Cutting Koa clean, or any other wood.

[Emiliano Achaval]

A few weeks ago, I told KellyDunn that sometimes no matter what you do, it is nearly impossible to cut Koa clean. I'm guessing that it can happen with a lot of woods. I got a sample here. Name the technique or tool, I tried. But, I know better than to beat a dead horse. I know when I achieved the best possible surface, and I move on. Not sure if there is a name for this phenomenon, but I call it "currents". If you watch the Kona ocean waters from up the hill, you can see the swirling currents doing something similar. The darker area also tells me there is something going on. When you can cut one area super clean but not right next to it, you know is not you. On the inside, one small area if you cut the right wat, you have a small patch of rough that if you cut from the inside out cuts clean, but the rest is torn. I tried Wayne Omura's super sharp little shear scraper. I tried 40/40 in 3 different sizes. I tried my Ellsworth gouge and my bottom bowl gouge. What else can I try? I'm open to suggestions. Bowl was finished today. So I'm done with this one. But there is a shed full of Koa waiting for me. As I was getting the bowl off the vacuum chuck, I heard a crack. Got a crack on the bottom, I need to apply 3 pewa tomorrow. First time ever I cracked a bowl with the vacuum

 

[Brian Gustin]

I am just wondering.. .since I have yet to even try it myself... but.. What would happen if you applied sanding sealer or similar a layer or two before final cut(s) ? I plan on trying it with my next piece of "SOFT" wood that goes on the lathe - It always seems to have end grain tear-out no matter how sharp my tools are (even sharp enough to slice a sheet of paper dragged along the edge) .. of course, being a relatively "new" turner (even 35-40 years ago, I wasn't all THAT good anyways) it could also be my technique.. but in the meantime I just have the urge to experiment..

 

[hockenbery]

I get torn grain from 3 causes
1 twisty grain in figured wood where some grain is going the wrong way to the cut
2 spindles cut at a angle to the grain where the grain of one side is going in the wrong direction
3 punky wood, really soft woods, or palm where the strong fibers are not dense enough to support the cut.

I go through a series of tools and cuts Ellsworth gouge push cut, Ellsworth gouge pull cut, Ellsworth gouge flute up shear cut. On the leading edge of the wing, Michelson ground gouge, spindle gouge, Hunter #4 (biggest I have).
my goal is to get to a shear scape surface.
light cuts bevel riding slow feed rate( higher lathe speed )

i stiffen fibers by wetting well with water if the tearout is minor, next I try thin shellac 2x the alcohol,

my last resort only used for word of great value is polyall 2000. It is an expensive watery thin 2 part resin, awful to work with a 60 second working time It platicises the wood. But I penetrates and it cuts cleanly.

 

[robo hippy]

Well, one very old very dry koa blank I turned, the tear out was terrible, no matter what I did, and of course it was on the up hill side. I got rid of it by spritzing the bowl with water. let it sit for a minute, and then take very light cuts. I think it took 3 or 4 attempts to get it clean enough to sand out. I recently had some very soft silver maple. Punky to some what solid. 600 grit CBN wheel and then to the leather wheel on my Tormek. That got the punky tear out down to 'sandable' range. Every piece of wood is different. I didn't have a 600 grit CBN wheel at the time...

robo hippy

 

[Karl Loeblein]

Wonder if soaking the roughed turned blank in dish washing detergent (mixed 50/50 with water) for a couple off days might help make smoother cuts. You can also add a small amount of detergent to a spray bottle of water if you want to try spritzing. Put a sheet of plastic down over bed ways to stop water from rusting it.

 

[Doug Rasmussen]

It can be done with very high positive carbide inserts, the type machinist supply houses sell for cutting aluminum. Don't use your conventional tools.

Set up a tool holder similar to what John Lucas uses for his router setup. Make it heavy to withstand any possible catches. Essentially the same concept with CNC machines where the cutter is held firmly and can't dig in for a catch.

Watching for the first time a Giles Gilson interview talking about using whatever it takes, technology or whatever, makes me wish I'd met him. Same thing Mark Lindquist told me.

 

[Odie]

The darker area also tells me there is something going on. When you can cut one area super clean but not right next to it, you know is not you.

Hi Emiliano.......

You are too advanced a turner to suggest your tools, or technique need adjustment, so I offer the following:

You didn't say if this was the roughing stage of a twice turned bowl, or the final turn of seasoned dry wood......which is it?.....or, maybe it's a wet bowl blank intended to be final turned at the first mounting.....?

