the bur tool.....made quite a difference, even so I'll need some practice.


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.20 end mill.


Reed I turned a cherry cylinder (3"x12") most of the afternoon, practicing with the scraper. Thanks for your help!

[John K Jordan]

I hold pieces in the Articulated Carving and Finishing Post from Best Wood Tools. (I see he has it on sale right now; I paid a lot more than that for mine.) You have to order it with the thread that will fit your lathe/chuck.

I, and some others I know, like this one best due to the way it’s designed. I’d hate to turn bowls and platters without it!

BTW, to burnish a burr I lay the burnishing rod on the lower bevel of the scraper, then raise the handle just a few degrees, apply moderate pressure against the edge, then slide the rod from one end of the edge to the other once or twice. Experiment with the angle, pressure, and # of passes. You should get whisper-thin shavings from the wood.

JKJ

[Lawrence Duckworth]

This is working! Thank 🏁🏁🏁


Btw John thanks for the fixture link. I ordered one this morning. I could have used one of these many times. Fwiw I welded an adapter to a length of pipe and dropped it in the banjo…. Probably not an original idea but it worked okay. Also ordered cabinet scrappers from Amazon. Gotta give it a try 🤷*♂️

[Kyle Iwamoto]

Another Thank You! to JKJ. A fixture is hopefully on it's way to me. They sometimes add a lot for shipping. Hopefully it won't cost too much to ship.
You should get a commission for selling them.... LOL

[John K Jordan]

...cabinet scrappers from Amazon. ...

If you shape the outlines of cabinet scrapers to fit bowls and such: I've tried different methods and the best for me is a coarse grit on a 1" belt sander. A bench grinder with either conventional or CBN wheels generated too much heat for me, turned the edges blue. A light touch on the bench grinder didn't. In general I prefer the better quality name-brand card scrapers but the cheaper ones are still useful.

Cabinet scraper sets often come with a gooseneck scraper. I found this more useful if I cut the end off with a metal-cutting disk on a Dremel. This gave me a small scraper to hold between thumb and fingers, and a larger curved scraper.
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That, BTW, is how I got started using these scrapers a decade and half ago. I was turning a cedar bowl and followed the advice of others to hold sandpaper against the rotating piece. Ack - the cedar started developing tiny heat checks! I thunked and thunked and cut the end off a gooseneck scraper, sharpened it, and found it worked like a charm to smooth without heat and required very little sanding. I've been evangelizing hand scrapers ever since.

My cedar bowl from long ago (my first "real" bowl after a couple of practice bowls):

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Note that you can and I occasionally do use a hand scraper on a rotating piece, but use common sense. One guy on a forum reported holding a largish scraper inside a closed form and when it got away from him it caught inside the piece and turned into a food processor. Yikes. (Drop a small scraper inside and it will simply fall to the inner surface, but no need to do that anyway.) When I want to use a scraper to smooth the inside of a rotating piece I use one of these, a scraper (Sorby's or mine) mounted on a Sorby handle. I probably use the Sorby teardrop scraper the most (1/8" thick carbon steel), turned to fit the profiles as needed.

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Note that you can also by small curved scrapers in sets. I bought one set from Highland Hardware and one from Woodcraft. They are thin and I don't like them as well thicker scrapers made from high quality cabinet scrapers, but they are cheap and still useful on occasion.

JKJ, certified "card carrying" scraper fanatic

[Kyle Iwamoto]

Wow! This is a great morning! Thanks JKJ!
I'm going home and cut my gooseneck scraper and reshape it too...
BTW I also use a 1/8" thick hardened steel, copying the idea of the ultimate scraper from Stew Mac. You can get a 1/8" X 1" flat stock from Grainger. This is like the small part of the cut off gooseneck. Card scrapers are way easier to sharpen.