I deal with similar areas on other kinds of woods. The very dark, almost black spots, and the definite line of separation reminds me of some of my previous experiences. In many of those cases, I suspect this is some kind of fungal growth. Could this be in your case, too?

It always seems to have end grain tear-out no matter how sharp my tools are (even sharp enough to slice a sheet of paper dragged along the edge)

I used to use paper for the "sharpness test". Different pieces of paper won't necessarily give the same indications of sharpness. It would be nice if there was such a thing as a "sharpness meter" that would tell us just how sharp it is, but there is no such critter that I know of! These days I use my thumb gently dragging sideways across the edge as my indication of sharpness. With a little practice, this works pretty good.

I hate to keep bringing up the "old boys", because some of you think modern methods are much better than what they had a long time ago.....but you know they used a leather strop to get the keenest possible edge on straight razors. I would imagine @robo hippy gets a similar level of sharpness using his leather wheel on a Tormek......

-----odie-----

 

[Brian Gustin]

I used to use paper for the "sharpness test". Different pieces of paper won't necessarily give the same indications of sharpness. It would be nice if there was such a thing as a "sharpness meter" that would tell us just how sharp it is, but there is no such critter that I know of! These days I use my thumb gently dragging sideways across the edge as my indication of sharpness. With a little practice, this works pretty good.

I hate to keep bringing up the "old boys", because some of you think modern methods are much better than what they had a long time ago.....but you know they used a leather strop to get the keenest possible edge on straight razors. I would imagine @robo hippy gets a similar level of sharpness using his leather wheel on a Tormek......

-----odie-----

I'm old school, I do the same thumb test for sharpness (which is rarely far off the mark).. but doubting myself sometimes, I will resort to using a sheet of printer paper and see if it will slice the paper without ragged edges.. I also hone (and strop.. learned knife and tool sharpening the old fashioned way at my grampa's knee on the farm when I was a kid.. many moons ago - he had a hand cranked HUGE wetstone wheel, approx 18 inch diameter and I did the cranking often..) .. so I am pretty confident in my sharpness level .. not so confident in my bevels, and techniques.. but as noted, I still get some bits of tear-out no matter what I try, in some woods (though I suspect it might just be some soft spots in the wood for whatever reason..) One thing I find interesting, some folks mentioned the idea using soap and water to treat wood .. I happened to discover by accident that some household spray cleaner can do a surprisingly nice job of making some wood cut better.. I grabbed it by mistake instead of my bottle of straight water (that I use to dampen natural edge turnings to try and reduce warp while turning) .. I was quite surprised when it my next cuts seemed to be so much smoother, cleaner, and could feel less "effort" from the tool... so, as they say - Your mileage may vary - but I think Im going to get a bottle of cheap dish detergent and another spray bottle just for turnings (I use the plain water for flat work too - raising grain, correcting minor cupping, steaming out dents, etc) .. and see if I can see any difference when I encounter some more "difficult" turnings.. and who knows, might see a difference next time I start seeing tear-out.. or maybe it's the cleaner, not the detergent... I dunno yet..

 

[Dean Center]

Emiliano, I think it's a result of your high humidity or possibly low elevation. Why don't you send me a crate of that koa and I'll see how it cuts at 20% humidity and 5000 feet elevation. I bet it comes out fine.

 

[Emiliano Achaval]

Hi Emiliano.......

You are too advanced a turner to suggest your tools, or technique need adjustment, so I offer the following:

You didn't say if this was the roughing stage of a twice turned bowl, or the final turn of seasoned dry wood......which is it?.....or, maybe it's a wet bowl blank intended to be final turned at the first mounting.....?

I deal with similar areas on other kinds of woods. The very dark, almost black spots, and the definite line of separation reminds me of some of my previous experiences. In many of those cases, I suspect this is some kind of fungal growth. Could this be in your case, too?


I used to use paper for the "sharpness test". Different pieces of paper won't necessarily give the same indications of sharpness. It would be nice if there was such a thing as a "sharpness meter" that would tell us just how sharp it is, but there is no such critter that I know of! These days I use my thumb gently dragging sideways across the edge as my indication of sharpness. With a little practice, this works pretty good.

I hate to keep bringing up the "old boys", because some of you think modern methods are much better than what they had a long time ago.....but you know they used a leather strop to get the keenest possible edge on straight razors. I would imagine @robo hippy gets a similar level of sharpness using his leather wheel on a Tormek......

-----odie-----

This was a Koa Calabash bowl. Sold it for $1500 so I'm a happy camper. It was roughed out on March 20, 2021. The dark area could be a punky zone. What it is strange to me is how it goes right up to a super clean area, separated by a clear demarcation line. I also tried wetting it with mineral oil, as suggested by David Ellsworth. Maybe it helped 20%. I also tried wetting it with mineral spirits. Again, maybe 20% improvement. I tried a super-sharp small tool made by Wayne Omura, fast speed, and tilted at a 45* angle. A sheer scrape action that Wayne uses it to clean up the inside of his Cook Pine bowl. A 25% improvement. I tried 3 different NRS from Dpug Thompson. I even tried one old tool, a Richard Raffan sheer scraper. Anybody remember that tool? Used to be my to go tool for the outside of bowls before the re-birth of NRS. I should try get me a leather wheel for one of my other 2 lathes. Does anybody know of a leather wheel available for a jacobs chuck? I have seen this Koa problem many, many times. I talked with Kelly Dunn about it, so I thought it was a good idea to ask for extra advice. I always say that turning is a never ending learning journey. I'm always willing to learn, to try new approaches. Thank you Odie for your help, for taking the time to write. Thank you to everyone that commented. Keep the advice coming, even if you think that it might be a silly idea, you never know!! Aloha

 

[Emiliano Achaval]

I am just wondering.. .since I have yet to even try it myself... but.. What would happen if you applied sanding sealer or similar a layer or two before final cut(s) ? I plan on trying it with my next piece of "SOFT" wood that goes on the lathe - It always seems to have end grain tear-out no matter how sharp my tools are (even sharp enough to slice a sheet of paper dragged along the edge) .. of course, being a relatively "new" turner (even 35-40 years ago, I wasn't all THAT good anyways) it could also be my technique.. but in the meantime I just have the urge to experiment..

On this occasion, I did not try sanding sealer. I have tried that before. Maybe I should have tried it here. In my experience, it works up to a point. Thanks for your comment. Aloha

 

[Emiliano Achaval]

I get torn grain from 3 causes
1 twisty grain in figured wood where some grain is going the wrong way to the cut
2 spindles cut at a angle to the grain where the grain of one side is going in the wrong direction
3 punky wood, really soft woods, or palm where the strong fibers are not dense enough to support the cut.

I go through a series of tools and cuts Ellsworth gouge push cut, Ellsworth gouge pull cut, Ellsworth gouge flute up shear cut. On the leading edge of the wing, Michelson ground gouge, spindle gouge, Hunter #4 (biggest I have).
my goal is to get to a shear scape surface.
light cuts bevel riding slow feed rate( higher lathe speed )

i stiffen fibers by wetting well with water if the tearout is minor, next I try thin shellac 2x the alcohol,

my last resort only used for word of great value is polyall 2000. It is an expensive watery thin 2 part resin, awful to work with a 60 second working time It platicises the wood. But I penetrates and it cuts cleanly.

I have tried all of the above, except the Michelson grind, and the Polyall 2000. I have to see if I can find that in Hawaii. I have a feeling is one of those things that I have to pay an extra $50 for hazardous shipping. The dark Koa area, could be an indication of punky wood. Have you seen this in mainland woods? Such an obvious demarcation line? Thank you Al!

 

[Emiliano Achaval]

Well, one very old very dry koa blank I turned, the tear out was terrible, no matter what I did, and of course it was on the up hill side. I got rid of it by spritzing the bowl with water. let it sit for a minute, and then take very light cuts. I think it took 3 or 4 attempts to get it clean enough to sand out. I recently had some very soft silver maple. Punky to some what solid. 600 grit CBN wheel and then to the leather wheel on my Tormek. That got the punky tear out down to 'sandable' range. Every piece of wood is different. I didn't have a 600 grit CBN wheel at the time...

robo hippy

Hello Reed! Thank you for your comment. Question: What tool were you using? You know what you are famous for, LOL But I'm guessing a bowl gouge. The eternal question would be, can I get a better final surface if I sharpen with a 600 cbn wheel, as opposed to my 180?

 

[Emiliano Achaval]

Wonder if soaking the roughed turned blank in dish washing detergent (mixed 50/50 with water) for a couple off days might help make smoother cuts. You can also add a small amount of detergent to a spray bottle of water if you want to try spritzing. Put a sheet of plastic down over bed ways to stop water from rusting it.