[Edward Weber]

The grinder burr is coarse and relatively weak while the burnished burr can be smooth and stronger and last longer.
JKJ
A burr produced by the grinder is simply an artifact formed during the process of removing metal. A small amount of metal is drawn accross the bevel and remains on the cutting edge. This is typically very thin and usually does not last long.
A burnished burr is stronger because it's formed by a type of cold forming, resulting in a work hardened burr. Cold forming actually changes the structure of the steel making it harder but a bit less durable (more brittle) Burrs don't last long.
Strength and durability are all relative especially when comparing a turning scraper and a cabinet scraper. The number of feet of wood that passes by the cutting edge and how the burr's are usually formed on each tool make it too dissimilar IMO to accurately compare.
Apples & Oranges

[John K Jordan]

Wow! This is a great morning! Thanks JKJ!
I'm going home and cut my gooseneck scraper and reshape it too...
BTW I also use a 1/8" thick hardened steel, copying the idea of the ultimate scraper from Stew Mac. You can get a 1/8" X 1" flat stock from Grainger. This is like the small part of the cut off gooseneck. Card scrapers are way easier to sharpen.

Four years ago I bought 54" of flat 1/8x1.5" tool steel. I have a plasma cutter and I'm not afraid to use it. When I can find time...

I usually buy from Online Metals. In general, their prices are less than Grainger and some other places I checked, sometimes significantly cheaper. Just got more free-machining steel and brass this week.

JKJ

[John K Jordan]

Another Thank You! to JKJ. A fixture is hopefully on it's way to me. They sometimes add a lot for shipping. Hopefully it won't cost too much to ship.
You should get a commission for selling them.... LOL

Maybe he has some in stock ready to send out. I had to wait a while when I got mine a few years ago. Then, and maybe still, it was a one-man operation.

I like this far more than the Treat Bosch carving jig. His design unlocks the piece with a lever and the chuck and wood has to be repositioned awkwardly until the handle is tightened. Just watch his video and see him fumble. The Best Wood Tools version has one locking handle that allows tilting to a comfortable angle. Loosening the second handle maintains the tilt but allows rotation. This is perfect for rotating a turning around the axis while scraping, sanding, or carving. Might be a bit more "trouble" than a single handle but well worth it, I think.

Fits in a 1" banjo as well as a supplied mount for the workbench. I fastened the mount to a piece of wood and clamp it in a woodworking vise on my workbench for those rarer times when working away from the lathe.

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I don't power sand with a rotating disk on a drill but I do sometimes use gentle, low-speed sanding with a pneumatic random orbital sander. The rotation around the axis is perfect for that - hold the sander still and rotate the piece under it. Here a student with a 3" palm ROS from WoodTurners Wonders, with a 2" Grex pistol grip ROS for the other side of these "small squarish dished platters". 400 and 600 grit disks in these ROS make a beautifully smooth surface in short order. The stand also makes hand sanding easier. even on rims.

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I used to do all this with the piece on the lathe with the power off and the spindle locked but this is far easier on my back and far, far easier to see what I'm doing. I believe it was turner John Lucas who showed me this device.

JKJ, addicted to pictures

[Lawrence Duckworth]

A burnished burr is stronger because it's formed by a type of cold forming, resulting in a work hardened burr.

I'm bettin that's why the 60/30 grind is preferred, I tried putting a bur on a skew with a pretty long grind and I swear I heard it cracking.

[John K Jordan]

...I tried putting a bur on a skew with a pretty long grind and I swear I heard it cracking.

Another (older) name for burnishing a burr is "ticketing" because of the "tick, tick" sound when used on some edges. The hardened burnishing rod was called a ticketer.

I read this in a book on woodturning published about 70 years ago. It also discussed using card scrapers on turnings. Sometimes we think we are on the cutting edge of turning but are using techniques and tools in use long ago! Of course, we have better steels, fancy variable speed/reverse lathes, lasers and cameras for hollowing...

But why did you want a burr on a skew chisel? To use it as a scraper? Blasphemy! :eek: :)

JKJ

[Reed Gray]

Grinder burrs are highly variable. I guess most of it depends on the metal. Standard M2 is good for roughing out at least 1 12 to 14 inch bowl. The M42 and V10 is good for 2 or 3 bowls. The Big Ugly tool with tantung on it, stellite is a very similar metal, is good for 10 or more bowls. My preference is for a 180 grit wheel. You don't have to apply much pressure, which is actually the difference between grinding and sharpening. I do think the 600 grit wheels produce a sharper burr, but it isn't as durable.

One experiment I need to do is to hone the scraper burrs sideways, rather than the standard grinder burr where the wheel is at 90 degrees to the top of the scraper. It does produce a different burr, but I haven't figures out exactly what those differences are....

robo hippy