I like the idea of a spray bottle with some detergent. Good one! And something worth trying. Ron Kent used to soak the Cook Pine logs in detergent. Have not tried yet on Koa.

 

[Emiliano Achaval]

Emiliano, I think it's a result of your high humidity or possibly low elevation. Why don't you send me a crate of that koa and I'll see how it cuts at 20% humidity and 5000 feet elevation. I bet it comes out fine.

Now, I'm curious. 20% humidity at 5000 ft elevation? I live a few miles from the rain forest, I'm at 1500 ft elevation. Really dry Koa at my house is 14.5% In comparison, in Kihei, down by the beach, sea level, dry Koa is a bit below 8%. Aloha!

 

[Emiliano Achaval]

It can be done with very high positive carbide inserts, the type machinist supply houses sell for cutting aluminum. Don't use your conventional tools.

Set up a tool holder similar to what John Lucas uses for his router setup. Make it heavy to withstand any possible catches. Essentially the same concept with CNC machines where the cutter is held firmly and can't dig in for a catch.

Watching for the first time a Giles Gilson interview talking about using whatever it takes, technology or whatever, makes me wish I'd met him. Same thing Mark Lindquist told me.

The little tool that Wayne gave me is a little piece cut off from a planer blade. It is his main tool to clean up the inside of his famous Cook pine bowls. I also tried the AZ Carbide Carbide little tool for the Jamieson tool. I used it in my Stewart arm brace. Thanks for taking the time to help me, Aloha

 

[robo hippy]

Well, I am famous for my scrapers... Excellent for bowl roughing, lousy for finish cuts, unless you are turning an end grain piece, then smooth as glass or smooth as your hand can guide the tool.

Having a 600 grit wheel is a big help for some woods, some times. I was up in Salem OR for a work shop at Terry Gerros's shop. Terry had a piece of rather soft big leaf maple on one lathe. It had some 'rough' spots on it. I took a gouge, Thompson V, I think, and sharpened it on the 600 grit wheel. It cleaned up the tear out and Terry wouldn't let me go home till he sharpened all his tools on my 600 grit wheel. I may have had my 1000 grit wheel at that time as well. With the soft maple I was turning, the 600 grit wheel was an improvement over the 180 grit wheel. The 180 took good care of the firmer wood, but there was still significant tear out in the softer wood. 600 grit was better, and 600 grit that was honed on the leather wheel for my tormek was better yet. If you want to make a honing wheel, I would suggest getting some MDF, turn it to perfectly round, then if you can find a leather shop, they can probably put some 'tooling/saddle leather around it for you. Adhesive is generally Barge Cement, which is a rubber cement, and the tooling or saddle leather is generally 1/8 to 3/16 thick. Even an old leather belt would work. With belt leather, you may have to sand the surface finish off of it. Very slow speed works great. All sorts of honing or 'polishing' compounds out there. I got some Norton polishing compound at my Ace Hardware store. They had no clue as to what honing compound was... Some day, I plan to make a honing station with several different V, U, and half round cove and bead features on it..... Some day...

Of course, those 'finish' cuts over tear out are VERY light.

Not sure how the LDD would work. It makes a great sanding lubricant. I guess it could help with tear out. Ron used the LDD for keeping the sap in the Norfolk Island Pine from gumming up the abrasives. I do love what it does to sanding out my warped bowls. Big difference in how soaked and non soaked pieces sand out. There is no after taste or smell at all. Kirkland tan/light brown is preferred. I can never seem to find it, so use lemon stuff that I buy at a local whole sale place. Blue or green LDD will stain your bowls. You want to keep a separate barrel for walnut as the soap pulls out color from the woods. No white wood.....

robo hippy

 

[hockenbery]

Have you seen this in mainland woods? Such an obvious demarcation line?

I see something similar in healed over limb scars. a turner friend calls them cat’s eyes.
when a limb breaks off from wind or ice a pocket is often left that fills with rain water. The center of the limb rots out.
the hole eventually closes over with bark looking like a burl. Often there is punky wood around the hollow Especially in ones that have not healed over. you have solid wood all around a punky area.
i have made a lot of hollow forms with the opening in these limb scars. The contour around the limb scar makes great natural edge openings.

also black water stains can color the wood around there water filled hollows.

 

[Emiliano Achaval]

Well, I am famous for my scrapers... Excellent for bowl roughing, lousy for finish cuts, unless you are turning an end grain piece, then smooth as glass or smooth as your hand can guide the tool.

Having a 600 grit wheel is a big help for some woods, some times. I was up in Salem OR for a work shop at Terry Gerros's shop. Terry had a piece of rather soft big leaf maple on one lathe. It had some 'rough' spots on it. I took a gouge, Thompson V, I think, and sharpened it on the 600 grit wheel. It cleaned up the tear out and Terry wouldn't let me go home till he sharpened all his tools on my 600 grit wheel. I may have had my 1000 grit wheel at that time as well. With the soft maple I was turning, the 600 grit wheel was an improvement over the 180 grit wheel. The 180 took good care of the firmer wood, but there was still significant tear out in the softer wood. 600 grit was better, and 600 grit that was honed on the leather wheel for my tormek was better yet. If you want to make a honing wheel, I would suggest getting some MDF, turn it to perfectly round, then if you can find a leather shop, they can probably put some 'tooling/saddle leather around it for you. Adhesive is generally Barge Cement, which is a rubber cement, and the tooling or saddle leather is generally 1/8 to 3/16 thick. Even an old leather belt would work. With belt leather, you may have to sand the surface finish off of it. Very slow speed works great. All sorts of honing or 'polishing' compounds out there. I got some Norton polishing compound at my Ace Hardware store. They had no clue as to what honing compound was... Some day, I plan to make a honing station with several different V, U, and half round cove and bead features on it..... Some day...

Of course, those 'finish' cuts over tear out are VERY light.

Not sure how the LDD would work. It makes a great sanding lubricant. I guess it could help with tear out. Ron used the LDD for keeping the sap in the Norfolk Island Pine from gumming up the abrasives. I do love what it does to sanding out my warped bowls. Big difference in how soaked and non soaked pieces sand out. There is no after taste or smell at all. Kirkland tan/light brown is preferred. I can never seem to find it, so use lemon stuff that I buy at a local whole sale place. Blue or green LDD will stain your bowls. You want to keep a separate barrel for walnut as the soap pulls out color from the woods. No white wood.....

robo hippy

After reading this, I'm so tempted to order a 600 grit wheel... It's like every time we had a traveling professional around here, teaching at all the clubs in Hawaii, I would always end up buying all kinds of new things to do what we learned... Thanks for your help!

 

[Emiliano Achaval]

I see something similar in healed over limb scars. a turner friend calls them cat’s eyes.
when a limb breaks off from wind or ice a pocket is often left that fills with rain water. The center of the limb rots out.
the hole eventually closes over with bark looking like a burl. Often there is punky wood around the hollow Especially in ones that have not healed over. you have solid wood all around a punky area.
i have made a lot of hollow forms with the opening in these limb scars. The contour around the limb scar makes great natural edge openings.

also black water stains can color the wood around there water filled hollows.

Maybe that's what we have here, water seeped in thru the hole in the branch right below it, but who knows, that was above it in nature. Thanks AL!

 

[Roger Wiegand]

Rather than a 600 grit wheel you might try Alan Lacer's teardrop diamond hone. It is also 600 grit if I recall, but you can use the flat to hone the outside bevel and then the round edges to finish the job by polishing the burr off the inside of the flute. I hone most of my tools many times between trips to the grinder (it's very fast if you keep up with it) and definitely see a difference between the honed edge and the edge off the grinder.

I don't have a solution to your actual problem to offer, I'm afraid.

 

[robo hippy]

Try things until you find some thing that works... Engineers, "if it ain't broke, take it apart and fix it anyway". I never seemed to get much benefit from the hand held hones, both round and card types. Removing the burr on the inside of the flute could help, as could honing the bevel. I will never forget seeing Eric Loffstrom taking his skew and tapping it on the bed of the lathe, then taking it to a 60 grit wheel to get a new bevel, then a few passes over some tooling leather charged with honing compound, then shaving his arm. Some times that extra fine edge helps. Nothing seems to help me with the skew chisel though....

robo hippy

 

[Donovan Bailey]

God bless 60 grit sanding disks. When you need them... you need them.

 

[Randy Anderson]

Emiliano, possible to get a picture of the $1,500 bowl? For those of us that sell bowls for a LOT less it's fun to see something from a market where you can get prices like that. Rural TN, not an option.